,

API6D Ball Valve Types and Features

API 6D is a standard set by the American Petroleum Institute (API) for valves used in pipelines transporting oil, natural gas, and other liquids. API 6D defines the design, manufacturing, testing, and quality assurance requirements for various types of valves, including ball valves, used in these critical applications.

Types of API 6D Ball Valves

API 6D Ball Valves are designed to ensure reliability, performance, and safety in pipeline systems. There are several types of ball valves that conform to the API 6D standard:

  1. Floating Ball Valve
    • Design: In a floating ball valve, the ball is not fixed to the stem but is allowed to “float” within the valve body. It is pressed against the valve seat by the fluid pressure, ensuring a tight seal when the valve is closed.
    • Application: Suitable for low-pressure and medium-pressure systems, as the ball relies on the pressure of the fluid to create a seal.
  2. Trunnion Mounted Ball Valve
    • Design: A trunnion-mounted ball valve has a ball that is fixed at two points (top and bottom) by trunnions (supporting shafts), allowing the ball to remain stationary and only rotate. This type of valve typically requires less actuator torque than a floating ball valve.
    • Application: Suitable for higher pressure applications and large-diameter pipeline systems. Trunnion valves are generally preferred in applications where sealing performance and low torque are crucial.
      China Trunnion Ball Valve
  3. Top Entry Ball Valve
    • Design: The valve body allows for maintenance or servicing of the valve components (such as the ball and seats) through the top without removing the valve from the pipeline.
    • Application: Used in systems where easy maintenance is essential without system shutdown or disassembly.
  4. Side Entry Ball Valve
    • Design: In a side-entry ball valve, the valve body is designed such that the ball and stem assembly is inserted from the side.
    • Application: Typically used in smaller sizes and more accessible locations for easier maintenance and installation.
  5. Full Port (or Full Bore) Ball Valve
    • Design: A full port ball valve has a bore (internal diameter) that matches the pipe’s internal diameter, offering minimal flow resistance and full flow capacity.
    • Application: Ideal for applications requiring unrestricted flow, like pipelines carrying sensitive materials or substances that need to maintain flow integrity.
  6. Reduced Port (or Reduced Bore) Ball Valve
    • Design: In a reduced port ball valve, the bore is smaller than the pipe diameter. This results in some flow restriction compared to a full port ball valve.
    • Application: Typically used where space is constrained, or flow capacity is less critical.

Key Features of API 6D Ball Valves

  1. Design Pressure and Temperature Range:
    • API 6D ball valves are designed to withstand a wide range of pressures and temperatures based on the valve class. The design ratings ensure that they perform safely and effectively in both standard and extreme conditions.
  2. Material Selection:
    • The materials used in API 6D ball valves are chosen for their resistance to corrosion, erosion, and wear, as well as their ability to handle high pressures and temperatures. Common materials include stainless steel, carbon steel, and various alloys like Inconel and Hastelloy.
  3. Fire-Safe Design:
    • Fire-safe ball valves are designed to continue to operate in the event of a fire. These valves are typically equipped with secondary sealing mechanisms (e.g., graphite or metal seals) that provide sealing integrity even under high heat conditions.
  4. Blowout-Proof Stem:
    • A blowout-proof stem is a critical feature for safety. It ensures that the valve stem cannot be dislodged, even under extreme pressure, preventing accidental release of valve contents.
  5. Anti-Static Features:
    • Some API 6D ball valves are designed with anti-static features that prevent the accumulation of static electricity, reducing the risk of sparks in volatile environments.
  6. Seat Materials:
    • The valve seats are typically made from soft materials like PTFE, PEEK, or elastomers, but can also be made from metal for higher temperature or more abrasive applications. Seat designs can vary depending on the application, with options for sealing at high pressures, low pressures, or extreme temperatures.
  7. End Connections:
    • API 6D ball valves typically come with various end connections, including flanged, threaded, and welded types. Flanged ends are most common, as they allow easy installation and removal from the pipeline.
  8. Actuation Options:
    • API 6D ball valves can be manually operated (via handwheel or lever) or automatically operated (via electric, pneumatic, or hydraulic actuators). Automated actuation is often used for remote operation or in hazardous environments.
  9. Double Block and Bleed (DBB) Feature:
    • Some API 6D ball valves offer a Double Block and Bleed feature, which ensures a tight seal on both sides of the valve and allows for the safe venting of any trapped fluids between the seats. This is essential for ensuring safe maintenance and operation.

API 6D Ball Valve Applications

  • Oil & Gas Pipelines: Used extensively in the transport of crude oil, natural gas, and refined products.
  • Chemical Processing: Valves are used for the controlled flow of chemicals and other reactive fluids.
  • Water Treatment: Used to control the flow of water in treatment plants.
  • Power Generation: In power plants, ball valves regulate steam, water, and fuel in various stages of the generation process.

Summary of API 6D Ball Valve Types and Features

Type of Valve Design Features Application Areas
Floating Ball Valve Ball “floats” to create a seal, relies on fluid pressure Low to medium pressure systems
Trunnion Mounted Ball Valve Ball fixed with trunnions, lower torque required High pressure and large-diameter pipelines
Top Entry Ball Valve Servicing from the top without removing valve from pipeline Applications requiring easy maintenance
Side Entry Ball Valve Ball assembly inserted from the side Smaller systems or accessible locations
Full Port Ball Valve Full bore matching pipe diameter Unrestricted flow, sensitive materials
Reduced Port Ball Valve Bore smaller than pipe diameter Space-constrained applications

Conclusion

API 6D ball valves are designed to provide reliable, durable, and safe service in pipeline systems, especially in the oil and gas, chemical, and power generation industries. The wide variety of designs and features available ensures that these valves can meet specific operational requirements, whether dealing with high pressure, extreme temperatures, or corrosive materials

/0 Comments/by
,

ISO 5211 Mounting Pad Flange Dimensions

ISO 5211 is an international standard that specifies the mounting dimensions for actuator flanges used to mount actuators onto valves, providing a standardized interface. The dimensions are used primarily for industrial valve automation.

ISO 5211 Mounting Pad Flange Dimensions

The flange dimensions depend on the size of the valve and the actuator. The standard specifies both the bolt circle diameter and the number of mounting holes, as well as the diameter of the mounting holes.

Here’s an overview of the mounting pad flange dimensions for ISO 5211 for different actuator sizes:

Actuator Size (DN) Bolt Circle Diameter (D) Number of Holes (N) Hole Diameter (P) Mounting Pad Thickness (T) Central Hole Diameter (H)
1 (small) 50 mm 4 10 mm 12 mm 25 mm
2 60 mm 4 12 mm 14 mm 30 mm
3 75 mm 4 14 mm 16 mm 40 mm
4 85 mm 4 16 mm 18 mm 45 mm
5 100 mm 4 18 mm 20 mm 50 mm
6 120 mm 4 20 mm 22 mm 60 mm
7 140 mm 4 22 mm 24 mm 70 mm
8 160 mm 4 25 mm 28 mm 80 mm
9 180 mm 4 30 mm 32 mm 90 mm

Key Points:

  1. D: Bolt Circle Diameter (the diameter of the circle formed by the centers of the bolt holes).
  2. N: Number of holes (standard is usually 4 or 8 holes, depending on the actuator size).
  3. P: Hole Diameter (diameter of the mounting holes for bolts).
  4. T: Mounting Pad Thickness (thickness of the flange).
  5. H: Central Hole Diameter (the diameter of the hole in the middle of the flange, typically for the valve shaft or stem).

Note that the exact dimensions can vary slightly depending on the manufacturer and specific application (e.g., for larger actuators). Always confirm with the specific actuator and valve manufacturer or consult the full ISO 5211 standard for more detailed information or any specific deviations from the general sizing.

/0 Comments/by
,

Double Block and Bleed (DBB) Valve Design and Features

A Double Block and Bleed (DBB) valve is a type of valve assembly used to isolate a section of a pipeline or system for maintenance, repair, or safety purposes, while also allowing for the draining or venting of the system to prevent hazardous situations. The “double block” refers to the use of two valves to isolate the flow path, while the “bleed” refers to a third valve that provides a venting or draining capability between the isolation valves.

Here are the key design features and components of DBB valves:

1. Basic Design and Functionality

  • Isolation Valves: Typically, a DBB valve features two isolation valves (usually ball valves or gate valves) arranged in series, which are designed to provide a double seal between the isolated section of the pipeline and the surrounding environment.
  • Bleed Valve: A third valve is incorporated between the two isolation valves, allowing any trapped fluid or pressure to be vented or drained. This prevents the build-up of hazardous or corrosive fluids and ensures safety before opening or working on the isolated section.

2. Components of a DBB Valve

  • Primary Isolation Valve (Upstream): The first valve is located upstream of the section to be isolated. It provides the first block against the flow of fluid.
  • Secondary Isolation Valve (Downstream): The second valve is positioned downstream of the isolated section. This valve provides an additional seal, further isolating the section.
  • Bleed Valve: Positioned between the two isolation valves, the bleed valve allows for venting or draining of the section to prevent fluid from accumulating or causing pressure hazards.

3. Valve Types Used in DBB Assemblies

  • Ball Valves: Common in DBB designs due to their ability to provide a reliable seal and their quick opening/closing action.
  • Gate Valves: Often used for larger systems where low-pressure drop and good shutoff capabilities are necessary.
  • Plug Valves: Sometimes used in specific applications where isolation and bleeding are needed in smaller bore pipelines.
  • Check Valves: In some configurations, check valves are incorporated to provide added safety by preventing backflow.

4. Advantages of DBB Valves

  • Increased Safety: DBB valves ensure a higher level of safety by providing two barriers (the double block) between the process fluid and the surrounding environment, preventing accidental releases.
  • Simplified Design: The DBB valve assembly simplifies the design of isolation and bleeding systems, reducing the need for multiple separate valves.
  • Reduced Risk of Leakage: With the double isolation, the risk of leakage is minimized, which is crucial in systems carrying hazardous, toxic, or flammable fluids.
  • Maintenance Flexibility: The bleed valve allows for safe draining, purging, or venting, which is essential when performing maintenance or replacing components.
  • Cost-Effective: By integrating the function of multiple valves into a single assembly, DBB valves reduce the number of individual components needed, lowering overall installation and maintenance costs.

5. Applications of DBB Valves

  • Oil and Gas: DBB valves are frequently used in the oil and gas industry, especially in wellhead systems, pipelines, and production facilities, to isolate parts of the system during maintenance or to safeguard against leaks of hazardous materials.
  • Chemical and Petrochemical Industries: Used to isolate reactors, storage tanks, or pipes carrying chemicals, ensuring no risk of fluid escape during maintenance or changes in operations.
  • Power Generation: Used in steam, water, and chemical systems to isolate sections for maintenance while ensuring the integrity and safety of the system.
  • Water Treatment: To isolate pipelines, pumps, or tanks while allowing for safe draining, particularly in wastewater systems.

6. Design Considerations

  • Pressure and Temperature Ratings: DBB valves must be designed to handle the maximum operating pressures and temperatures of the system they are installed in.
  • Leakage Requirements: The valves must meet strict leakage standards, often defined by industry codes like API (American Petroleum Institute) or ISO (International Organization for Standardization), to ensure that no hazardous fluid escapes during isolation.
  • Material Selection: The materials used in DBB valves need to be compatible with the fluids being handled. Common materials include stainless steel, carbon steel, and various alloys, depending on the corrosive nature of the fluid.
  • Size and Flow Capacity: The size of the DBB valve must be chosen based on the system’s flow rate, pressure, and other operational conditions. The valve should provide a low-pressure drop across the system when in the open position.
  • Valve Actuation: DBB valves can be manually operated or automated with actuators (pneumatic, electric, or hydraulic) for remote control, especially in high-risk environments.

7. Standards and Codes

DBB valves are often subject to various industry standards, including:

  • API 6D (for pipeline valves),
  • ASME B16.34 (for pressure–temperature ratings of valves),
  • ISO 5208 (for valve testing),
  • API 598 (for valve inspection and testing),
  • PED 2014/68/EU (Pressure Equipment Directive for Europe),
  • ATEX (for equipment used in explosive atmospheres).

8. Challenges and Limitations

  • Complexity: The design of DBB valves can be more complex than single valve isolation methods, requiring careful attention to sealing and proper venting.
  • Size and Weight: DBB valve assemblies can be larger and heavier than individual isolation valves, which may be a concern in tight spaces.
  • Cost: While DBB valves offer significant safety benefits, they tend to be more expensive than conventional single isolation valves, especially for high-performance and high-integrity systems.

9. Conclusion

The Double Block and Bleed (DBB) Valve is an essential valve assembly that ensures high safety, operational reliability, and ease of maintenance in critical systems. By incorporating two isolation valves and a bleed valve, it guarantees that the isolated section of a pipeline or system is fully sealed off from the environment and any trapped fluid can be safely vented. Whether in the oil and gas, chemical, or power industries, DBB valves provide a simple yet effective solution for isolating and maintaining high-risk systems.

/0 Comments/by
,

How Does The Pneumatic Actuator of Control Valve Work

A pneumatic actuator in a control valve uses compressed air to move a valve stem, adjusting the position of the valve and regulating the flow of fluids or gases in a system. This type of actuator is commonly used in industrial processes for automation, where precise control over fluid flow is needed. Here’s how it works in a control valve system:

Piston Actuator Sketch

 

Key Components of a Pneumatic Actuator:

  1. Actuator Housing: The body that contains the internal mechanisms and the diaphragm or piston.
  2. Diaphragm or Piston: The component that responds to the pressure of the compressed air to create linear or rotary motion.
  3. Spring: Provides force to return the actuator to its default position when there is no air pressure (fail-safe operation).
  4. Air Supply: The compressed air, usually between 3-15 psi (pounds per square inch), that powers the actuator.
  5. Positioner: A device that ensures the valve reaches the correct position based on the control signal.

Pneumatic Diaphragm Actuator Sketch

How It Works:

  1. Control Signal: A control signal, usually in the form of a 4-20 mA electrical signal, is sent to a positioner or directly to the actuator.
  2. Positioner (if used): The positioner takes the electrical signal and adjusts the air pressure sent to the actuator. The positioner ensures that the actuator responds accurately to the control signal. It compares the signal to the actuator’s actual position and adjusts the air flow to maintain the desired position.
  3. Compressed Air to Actuator: The actuator receives compressed air through one or more ports. If the actuator uses a diaphragm, the compressed air acts on one side of the diaphragm, pushing it to move the valve stem in the desired direction. For a piston-type actuator, the air pressure acts on a piston inside a cylinder, generating linear or rotary motion to move the valve.
  4. Movement of Valve: As the diaphragm or piston moves, it pushes or pulls the valve stem. Depending on the design of the valve (e.g., globe, ball, or butterfly), this motion adjusts the opening or closing of the valve, controlling the flow of the process fluid.
  5. Spring Return (if applicable): Many pneumatic actuators include a spring that returns the valve to a failsafe position (such as fully open or fully closed) when there is no air supply. This is especially important for safety, to prevent unintended flow in case of a failure.
  6. Feedback Mechanism: Some pneumatic actuators have a feedback mechanism that informs the control system of the valve position. This ensures continuous control and helps to maintain precise operation.

Types of Pneumatic Actuators:

  • Single-acting actuators: The spring drives the actuator back to the fail-safe position when air is not supplied.
  • Double-acting actuators: The actuator moves in both directions (open and close) using air pressure on both sides, without the need for a spring.

Direct acting and reverse acting diaphragm actuator

Common Applications:

  • Process Control: In chemical, oil & gas, water treatment, and power generation plants.
  • HVAC Systems: For controlling airflow and temperature in heating, ventilation, and air conditioning systems.
  • Fluid Flow Regulation: To precisely control the flow of liquids and gases through pipelines.

Net effect of various combination for three-port valves

Summary of the Process:

  1. The control system sends an electrical signal to the positioner.
  2. The positioner adjusts the air supply to the actuator.
  3. The actuator moves the valve stem, adjusting the valve position.
  4. The valve modulates the flow of the fluid or gas according to the control system’s requirements.

Pneumatic actuators are popular for their reliability, speed, and ability to operate in hazardous environments where electricity may not be safe or practical.

/0 Comments/by
,

Understand API 609 Butterfly Valves Types

A butterfly valve is used to shut off or modulate the flow of a fluid (isolation and regulation). API 609 Centric butterfly valves (soft seated) are preferred to gate and ball valves for low-pressure and non-critical applications as they are cheaper, lighter, and easier to install. Eccentric butterfly valves (double offset and triple offset valves) with metal seats have surged in popularity and compete with globe and ball valves for some applications.

BUTTERFLY VALVE

WHAT IS A BUTTERFLY VALVE

A butterfly valve is a type of flow control device used to regulate or isolate fluid flow through a pipe. It consists of a rotating disc, known as the butterfly, which is mounted on a rod. When the valve is fully open, the disc is turned parallel to the flow of fluid, allowing for almost unrestricted flow. When the valve is closed, the disc is rotated so that it completely blocks off the flow path.

triple eccentric butterfly valve
triple eccentric butterfly valve

Key Features Of Butterfly Valves

  • Compact and Lightweight: Butterfly valves have a compact design and are lighter than some other types of valves, such as ball or gate valves, making them easier to install and requiring less support.
  • Quick Operation: The disc rotates 90 degrees to open or close, providing a quick action that can be beneficial in both manual and automated operations.
  • Cost-Effective: Generally, butterfly valves are less expensive than other valve types, especially for large-diameter pipes.
  • Versatility: Suitable for a wide range of applications, handling liquids, gases, and slurries. They can be used in various industries, including water and wastewater treatment, chemical processing, and HVAC systems.

Types Of Butterfly Valves

  1. Concentric Butterfly Valves: Also known as rubber-lined butterfly valves, these have a resilient rubber seat with a metal disc. Suitable for lower pressure and temperature applications.
  2. Double Offset Butterfly Valves: Designed with two offsets to reduce wear on the valve seat and disc during operation, enhancing longevity and performance. Suitable for higher pressure and temperature applications.
  3. Triple Offset Butterfly Valves: Feature a third offset that creates a cone-shaped sealing surface, allowing for metal-to-metal sealing, minimal wear, and use in high temperature and pressure applications.

Operation

Butterfly valves can be operated manually with a handle, or they can be actuated pneumatically, electrically, or hydraulically for automatic operation. The choice of operation mode depends on the application’s requirements, including the need for precise control, the size of the valve, and the operating environment.

Applications

Butterfly valves are versatile and can be used across a wide range of applications, including:

  • Isolating and Regulating Flow: In piping systems for water supply, wastewater treatment, and industrial processes.
  • HVAC: For regulating airflow in heating, ventilation, and air conditioning systems.
  • Chemical Processing: For controlling the flow of various chemicals and slurries.

In summary, butterfly valves are a popular choice for many flow control applications due to their compact design, cost-effectiveness, and versatility. They are suitable for a wide variety of fluids and gases and can be tailored for specific operational needs with different types and materials.

A butterfly valve is a regulating and shut-off device that can be an alternative, in some applications, with globe and ball valves.

Classification Of Butterfly Valves

Butterfly valves may be classified based on multiple features:

  • Design: centric, double eccentric, triple eccentric
  • Valve-end connection type: wafer, lug (semi or full), flanged and double flanged
  • Seat material: soft (example: Teflon, Buna, rubber, etc) or metal-to-metal (SS304, SS316)
  • Body and disc materials (from cast iron to high nickel alloys)
  • Type of valves’ actuation: manual (lever, gear, worm gear) and actuated (electric, pneumatic, hydraulic, and gas-over-oil types)

Types of butterfly valves

Butterfly valves can be used for a wide range of applications such as water supply, wastewater treatment, fire protection, the chemical and oil industries, fuel handling systems, and also for applications within the power generation industry.

With the introduction of the double and triple eccentric designs, butterfly valves are more and more used also in the oil and gas industry and have started to compete with more traditional valves, such as globe and ball valves.

 

BUTTERFLY VALVES PARTS

Butterfly valves are comprised of several key components that allow them to effectively control fluid flow. Each part plays a crucial role in the valve’s operation, durability, and ability to provide a tight seal.

Butterfly valve parts

Here are the main components of a butterfly valve:

1. Body

The outer casing of the valve holds all internal components together and connects the valve to the piping system. The body material varies depending on the application and can include cast iron, stainless steel, PVC, and others.

2. Disc

The circular element that pivots within the flow stream to open or close the valve. The disc’s rotation controls the flow through the valve. Materials for the disc often match or are compatible with the body material and are selected based on the fluid’s properties.

3. Stem

The shaft that connects the disc to the actuator or handle outside the valve body. The stem can be one-piece with the disc or two-piece, where the disc is mounted between two stems. Stems are typically made from stainless steel or other corrosion-resistant materials.

4. Seat

The sealing surface against which the disc closes. The seat can be integral to the valve body or a replaceable component. It is made from materials like rubber, PTFE, or metal, depending on the application’s sealing requirements and the fluid’s characteristics.

5. Actuator

The mechanism used to rotate the disc. Actuators can be manual (handles or gears) or automatic (pneumatic, hydraulic, or electric). The choice of actuator depends on the valve size, required control level, and operational environment.

6. Handle Or Hand Lever

For manual operation, a handle or lever is attached to the stem, allowing the operator to rotate the disc. It usually includes a locking mechanism to secure the valve in the open or closed position.

7. Gearbox

In larger butterfly valves or in applications requiring precise control, a gearbox is used in conjunction with the hand lever or actuator to facilitate easier operation by reducing the effort needed to turn the valve.

8. Bushings

Located between the stem and the body or between the stem and the disc, bushings reduce friction and wear during operation, contributing to the valve’s smooth operation and longevity.

9. Packing

A seal around the stem to prevent fluid from leaking out of the valve body along the stem. Packing materials vary but often include PTFE or graphite, chosen for their sealing properties and resistance to the process fluid.

10. Flanges Or Ends

Butterfly valves can have different end configurations to connect to the piping system, including wafer, lug, flanged, or butt-weld ends. The selection depends on the piping system design and the requirements for disassembly and maintenance.

Each component of a butterfly valve is critical to its performance, affecting everything from how well the valve seals to how easily it can be operated and maintained. Selecting the right materials and design for these components is essential to ensure the valve meets the application’s demands.

HOW BUTTERFLY VALVES FUNCTION

A butterfly valve functions by using a rotating disc to control the flow of fluid through a pipe. The disc, which is the main component of the valve, is connected to an actuator or a manual handle at the top of the valve.

Butterfly valve

Here’s a step-by-step explanation of how a butterfly valve operates:

1. Open Position

  • When the valve is fully open, the disc is rotated so that it lies parallel to the flow direction, allowing fluid to pass through with minimal obstruction. The handle or actuator is typically aligned parallel to the pipe in this position, indicating that the valve is open.

2. Closing The Valve

  • To close the valve, the handle or actuator is turned, which rotates the disc. As the disc rotates towards a perpendicular position relative to the flow path, it begins to block the flow of fluid through the pipe.

3. Closed Position

  • When the disc is rotated to a position perpendicular to the flow direction, it fully obstructs the pipe, stopping the flow entirely. In this position, the handle or actuator is aligned perpendicular to the pipe, indicating that the valve is closed.

4. Controlling Flow

  • Butterfly valves can also be used to regulate the flow of fluid through the pipe by adjusting the disc’s angle. By partially opening or closing the valve (i.e., positioning the disc at various angles between fully open and fully closed), the operator can control the flow rate through the valve. This throttling capability allows for the precise adjustment of flow, although it’s important to note that butterfly valves may not provide as fine control as some other valve types designed specifically for flow regulation.

5. Actuation

  • Butterfly valves can be operated manually or automated with actuators. Manual operation is common for smaller valves or in applications where precise control is not critical. For larger valves or where remote control and precise adjustments are necessary, pneumatic, electric, or hydraulic actuators are used.

Key Features

  • Compact and Lightweight: Butterfly valves have a simple, compact design, making them easy to install and requiring less space compared to other valve types, like gate or globe valves.
  • Quick Operation: The quarter-turn operation of butterfly valves allows for rapid opening and closing, which is beneficial in emergency situations or applications requiring frequent operation.
  • Versatility: Suitable for a wide range of applications, handling liquids, gases, and semi-solids in various industries, including water treatment, chemical processing, HVAC, and more.

Again, it is important to understand that the key component of a butterfly valve is the disc, a metal ring that is positioned at the centerline of the pipe and connected to an external actuator (manual level or actuator) via a rod.

The functionality of a butterfly valve revolves around the rotation of such disc to open, close, or throttle the flow of fluid in a piping system. In the closed position, the disc blocks the bore of the valve, and, in an open position, the disc allows the passage of the fluid.

A quarter-turn movement is needed to switch the valve from a fully open to a fully closed position (and such movement can be executed as quickly as for ball valves).

     Butterfly valve working principle

This design offers a balance of simplicity, efficiency, and versatility, making butterfly valves a popular choice for many fluid control applications.

Compared to a ball valve, the disc of a butterfly valve is always in contact with the fluid conveyed by the pipeline and creates, therefore, a pressure drop.

PRESSURE DROP IN BUTTERFLY VALVES

The pressure drop across a butterfly valve, like other control valves, is an essential factor to consider in system design and valve selection. Pressure drop refers to the reduction in pressure as fluid passes through a valve, a phenomenon that occurs due to friction and flow resistance introduced by the valve’s presence in the flow path.

Factors Affecting Pressure Drop In Butterfly Valves

  1. Valve Design: The inherent design of butterfly valves, which includes a disc that pivots within the flow stream, inherently introduces some level of flow resistance. The size of the valve (relative to the pipe diameter), the disc shape, and the seat design can influence the extent of this resistance.
  2. Disc Position: The pressure drop is significantly influenced by the disc’s position. When fully open (parallel to the flow direction), the pressure drop is minimal. However, as the disc begins to close (rotating towards a perpendicular position to the flow), it increasingly obstructs the flow path, leading to a higher pressure drop.
  3. Flow Rate: The rate at which fluid flows through the valve directly affects the pressure drop; higher flow rates generally result in higher pressure drops due to increased friction and turbulence around the disc and within the valve body.
  4. Fluid Properties: The type of fluid (its density and viscosity) also impacts the pressure drop. More viscous fluids tend to create higher pressure drops compared to less viscous ones under the same conditions.

Calculating Pressure Drop

The pressure drop across a butterfly valve can be calculated using various formulas and coefficients that account for the factors mentioned above. One common method involves using the valve’s flow coefficient (Cv) for a given valve opening position. The Cv value represents the flow rate of water (in US gallons per minute) at a temperature of 60°F that will flow through the valve with a pressure drop of 1 psi.

The general formula to estimate the pressure drop () in psi is:

ΔP = Q^2 / 

Where Q is the flow rate through the valve in US gallons per minute (GPM), and Cv is the flow coefficient of the valve at the specific opening position.

Considerations For System Design

  • Selection: Choose a valve size and type that minimizes the pressure drop consistent with the application’s requirements. Full-port (or full-bore) butterfly valves generally offer lower pressure drops.
  • Operation: Understand that frequent operation near the closed position increases the pressure drop and can impact pump performance and energy consumption.
  • Application: In applications sensitive to pressure drop, consider the valve’s impact on the overall system and evaluate if an alternative valve type or size might be more appropriate.

In summary, while butterfly valves are favored for their compact design and quick operation, their influence on system pressure must be considered, especially in applications where maintaining pressure is critical. Proper valve selection and system design can help manage pressure drops to acceptable levels.

BUTTERFLY VALVE SPECIFICATIONS (ASME/API)

The American Petroleum Institute (API) and the American Society of Mechanical Engineers (ASME) provide standards and specifications that cover various aspects of butterfly valves, including design, materials, testing, and performance requirements. These standards ensure that butterfly valves meet certain criteria for safety, reliability, and interoperability in different industrial applications. Here are some of the key API and ASME specifications relevant to butterfly valves:

API Standards

API 609: Butterfly Valves: Double-flanged, Lug- and Wafer-type

This specification covers design, materials, face-to-face dimensions, pressure-temperature ratings, and testing requirements for butterfly valves with double-flanged, lug, and wafer-type configurations. It’s applicable for valves intended for general-purpose, isolation, and control applications in piping systems.

ASME Standards

  • ASME B16.34: Valves – Flanged, Threaded, and Welding End

    Although primarily known for gate, globe, and check valves, ASME B16.34 also includes general valve design criteria that can apply to butterfly valves, such as pressure-temperature ratings, shell material categories, and testing requirements.

  • ASME B16.5: Pipe Flanges and Flanged Fittings

    This standard covers dimensions and ratings for flanges that can be used with butterfly valves, ensuring compatibility with piping systems.

  • ASME B16.47: Large Diameter Steel Flanges

    Similar to ASME B16.5 but focuses on larger diameter flanges, which might be relevant for larger butterfly valve applications.

  • ASME B16.10: Face-to-Face and End-to-End Dimensions of Valves

    Provides the standard face-to-face and end-to-end dimensions for butterfly valves, facilitating proper integration and replacement in piping systems.

Other Relevant Standards

  • ISO 5211: Industrial valves — Part-turn actuator attachments

    This international standard, often referenced alongside API and ASME standards, specifies the requirements for the attachment of part-turn actuators to industrial valves, including butterfly valves. It’s crucial to ensure that actuators and valves are compatible and can be securely attached to each other.

  • MSS SP-67: Butterfly Valves

    Issued by the Manufacturers Standardization Society (MSS), this standard covers detailed requirements for butterfly valves, including design, dimensions, pressure rating, and testing. It’s widely recognized and used alongside API and ASME standards.

  • MSS SP-68: High-Pressure Butterfly Valves with Offset Design

    MSS focuses on high-pressure butterfly valves with an offset design, providing criteria for pressure integrity and performance.

These API and ASME standards, along with other relevant specifications, guide manufacturers and users of butterfly valves in ensuring quality, safety, and efficiency in their operations. Compliance with these standards is often a requirement in industrial projects, especially those involving critical applications in the oil & gas, chemical, water treatment, and power generation sectors.

TYPES OF BUTTERFLY VALVES

Butterfly valves are categorized based on their design, sealing mechanism, and application requirements. The various types offer distinct advantages and are suited to specific operational environments.

Here are the primary types of butterfly valves:

1. Concentric (Zero Offset) Butterfly Valves

  • Design: Features a disc centered directly in the middle of the valve body, with the stem passing through the disc center. The seat is typically made of a resilient material such as rubber or Teflon.
  • Application: Best suited for lower pressure and temperature applications. The simple design is effective for water, air, and other non-corrosive media.

The concentric type of butterfly valve is typically used in water (treatment, transmission, and distribution) and clean wastewater treatment plants, fire protection systems (indoor/outdoor), and gas supply (natural and flare gas).

Moreover, these types of butterfly valves may also be found in the following types of installations:

  • Pumping installations
  • HVAC
  • Aeration systems
  • Filter Installations
  • Pumping installations
  • Membrane installations

  • 2. Double Offset (High-Performance) Butterfly Valves

    • Design: Also known as high-performance butterfly valves, they have two offsets. The first offset is to the side of the pipe centerline, while the second offset moves the shaft behind the disc plane. This design minimizes seat wear and allows for tighter sealing.
    • Application: Ideal for higher pressure and temperature conditions, handling a wider range of fluids, including corrosive and abrasive types.

    Double eccentric butterfly valves find application in underground water supply systems and compete with gate valves (especially in larger bore sizes) because they are lighter, cheaper, and minimize the excavation works.

    Double and triple-offset butterfly valves are also denominated “eccentric”. The main differences between the concentric and eccentric types of butterfly valves can be summarized as follows:

    • Concentric butterfly valve: the stem is centered in the middle of the disc and the is disc centered in the bore
    • Eccentric butterfly valve (double offset and triple offset): has one or more stub shafts (stems) which are located in an offset position from the center of the valve. Eccentric butterfly valves are also defined as the double or the triple offset.

     

    Concentric butterfly valve       Double eccentric butterfly valve  Triple eccentric butterfly valve
    A concentric butterfly valve (left), a double offset butterfly valve (center), triple offset butterfly valve (right)

    3. Triple Offset Butterfly Valves

    • Design: Features three offsets, with the third being the geometrical shape of the seating surface (conical shape). This design eliminates friction between the seat and the disc during operation and allows for metal-to-metal sealing.
    • Application: Suitable for extreme pressure and temperature applications, including steam, oil, and gas services. It provides reliable performance in demanding conditions.

    Triple-offset butterfly valves are generally manufactured in high-grade materials like stainless steel and duplex/super duplex steel and compete with ball valves in mission-critical applications with remarkable corrosion and high temperature/pressure.

    Triple-offset butterfly valves are the most sophisticated type and have gained market share in recent years, due to the dramatic performance improvement achieved by specialized manufacturers.

    4. Lugged Butterfly Valves

    • Design: The valve body has lugs (extensions with bolt holes) that allow it to be bolted directly to the pipe flanges. This provides a secure and rigid connection and allows for easy removal of downstream piping without affecting the upstream side.
    • Application: Used in applications where the valve must be easily removed for maintenance or where the system requires dead-end service capability.

    5. Wafer Butterfly Valves

    • Design: Designed to fit between two pipe flanges (the wafer shape), these valves are held in place by the bolts that connect the flanges. They are compact and cost-effective but not suitable for end-of-line service where removal is necessary.
    • Application: Commonly used in systems where space is limited and in applications that do not require disassembly of the pipe system for valve maintenance.

    • 6. Rubber-Lined Butterfly Valves

      • Design: Features a body and disc lined with rubber or another elastomeric material, providing enhanced corrosion resistance and a tight seal.
      • Application: Ideal for handling corrosive fluids, slurries, and other abrasive media in water treatment, chemical processing, and similar industries.

      7. Metal-Seated Butterfly Valves

      • Design: Constructed with metal seats, these valves are designed to withstand higher temperatures and more abrasive conditions than their rubber-lined counterparts.
      • Application: Suitable for high-temperature applications, such as steam services, and where higher durability is required.

      Each type of butterfly valve offers unique features and benefits, making them suitable for a broad range of applications. Selecting the right type depends on factors such as the nature of the fluid, operating pressure and temperature, and specific system requirements.

      A key first classification is between concentric or eccentric butterfly valves:

      DIFFERENCES BETWEEN DOUBLE VS. TRIPLE ECCENTRIC BUTTERFLY VALVE

      Double and triple eccentric butterfly valves are both designed to offer improved performance over traditional concentric butterfly valves, especially in high-pressure and high-temperature applications. The terms “double” and “triple” refer to the number of offsets (eccentricities) in the valve design, which significantly affect how the valve operates and seals. Understanding the differences between these two types of eccentric butterfly valves is crucial for selecting the right valve for specific operational needs.

      Double Eccentric Butterfly Valves (Double Offset)

      • Design: The first offset is the shaft placement off the pipe or disc centerline, which allows the disc to move off the seat upon opening, reducing wear on the sealing surface. The second offset is the shaft placement behind the disc plane, creating a cam action during operation that enhances sealing capability and reduces operating torque.
      • Sealing: Typically utilizes a resilient (soft) seat, which can be made of materials like PTFE, rubber, or other polymers, allowing for tight shut-off in various applications.
      • Applications: Suitable for higher pressure and temperature applications than concentric valves but below the extreme conditions that triple offset valves are designed for. Commonly used in water distribution, HVAC systems, light industrial processes, and chemical applications where a tight seal and durability are required.

      Triple Eccentric Butterfly Valves (Triple Offset)

      • Design: Incorporates three offsets: two similar to the double eccentric design and a third offset, which involves angling the conical shape of the seating surface. This geometry ensures that the disc only contacts the seat at the final point of closure, minimizing wear and allowing for a metal-to-metal seal.
      • Sealing: The metal-to-metal seat design enables the triple offset valve to handle extreme temperatures, pressures, and corrosive media, providing a long-lasting, bubble-tight seal.
      • Applications: Engineered for the most demanding applications, including high-pressure steam, oil and gas pipelines, power generation, and process industries where reliability and performance under extreme conditions are paramount.

      Key Differences (Double/Triple Eccentric Types)

      • Sealing Mechanism: Double eccentric valves usually have resilient seats for good sealing at lower pressures and temperatures, while triple eccentric valves use a metal-to-metal seat design for harsh conditions.
      • Wear and Tear: Triple offset valves minimize wear on the sealing surfaces due to the disc only making contact at full closure, unlike double offset valves, which may experience more wear due to their soft sealing materials.
      • Application Suitability: Double offset valves are versatile for a wide range of applications but might not be suitable for the highest pressures and temperatures. Triple offset valves are designed for extreme conditions where performance and durability are critical.

      In summary, the choice between double and triple eccentric butterfly valves depends on the specific application requirements, including pressure, temperature, and the nature of the media being handled. Triple offset valves are typically chosen for their ability to perform in extreme conditions, offering durability and a reliable seal, whereas double offset valves provide an efficient and cost-effective solution for a broad range of less severe applications.

      Detail of double offset butterfly valve .        Triple eccentric structure
      The images show the design difference between a double and a triple eccentric butterfly valve (respectively at the left and right side of the diagram).

      MATERIALS FOR BUTTERFLY VALVES

      VALVE BODY

      Butterfly valves, like any other type of valve, are available in multiple material grades and combinations of materials (body, disc, seat).

      The selection of the materials is based on the fluid to be shut off, the pressure, and the temperature of the application at hand.

      The body material of a butterfly valve is a critical factor that determines its suitability for specific applications, especially considering the fluid it will handle, the operating environment, pressure, and temperature conditions. Various materials are used for butterfly valve bodies, each offering different properties in terms of strength, corrosion resistance, and cost.

      Here is a list of the main materials used for butterfly valve bodies, which are generally cast grades.

      CAST IRON

      • Properties: Good mechanical strength, excellent vibration and shock resistance, and cost-effectiveness.
      • Applications: Widely used in water and wastewater treatment, air conditioning systems, and other low to medium-pressure applications.

      DUCTILE IRON

      • Properties: Higher strength and ductility compared to cast iron, with good corrosion resistance.
      • Applications: Suitable for higher pressure applications than cast iron, including water distribution, gas supply, and some industrial processes.

      Note that cast iron and ductile iron are the cast materials preferred for butterfly valves used in water treatment, distribution, and transmission.

      CARBON STEEL

      Carbon steel is the most common material for body and disc in oil & gas applications:

      • Properties: High strength and durability, with good resistance to high pressure and temperature.
      • Applications: Used in oil and gas, power generation, and other industrial applications where high-pressure and temperature resistance is required.

      The most common grades used for butterfly valve bodies and discs are ASTM A216 WCB and LCC (Low Carbon Content), which are both cast types. They are used, respectively, for high-temperature and low-temperature service.

      The main advantage of carbon steel (CS) butterfly valves is their relatively low cost combined with acceptable performance (especially for low-pressure applications). The weakness of carbon steel valves is their poor resistance to corrosion (which can be improved by applying external paints or internal lining materials such as Teflon)

      STAINLESS STEEL

      Stainless steel butterfly valves are widely utilized across various industries for their durability, corrosion resistance, and suitability for handling a broad range of fluids, including corrosive substances, water, steam, and gas. Constructed from stainless steel for both the body and the disc, these valves offer several advantages and are chosen for specific applications based on their material properties.

      Advantages Of Stainless Steel Butterfly Valves
      • Corrosion Resistance: Stainless steel offers excellent resistance to corrosion caused by various chemicals and environmental conditions. This makes it ideal for applications in chemical processing, pharmaceuticals, and food and beverage industries, where maintaining purity is critical.
      • High Strength and Durability: Provides strength and durability under high-pressure conditions, ensuring a long service life even in demanding applications.
      • Temperature Resistance: Capable of withstanding both high and low temperatures, making them suitable for applications involving steam, hot fluids, or cold water systems.
      • Hygienic Properties: The smooth, non-porous surface of stainless steel is easy to clean and disinfect, which is essential for sanitary applications in the food, beverage, and pharmaceutical industries.
      • Aesthetic Appearance: Stainless steel has a clean and modern appearance, which is often preferred in visible installations.
      Common Grades Of Stainless Steel For Butterfly Valves
      • 304 Stainless Steel: Offers good corrosion resistance and is widely used in general applications that do not involve exposure to corrosive chemicals and extreme temperatures.
      • 316 Stainless Steel: Contains molybdenum, which enhances its corrosion resistance, especially against chlorides and other industrial solvents. It is preferred for more corrosive environments, such as seawater and chemical processing.
      • 316L Stainless Steel: A low-carbon variant of 316, it has reduced carbon content that minimizes carbide precipitation during welding, improving corrosion resistance in welded joints.
      Applications

      Stainless steel butterfly valves are chosen for their robust performance in various settings, including:

      • Chemical Processing: For controlling the flow of aggressive chemicals, acids, and solvents.
      • Food and Beverage Production: In systems requiring strict hygiene standards and resistance to food acids and cleaning agents.
      • Pharmaceutical Manufacturing: Where cleanliness and contamination prevention are paramount.
      • Water Treatment and Distribution: Suitable for handling both clean and wastewater, as well as desalination processes.
      • Oil and Gas Industry: For applications requiring resistance to corrosion from saltwater, chemicals, and high-pressure conditions.
      Selection Considerations

      When selecting a stainless steel butterfly valve, it’s crucial to consider:

      • Type of Fluid: Ensure compatibility with the fluid’s properties, including corrosiveness, temperature, and cleanliness requirements.
      • Pressure and Temperature Ratings: Choose a valve that can withstand the system’s operating pressure and temperature range.
      • Connection Type: Consider the valve’s connection type (wafer, lug, flanged) for compatibility with the piping system.
      • Actuation Method: Determine whether manual, pneumatic, electric, or hydraulic actuation is best suited for the application’s operational needs.

      In summary, stainless steel butterfly valves offer a reliable and efficient solution for flow control in a wide range of industrial applications. Their corrosion resistance, strength, and temperature tolerance make them a versatile choice for many fluid handling systems.

      DUPLEX & SUPERDUPLEX STEEL

      Butterfly valves made from duplex and super duplex stainless steels are engineered for applications requiring exceptional strength and corrosion resistance, especially in harsh and aggressive environments. Duplex stainless steels combine the properties of austenitic and ferritic stainless steels, resulting in materials that offer both high strength and excellent resistance to corrosion, including stress corrosion cracking. Super duplex stainless steels provide even higher corrosion resistance and strength, making them suitable for more demanding applications.

      Characteristics Of Duplex And Super Duplex Stainless Steel Butterfly Valves
      • High Strength: Duplex and super duplex stainless steels have higher strength compared to austenitic stainless steels, allowing for the design of thinner valve bodies and components without compromising integrity.
      • Superior Corrosion Resistance: These materials are highly resistant to a wide range of corrosive environments, including those containing chlorides, making them ideal for use in marine, chemical processing, and oil & gas applications.
      • Good Fatigue Resistance: The combination of strength and corrosion resistance makes duplex and super duplex valves highly resistant to fatigue, extending their service life under cyclic loading conditions.
      • Resistance to Stress Corrosion Cracking: Particularly in chloride-containing environments, duplex, and super duplex steels exhibit superior resistance to stress corrosion cracking, a common issue for standard austenitic stainless steels in certain conditions.
      Common Grades
      • Duplex Stainless Steel (UNS S31803, S32205): Features a balanced microstructure of austenite and ferrite, offering good resistance to pitting and crevice corrosion, high strength, and good weldability.
      • Super Duplex Stainless Steel (UNS S32750, S32760): Contains higher levels of chromium, molybdenum, and nitrogen, providing even greater resistance to corrosion and increased strength compared to duplex stainless steel.
      Applications

      Butterfly valves constructed from duplex and super duplex stainless steels are particularly suited for:

      • Offshore Oil and Gas Operations: In environments exposed to seawater, sour gas, and other corrosive substances.
      • Chemical Processing: For handling aggressive chemicals, especially where chloride-induced corrosion is a concern.
      • Desalination Plants: Where valves are exposed to highly corrosive seawater.
      • Marine Applications: Including shipping and coastal facilities, where saltwater corrosion is an ongoing challenge.
      • Pulp and Paper Industry: For processes involving corrosive chemicals used in paper production.
      Selection Considerations

      When choosing duplex or super duplex stainless steel butterfly valves, factors to consider include:

      • Corrosion Resistance Needs: Assess the specific corrosive elements present in the application environment to select the most appropriate material grade.
      • Pressure and Temperature Requirements: Ensure the selected valve can withstand the operating pressures and temperatures of the system.
      • Cost-Effectiveness: While duplex and super duplex steels offer superior properties, they also come at a higher cost compared to standard stainless steels. Evaluate the long-term benefits of their use in reducing maintenance and replacement costs.
      • Weldability and Fabrication: Consider the welding and fabrication requirements, as duplex and super duplex materials may require specific techniques and precautions during manufacturing and installation.

      In summary, butterfly valves made from duplex and super duplex stainless steels provide a robust solution for controlling flow in environments where corrosion resistance and mechanical strength are critical. Their superior properties make them an excellent choice for demanding industrial applications where conventional stainless steels might not suffice.

      NICKEL ALLOY STEEL

      Butterfly valves made from nickel alloys are designed for the most demanding applications, offering exceptional resistance to corrosion, heat, and pressure. Nickel alloys, such as Inconel, Hastelloy, Monel, and Nickel 200/201, are renowned for their ability to withstand extreme environments, making them ideal for critical and high-performance applications across various industries.

      Characteristics
      • Corrosion Resistance: Nickel alloys provide excellent resistance to a wide range of corrosive environments, including seawater, chlorine, and acidic or alkaline substances. They are particularly effective against corrosion that challenges other materials, such as stress-corrosion cracking.
      • High-Temperature Performance: These alloys maintain their strength and resistance even at very high temperatures, making them suitable for applications involving heat.
      • Durability: The inherent strength and corrosion resistance of nickel alloys ensure that butterfly valves made from these materials have a long service life, even in harsh conditions.
      Common Nickel Alloys Used For Butterfly Valves
      • Inconel (e.g., Inconel 625, Inconel 718): Known for high strength and excellent corrosion resistance, especially in high-temperature environments.
      • Hastelloy (e.g., Hastelloy C-276, Hastelloy C-22): Offers outstanding resistance to strong oxidizing agents and is used in severe corrosive environments.
      • Monel (e.g., Monel 400, Monel K-500): Exhibits excellent resistance to seawater and caustic environments, combining good corrosion resistance with high strength.
      • Nickel 200/201: Pure nickel or nearly pure nickel, providing excellent resistance to corrosion by alkaline substances and good thermal, electrical, and magnetostrictive properties.
      Applications

      Nickel alloy butterfly valves are used in situations where conventional materials would fail, including:

      • Chemical Processing: For handling aggressive chemicals, solvents, and gases that require superior corrosion resistance.
      • Oil and Gas Industry: Especially in sour gas applications where hydrogen sulfide can cause sulfide stress cracking in other materials.
      • Power Generation: In applications involving high temperatures or corrosive gases.
      • Marine and Offshore: For seawater systems and environments exposed to marine atmospheres, where corrosion resistance is critical.
      • Pharmaceuticals: In processes requiring clean, non-contaminating materials.
      Selection Considerations

      When choosing nickel alloy butterfly valves, consider:

      • Specific Corrosion Resistance Needs: Match the alloy to the particular corrosive agents present in the process or environment.
      • Temperature Range: Ensure the chosen alloy can withstand the operational temperature extremes.
      • Pressure Ratings: Verify that the valve can handle the system’s pressure requirements without compromising its integrity or performance.
      • Cost-Effectiveness: Nickel alloys tend to be more expensive than other materials, so consider the long-term benefits of reduced maintenance and replacement costs against the initial investment.

      Nickel alloy butterfly valves represent a high-end solution for controlling flow in applications where extreme conditions would compromise lesser materials. Their use can significantly enhance system reliability, safety, and longevity, albeit at a higher initial cost. The choice of a specific nickel alloy should be based on a thorough analysis of the application’s requirements, including exposure to corrosive substances, temperature, and pressure conditions.

      TITANIUM AND TITANIUM ALLOYS

      Butterfly valves made from titanium are renowned for their exceptional strength-to-weight ratio, outstanding corrosion resistance, and excellent durability under challenging conditions. Titanium and its alloys are lightweight yet offer mechanical properties comparable to those of some steel grades, making them an excellent choice for butterfly valves in specific applications.

       

      Characteristics
      • Corrosion Resistance: Titanium is exceptionally resistant to corrosion by seawater, chlorides, and many acidic environments, making it suitable for applications where other materials might fail.
      • Strength and Durability: Despite being lightweight, titanium maintains high strength and withstands extreme pressures and temperatures, contributing to the longevity of the valve.
      • Non-Magnetic and Biocompatible: Titanium is non-magnetic and biocompatible, expanding its use to applications where magnetic interference is a concern or where it contacts biological materials.
      • Temperature Resistance: Titanium valves can operate effectively across a broad temperature range, maintaining their integrity in both low and high-temperature environments.
      Applications

      Titanium butterfly valves are ideal for industries and applications that demand material properties beyond what conventional metals can provide, including:

      • Chemical Processing: For handling highly corrosive substances, such as chlorine and acids, where titanium’s corrosion resistance ensures reliability and safety.
      • Seawater and Desalination: In seawater desalination plants, offshore platforms, and marine applications, where the resistance to seawater corrosion is critical.
      • Pharmaceutical and Food Processing: Where the non-toxic and biocompatible nature of titanium is essential for avoiding contamination.
      • Aerospace and High-Performance Engineering: In applications requiring materials that can withstand high temperatures and pressures without significant weight penalties.
      Selection Considerations

      When selecting titanium butterfly valves, consider the following factors:

      • Grade of Titanium: Various grades of titanium offer different properties. For example, Grade 2 titanium is commercially pure and widely used for general corrosion resistance, while Grade 5 (Ti-6Al-4V) is an alloy known for its higher strength and used in more demanding applications.
      • Cost: Titanium is more expensive than many other materials due to its processing complexity and raw material costs. Consider the long-term benefits of reduced maintenance and longer service life against the initial investment.
      • Compatibility: Ensure the specific grade of titanium chosen is compatible with the fluid media, operating conditions, and environmental exposure of the application.
      • Fabrication and Repair: Consider the availability of resources for fabrication and repair, as working with titanium requires specific expertise and equipment.

      Titanium butterfly valves represent a high-end solution for controlling flow in demanding applications where conventional materials are inadequate. Their selection is justified in environments that require exceptional corrosion resistance, strength, and durability, despite their higher initial cost. The benefits of using titanium include extended equipment life, reduced maintenance, and improved safety and reliability in critical applications.

      ALUMINIUM

      • Properties: Lightweight, good corrosion resistance, and ease of machining.
      • Applications: Primarily used in low-pressure applications, such as air handling, vacuum services, and dry bulk handling.

      BRONZE

      • Properties: Good corrosion resistance, especially against seawater and other saline solutions.
      • Applications: Used in marine, desalination, and certain chemical processing applications where corrosion resistance is paramount.

      NICKEL ALUMINIUM BRONZE

      This is a copper alloy that contains approximately 10% aluminum, 5% nickel, and 5% iron. It features strong corrosion resistance, especially in seawater applications, and resists the formation of a biofilm, a frequent cause of corrosion problems for stainless steels.

      Butterfly valves API 609 may have soft or metal seats. Valves with soft seats are also called “soft-seated” or “resilient” butterfly valves and are of the centric type. Eccentric designs (double or triple offset) are available, generally, with metal seat designs, which could also be fireproof.

      For less critical applications, butterfly valves are also available in plastic-grade materials, such as PVC, CVPC, Polypropylene (PP), and Polyethylene (PE). Here are the main features of plastic butterfly valves:

      PVC

      • Properties: Excellent corrosion resistance to a wide range of chemicals, lightweight, and cost-effective.
      • Applications: Suitable for low-pressure applications, including water treatment, chemical processing, and irrigation systems.

      CPVC

      • Properties: Similar to PVC but can withstand higher temperatures.
      • Applications: Used in hot water distribution, and chemical processing where higher temperature resistance than PVC is needed.

      PP/PE

      • Properties: Excellent chemical and corrosion resistance, lightweight, and suitable for a wide range of temperatures.
      • Applications: Chemical processing, water treatment, and applications involving aggressive or corrosive fluids.

       

      VALVE SEAT

      SOFT SEATED BUTTERFLY VALVE (“RESILIENT”)

      Soft-seated butterfly valves are designed to provide a tight seal and are typically used in applications where the sealing of gases or liquids is critical and where the operating conditions are within moderate temperature and pressure ranges. The “soft seat” refers to the use of elastomeric or other non-metallic, resilient materials for the sealing mechanism between the disc and the valve body, enhancing the valve’s ability to create a tight shut-off.

      Soft seated butterfly valve

      Key Features
      • Sealing Material: The soft seat is usually made from materials such as PTFE (Polytetrafluoroethylene), NBR (Nitrile Butadiene Rubber), EPDM (Ethylene Propylene Diene Monomer), or Viton (a type of fluoroelastomer). Each material offers different properties in terms of chemical resistance, temperature tolerance, and wear characteristics, making them suitable for various applications.
      • Tight Shut-Off: Soft-seated butterfly valves are known for their excellent sealing capabilities, providing a near bubble-tight closure. This makes them ideal for applications requiring precise control over the flow and leakage prevention.
      • Low Torque Operation: The soft seating material reduces the friction between the disc and the seat, allowing for easy operation with minimal torque requirements.
      • Application Versatility: These valves are used in a wide range of applications, from water and wastewater treatment to chemical processing, food and beverage, and HVAC systems, handling a variety of fluids, including corrosive and abrasive media.
      Applications

      Soft-seated butterfly valves are versatile and can be employed in various industrial and commercial applications, including:

      • Water and Wastewater: For controlling and regulating water flow in treatment plants, distribution systems, and irrigation.
      • Chemical Processing: Handling mild to moderately corrosive fluids, depending on the seat material’s chemical compatibility.
      • Food and Beverage: In processes requiring sanitary conditions, where non-toxic and cleanable sealing materials like PTFE are essential.
      • Air and Gas Handling: For applications involving air, natural gas, and other gases where a tight seal is crucial to prevent leakage.
      Considerations

      While soft-seated butterfly valves offer many advantages, there are considerations to keep in mind when selecting them for specific applications:

      • Temperature Limits: The elastomeric and plastic materials used for the seats have upper temperature limits, beyond which they may degrade or lose their sealing properties.
      • Chemical Compatibility: It’s essential to ensure that the seat material is compatible with the process fluid to prevent damage and ensure long-term reliability.
      • Wear and Tear: While soft seats provide excellent sealing, they may be more prone to wear and damage from abrasive media than metal-seated valves.

      In summary, soft-seated butterfly valves offer excellent sealing capabilities and are suitable for a wide range of applications requiring precise flow control and tight shut-off. Selecting the appropriate seat material based on the application’s specific requirements is crucial for optimal performance and longevity.

      Soft seated butterfly valves (resilient) feature EPDM, VITON, NBR, BUNA-N, and similar soft seats. Soft-seat butterfly valves are generally of the concentric type and suit low-pressure and non-critical applications

      METAL SEATED BUTTERFLY VALVE

      Metal-seated butterfly valves are designed for more demanding applications where high temperatures, higher pressures, and abrasive or corrosive media are present. Unlike soft-seated valves, which use elastomeric materials for sealing, metal-seated valves rely on metal-to-metal contact between the disc and the seat, providing durability and resistance in harsh conditions.

      Key Features
      • Durability: Metal seats are highly durable and resistant to wear, making them suitable for applications involving abrasive particles or high-velocity flows that could damage softer seat materials.
      • High Temperature and Pressure Resistance: Metal-seated butterfly valves can withstand higher temperatures and pressures than their soft-seated counterparts, making them ideal for industrial processes involving steam, hot gases, or high-pressure fluids.
      • Corrosion Resistance: Depending on the metals used (such as stainless steel, Hastelloy, Inconel, or others), these valves offer excellent resistance to corrosion and chemical attack.
      • Leakage: Metal-seated valves may not provide the same level of tight shut-off as soft-seated valves. They are generally designed to meet industry standards for acceptable leakage rates under specific conditions, which is often sufficient for many high-temperature and high-pressure applications.
      Materials For Metal Seats

      The choice of materials for metal seats in butterfly valves is critical for ensuring the valve’s durability, performance, and resistance to the operating environment’s conditions, such as temperature, pressure, and corrosion. Here are some commonly used materials for metal seats in butterfly valves, along with their characteristics and applications:

      1. Stainless Steel
      • Characteristics: Stainless steel offers excellent corrosion resistance, strength, and temperature resistance. Common grades used include 304, 316, and 316L, with 316/316L being preferred for better corrosion resistance due to their molybdenum content.
      • Applications: Widely used in water and wastewater treatment, food and beverage processing, and chemical industries where corrosion resistance is essential.
      2. Carbon Steel
      • Characteristics: Carbon steel provides good strength and thermal properties at a lower cost than stainless steel but is more susceptible to corrosion. It is often protected with coatings or treatments.
      • Applications: Suitable for applications where corrosion is not a significant concern, such as in certain oil and gas or power generation processes.
      3. Alloy Steel
      • Characteristics: Alloy steels, such as Chrome-Moly (e.g., A182 F22), are used for their enhanced strength, durability, and resistance to high temperatures and pressures.
      • Applications: Ideal for high-temperature and high-pressure applications, including steam service, boiler feed water, and thermal oil systems.
      4. Titanium
      • Characteristics: Titanium and its alloys offer exceptional corrosion resistance, especially to chlorides, along with high strength-to-weight ratios and excellent temperature tolerance.
      • Applications: Used in seawater, brine, and other corrosive environments, including chemical processing, desalination, and marine applications.
      5. Hastelloy
      • Characteristics: Hastelloy alloys are nickel-based and known for their outstanding resistance to severe corrosive environments, including strong acids.
      • Applications: Suitable for aggressive chemical applications, such as handling sulfuric acid, hydrochloric acid, and chlorine.
      6. Inconel
      • Characteristics: Inconel alloys are nickel-chromium-based and are known for their ability to withstand extreme temperatures, oxidation, and corrosion.
      • Applications: Used in high-temperature applications, such as heat treating equipment, gas turbine components, and nuclear reactors.
      7. Monel
      • Characteristics: Monel alloys are nickel-copper-based and offer excellent corrosion resistance, especially to saltwater and acidic conditions.
      • Applications: Ideal for marine, chemical, and hydrocarbon processing where high corrosion resistance is required.
      8. Bronze
      • Characteristics: Bronze, particularly aluminum bronze, provides good corrosion resistance, especially against seawater and other mildly corrosive environments.
      • Applications: Commonly used in water, gas, and some chemical applications where its corrosion resistance and strength are beneficial.

      The selection of metal seat material for a butterfly valve depends on the specific requirements of the application, including the type of medium being handled, operating temperatures and pressures, and the presence of corrosive substances. Matching the seat material to these conditions ensures optimal performance, durability, and reliability of the valve in its operational environment.

      Special treatments and coatings for butterfly valve seats enhance their performance, durability, and suitability for specific applications, especially in challenging environments. These treatments can improve the seat’s resistance to wear, corrosion, temperature, and chemical attack, extending the valve’s service life and reliability. Here are some common treatments and materials used for enhancing butterfly valve seats:1. Polytetrafluoroethylene (PTFE) Coating

      • Characteristics: PTFE, or Teflon, offers excellent chemical resistance and a low coefficient of friction, minimizing wear on the seat.
      • Applications: Suitable for chemical processing industries, food and beverage, and any application requiring high chemical resistance and non-stick properties.

      2. Reinforced PTFE (RPTFE)

      • Characteristics: RPTFE includes a filler (usually glass or carbon) to improve the material’s strength, wear resistance, and dimensional stability.
      • Applications: Used in applications where pure PTFE’s properties are desired but with enhanced durability and reduced deformation under load.

      3. Nylon Coating

      • Characteristics: Nylon provides good wear resistance and strength, along with excellent resistance to certain chemicals.
      • Applications: Common in oil and gas applications and other areas where the seat may be exposed to hydrocarbons and where impact resistance is beneficial.

      4. Elastomeric Coatings (EPDM, NBR, Viton)

      • Characteristics: Rubber materials like EPDM (ethylene propylene diene monomer), NBR (nitrile butadiene rubber), and Viton (fluoroelastomer) offer good sealing capabilities, flexibility, and, in the case of Viton, high-temperature and chemical resistance.
      • Applications: Chosen based on their compatibility with the fluid medium. EPDM is suitable for water and mild chemicals, NBR for oils and fuels, and Viton for high-temperature and chemical applications.

      5. Stellite Overlay

      • Characteristics: Stellite is a cobalt-chromium alloy known for its excellent wear and corrosion resistance, as well as its ability to perform under high temperatures.
      • Applications: Ideal for severe service applications, such as those in the power generation and oil and gas industries, where valves are subject to high wear and harsh conditions.

      6. Electroless Nickel Plating

      • Characteristics: Provides a uniform and corrosion-resistant coating that also offers good wear resistance and hardness.
      • Applications: Used in a wide range of applications, including water and wastewater treatment and processing industries, for general corrosion protection.

      7. Ceramic Coating

      • Characteristics: Ceramic coatings provide exceptional hardness, wear resistance, and thermal protection.
      • Applications: Suitable for extreme wear and high-temperature applications, such as in the mining and minerals processing industry.

      8. Chrome Plating

      • Characteristics: Chromium plating enhances surface hardness, wear resistance, and corrosion protection.
      • Applications: Applied in industrial applications where durability and longevity of the seat are critical.

      Selecting the appropriate seat material and treatment depends on the valve’s application, including the nature of the fluids involved, operating pressures and temperatures, and specific industry requirements. By customizing the seat material and applying specialized treatments, butterfly valves can achieve optimal performance and reliability in a wide range of environments.

      Applications

      Metal-seated butterfly valves are chosen for their robustness in challenging environments, including:

      • Power Generation: For handling steam and high-temperature water in cooling systems and boilers.
      • Chemical and Petrochemical Industries: In processes involving corrosive fluids, high temperatures, and where valve durability is crucial.
      • Mining and Minerals Processing: For slurry and abrasive material handling where valve wear is a concern.
      • Pulp and Paper Manufacturing: In applications involving high-temperature liquids and corrosive chemicals used in the pulping process.
      • Considerations

        When selecting a metal-seated butterfly valve, several factors should be considered to ensure it meets the application’s needs:

        • Sealing Requirements: While metal-seated valves are durable and handle extreme conditions, they might not achieve the absolute tight shut-off possible with soft-seated valves. Consider the application’s leakage tolerance.
        • Material Compatibility: Choose a valve body and seat material that is compatible with the process media and conditions to ensure long-term reliability and performance.
        • Operational Torque: Metal-to-metal seating can require higher torque to operate the valve, impacting actuator selection and operational energy costs.
        • Cost: Metal-seated valves, especially those made from exotic alloys for enhanced corrosion resistance, can be more expensive than soft-seated valves. However, their durability in harsh conditions may offer a lower total cost of ownership over time.

        In summary, metal-seated butterfly valves are an excellent choice for industrial applications that demand high durability, temperature resistance, and the ability to handle abrasive or corrosive media. Proper selection of valve materials and understanding the specific operational requirements are key to maximizing the performance and lifespan of these valves in demanding environments.

        Double eccentri butterfly valve .     Triple eccentric butterfly valve
        Double offset and triple offset butterfly valve (metal seated)

/by
,

How to understand Floating Ball Valves and Trunnion Ball Valves

A ball valve features a spherical disc to open and close the flow of the fluid. Ball valves represent the industry standard for pipeline shut-off applications, as their design guarantees very tight and leak-free sealing even after years of operation. The two key types of ball valves are the floating and the trunnion designs (side or top entry). The body can be cast or forged and monolithic or split (in 2 or 3 pieces). The API 6D and ASME B16.34 are key specifications.

BALL VALVES

WHAT IS A BALL VALVE

A ball valve is a type of quarter-turn valve that controls the flow of a fluid through it with a spherical disc known as a ball. The ball has a hole, or port, through the middle so that when the port is in line with both ends of the valve, flow will occur. When the valve is closed by turning the handle 90 degrees, the ball is rotated so that the hole is perpendicular to the flow paths of the valve body, effectively blocking the flow.

Ball valve floating and trunnion

Key Features

  • Quarter-Turn: The valve operates with a simple 90-degree turn of a handle or lever, making it quick and easy to open or close.
  • Full Port Design: Many ball valves are full port, meaning the hole in the ball is the same size as the pipeline, resulting in minimal friction loss.
  • Durability: Ball valves are known for their durability and long service life, even in high-pressure applications.
  • Versatility: Suitable for a wide range of applications, from water and gas to chemicals and corrosives, depending on the materials used in construction.
  • Sealing Mechanism: Provides excellent sealing capabilities, with many ball valves designed to be leak-proof.

Types

  • Floating Ball Valve: The ball is held in place by the compression of two elastomeric seats against it. The ball moves slightly within the valve body to maintain contact with the downstream seat, ensuring a tight seal.
  • Trunnion Mounted Ball Valve: The ball is anchored at the top and bottom, reducing the operating torque and allowing for the control of larger sizes and higher pressure services.
  • Top Entry & Side Entry: Refers to how the ball valve is assembled, which impacts maintenance and repair ease.

Each type of ball valve is explained in greater detail below.

Applications

Ball valves are used in a variety of applications across many industries, including water supply, gas supply, oil and petrochemical processes, manufacturing, and more. Their ability to quickly shut off flow makes them particularly useful for emergency and shut-off applications. Material selection for the valve body, ball, and seals (often made from metal, plastic, or ceramic) can vary based on the fluid’s nature, ensuring compatibility and performance across a wide range of temperatures and pressures.

BALL VALVE PARTS

A ball valve consists of several key components, each playing a crucial role in its functionality. Understanding these parts can help in selecting the right valve for a specific application, as well as in maintenance and troubleshooting. Here’s an overview of the main parts of a ball valve:

1. Body

The outer casing of the valve that holds all other components together. It can be made from a variety of materials, including stainless steel, brass, plastic, and others, depending on the application requirements.

2. Ball

The core component that controls flow through the valve. It is a spherical disc with a hole (or bore) through its center. The material of the ball usually matches or complements the body material for compatibility with the fluid being handled.

Special Treatments For The Ball Of A Ball Valve

The ball of a ball valve can undergo various special treatments to enhance its performance, durability, and suitability for specific applications. These treatments can improve the ball’s resistance to wear, corrosion, and galling, as well as its sealing capabilities. Here are some commonly applied special treatments for the ball of a ball valve:

1. Hard Coatings
  • Chrome Plating: A thin layer of chromium is electroplated onto the ball surface, enhancing its wear and corrosion resistance. This treatment is suitable for applications involving abrasive materials or corrosive fluids.
  • Nickel Plating: Similar to chrome plating, nickel plating provides corrosion resistance and increased durability, especially in environments where the valve is exposed to harsh chemicals.
  • Tungsten Carbide Coating: Applied using High-Velocity Oxygen Fuel (HVOF) spraying, this coating offers exceptional hardness and resistance to extreme wear and erosion.
2. Soft Coatings
  • PTFE (Polytetrafluoroethylene): A soft coating that provides excellent chemical resistance and reduces friction between the ball and seats. This is particularly beneficial in applications requiring tight sealing and low operating torque.
  • Enamel Coating: Offers good corrosion resistance and is used in applications where chemical compatibility is a concern.
3. Electroless Nickel Coating

This process deposits a uniform nickel-phosphorus or nickel-boron alloy coating on the ball, offering excellent corrosion and wear resistance. It’s particularly useful in offshore and marine applications, as well as in the processing of corrosive fluids.

4. Nitriding

Nitriding enhances the surface hardness of the ball through a heat-treating process that diffuses nitrogen into the surface. This treatment improves wear resistance and fatigue strength, making it suitable for high-pressure and high-velocity applications.

5. Cryogenic Treatment

This treatment involves cooling the ball to cryogenic temperatures and then gradually warming it up. The process stabilizes the structure of the material, improving its toughness and wear resistance. It’s especially beneficial for valves used in cryogenic services.

6. Molybdenum Disulfide Coating

A dry lubricant coating that reduces friction and improves wear resistance. It’s useful in applications where lubrication is difficult or where the valve must operate under high loads or extreme temperatures.

7. Fusion Bonded Epoxy Coating

A thick, protective coating that offers excellent corrosion protection. It’s widely used in water and wastewater applications, as well as in pipelines transporting corrosive gases and liquids.

The choice of treatment depends on the specific operational conditions, including the type of fluid handled, pressure, temperature, and the presence of abrasive or corrosive elements. These specialized treatments can significantly extend the life of a ball valve and enhance its performance in demanding industrial applications.

3. Seats

Rings that provide a seal between the ball and the valve body. When the valve is closed, the ball presses against these seats to create a tight seal, preventing fluid from leaking past. Seats can be made from soft materials (like PTFE) for better sealing or hard materials for high-temperature applications.

Special Treatments For The Seats Of A Ball Valve

The seats of ball valves play a crucial role in ensuring tight sealing and smooth operation across a wide range of applications, from low-pressure residential systems to high-pressure industrial processes. To enhance their performance, durability, and resistance to harsh conditions, several special treatments and material enhancements can be applied to ball valve seats. Here are some of the notable treatments and materials used:

1. Soft Seating Materials
  • PTFE (Polytetrafluoroethylene): Offers excellent chemical resistance and a low friction coefficient, suitable for a broad temperature range. Variants like reinforced PTFE (RPTFE) have added fillers to improve strength and wear resistance.
  • PEEK (Polyether Ether Ketone): A high-performance thermoplastic with excellent mechanical and chemical resistance properties, suitable for high-pressure and high-temperature applications.
  • Nylon: Provides good wear resistance and strength, suitable for certain types of oils and hydrocarbons.
2. Metal Seating

Hard Facing: Metal seats can be coated or overlaid with harder materials such as Stellite, tungsten carbide, or chromium carbide through processes like welding or thermal spraying. These treatments improve wear resistance, thermal stability, and longevity in severe service conditions, including abrasive and corrosive environments.

3. Elastomeric And Composite Materials
  • Viton, Buna-N (Nitrile): Elastomers offer good sealing capabilities and resistance to a variety of chemicals and temperatures. They are used in applications where softer sealing materials are needed for improved sealing at lower pressures.
  • Composite Materials: Seats made from a combination of materials, such as fibrous reinforcements in a resin matrix, offer enhanced performance characteristics, including resistance to wear and chemical attack.
4. Surface Treatments
  • Electroless Nickel Plating (ENP): A chemical process that deposits a nickel-phosphorus coating on the surface of the seat. ENP improves corrosion resistance and hardness, enhancing the seat’s durability in corrosive environments.
  • Surface Coatings: Various coatings can be applied to improve resistance to chemicals, temperature, and wear. Examples include PFA (Perfluoroalkoxy) and FEP (Fluorinated Ethylene Propylene) coatings, which are types of fluoropolymers with excellent chemical resistance.
5. Seat Design Enhancements
  • Live-Loaded Seats: Some ball valve seats are designed with live-loading mechanisms, such as spring energizers, to maintain consistent sealing force against the ball. This compensates for wear and thermal expansion, ensuring a reliable seal over the valve’s lifespan.

Selecting the appropriate seat material and treatment depends on several factors, including the type of fluid being handled, operating pressures and temperatures, and specific application requirements. By choosing the right seat treatment, users can significantly enhance the performance, reliability, and service life of ball valves in their systems.

4. Stem

Connects the ball to the control mechanism (like a handle or actuator) outside the valve. The stem allows for the rotation of the ball, typically a quarter turn (90 degrees) from the open to the closed position. It’s designed to prevent leakage from the valve body to the atmosphere.

5. Handle Or Actuator

Used to manually or automatically control the valve’s position. A manual handle is turned to rotate the stem and the attached ball. Actuators, which can be pneumatic, electric, or hydraulic, allow for remote operation and can be used for more precise control in automated processes.

6. Packing

A sealant material around the stem to prevent leaks. Packing is often made from PTFE or graphite and is compressed by a packing nut or gland follower to ensure a tight seal.

7. O-Rings/Gaskets

Provide additional sealing at various points, such as between the valve body and the bonnet (if the valve design includes a bonnet) and around the stem. The material depends on the application’s temperature and pressure conditions.

8. Bonnet

Some ball valve designs include a bonnet, which is a section of the valve body covering the opening where the internal parts are inserted. It can be bolted, screwed, or welded to the valve body.

9. End Connections

The interface points where the valve connects to the piping system. Common types include threaded, flanged, and socket weld connections, chosen based on the piping system’s design and requirements.

Understanding these components and their materials is essential for selecting a ball valve that meets the operational requirements of temperature, pressure, flow control, and compatibility with the processed fluids. Proper selection ensures reliable performance and longevity of the valve in the system.

BALL VALVE ADVANTAGES AND DISADVANTAGES

Ball valves have the following advantages advantages:

  • can be quickly opened and closed with a quarter-turn movement
  • ensure a very tight seal without the need for high torque forces
  • have a compact design (this is the main difference between a ball valve and a gate valve – which are both on/off devices)

The disadvantages of ball valves are:

  • valve has poor regulating and throttling capabilities, as it is designed for pipeline shut-off instead of flow modulation (this is an ideal function for globe valves): throttling causes the partially exposed seat to erode because of the high-velocity flow and pressure experienced by the valve. The wear may lead to a leakage of the valve progressively.
  • valve can’t be used for slurries, as the accumulation of suspended particles and debris would make the valve leak. These particles may solidify in the cavities in the proximity of the ball and seats.  Ball valves are way more very efficient with gases and other liquid fluids (even challenging chemicals such as dry chlorine, hydrofluoric acid or hydrochloric acid, and oxygen).
  • may be difficult to clean (except for top entry design)

The open, close,d or partially open position of the valve can be detected by looking at the position of the lever:

  • when the lever is aligned to the pipe, the valve is open; when it is perpendicular to the pipe, the valve is closed;
  • when it is in any other position, the valve is partly open (or partly closed) and is modulating the flow.

These valves belong to the family of “quarter turn” valves or “1/4 turn valves” (together with butterfly and plug valves), as the opening and closing operations are executed by turning a lever connected to the disc by 90 degrees.

The key ball valve specifications are the API 6D, BS 5351 (forged) and ASME B16.34 (pressure and temperature ratings), ASME B16.5/B16.47 (flanged ends) and ASME B16.25 (butt welding ends).

HOW DOES A BALL VALVE WORK?

A ball valve operates using a simple but effective mechanism that involves a quarter-turn rotational motion to open or close the flow of fluid. The core component of a ball valve is a spherical disc, known as the ball, which has a hole or port through its center. Here’s a breakdown of how a ball valve works:

In The Open Position

  • The handle or lever of the ball valve is aligned with the pipe, indicating that the valve is open.
  • The hole in the ball is positioned in line with the flow direction of the pipe, allowing fluid to pass through the valve with minimal resistance.
  • As the ball rotates to this position, the fluid can flow freely through the hole, enabling full flow through the valve.

In The Closed Position

  • To close the valve, the handle or lever is turned 90 degrees from the open position. This quarter-turn movement rotates the ball so that the hole is perpendicular to the flow direction of the pipe.
  • When the hole or port in the ball is perpendicular to the flow path, it blocks the flow of fluid, effectively stopping the flow through the valve.
  • The sealing mechanism around the ball (typically elastomeric seats) ensures a tight seal when the valve is closed, preventing leaks.

Key Functional Aspects

  • Quarter-Turn Operation: The ball valve’s design allows for quick and easy operation, making it an efficient choice for controlling fluid flow. The 90-degree turn offers a clear visual indication of the valve’s position.
  • Sealing: The effectiveness of a ball valve’s seal, when in the closed position, is aided by the pressure of the fluid which pushes the ball against the downstream seat. This pressure enhances the sealing effectiveness, making ball valves suitable for high-pressure applications.
  • Versatility: Ball valves can handle various fluids, including gases, liquids, and slurries. Their design minimizes pressure drop and allows for bidirectional flow control in the fully open position.
  • Durability: The simplicity of the ball valve’s design contributes to its durability and reliability, with many ball valves capable of maintaining their sealing ability over thousands of cycles.

Ball valves are favored for applications requiring reliable and rapid shut-off, offering a practical solution for flow control across a broad range of industrial and residential settings.

BALL VALVE TYPES

Ball valves can be classified according to multiple criteria:

  • Ball valve design: floating, trunnion mounted, and double bleed and block
  • Number of valve’s ports: the standard type is with 2 ports design (1 inlet, 1 outlet), but 3-way design is also available (1 inlet and 2 outlets or vice-versa)
  • Bore size: full bore or reduced bore (FB vs. RB), and V-notch
  • Body assembly: unibody (the ball body is made out of one single piece of cast or forged steel), 2 pieces or 3 pieces (the body results from the assembly of two or three different parts)
  • Ball access: side entry or top entry (depending on the fact that the ball can be accessed, for maintenance, from the side of the valve or from its top)
  • Seat Type: metal or soft (Teflon)

Let’s now delve into the characteristics of each different type of ball valve.

FLOATING BALL VALVE

A floating ball valve is a type of ball valve where the ball is not rigidly fixed but is allowed to float between the valve seats. In this design, the ball is held in place by the compression of two elastomeric seats, one on each side of the ball.

The ball has some freedom to move (float) within the valve body. The term “floating” refers to the ball’s ability to move slightly along the axis of the valve.

How It Works

When the valve handle (or actuator) is turned to open the valve, the ball rotates to a position where the hole through the ball is aligned with the valve’s inlet and outlet, allowing fluid to flow through. When the valve is closed, the handle rotates the ball so that it blocks the flow path.

Upon closing the valve, the pressure of the fluid acts on the ball, pushing it against the downstream seat. This action enhances the seal and prevents fluid from leaking past the ball. The floating design means that the sealing pressure against the ball increases with increased fluid pressure, thereby improving the sealing efficiency as the system pressure rises.

Advantages Of Floating Ball Valves

  • Tight Sealing: The pressure-assisted sealing mechanism ensures a reliable seal between the ball and the seats, making floating ball valves suitable for a wide range of applications.
  • Simplicity and Durability: With fewer moving parts and a simple design, floating ball valves are durable and require minimal maintenance.
  • Versatility: They can be used in various applications, handling a wide range of fluids and operating conditions.

Applications

Floating ball valves are commonly used in industries such as water and wastewater treatment, chemical and petrochemical processing, oil and gas, and manufacturing. They are suitable for applications requiring reliable shut-off capabilities, such as in pipelines, storage facilities, and distribution systems. Floating ball valves are typically used in low to medium-pressure and temperature applications.

Considerations

While floating ball valves are suitable for a wide range of applications, the floating design may not be as effective in very high-pressure systems where the ball could be pushed too hard against the seat, potentially leading to seat deformation and increased operational torque. For such high-pressure applications, trunnion-mounted ball valves, where the ball is supported by bearings and the pressure load is not entirely on the seats, might be more appropriate.

Floating and trunnion ball valves design

When the shaft of the floating ball valve is moved, a load is applied to the ball which gets pressed against its seats.

This design, which is lightweight and economical, suits bore sizes up to 10 inches: above this bore size, the seats of the valve would not be able to withstand heavier and heavier balls and the valve would not operate safely and efficiently.

Floating valves allow a bi-directional shut-off of the flow (as the trunnion type).

Floating ball valve

TRUNNION BALL VALVE

A trunnion ball valve is a type of ball valve that utilizes a fixed ball design to control the flow of fluid. Unlike floating ball valves, where the ball is allowed to float between the valve seats, in trunnion ball valves, the ball is anchored at the top and bottom by trunnions. These trunnions, essentially extensions of the ball or additional support mechanisms, hold the ball in a fixed position while allowing it to rotate.

Trunnion ball valve

How It Works

The ball in a trunnion ball valve has a hole through its center. When the valve is open, this hole is aligned with the flow path, allowing fluid to pass through. Turning the valve’s handle or actuator rotates the ball to block the flow path, stopping the flow. The trunnions absorb the line pressure, reducing the load on the valve seats and ensuring a tight seal regardless of pressure fluctuations.

Key Features And Advantages

  • Low Operational Torque: Because the ball is supported by trunnions, there’s less friction between the ball and the seats during operation, which translates to lower torque requirements. This makes it easier to operate, especially for larger valve sizes or in high-pressure applications.
  • High Pressure and Temperature Capabilities: Trunnion ball valves are well-suited for high-pressure and high-temperature applications. The trunnion design effectively manages the thrust from line pressure, preventing excess stress on the valve components.
  • Durability and Reliability: The fixed ball design minimizes wear on the seats and ensures consistent performance over time, contributing to the valve’s longevity and reliability.
  • Double Block and Bleed (DBB) Capability: Many trunnion ball valves offer DBB functionality, allowing for maintenance and pressure verification without shutting down the entire system.

Applications

Trunnion ball valves are used in a wide range of industrial applications, especially where high pressure and large diameters are involved, such as:

  • Oil and Gas: For controlling flow in pipelines, processing facilities, and offshore platforms.
  • Petrochemical and Chemical Manufacturing: In systems requiring robust valves that can handle high pressures and corrosive fluids.
  • Power Generation: For steam, water, and feedwater systems within power plants.
  • Water and Wastewater Treatment: In high-pressure lines and for applications requiring durable and reliable shut-off.

Considerations

While trunnion ball valves offer several advantages, they are typically more expensive than floating ball valves due to their more complex design and manufacturing process. They are also generally larger and heavier, which may be a consideration for installation and support structures. Despite these factors, their reliability and performance in demanding conditions make them a preferred choice for many high-pressure and large-scale applications.

TOP ENTRY BALL VALVE

A top entry ball valve is a type of ball valve where the main components, including the ball and seats, can be accessed and serviced from the top of the valve without removing the entire valve body from the pipeline. This design provides a significant advantage in terms of maintenance and repair.

Top entry ball valve

Design And Operation

  • Ball Mechanism: Similar to other ball valves, a top entry ball valve uses a spherical ball with a hole through its center to control fluid flow. The valve opens when the ball’s hole is aligned with the flow path and closes when rotated 90 degrees.
  • Access: The distinguishing feature of a top entry ball valve is the single-piece body design that allows access to the valve internals through a removable bonnet or cover on the top. This design means that the valve internals can be inspected, repaired, or replaced without detaching the valve body from the pipeline.
  • Sealing and Support: Top entry ball valves can be designed with floating or trunnion-supported balls, depending on the application requirements. They also feature robust sealing mechanisms to prevent leaks, which can be easily replaced or serviced due to the top entry design.

Advantages

  • Ease of Maintenance: The primary advantage is the ease of maintenance and repair. Valve components can be serviced directly on the line, reducing downtime and operational costs.
  • Versatility: Top entry ball valves are suitable for a wide range of applications, pressures, and temperatures. They can be used in critical and high-performance settings, including the oil and gas industry, power generation, and process industries.
  • Durability and Reliability: These valves are built for durability and reliability, with designs that can handle high pressure and adverse conditions effectively.

Applications

Top entry ball valves are used in various industrial applications where valve accessibility and ease of maintenance are crucial, especially in high-pressure and high-temperature environments. Common applications include:

  • Oil and Gas: For onshore and offshore pipelines, production facilities, and refining processes where rapid maintenance may be required.
  • Chemical Processing: In systems handling corrosive or hazardous materials that may require frequent maintenance.
  • Power Generation: In feedwater, steam, and other critical power plant systems.

Differences Top-Entry And Side-Entry Ball Valves

Top entry and side entry ball valves are two distinct designs within the ball valve family, each offering specific advantages for different applications. The primary difference lies in how the ball and internal components are accessed and maintained. Here’s a breakdown of each type:

Top Entry Ball Valve

Design: In a top entry ball valve, the ball and seats can be accessed from the top of the valve. The valve body is a single piece, with a removable bonnet or cover on top that provides direct access to the valve internals without removing the valve from the pipeline.

Advantages:

  • Maintenance: Allows for easier maintenance, inspection, and replacement of the internals (ball, seats, seals) without detaching the valve from the pipeline, saving time and reducing downtime.
  • Application: Suitable for high-pressure and high-temperature applications, as well as in situations where inline maintenance is necessary or where system downtime needs to be minimized.

Considerations:

  • Typically more expensive due to the precision engineering required for the top entry design.
  • Often used in critical or hard-to-reach areas where valve removal would be challenging.
Side Entry Ball Valve (Split Body Ball Valve)

Design: The side entry ball valve, often referred to as a split body ball valve, features a body that is divided into two or three pieces, bolted together. The ball is inserted from the side when assembling the valve. The body joint is typically along the horizontal axis for a two-piece design and may include a third piece (center piece) for three-piece designs.

Advantages

  • Cost-Effectiveness: Generally more cost-effective than top entry valves, making them suitable for a wide range of applications.
  • Versatility: Available in a wide variety of sizes and pressure ratings, suitable for many industrial applications.

Considerations

  • Maintenance or repair requires the valve to be removed from the pipeline, which can increase system downtime.
  • The seal at the body joint may have specific pressure limitations, influencing the valve’s suitability for high-pressure applications.
Key Differences (Top Vs. Side Entry)
  • Maintenance Accessibility: Top entry valves allow for inline maintenance without removing the valve from the pipeline, while side entry valves need to be fully removed for servicing.
  • Construction and Cost: Top entry valves have a one-piece body design that can be more expensive to manufacture, whereas side entry valves have a split body design that is generally more cost-effective.
  • Application Suitability: The choice between top entry and side entry may depend on the application’s maintenance requirements, cost considerations, and pressure/temperature demands.

In summary, the decision between a top entry and side entry ball valve often comes down to the specific needs of the application, including maintenance practices, budget constraints, and operational conditions. Each type offers unique benefits that make it suitable for different industrial environments.

Trunnion-mounted ball valves, as well as floating ball valves, are available with a “side entry” and “top entry” design.

The top entry design is specified when frequent inline maintenance activities are expected on the valve.

This is because top-entry ball valves allow easier and faster access to the ball and the valve trim compared to side-entry valves (which require more maintenance time and space for the same operations).

Final Considerations About Top-Etntry Ball Valves

While top-entry ball valves offer significant maintenance advantages, they may come with a higher initial cost compared to other ball valve types due to their design complexity and manufacturing requirements. Additionally, their selection should consider the specific application’s pressure, temperature, and fluid compatibility to ensure optimal performance and longevity.

3-WAYS BALL VALVE (OR “MULTIPORT”)

A 3-way ball valve is a type of ball valve designed to control the flow of fluids in three different directions. It is characterized by having three ports (inlet and two outlets, or one inlet and two outlets), making it versatile for various applications where flow diversion, mixing, or directional control is needed. The internal ball typically has either an L-shaped or T-shaped port, allowing for different flow patterns depending on its position.

Multiport Ball Valve (3 ways)

How It Works

  • L-Port Configuration: The L-shaped port connects the center port to one of the side ports at a time, making it suitable for diverting flow from one line to another. By rotating the ball, the valve can alternate between connecting the inlet to either of the two outlets.
  • T-Port Configuration: The T-shaped port can connect all three ports simultaneously or block one port while connecting the other two. This configuration is useful for mixing two inlet flows or dividing one inlet flow into two outlets.

3 Way Ball Valve L and T

Key Features

  • Versatility: 3-way ball valves can serve multiple functions, such as stopping and starting flow, changing the flow direction, mixing, or splitting the flow within a single valve body.
  • Easy Operation: Like other ball valves, 3-way ball valves offer quick and efficient operation, typically with a quarter-turn mechanism to change flow paths.
  • Compact Design: These valves can replace multiple two-way valves and fittings in a system, saving space and reducing potential leak points.

Applications

3-way ball valves are widely used across various industries for different purposes, including:

  • Chemical Processing: For directing chemical flows between different processing stages or mixing chemicals.
  • HVAC Systems: To control the direction of heating or cooling media.
  • Food and Beverage: In systems requiring the diversion of fluids or mixing of ingredients.
  • Water Treatment: For directing water flow through different treatment paths.

Selection Considerations

When selecting a 3-way ball valve, consider:

  • Flow Requirements: Determine the required flow pattern (L-port or T-port) based on the application’s needs.
  • Material Compatibility: Ensure the valve materials are compatible with the fluids being handled, considering factors like corrosion resistance and food safety.
  • Pressure and Temperature: Select a valve that can withstand the operating pressure and temperature conditions of the system.
  • Actuation: Decide between manual operation or automated actuation (electric, pneumatic, hydraulic) based on system requirements.

In summary, 3-way ball valves offer a flexible and efficient solution for controlling flow directions in a piping system, accommodating a variety of operational needs with simple adjustments.

FULL PORT VS REDUCED PORT BALL VALVES

These concepts refer to the relation between the bore diameter of the valve and the connected piping system. The term “port” can be also referred to as “bore” (full bore/small bore).

Full bore vs Reduced Bore Ball Valve

Full port and reduced port ball valves are two common design variations found in ball valves, each serving specific operational purposes based on flow requirements and pressure drop considerations. Understanding the differences between them is crucial for selecting the appropriate valve type for a particular application.

Full Port Ball Valve (Full Bore)

  • Design: In a full port ball valve, the diameter of the ball’s hole (bore) matches the inner diameter of the connecting pipeline. This design ensures that there is no restriction in the flow path when the valve is fully open.
  • Advantages: Minimal pressure drop across the valve, which is especially beneficial in applications requiring the preservation of flow rate and pressure. It also allows for pigging operations in pipelines, where a cleaning pig is sent through the pipe to remove debris and buildup.
  • Applications: Full port valves are ideal for applications where flow efficiency is critical and for systems that require regular pigging for maintenance.

Reduced Port Ball Valve (Reduced Bore)

  • Design: The bore diameter of a reduced port ball valve is smaller than the pipeline’s diameter. This results in a flow path that is somewhat restricted compared to the full port design.
  • Advantages: Reduced port valves are generally smaller and less expensive than full port valves of the same nominal size. The smaller bore also requires less torque to operate, which can reduce the size and cost of the actuation mechanism.
  • Applications: Suitable for applications where flow rate and pressure drop are less critical. They are commonly used in applications where space and cost savings are desired without significantly compromising the system’s performance.

Key Differences

  • Flow Path and Pressure Drop: Full port valves offer an unrestricted flow path, resulting in lower pressure drops, while reduced port valves introduce some restriction and higher pressure drops.
  • Size and Cost: Reduced port valves are typically more compact and cost-effective than full port valves, making them attractive for applications where space is limited, and the full flow capacity is not required.
  • Operational Efficiency: The choice between full and reduced port often depends on the system’s requirements for flow efficiency and pressure maintenance. Full port valves are preferred in systems that cannot tolerate significant pressure drops or where pipeline pigging is necessary.

In summary, the choice between full port and reduced port ball valves depends on the specific requirements of the application, including considerations of flow rate, pressure drop, operational efficiency, and cost. Understanding these differences ensures the selection of the most appropriate valve type to meet the system’s needs effectively.

V-PORT BALL VALVE

A V-Port ball valve, also known as a V-Ball or V-Notch ball valve, is a specialized type of ball valve designed for more precise flow control and regulation compared to standard ball valves. This valve features a ball with a V-shaped cutout on its surface, giving it the name “V-Port.” The unique shape of the V-Port allows for better throttling control and rangeability, making it particularly suited for applications requiring precise flow modulation.

v port ball valves
v port ball valves

Design And Operation

  • V-Port Design: The angle of the V-notch cut into the ball can vary, typically ranging from 15 to 90 degrees. The shape and angle of the V-Port directly affect the flow characteristics, allowing for linear or equal percentage flow control. As the valve is opened or closed, the V-shaped portion provides a gradual change in flow area, enabling fine adjustment of flow rate.
  • Operation: Like other ball valves, V-Port ball valves operate with a quarter-turn mechanism. Rotating the valve handle 90 degrees opens or closes the valve, but the precise shape of the V-Port allows for more nuanced control over the flow as the valve moves between open and closed positions.

Advantages

  • Enhanced Flow Control: The V-Port design offers superior control over fluid flow, especially in partially open positions, making it ideal for throttling applications.
  • High Rangeability: V-Port ball valves can effectively manage a wide range of flow rates, providing flexibility across various operational conditions.
  • Reduced Cavitation and Flashing: The gradual change in flow area helps minimize the risks of cavitation and flashing, common challenges in fluid control applications.
  • Durability: V-Port ball valves maintain the inherent durability and reliability of traditional ball valves, suitable for high-pressure and high-temperature applications.

Applications

V-Port ball valves are used in diverse industries where precise flow regulation is required, including:

  • Chemical Processing: For controlling the flow of aggressive or corrosive fluids.
  • Water and Wastewater Treatment: In applications requiring fine adjustment of water flow.
  • Food and Beverage Production: Where precise flow control is necessary for process accuracy.
  • Pulp and Paper Manufacturing: For controlling the flow of slurry and other process fluids.

Selection Considerations

When selecting a V-Port ball valve, consider factors such as the specific flow control requirements, the fluid properties (including viscosity and potential for particulate matter), operating pressures and temperatures, and the valve materials’ compatibility with the process fluid.

In summary, V-Port ball valves offer enhanced flow control capabilities, making them a valuable option for applications requiring precise flow regulation. Their design combines the robustness and reliability of standard ball valves with improved performance for throttling and modulation tasks.

SEGMENTED BALL VALVE

A segmented ball valve, also known as a V-notch ball valve, is a specialized type of ball valve designed to provide precise flow control, especially in applications involving liquids with varying viscosities or slurries. It combines the robust sealing characteristics of a traditional ball valve with enhanced control capabilities, thanks to its unique ball design.

segmented ball valve
segmented ball valve

Design

The key feature of a segmented ball valve is its ball segment or V-notch design. The ball has a V-shaped cutout on one side, which gradually opens or closes as the valve is turned, allowing for more precise modulation of flow than a standard ball valve. The “segment” refers to the part of the ball that is cut out, and it can rotate within the valve body to regulate the flow.

How It Works

As the valve handle or actuator is turned, the V-notch segment of the ball rotates, aligning more or less with the flow path. This design allows for a range of flow control, from fully open to nearly closed, with the V-notch providing a shearing action that is effective at controlling the flow of slurry or viscous fluids.

Key Features

  • Precise Flow Control: The V-notch design enables finer control over the flow rate, making it suitable for throttling applications.
  • Shearing Action: The V-notch can cut through solids and slurries in the fluid, reducing clogging and ensuring smoother operation in challenging conditions.
  • High Rangeability: The valve offers a wide range of flow capacities, from fully open to minimal flow, allowing for versatile use across different applications.
  • Durability: Segmented ball valves are designed to withstand harsh operating conditions, including high pressures and temperatures.

Applications

Segmented ball valves are used in various industrial applications where precise flow control and durability are required, including:

  • Chemical Processing: For handling corrosive fluids, viscous products, or slurry mixtures where precise flow modulation is necessary.
  • Pulp and Paper Manufacturing: In processes involving fibrous slurries, where the valve’s shearing action can prevent clogging.
  • Water and Wastewater Treatment: For controlling the flow of water with varying levels of particulate matter.
  • Food and Beverage: In applications involving viscous liquids or products with solids.

Considerations

When selecting a segmented ball valve, it’s important to consider the specific requirements of your application, including the fluid’s nature, pressure and temperature conditions, and the degree of flow control needed. The material of the valve and its components should be compatible with the process fluid to ensure longevity and reliability.

In summary, segmented ball valves offer an efficient solution for applications requiring precise flow control and the ability to handle difficult fluids, combining the benefits of ball valve sealing with the adjustability of a control valve.

BALL CONTROL VALVE

A ball control valve is a type of control valve that uses a ball with a hole through it to regulate the flow of a fluid. It combines the spherical closure element of a traditional ball valve with the ability to modulate flow, making it suitable for precision control applications. Ball control valves are designed to offer variable control of fluid flow, allowing for adjustment from full flow to minimal flow based on the position of the ball.

control ball valve
control ball valve

Design Features

  • Rotary Ball: The core component is a rotary ball with a bore through the center. The position of the ball (and thus the alignment of the bore with the flow path) is adjusted to control the flow rate.
  • V-Port: Many ball control valves feature a V-shaped cut or notch on the ball or in the bore, enhancing their ability to provide finer control over a wide range of flow rates. The “V” shape allows for more precise control as the valve moves from the closed to the open position.
  • Actuation: Ball control valves are often operated by pneumatic, electric, or hydraulic actuators, allowing for remote control and automation of the valve’s position in response to system demands.

  • Operational Advantages

    • Precise Flow Control: Offers excellent control over flow rates, making it ideal for applications where the flow needs to be adjusted or regulated accurately.
    • High Rangeability: The design allows for a wide range of flow capacities, enabling precise control from fully open to nearly closed positions.
    • Good Shut-Off Capabilities: When fully closed, ball control valves provide a tight seal, similar to standard ball valves, making them suitable for on/off control in addition to flow modulation.
    • Durability: The robust design of ball control valves, especially those with hard-sealed components, can handle high-pressure applications and aggressive media.

    Applications

    Ball control valves are used in a variety of industries and applications, including:

    • Process Industries: For controlling the flow of gases, liquids, and even slurries in chemical, petrochemical, and pharmaceutical processes.
    • Water Treatment: In systems requiring precise control of water flow, such as in filtration, distribution, and wastewater treatment.
    • Oil and Gas: For regulating the flow in pipelines, production processes, and refining operations.
    • Food and Beverage: In applications involving the control of liquids and semi-liquids during processing and manufacturing.

    Selection Considerations

    When selecting a ball control valve, consider factors such as:

    • Fluid Compatibility: Ensure the materials of the valve are compatible with the process fluid to prevent corrosion and wear.
    • Pressure and Temperature Ratings: The valve must be capable of operating within the system’s pressure and temperature ranges.
    • Flow Characteristics: Consider the required flow pattern (e.g., linear or equal percentage) and rangeability to ensure the valve meets the application’s control needs.

    In summary, ball control valves are an effective solution for applications requiring both precise flow modulation and reliable shut-off capabilities. Their versatility and durability make them a popular choice in various industrial processes where control accuracy is paramount.

    BALL VALVE VS. OTHER TYPES OF VALVES

    Ball Valve Vs Gate Valve

    Ball valves and gate valves are two commonly used types of valves in piping systems, each serving specific purposes with distinct advantages and operational differences. Here’s a comparison to highlight the key aspects of ball valves versus gate valves:

    Ball Valve

    • Operation: Utilizes a rotating ball with a hole through its center to control flow. Turning the valve’s handle 90 degrees opens or closes the flow path.
    • Sealing: Offers a tight seal with low torque, making it suitable for applications requiring a leak-proof operation.
    • Flow Control: Provides excellent on/off control but is not typically used for flow modulation, as partial opening can create turbulent flow and potentially damage the valve.
    • Pressure Drop: Generally experiences a lower pressure drop when fully open compared to gate valves, due to the straight flow path.
    • Applications: Widely used for gas and liquid applications where quick and full shutoff is required, including residential, industrial, and commercial plumbing and water systems.

    Gate Valve

    • Operation: Operates by lifting a gate out of the path of the fluid. Turning the handle or wheel opens or closes the valve by moving the gate vertically.
    • Sealing: When fully open or fully closed, gate valves provide a good seal. However, they are prone to wear and leakage over time, especially in the partially open position.
    • Flow Control: Primarily designed for on/off control and not recommended for throttling as the partially open gate can be damaged by the fluid flow.
    • Pressure Drop: When fully open, gate valves offer very little resistance to flow, resulting in a minimal pressure drop.
    • Applications: Ideal for applications where a straight flow path and minimal restriction are desired, such as in water and wastewater treatment, oil and gas industries, and other situations requiring minimal valve operation.

    Key Differences

    • Functionality: Ball valves are better for applications requiring fast, frequent operation and tight shutoff. Gate valves are preferred for applications where the valve remains either fully open or fully closed for extended periods.
    • Flow Regulation: Ball valves are not suited for precise flow control, while gate valves, although not designed for throttling, can provide finer control when opening and closing.
    • Maintenance: Ball valves generally require less maintenance than gate valves, as their design is simpler and more resistant to wear from the turbulent flow.
    • Cost: The cost can vary depending on the size, material, and specific application requirements. However, ball valves tend to be more cost-effective for smaller sizes, while gate valves can be more economical for larger diameters.

    In summary, the choice between a ball valve and a gate valve depends on the specific requirements of the application, including the need for flow control, frequency of operation, and budget considerations. Each valve type offers distinct advantages that make it suitable for different operational contexts.

  • Ball Valve Vs Globe Valve

    Ball valves and globe valves are both critical components used in piping systems for controlling flow, but they have distinct design features, operational mechanics, and applications that make them suited to different tasks.

    Trunnion forged ball valve

    Here’s a breakdown of the key differences between ball valves and globe valves:

    Ball Valve

    • Design: Features a spherical disc (the ball) with a hole through its center. The ball rotates within the valve body to open or close the flow path.
    • Operation: Operates with a quarter-turn (90-degree) movement, offering quick and easy shutoff. The handle’s position (parallel or perpendicular to the pipe) indicates the valve’s status (open or closed).
    • Flow Control: Primarily used for on/off control due to its design. While it can be used for throttling, it’s not as precise as a globe valve for this purpose.
    • Sealing: Provides a tight seal with minimal wear over time, making it suitable for applications requiring leak-proof operation.
    • Pressure Drop: Generally has a lower pressure drop when fully open, as the flow path is straight through the ball.
    • Applications: Widely used in applications requiring fast and frequent operation, including gas, liquid, and even slurry services, due to its robust design and effective sealing.

    Globe Valve

    • Design: Characterized by a body with a Z-shaped partition and a moveable disc or plug that seats against an opening in the partition to regulate flow.
    • Operation: Utilizes a multi-turn stem operation, requiring several turns to open or close, which allows for precise control of the flow rate.
    • Flow Control: Excellently suited for throttling and regulating flow due to its design, which allows for fine adjustments of the disc position.
    • Sealing: Effective sealing capabilities, but the design can lead to more wear on the seating surface due to the disc’s sliding motion against the seat.
    • Pressure Drop: Typically experiences a higher pressure drop compared to ball valves because of the tortuous flow path.
    • Applications: Commonly used in applications requiring precise flow control, such as in heating and cooling systems, and in processes where flow needs to be adjusted regularly.

    Key Differences

    • Functionality and Control: Ball valves are best for quick, on/off control but can offer some throttling capabilities. Globe valves excel in applications requiring precise flow regulation.
    • Pressure Drop: Ball valves have a lower pressure drop in the open position due to the straight-through flow path, making them more efficient for certain applications. Globe valves, with their Z-shaped flow path, incur a higher pressure drop but provide better flow control.
    • Operational Speed: Ball valves can be operated quickly with a quarter-turn, making them suitable for emergency and safety-related applications. Globe valves require multiple turns, offering slower but more precise control.

    Choosing between a ball valve and a globe valve depends on the specific needs of the application, including the type of control required (on/off vs. throttling), operational efficiency (pressure drop concerns), and the fluid service conditions (temperature, pressure, and corrosiveness).

    Ball Valve Vs. Butterfly Valve

    Ball valves and butterfly valves are both popular choices for controlling the flow of fluids in piping systems, but they have distinct features, operating mechanisms, and suitability for different applications. Understanding their differences is key to selecting the most appropriate valve for a specific use case.

    Ball Valve

    • Design: Features a spherical disc (the ball) with a hole through its center. The ball rotates within the valve body to open or close the flow path.
    • Operation: Utilizes a quarter-turn mechanism for operation, allowing for quick and easy shutoff. The handle’s position directly indicates the valve’s open or closed status.
    • Sealing: Typically offers excellent sealing capabilities due to the tight fit between the ball and the valve seats, making it suitable for gas and high-pressure applications.
    • Flow Control: While primarily used for on/off control, some ball valves are designed for flow regulation. However, they are not as precise in controlling flow as butterfly valves.
    • Pressure Drop: When fully open, ball valves usually present a minimal pressure drop because the hole in the ball allows for nearly unrestricted flow.

    Butterfly Valve

    • Design: Consists of a flat disc that rotates around a central axis within the valve body. The disc’s position relative to the flow direction controls the fluid passage.
    • Operation: Also operates with a quarter-turn mechanism, allowing for rapid opening and closing. The lever or gear operator indicates the valve’s position.
    • Sealing: Offers good sealing with the use of elastomeric seat materials but may not be as tight as a ball valve, especially under high-pressure conditions.
    • Flow Control: Excellently suited for throttling applications due to the ease with which the disc can be positioned to regulate flow. Provides more precise flow control compared to ball valves.
    • Pressure Drop: Even when fully open, the presence of the disc within the flow path means butterfly valves typically have a higher pressure drop than ball valves.

    Key Differences

    • Application Suitability: Ball valves are preferred for applications requiring tight shutoffs, such as in gas transmission and high-pressure scenarios. Butterfly valves are favored in applications where precise flow control and regulation are necessary, especially in larger diameter pipes where ball valves would be impractical or too expensive.
    • Operational Efficiency: Ball valves provide a more secure seal and are generally more effective for on/off control, while butterfly valves offer superior capabilities for flow modulation and adjustment.
    • Cost and Space Considerations: Butterfly valves tend to be more cost-effective for larger sizes and require less space for installation due to their compact design compared to ball valves.

    The choice between a ball valve and a butterfly valve ultimately depends on specific factors like the fluid’s nature, pressure, and temperature conditions, required flow control precision, space availability, and budget constraints. Each valve type has its advantages and ideal use cases, ensuring optimal performance for various applications.

  • MATERIALS FOR BALL VALVES

    Cast Vs. Forged Ball Valves Body Materials

    Ball valves are manufactured either with cast or forged body materials (which can be monoblock, or split, body types).

    When Forged Bodies?

    Generally, ball valves below 2 inches in diameter are manufactured in 2 pieces or 3 pieces body configurations (the most common materials used for forged ball valves are ASTM A105 for high-temperature service, ASTM A350 LF2/LF3 for low-temperature service, and ASTM A182 F304/F316 for stainless steel valve or higher grades, such as duplex valves ASTM A182 F51 and super duplex ASTM A182 F53/F55).

    Forged bodies are also used for high-pressure valves of higher bore sizes (with 2 or 3-piece split body construction).

    Examples of forged ball valves (small size and stainless steel valve with a forged body, trunnion mounted).

    ball valve sphere

    When Cast Bodies?

    Valves in sizes above 2 inches are generally manufactured with cast body materials (the most common grades are ASTM A216 WCB for high temp. service, ASTM A352 for low-temperature service and ASTM A351 CF8, CF8M for cast stainless steel valves).

    ASTM Materials For Ball Valves

    • Carbon Steel: ASTM A216 WCB is a common grade used for the valve body in moderate temperature applications. It offers good strength and toughness.
    • Stainless Steel: ASTM A351 CF8M (equivalent to SS316) and ASTM A351 CF8 (equivalent to SS304) are widely used for corrosion resistance in harsh environments.
    • Alloy Steel: ASTM A494 CW-6MC (Inconel 625), ASTM A494 CW-12MW (Hastelloy C), and other alloys are used for high-temperature and high-corrosion applications.
    • Bronze and Brass: ASTM B62 (Bronze) and ASTM B16 (Brass) are used for general low-pressure applications and are particularly common in plumbing and water systems.

    API Materials For Ball Valves

    • API 608: Specifies the requirements for ball valves used in the petroleum and natural gas industries. This standard covers material requirements for different classes of service, including carbon steel, stainless steel, and alloy materials.
    • API 6D: While primarily a specification for pipeline valves (including gate, plug, and ball valves), API 6D also outlines material specifications for ball valves used in pipeline applications. Materials are chosen based on the pressure and temperature class of the valve.

    Material Selection Considerations

    • Corrosion Resistance: Stainless steel and alloy materials are selected for services involving corrosive fluids, while carbon steel may be sufficient for water, steam, and oil where corrosion is not a significant concern.
    • Temperature and Pressure: High-temperature and high-pressure applications may require alloy steels or special alloys to maintain integrity under extreme conditions.
    • Compatibility: The material must be compatible with the fluid to prevent contamination or degradation of the valve components.
/by
,

Understand Check Valves (BS 1868, API 6D, API 602)

A check valve prevents potentially damaging backflows to protect equipment like pumps and compressors. Non-return valves allow the flow of the fluid in one direction only and block reverse flows. This type of valves is available with cast and forged bodies (BS 1868, API 6D, API 602) and in several designs as swing, ball, lift, stop and piston designs.

CHECK VALVE

WHAT IS A CHECK VALVE?

Briefly, a check valve is a protection device that prevents the fluid from flowing in an unwanted direction within the piping system or the pipeline (as backflows may damage upstream equipment).

A check valve, also known as a non-return valve or one-way valve, is a type of valve that allows fluid (liquid or gas) to flow through it in only one direction. Check valves are used to prevent the backflow of fluid, automatically preventing reversed flow when the fluid in the line reverses direction. They are crucial components in various piping systems to ensure the safety and efficiency of operations.

Swing check valve

Design And Operation

Check valves operate automatically and most do not have any valve handle or stem. The design of a check valve incorporates a mechanism that opens with forward flow and closes against reverse flow. This mechanism can vary depending on the type of check valve, but common types include ball check valves, swing check valves, and lift check valves:

  • Ball Check Valve: Utilizes a ball that rests on a seat within the valve body. Forward flow lifts the ball off the seat, allowing flow, while reverse flow presses the ball back onto the seat, blocking the flow.
  • Swing Check Valve: Features a disc or a door that swings on a hinge or a shaft. The disc swings off the seat to permit forward flow and swings back to the seat to block reverse flow.
  • Lift Check Valve: Contains a disc or cone that lifts vertically off the seat by the pressure of the forward flow. When the flow stops or reverses, gravity or reverse flow pushes the disc back onto the seat to stop backflow.

Applications

Check valves are used in a wide range of applications to protect equipment, maintain process conditions, and ensure directional flow, including:

  • Pump Protection: To prevent backflow that could damage pumps and drive systems.
  • Preventing Contamination: To stop backflow in systems where contamination could be a significant issue, such as in potable water supply.
  • Pressure Maintenance: In systems where pressure needs to be maintained in one part of the system, preventing fluid from flowing back and reducing pressure.
  • Safety Applications: In systems where reverse flow could lead to hazardous conditions or equipment failure, such as in gas supply systems.

Advantages And Limitations

Advantages:

  • Automatic operation, requiring no external controls or power.
  • Simple design, leading to reliability and ease of maintenance.
  • Available in a wide range of sizes and materials, suitable for various applications and fluids.

Limitations:

  • Potential for water hammer or surge pressures due to the rapid closing of the valve, especially in fast-flowing systems.
  • Limited flow control capabilities since they are designed primarily for preventing backflow rather than regulating flow.
  • Possibility of leakage if debris prevents the valve from fully closing.

In summary, check valves play a vital role in ensuring the unidirectional flow of fluids in piping systems, offering protection against reverse flow and its associated problems. Selecting the appropriate type of check valve depends on specific system requirements, including flow rate, pressure, and the nature of the fluid.

Cast steel valves are available with flanged and butt weld ends.
Forged, small-size, valves are available with threaded and socket weld connections.

These valves are represented by the following symbol in piping P&ID diagrams: Symbol for check valve in P&ID diagram

HOW TO SELECT A CHECK VALVE?

Selecting the right check valve for a particular application requires careful consideration of various factors to ensure optimal performance, reliability, and safety of the piping system. Here’s a step-by-step guide on how to select a check valve:

1. Understand The Application

  • Fluid Type: Determine the type of fluid (water, oil, gas, etc.), as this will influence the material selection for the check valve to ensure compatibility and prevent corrosion.
  • Flow Conditions: Consider the flow rate, pressure, and temperature of the system. The check valve must be capable of operating effectively under these conditions.

2. Determine The Correct Size

  • Pipe Size: The check valve should match the size of the connecting pipe to ensure proper fit and minimize installation issues.
  • Flow Requirements: Calculate the required flow rate (Cv) to ensure the valve can handle the system’s flow without causing excessive pressure drop or flow restriction.

3. Select The Valve Type

Based on the application requirements, decide on the type of check valve needed. Common types include:

Each type of check valve is discussed later in greater detail.

4. Choose The Material

  • Body and Trim Material: Select materials that are compatible with the fluid type and the operating conditions (temperature and pressure). Common materials include stainless steel for corrosive fluids, cast iron for water applications, and PVC for chemical services.
  • Sealing Material: Ensure the sealing material (e.g., NBR, EPDM, Viton) is suitable for the fluid type and temperature.

5. Consider End Connections

  • Connection Type: Choose the appropriate end connection (flanged, threaded, wafer, socket weld, etc.) based on the piping system design and ease of maintenance.

6. Evaluate Special Requirements

  • Leakage: Determine the acceptable level of leakage, if any. Some systems may require a zero-leakage valve.
  • Orientation: Consider the installation orientation (horizontal, vertical flow up, vertical flow down) as it may affect the valve’s operation.
  • Pressure Drop: Minimize pressure drop by selecting a valve with an appropriate flow design.
  • Back Pressure: Ensure the system provides sufficient back pressure to close the valve properly.

7. Regulatory And Standards Compliance

  • Verify that the check valve meets any applicable industry standards (e.g., API, ASME, ANSI) and regulatory requirements for safety and performance.

8. Manufacturer And Warranty

  • Select a reputable manufacturer with proven experience in check valves for similar applications. Review warranty terms and post-sale support.

By systematically addressing these selection criteria, you can ensure that the chosen check valve will perform efficiently and reliably within your specific application, contributing to the overall safety and effectiveness of the piping system.

APPLICABLE SPECIFICATIONS (BS, API, ASME)

The key specifications that cover this type of valve are:

Check valves, critical components in various piping systems, are governed by numerous standards to ensure their reliability, safety, and performance. These standards, set by recognized bodies like the British Standards (BS), the American Petroleum Institute (API), and the American Society of Mechanical Engineers (ASME), specify design criteria, material specifications, testing requirements, and performance characteristics for check valves. Here’s a brief overview of some key BS, API, and ASME specifications applicable to check valves:

British Standards (BS)

  • BS 1868: Steel Check Valves for the Petroleum, Petrochemical, and Allied Industries
    • Specifies requirements for steel check valves with flanged and butt-welding ends, designed for the petroleum, petrochemical, and allied industries. It covers valves of nominal sizes DN 50 to DN 600 and specifies body materials, pressure-temperature ratings, and testing.
  • BS EN 12334: Industrial Valves – Check Valves of Metallic Materials
    • This European Standard specifies requirements for check valves made from metallic materials excluding steel and applies to check valves used for all industrial applications. It includes provisions for nominal sizes, pressure designations, and aspects of design, testing, and marking.

    • American Petroleum Institute (API)

      • API 6D: Specification for Pipeline and Piping Valves
        • While API 6D covers a broad range of pipeline valves, it includes specific requirements for check valves used in pipeline applications. It addresses aspects like design, materials, testing, and documentation for valves intended for use in the petroleum and natural gas industries.
      • API 594: Check Valves: Flanged, Lug, Wafer, and Butt-Welding
        • API 594 is dedicated to check valves and covers design, materials, face-to-face dimensions, pressure-temperature ratings, and testing for check valves with flanged, lug, wafer, and butt-welding ends. It applies to types A (single plate) and B (double plate).
      • API 598: Valve Inspection and Testing
        • While not specific to check valves, API 598 covers the inspection and testing of all types of valves, including check valves. It outlines the testing methods and acceptance criteria for pressure testing to ensure valve integrity and leak tightness.
      • API 620: Forged check valves

      American Society Of Mechanical Engineers (ASME)

      • ASME B16.34: Valves – Flanged, Threaded, and Welding End
        • This standard establishes requirements for materials, pressure-temperature ratings, dimensions, tolerances, and markings for gate, globe, check, ball, and butterfly valves. It includes criteria that check valves must meet for design and construction.
      • ASME B16.10: Face-to-Face and End-to-End Dimensions of Valves
        • ASME B16.10 specifies the face-to-face and end-to-end dimensions of valves, including check valves. This standard ensures compatibility and interchangeability in valve replacements and installations.
      • ASME B16.25: Buttweld ends

      Adherence to these BS, API, and ASME specifications is essential for the proper selection, installation, and maintenance of check valves in various industrial applications. Compliance with these standards guarantees that check valves meet the necessary quality, safety, and performance requirements for their intended use.

      CHECK VALVE TYPES

      Check valves, essential components in preventing backflow in piping systems, come in various designs to accommodate different flow dynamics, pressure conditions, and installation requirements. Here’s a detailed explanation of the different types of check valves:

      Swing, Ball, Lift, Piston valves

      SWING CHECK VALVE

      Swing check valves are a type of non-return valve used in piping systems to prevent backflow. They operate automatically, allowing fluid to flow through in one direction and preventing reverse flow. The design and operation of swing check valves make them suitable for a wide range of applications, particularly where low-pressure drop and self-acting backflow prevention are required.

      Swing Check Valve Design

      The primary components of a swing check valve include:

      • Body: The outer casing of the valve, which contains the internal components. It can be made from various materials, including cast iron, steel, stainless steel, and PVC, depending on the application requirements.
      • Disc: A movable door-like element that swings on a hinge or a shaft. The disc opens with forward flow and swings back to its closed position when the flow stops or reverses, blocking the flow.
      • Seat: The surface against which the disc seals when the valve is closed. The seat can be integral to the valve body or replaceable, and it is often designed to ensure a tight seal to prevent backflow.
      • Hinge or Shaft: Enables the swinging motion of the disc. In some designs, a lever and weight or spring mechanism may be added to assist in closing the valve more rapidly or controlling the swing to reduce the water hammer.

      Operation

      In operation, the pressure of the forward flow pushes the disc open, allowing fluid to pass through the valve. When the flow stops or reverses, the disc swings back to its closed position, either due to gravity or assisted by a lever and weight mechanism, preventing backflow. The simplicity of this mechanism ensures reliability and minimal maintenance.

      Advantages

      • Low-Pressure Drop: When fully open, swing check valves provide a relatively straight flow path, resulting in a low-pressure drop across the valve.
      • Simple and Reliable: The design is straightforward, with few moving parts, contributing to the valve’s reliability and ease of maintenance.
      • Versatility: Suitable for a wide range of fluids, including water, oil, and gas, and can be used in various applications, from low to high-pressure systems.

      Applications

      Swing check valves are commonly used in:

      • Water Supply Systems: To prevent backflow and protect equipment like pumps.
      • Wastewater Treatment: Where preventing reverse flow is crucial for process integrity.
      • Industrial Processes: In chemical, petrochemical, and other industrial plants where backflow prevention is necessary.

      Considerations

      While swing check valves are suitable for many applications, proper selection involves considering factors like the risk of water hammer (sudden closing can lead to pressure surges), the need for rapid closure, and the compatibility of valve materials with the fluid. Additionally, they are not recommended for pulsating flows as the constant opening and closing may lead to premature wear or failure.

      In summary, swing check valves offer a simple, efficient solution for preventing backflow in piping systems, combining low-pressure drop with reliable operation across a broad range of applications.

      swing check type

      STOP CHECK VALVE

      Stop check valves are specialized valves that combine the features of a check valve and a globe valve, offering both backflow prevention and the ability to manually stop the flow of fluid in a piping system. They provide a unique functionality that allows operators to control the valve’s position, acting as a check valve when left to operate automatically or as an isolation valve when manually adjusted.

      stop-check design

      Design Of Stop Check Valves

      The key components of a stop check valve include:

      • Body: The outer casing that houses the valve’s internal mechanisms. It can be made of various materials suited to the application’s needs, such as cast iron, stainless steel, or other alloys.
      • Disc: A movable element that lifts away from the valve seat to allow flow in one direction and seats back to block flow in the opposite direction. Unlike standard check valves, the disc in a stop check valve can also be manually positioned to fully close, regardless of flow direction.
      • Stem: Connected to the disc, the stem can be moved manually (e.g., via a handwheel or actuator) to lift the disc from the seat or to firmly press it against the seat, effectively stopping flow.
      • Seat: The area against which the disc seals to prevent backflow or to stop flow entirely when the valve is manually closed.
      • Bonnet: The top part of the valve that contains the stem and, in some designs, may house packing material to prevent leaks along the stem.

      Operation

      In its default mode, a stop check valve functions as a check valve, allowing flow in one direction and automatically preventing backflow by seating the disc against the valve seat under reverse flow conditions. However, the key feature of a stop check valve is its ability to be manually closed by an operator, overriding the automatic function. This is accomplished by turning the handwheel or actuator, which moves the stem and disc into a closed position against the seat, regardless of flow direction or pressure.

      Advantages

      • Dual Functionality: Provides the benefits of a check valve and a globe valve in a single unit, offering flexibility in applications that require both backflow prevention and flow isolation.
      • Manual Override: The ability to manually stop flow, irrespective of system pressure or flow direction, enhances control over the system.
      • Safety and Protection: Helps protect against reverse flow that could damage equipment, while also allowing for system maintenance by isolating parts of the system.

      Applications

      Stop check valves are commonly used in high-pressure and high-temperature applications, such as:

      • Boilers: To prevent the backflow of water or steam that could damage the boiler or other equipment in steam systems.
      • Power Generation: In feedwater lines, to control flow to steam generators and allow for system isolation for maintenance.
      • Process Industries: Where process safety requires both the prevention of backflow and the ability to isolate sections of the system for maintenance or emergency shutdowns.

      Considerations

      When selecting a stop check valve, it’s essential to consider the fluid characteristics, pressure and temperature conditions, and the specific requirements for flow control and isolation. Additionally, like all valves, regular maintenance is necessary to ensure reliability, especially given the critical safety functions these valves often serve.

      In summary, stop check valves offer a versatile solution for systems requiring both backflow prevention and the capability to manually stop flow, making them invaluable in various industrial applications where safety, control, and maintenance are paramount.

      BALL CHECK VALVE

      A ball check valve is a type of check valve that uses a ball to prevent backflow in a piping system. It operates automatically, allowing fluid to flow through it in one direction and preventing reverse flow by utilizing a ball that moves within the valve body. Ball check valves are simple, reliable, and effective for a wide range of applications, particularly where viscous fluids or fluids with suspended solids are present.

    • Design

      The key components of a ball check valve include:

      • Body: The outer casing of the valve, which can be made from various materials such as cast iron, stainless steel, PVC, or other corrosion-resistant alloys, depending on the fluid characteristics and application requirements.
      • Ball: The movable element inside the valve that seals against reverse flow. The ball is typically made of metal, rubber, or plastic. Its material and density are chosen based on the fluid type and the required sealing capability.
      • Seat: The surface inside the valve body against which the ball seals when the valve is closed. The seat is often designed to match the contour of the ball for a tight seal and can be made from materials similar to or compatible with the ball.
      • Cover or Bonnet: A removable part that provides access to the interior of the valve for maintenance, inspection, or replacement of the ball and seat.

      Operation

      In operation, forward fluid pressure pushes the ball away from the seat, allowing fluid to flow through the valve. When the fluid flow stops or reverses direction, the ball rolls or is pushed back against the seat by the reverse flow, effectively sealing the valve and preventing backflow. In some designs, a spring or external weight may assist in closing the valve, especially in horizontal installations where gravity alone may not be sufficient to seal the valve.

      Advantages

      • Versatility: Effective for a broad range of fluids, including liquids and gases, and particularly suitable for viscous fluids and slurries.
      • Low Maintenance: The simple design has few moving parts, reducing the risk of malfunction and the need for maintenance.
      • Durability: When made with appropriate materials, ball check valves can be highly durable and resistant to wear and corrosion.
      • Self-Cleaning: The rolling action of the ball can help dislodge small particles, preventing clogging and ensuring reliable operation.

      Applications

      Ball check valves are used in various applications, including:

      • Wastewater and Sewage Systems: For preventing backflow in sewage lines and treatment facilities.
      • Chemical Processing: In systems handling viscous chemicals or fluids with suspended solids.
      • Pumping Systems: To prevent reverse flow and protect pumps in water, oil, and other liquid transfer systems.
      • Agricultural Irrigation: In irrigation systems to maintain water flow direction and prevent contamination.

      Selection Considerations

      When selecting a ball check valve, consider:

      • Fluid Characteristics: Ensure compatibility with the valve materials to prevent corrosion or degradation.
      • Pressure and Temperature: Choose a valve rated for the system’s maximum pressure and temperature conditions.
      • Installation Orientation: While ball check valves are versatile, confirm the valve’s suitability for the intended orientation, especially in horizontal lines.
      • Valve Sizing: Proper sizing is crucial to minimize pressure drop while ensuring effective backflow prevention.

      Ball check valves offer a practical solution for preventing backflow in a wide range of applications. Their simplicity, reliability, and effectiveness make them a preferred choice in systems where maintenance should be minimal, and fluid characteristics are challenging.

      Ball check valves belong to the family of “lift valves”, and have a seat design similar to globe valves.

    • A variant of the ball design is the so-called piston type. This type of valve is used for high-pressure services where the fluid can change direction suddenly and with good force (this because the disc is precisely guided and fits perfectly into the seat).

      Ball and piston check valves can be installed both horizontally and vertically.

      DUAL PLATE CHECK VALVE

      A dual plate check valve, also known as a double door check valve or a butterfly check valve, is an advanced design of the traditional check valve. It operates automatically to prevent the backflow of fluid in a piping system, ensuring flow in only one direction. The valve features two spring-loaded plates (or discs) that open with forward flow and close rapidly to prevent reverse flow, making it an efficient and reliable choice for a wide range of applications.

      dual plate check valve

      Design

      The key components and design features of a dual plate check valve include:

      • Body: The outer shell of the valve that houses the internal components. It can be made from various materials, including cast iron, stainless steel, carbon steel, and other alloys, depending on the application’s specific requirements for pressure, temperature, and corrosion resistance.
      • Plates (Discs): Two semi-circular plates are hinged on either side of the valve body, allowing them to swing open or close. The plates are typically lightweight, enhancing their ability to respond quickly to changes in flow direction.
      • Springs: Each plate is equipped with a spring that facilitates quick closing of the plates when the forward flow stops or when there is a reversal in flow direction. The springs help in minimizing the risk of water hammer and valve slam.
      • Seat: A sealing surface inside the valve body against which the plates close. The seat can be integral to the valve body or replaceable and is designed to ensure a tight seal when the valve is closed.
      • Hinge Pins: Pins around which the plates pivot. They are designed to ensure smooth and reliable operation of the plates.

      Operation

      In operation, forward flow exerts pressure on the plates, causing them to swing open and allow fluid to pass through the valve. The design of the plates and the presence of springs ensure that they open with minimal pressure drop. When the flow decreases or reverses, the springs assist in quickly closing the plates, preventing backflow. The rapid response of the plates helps to significantly reduce the potential for water hammer.

      Advantages

      • Compact and Lightweight: Dual plate check valves are more compact and lighter than traditional swing check valves, making them easier to install and requiring less support structure.
      • Low-Pressure Drop: The design allows for a smoother flow path when open, resulting in a lower pressure drop compared to other types of check valves.
      • Quick Closure: The spring-loaded plates close rapidly, reducing the risk of water hammer and backflow.
      • Versatility: Suitable for a wide range of applications and can be installed in both horizontal and vertical orientations with upward flow.

      Applications

      Dual plate check valves are used in various industrial applications, including:

      • Water and Wastewater Treatment: To prevent backflow in treatment plants and distribution systems.
      • Oil and Gas: In pipelines and processing facilities for protecting equipment and ensuring unidirectional flow.
      • HVAC Systems: To prevent reverse flow in heating and cooling systems.
      • Process Industries: In chemical, petrochemical, and food and beverage processing plants to protect sensitive equipment and maintain process integrity.

      Selection Considerations

      When selecting a dual plate check valve, it’s important to consider:

      • Fluid Characteristics: Compatibility with the valve materials to prevent corrosion and ensure durability.
      • Operating Conditions: The valve’s rating must match the system’s maximum pressure and temperature.
      • Installation Space: The compact design is advantageous in tight spaces, but the orientation and location should still be considered for optimal performance.
      • Maintenance Requirements: Though generally low maintenance, access for inspection or replacement of components should be considered.

      In summary, dual plate check valves offer an efficient and reliable solution for preventing backflow in piping systems, combining compact design with quick operation and low-pressure drop. Their versatility and performance advantages make them suitable for a broad range of applications across various industries.

      TITLING DISC CHECK VALVE

      A tilting disc check valve is a type of check valve designed to allow fluid to flow in one direction and prevent backflow. It features a disc that tilts on a hinge or pivot point, opening in response to forward flow and closing when the flow stops or reverses. This design offers improved dynamics over traditional swing check valves, making it particularly effective in applications where rapid closure is needed to prevent reverse flow and minimize the risk of water hammering.

      titling disc check valve
      titling disc check valve

      Design Features

      • Disc Mechanism: The disc in a tilting disc check valve is mounted such that it tilts around a point or axis that is offset from the center of the disc. This allows the disc to open with a smaller amount of fluid pressure compared to swing check valves and to close more quickly as the flow diminishes.
      • Seat: The valve seat is designed to provide a tight seal when the disc closes. The seating arrangement can be configured to reduce wear and enhance the sealing capability.
      • Body: The valve body can vary in design but is typically streamlined to facilitate smooth fluid flow and minimize pressure drop across the valve.

      Operational Advantages

      • Quick Response: The tilting mechanism allows for rapid opening and closing of the valve, which helps in preventing the backflow more effectively and reduces the potential for water hammer, a pressure surge caused when a fluid in motion is forced to stop or change direction suddenly.
      • Low-Pressure Drop: When open, the valve offers minimal obstruction to the flow, resulting in a lower pressure drop compared to some other check valve designs.
      • Long Service Life: The design of the tilting disc check valve, including the way the disc interacts with the flow, can contribute to reduced wear on the valve components, leading to a longer service life.

      Applications

      Tilting disc check valves are suitable for a wide range of applications, particularly in systems where rapid valve closure is necessary to protect equipment and ensure system integrity. Common applications include:

      • Water Supply Systems: Used in high-rise buildings and municipal water distribution networks to prevent backflow.
      • Power Generation: Installed in cooling water systems, feedwater systems, and condensate pump discharge lines to prevent reverse flow.
      • Process Industries: Utilized in chemical and petrochemical plants, where the prevention of backflow is critical to process safety and efficiency.
      • HVAC Systems: Implemented heating and cooling systems to maintain directional flow and system balance.

      Selection Considerations

      When selecting a tilting disc check valve, consider the following:

      • Fluid Characteristics: Ensure the valve materials are compatible with the fluid, including considerations for temperature, pressure, and potential corrosiveness.
      • Installation Orientation: While versatile, the specific design of the tilting disc check valve may make it more suitable for certain orientations. Consult manufacturer recommendations.
      • Maintenance Requirements: Consider the ease of maintenance and access to internal components, as regular inspection may be necessary to ensure optimal performance.

      Tilting disc check valves offer an efficient solution for preventing backflow in fluid systems, combining quick response, durability, and effective operation across a variety of applications.

    • FOOT CHECK VALVE

      A foot check valve is a specific type of check valve designed to be installed at the bottom of a pump suction line, primarily used to maintain the pump’s prime by preventing the backflow of fluid. These valves are typically submerged in the source fluid, such as a well or a tank. Foot check valves are essential components in pumping systems where the pump is located above the fluid level, ensuring a steady and reliable supply of fluid to the pump and preventing the system from running dry.

      foot check valve
      foot check valve

      Design Features

      • Body: Foot check valves are commonly made from durable materials such as cast iron, stainless steel, PVC, or bronze, depending on the application and the type of fluid being handled.
      • Screen or Strainer: A key feature of foot check valves is the integrated screen or strainer at the inlet. This screen prevents debris, sediment, and other particulates from entering the pump suction line, protecting the pump and the system from damage.
      • Valve Mechanism: The valve mechanism can vary but often includes a ball, disc, or flap that opens under the pressure of incoming fluid when the pump operates. When the pump stops, the mechanism seals against a seat to prevent fluid from flowing backward.

      Operational Advantages

      • Maintains Prime: By preventing the backflow of fluid, foot check valves help maintain the pump’s prime, which is crucial for efficient pump operation and to avoid pump damage due to dry running.
      • Filtration: The built-in screen or strainer filters out debris, ensuring that the fluid entering the pump is free from particulates that could cause wear or clogs.
      • Versatility: Suitable for a wide range of applications, including water, chemicals, and other fluids, depending on the construction materials.

      Applications

      Foot check valves are used in various applications where pumps need to draw fluid from a source below the pump, such as:

      • Water Supply Systems: In wells, cisterns, or tanks where pumps supply water to residential, agricultural, or industrial systems.
      • Irrigation Systems: To ensure a constant supply of water and prevent contamination of the water source by soil or debris.
      • Flood Control and Drainage: In pumping stations that remove water from low-lying areas.
      • Industrial Processes: Where liquid ingredients or products are transferred from storage tanks into processing systems.

      Selection Considerations

      When choosing a foot check valve, it’s essential to consider:

      • Fluid Compatibility: Select materials that are compatible with the fluid to prevent corrosion or chemical degradation.
      • Screen Mesh Size: The mesh size of the screen should be suitable for filtering out debris while allowing sufficient flow to meet the system’s demands.
      • Pressure and Flow Requirements: Ensure the valve can handle the system’s pressure and flow rate without causing excessive pressure drop or hindering pump performance.
      • Maintenance Accessibility: Consider how easily the valve can be accessed for cleaning or maintenance, especially since foot check valves are often submerged.

      In summary, foot check valves play a critical role in pumping systems, providing both a non-return function to maintain the pump prime and a filtration role to protect the pump and the system. Their selection and maintenance are vital for the reliability and efficiency of fluid transfer operations.

      PRESSURE SEAL CHECK VALVE

      Pressure seal check valves are a type of check valve designed for high-pressure and high-temperature applications, commonly found in power generation, oil and gas, and industrial process systems. Unlike traditional bolted bonnet check valves, pressure seal check valves use a pressure seal bonnet design that ensures a tighter seal as system pressure increases. This design is particularly effective in environments where safety and efficiency are paramount, and where operating conditions can exceed pressures of 600 psi and temperatures above 1000°F (538°C).

    • Pressure seal check valve

      Design

      The key components of a pressure seal check valve include:

      • Body: The main structure that contains the internal components. It can be made of materials suited for high pressure and temperature, such as carbon steel, alloy steel, or stainless steel.
      • Bonnet: Instead of being bolted to the body, the bonnet in a pressure seal valve is sealed using a pressure seal gasket. As system pressure rises, the gasket is further compressed, enhancing the seal between the bonnet and the valve body.
      • Pressure Seal Gasket: A unique component of pressure seal valves, this gasket is usually made of flexible graphite for high-temperature applications or metal for extremely high pressures. It is designed to ensure a tight seal that improves with increased pressure.
      • Disc: The movable part that opens to allow flow in the forward direction and seats against the valve seat to prevent backflow. The design of the disc can vary but typically mirrors that of swing or lift check valves.
      • Seat: The surface against which the disc seals when the valve is closed. It can be integral to the valve body or replaceable, depending on the design.

      Operation

      In operation, forward flow pressure pushes the disc away from the seat, allowing fluid to pass through the valve. When flow stops or reverses, the disc moves back to the seat, preventing backflow. The unique pressure seal design ensures that as system pressure increases, the seal between the bonnet and the body becomes tighter, which is particularly advantageous in high-pressure applications where ensuring a reliable seal is challenging.

      Advantages

      • High-Pressure and Temperature Capability: Designed to operate reliably in conditions where standard check valves might fail, making them ideal for critical applications.
      • Improved Seal Integrity: The pressure seal design ensures that the valve’s sealing capability improves under higher pressures, providing a robust solution for high-pressure systems.
      • Compact Design: Pressure seal valves tend to be more compact than their bolted bonnet counterparts, beneficial in systems where space is limited.

      Applications

      Pressure seal check valves are used in applications that demand reliable operation under high pressure and temperature, such as:

      • Power Generation: In steam, feedwater, and other high-pressure systems within power plants.
      • Oil and Gas Production: For high-pressure drilling and production systems.
      • Chemical Processing: In processes involving high-pressure reactions or transfers.

      Selection Considerations

      When selecting a pressure seal check valve, consider:

      • System Pressure and Temperature: Ensure the valve material and design are rated for the system’s maximum operating pressure and temperature.
      • Fluid Compatibility: Choose materials that are compatible with the fluid to prevent corrosion or degradation of the valve components.
      • Maintenance Requirements: While durable, pressure seal valves can be more challenging to maintain due to their design. Consider ease of maintenance and access when selecting a valve.

      Pressure seal check valves offer a reliable solution for controlling flow in high-pressure and high-temperature systems, ensuring safety and efficiency in demanding industrial environments.

      DUCKBILL CHECK VALVE

      A duckbill check valve is a unique type of check valve that gets its name from the duckbill-shaped flexible rubber or elastomer flap that acts as the valve mechanism. This design allows the valve to permit fluid flow in one direction while preventing backflow in the opposite direction. Duckbill check valves are known for their simplicity, reliability, and low maintenance, making them an excellent choice for various fluid control applications, especially where backflow prevention is critical.

      Duckbill Valve
      Duckbill Valve

      IN-LINE CHECK VALVE

      An inline check valve, also known as an in-line check valve, is a type of check valve designed for simple, direct installation within the pipeline. Its primary function is to allow fluid (liquid or gas) to flow in one direction only, preventing backflow which could potentially cause damage or disrupt the operation of a system. Inline check valves are known for their compact design, which makes them particularly suitable for applications with limited space.

      Inline Check Valve
      Inline Check Valve

      Design Features

      • Compact and Simple: Inline check valves have a straightforward and compact design, allowing for easy installation directly into a piping system without the need for special fittings or extensive modifications.
      • Body Construction: The valve body is typically cylindrical and can be made from a variety of materials, including metals like brass, stainless steel, and PVC, to suit different application needs and fluid compatibility.
      • Closure Mechanism: The closure component inside an inline check valve varies by design but commonly includes a ball, disc, or piston that moves away from the valve seat to allow flow and seals against the seat to prevent backflow. Some designs use a spring to ensure the closure mechanism responds quickly to changes in flow direction.
      • Connection Types: Inline check valves are available with various types of end connections, such as threaded, socket weld, or flanged, to match the piping system requirements.

      Operational Advantages

      • Low Pressure Drop: Many inline check valve designs are optimized to minimize pressure drop across the valve when it is in the open position, maintaining system efficiency.
      • Fast Response to Flow Changes: The simplicity of the design often allows for a quick response to stopping backflow, protecting the system from potential damage.
      • Versatility: Inline check valves can be used in a wide range of applications and are compatible with many types of fluids and gases.

      Applications

      Inline check valves are used across various industries and applications, including:

      • Water and Wastewater Systems: To prevent backflow and protect pumps and other equipment.
      • Chemical Processing: For ensuring unidirectional flow of chemicals in processing lines.
      • HVAC Systems: In heating and cooling lines to maintain proper flow direction.
      • Hydraulic and Pneumatic Systems: To prevent reverse flow in systems that rely on pressurized fluids or air.

      Selection Considerations

      When selecting an inline check valve, consider the following:

      • Material Compatibility: Choose a valve material that is compatible with the fluid or gas to prevent corrosion or chemical degradation.
      • Operating Conditions: Ensure the valve can withstand the system’s pressure and temperature conditions.
      • Flow Requirements: Select a valve size and design that meets the flow rate requirements without causing excessive pressure drop.
      • Maintenance and Accessibility: Consider how the valve design will impact maintenance needs and whether it can be easily accessed for service if necessary.

      Inline check valves offer a convenient and efficient solution for ensuring unidirectional flow in piping systems. Their compact design, ease of installation, and reliability make them a popular choice for many applications where backflow prevention is critical.

      SUMP PUMP CHECK VALVE

      A sump pump check valve is a critical component in a sump pump system, designed to prevent the backflow of water from the discharge pipe back into the sump pit after the pump has turned off. Sump pumps are commonly used in basements and crawl spaces to remove accumulated water, preventing flooding and water damage. The check valve ensures that once water is pumped out of the pit and through the discharge line, it does not return, thereby enhancing the efficiency of the pump and reducing the risk of flooding.

      Design

      The design of a sump pump check valve is relatively simple, comprising a few key components:

      • Body: Usually made of durable plastic, PVC, or sometimes metal, designed to withstand the water pressure and any debris that might be present in the water.
      • Flapper or Ball: The mechanism inside the valve that allows water to flow in one direction and blocks it from flowing backward. In sump pump check valves, a flapper or a ball is common, which moves or tilts to open when water is pumped through and seals shut when the flow stops.
      • Connectors: Ends that attach to the discharge pipe of the sump pump and the discharge line leading away from the house. These can be designed for various types of connections, including threaded, slip-on, or barbed, depending on the installation requirements.

      Operation

      When the sump pump activates, water pressure opens the flapper or moves the ball, allowing water to pass through the valve and into the discharge line. When the pump shuts off, the decrease in pressure allows the flapper or ball to return to its closed position, creating a seal that prevents water from flowing back into the sump pit. This one-way operation is crucial for maintaining the effectiveness of the sump pump system and preventing cycling (where the pump turns on and off frequently), which can lead to premature pump failure.

      Advantages

      • Prevents Backflow: Keeps pumped water from returning to the sump pit, reducing the workload on the sump pump and minimizing wear.
      • Reduces Cycling: By preventing backflow, it reduces the frequency of pump activation, thereby extending the life of the pump.
      • Simple Installation: Most sump pump check valves are designed for easy installation and can be added to existing systems without significant modifications.

      Applications

      Sump pump check valves are used in residential, commercial, and industrial settings where sump pumps are installed to control water accumulation. These include:

      • Basements and Cellars: To prevent flooding from groundwater or stormwater intrusion.
      • Crawl Spaces: To manage moisture and prevent water damage.
      • Outdoor Drainage Systems: Where pumps are used to move water away from buildings or sensitive areas.

      Selection Considerations

      When choosing a sump pump check valve, consider:

      • Compatibility: Ensure the valve fits the discharge pipe diameter of your sump pump system.
      • Material: Select a material compatible with the type of water being pumped, especially if debris or chemicals may be present.
      • Valve Type: Consider the mechanism (flapper vs. ball) based on the pump’s flow rate and the head pressure.
      • Ease of Maintenance: Some designs allow for easier cleaning and maintenance, which can be beneficial in systems that handle debris-laden water.

      In summary, a sump pump check valve is an essential component that enhances the efficiency and longevity of a sump pump system by preventing backflow of water into the sump pit, ensuring that once water is removed, it stays out.

      CHECK VALVE MATERIALS (ASME, API)

      Materials used for check valves in various industries, particularly those handling critical processes, need to meet specific standards to ensure reliability, safety, and longevity. The American Society of Mechanical Engineers (ASME) and the American Petroleum Institute (API) provide guidelines and standards for materials used in the manufacturing of check valves. These standards help in selecting materials that are suitable for the intended application, especially considering the operational pressures, temperatures, and fluid characteristics. Below are some key materials standards from ASME and API relevant to check valves:

      ASME Material Standards

      • ASME B16.34 – Valves – Flanged, Threaded, and Welding End
        • This standard covers material requirements for ferrous and non-ferrous valve construction, including temperature and pressure ratings for various materials. It is widely referenced for valve materials in piping systems.

      API Material Standards

      • API 600 – Steel Gate Valves – Flanged and Butt-Welding Ends, Bolted Bonnets
        • Though primarily focused on gate valves, API 600 includes material specifications applicable to check valves, especially regarding carbon steel, alloy steel, stainless steel, and other materials for high-pressure and high-temperature service.
      • API 602 – Compact Steel Gate Valves – Flanged, Threaded, Welding, and Extended-Body Ends
        • This standard, while focusing on gate valves, also touches on material specifications for smaller size valves that can be relevant to compact check valves in similar service conditions.

      Common Materials For Check Valves

      • Carbon Steel: Widely used due to its strength and durability, suitable for a broad range of temperatures and pressures. ASME and API standards specify different grades, such as ASTM A216 WCB, for various service conditions.
      • Stainless Steel: Offers excellent corrosion resistance and is used in applications involving corrosive fluids or stringent cleanliness requirements. Common grades include ASTM A351 CF8M (316 stainless steel).
      • Alloy Steel: Used for applications requiring higher strength and resistance to high temperatures or pressures. Alloys like ASTM A217 WC6 are commonly specified for services with elevated temperatures.
      • Bronze and Brass: Offer good corrosion resistance and are commonly used in low to moderate temperature and pressure applications, such as water, gas, and some chemical services.
      • Ductile Iron: Provides good strength, durability, and some corrosion resistance, making it suitable for water and other non-corrosive services at lower costs than steel.

      Considerations For Material Selection

      1. Fluid Service: The material must be compatible with the fluid to prevent corrosion or degradation that could lead to valve failure.
      2. Pressure and Temperature: The material should withstand the maximum expected pressure and temperature in the system.
      3. Environment: External environmental conditions, such as exposure to corrosive atmospheres, should also be considered.

      By adhering to ASME and API material standards, engineers and specifiers can ensure that check valves will perform reliably and safely in their intended applications, maintaining system integrity and protecting against failure.

      CHECK VALVE TRIM

      Check valve trim refers to the internal components of a check valve that come into direct contact with the process fluid and are critical to the valve’s operation and performance. The trim typically includes parts such as the disc (or ball), seat, stem (if applicable), and any springs or other mechanisms that contribute to the opening and closing of the valve. The material selection and design of the check valve trim are crucial for ensuring proper function, durability, and compatibility with the fluid being handled.

      Components Of Check Valve Trim

      • Disc or Ball: The movable part that seals against the seat to prevent backflow. In ball check valves, a ball acts as the movable element, whereas other types of check valves may use a disc or other shapes.
      • Seat: The surface against which the disc or ball seals when the valve is closed. It can be integrated into the valve body or designed as a replaceable component. The seat must provide a tight seal to effectively prevent backflow.
      • Stem: In some types of check valves, such as lift check valves, a stem connects the disc to an actuator or mechanism outside the valve body. The stem facilitates the movement of the disc within the valve.
      • Spring: Many check valves incorporate a spring to assist in closing the valve, ensuring quick response to flow changes and helping to prevent flow reversal and water hammer.

      Material Considerations

      The choice of materials for check valve trim is determined by factors such as:

      • Fluid Compatibility: The trim materials must be chemically compatible with the process fluid to avoid corrosion, degradation, or contamination.
      • Operating Conditions: The materials must withstand the temperature and pressure conditions of the application without losing structural integrity or performance.
      • Wear Resistance: Components like the disc and seat are subject to wear due to repeated opening and closing; thus, materials should be selected for their durability and wear resistance.

      Common materials used for check valve trim include:

      • Stainless Steel: Offers excellent corrosion resistance and strength, suitable for a wide range of applications.
      • Brass: Commonly used in low-pressure applications and compatible with many types of fluids.
      • Bronze: Provides good corrosion resistance and is often used in water and steam applications.
      • Alloy Steels: Selected for high-pressure, high-temperature applications where additional strength and durability are required.
      • Plastics and Composites: Used in applications where corrosion resistance is paramount, such as in aggressive chemical environments.

      Selection Guidelines

      When selecting check valve trim materials, consider the following:

      • Review Fluid Service: Analyze the chemical properties of the fluid, including any potential for corrosion or chemical reaction.
      • Assess Operating Conditions: Ensure the materials can handle the maximum expected temperature and pressure.
      • Consider Flow Characteristics: For applications involving abrasive or viscous fluids, select materials that resist wear and erosion.
      • Compliance with Standards: Ensure that the materials meet relevant industry standards and regulations, such as those set by ASME, API, or NACE for specific applications.

      Choosing the appropriate trim materials is essential for the reliability and longevity of check valves, ensuring they function correctly under the intended service conditions and minimize maintenance requirements.

      CHECK VALVE GA DIAGRAM

      he body of non-return valves below 2 inches is generally made of forged steel (common grades are ASTM A105 for high-temperature service, ASTM A350 for low-temperature service, and, ASTM A182 F304/F316 for corrosive service), whereas the bodies for larger bore sizes check valves are made of cast steel (ASTM A216 WCB for high-temperature service, ASTM A351 for low-temperature conditions and ASTM A351 CF8 and CF8M – i.e. SS304 and SS316).

      Check valve assembly drawingStandard check valves materials

/by
,

Understand Globe Valves (BS 1873 & API 602)

What is a globe valve? When shall it be used instead of gate and ball valves? In this article, we illustrate the scope of this type of valve (which is, in a word, to regulate the flow), the differences with other types of valve, the alternative designs, and specifications (BS 1873  for the cast steel and API 602/BS 5352 for the forged steel type).

 GLOBE VALVE

WHAT IS A GLOBE VALVE?

Definition Of Globe Valve

A globe valve is a type of valve used for regulating flow in a pipeline, or to shut off the flow, consisting of a movable disk-type element and a stationary ring seat in a generally spherical body (even if for shut-off operations ball valves and gate valves shall always be preferred).

globe valve
globe valve

The term “globe” comes from the valve’s spherical body shape, though the actual shape can vary, especially in modern designs. The key function of a globe valve is to start, stop, or throttle the flow of fluid through a pipeline; it achieves this through the precise positioning of the disk against the valve seat, which forms a gap allowing the fluid to pass through in a controlled manner.

 

 

Globe valves are bi-directional valves, different from check valves, meaning that the fluid can flow either way within the valve.

Globe valves offer a reliable solution for flow control applications, combining good sealing capabilities with the ability to precisely regulate flow. Their versatility and efficiency make them a valuable component in various piping systems.

Design And Operation

The basic components of a globe valve include the body, seat, stem, disc, and handwheel or actuator. The valve’s operation is straightforward:

  • Turning the handwheel or activating the actuator moves the stem and the attached disc toward or away from the seat.
  • When the disc moves towards the seat, it restricts the flow path, reducing flow or stopping it completely when fully closed.
  • Moving the disc away from the seat opens the flow path, allowing fluid to pass through.

Key Features

  • Flow Regulation: Globe valves excel at regulating flow rates due to their design, which allows for fine adjustments of the disc position.
  • Sealing Capability: The close contact between the disc and seat provides good sealing capabilities, minimizing leaks when the valve is closed.
  • Directional: Typically, globe valves are used in applications where the flow direction is important, as they are designed to handle flow in one direction, which helps in reducing pressure drop and preventing backflow.

Applications

Globe valves are used across various industries where flow needs to be precisely controlled, including:

  • Water and Wastewater Management: For regulating flow and pressure within distribution networks.
  • HVAC Systems: In heating and cooling systems for controlling the flow of hot or cold water.
  • Chemical and Petrochemical Industries: For managing the flow of various chemicals in processing plants.
  • Steam Services: Such as in power plants, where steam flow must be carefully controlled.

Globe Valves Selection Considerations

Selecting the right globe valve for your application involves careful consideration of various factors to ensure optimal performance, reliability, and safety. Globe valves are used for regulating flow in a piping system, and the correct selection is crucial for effective system operation. Here’s a detailed guide on how to select a globe valve:

1. Understand The Application
  • Fluid Characteristics: Identify the type of fluid (liquid, gas, corrosive, toxic, etc.) the valve will handle. This determines the material selection for the valve body, trim, and sealing components.
  • Pressure and Temperature: Determine the operating pressure and temperature range. This information is crucial for selecting a valve that can withstand the system’s conditions without failure.
  • Flow Requirements: Consider the flow rate and the necessity for flow regulation or throttling. Globe valves offer excellent throttling capabilities, but the degree of control required will influence the valve design.
2. Select The Proper Valve Size
  • Pipe Size: The valve size should correspond to the pipe size in the system to ensure proper fit and avoid unnecessary pressure drops.
  • Cv Value: Calculate the valve’s flow coefficient (Cv) required based on the flow rate, fluid density, and the pressure drop across the valve. The Cv value helps in selecting a valve size that meets the flow requirements without excessive pressure loss.
3. Choose The Valve Body Material
  • Compatibility: The valve material must be compatible with the fluid to prevent corrosion. Common materials include carbon steel, stainless steel, bronze, and special alloys for corrosive applications.
  • Temperature and Pressure: The material must also be suitable for the operating temperature and pressure. Refer to ASTM, ASME, and other relevant standards for guidance on material properties under specific conditions.
4. Determine The Valve End Connections
  • Connection Type: Globe valves are available with flanged, threaded, butt-weld, and socket-weld end connections. The choice depends on the piping system design, pressure rating, and ease of installation or maintenance.
  • Standards Compliance: Ensure the selected end connections comply with industry standards, such as ASME B16.5 for flanged connections, to ensure compatibility and integrity in the piping system.
5. Select The Appropriate Trim Material
  • Service Conditions: The trim (disc, seat, and stem) material should be selected based on the fluid type, pressure, temperature, and potential for wear or corrosion. The trim material may differ from the body material to optimize performance and lifespan.
  • Leakage Class: Consider the required leakage class based on system requirements. Different trim designs offer varying levels of sealing efficiency, affecting the valve’s ability to completely shut off or precisely regulate flow.
6. Actuation Method
  • Manual vs. Automated: Decide between manual operation (handwheel or gear operator) and automated actuation (pneumatic, hydraulic, or electric). Automated actuators are preferred for remote control, frequent operation, or where precise control is needed.
  • Actuator Sizing: Ensure the actuator is properly sized to operate the valve under all expected conditions, including the maximum differential pressure.
7. Consider Special Features
  • Bellows Seal: For toxic or hazardous fluids, consider a globe valve with a bellows seal to prevent stem leakage.
  • Cage Guided: Cage-guided trims provide stability to the plugin in high-flow conditions, reducing vibration and wear.
8. Compliance And Certifications

Ensure the globe valve meets relevant industry standards and certifications for safety, performance, and quality. Common standards include ASME, API, and ANSI specifications relevant to globe valves.

9. Consult With Manufacturers Or Experts

When in doubt, consult with valve manufacturers or industry experts. They can provide valuable insights and recommendations based on experience with similar applications.

Selecting the right globe valve is a process that requires an understanding of the application requirements, knowledge of valve design principles, and consideration of the operating environment. By systematically addressing these factors, you can ensure the selected globe valve will perform efficiently and reliably in your system.

GLOBE VALVE ADVANTAGES AND DISADVANTAGES

Globe valves, recognized for their ability to regulate flow in piping systems, come with a set of advantages and disadvantages that make them suitable for specific applications while less ideal for others. Understanding these pros and cons is essential for selecting the right valve type for a particular system requirement.

Advantages Of Globe Valves

  1. Precise Flow Control: One of the primary advantages of globe valves is their exceptional capability to regulate flow. The design allows for fine adjustments of the disc position, providing superior control over the flow rate.
  2. Good Sealing Capability: Globe valves offer a tight seal when closed, thanks to the close contact between the disc and the seat. This minimizes leaks and ensures effective isolation.
  3. Bi-Directional: While typically used in one direction, globe valves can be designed for bi-directional flow, adding to their versatility in system design.
  4. Availability in Various Designs: Globe valves come in several body designs (Z-body, Y-body, and angle body), each offering specific advantages for different applications, such as minimized pressure drop or enhanced flow control.
  5. Ease of Maintenance: Many globe valve designs allow for easy access to internal components, facilitating maintenance, repairs, and part replacements without removing the valve from the pipeline.

Disadvantages Of Globe Valves

  1. Pressure Drop: The biggest drawback of globe valves is the inherent pressure drop across the valve, even when fully open. The flow path through the valve body is not straight, causing changes in flow direction and resistance that result in pressure loss.
  2. Size and Weight: Globe valves tend to be larger and heavier than other valve types (like ball valves) of the same nominal size and pressure class, potentially requiring more space and support in a piping system.
  3. Higher Operating Torque: Due to the design and the need for a tight seal, globe valves may require a higher torque to operate, especially in higher-pressure applications. This can necessitate larger or more powerful actuators.
  4. Cost Considerations: Globe valves can be more expensive than other valve types, particularly in larger sizes, due to their complex design and the materials required for manufacturing.
  5. Not Ideal for Slurry Applications: The tortuous flow path in a globe valve can lead to the accumulation of solids or slurries, which can affect the valve’s operation and lead to wear or damage.

In conclusion, globe valves are highly effective for applications requiring precise flow control and where the benefits of their design outweigh the potential drawbacks, such as in throttling applications and systems where a high degree of flow regulation is needed. However, for applications where pressure drop is a concern or where a straight-through flow path is required, alternative valve types may be more suitable.

 

Globe valve disadvantage: pressure drop
Globe valve disadvantage: pressure drop

MAIN PARTS OF GLOBE VALVES

A globe valve, widely used for regulating fluid flow in piping systems, consists of several key components that enable its operation and functionality. These main parts include:

1. Body

The body of the globe valve serves as the main structure that houses the internal components. It’s typically spherical or globular in shape, which is where the valve gets its name. The body material varies depending on the application and can include cast iron, stainless steel, brass, and other alloys suitable for specific fluid services.

2. Bonnet

The bonnet is attached to the valve body and provides a leak-proof closure at the top. It encases the stem and other internal parts, protecting them from external elements and containing the fluid pressure. The bonnet can be bolted, screwed, or welded to the valve body.

3. Seat

The seat is a critical component that provides a sealing surface for the disc to rest against when the valve is closed. It’s either integrated into the valve body or designed as a replaceable component. The seat material is selected based on the fluid type, temperature, and pressure, aiming for durability and a tight seal.

4. Disc

The disc, or plug, is the component that moves perpendicular to the flow path to regulate or block fluid flow. In globe valves, the disc can be a solid plug, a ring, or other shapes designed for specific flow characteristics. The disc’s precise positioning against the seat allows for effective flow control.

5. Stem

The stem connects the actuator (such as a handwheel or an electric actuator) to the disc. As the actuator is operated, the stem transmits the motion to the disc, moving it towards or away from the seat to open or close the valve. Stems can be rising (moving up and down with the disc) or non-rising, depending on the valve design.

6. Actuator

The actuator operates the valve, typically through a handwheel, lever, gear mechanism, or an automated actuator (electric, pneumatic, or hydraulic). Manual actuators like handwheels or levers are common for smaller valves or in applications where automatic control is not required.

7. Packing

Packing material is used to create a tight seal around the stem, preventing fluid leakage out of the valve body. It’s usually made from flexible materials like PTFE (Teflon), graphite, or other composites that can withstand the fluid’s temperature and chemical properties.

8. Gland And Gland Flange

The gland and gland flange assembly compresses the packing around the stem to ensure a tight seal. The gland flange allows for adjustments to the packing tightness, ensuring the seal’s effectiveness over time.

Each of these components plays a vital role in the globe valve’s operation, contributing to its ability to precisely control fluid flow, withstand varying pressure and temperature conditions, and maintain a reliable seal in diverse applications.

The image depicts the operation of a globe valve and its primary components: essentially, the flow is controlled by a disc that can be raised (either manually or with actuators) away from the seat, thereby adjusting the amount of flow permitted.

Fluid flow through a globe valve, pressure drop

KEY APPLICABLE SPECIFICATIONS (BS, API, ASME)

Globe valves, widely used for flow regulation in piping systems, are subject to various standards and specifications to ensure their reliability, safety, and compatibility across different applications. These standards are set by prominent organizations such as the British Standards Institution (BS), the American Society of Mechanical Engineers (ASME), and the American Petroleum Institute (API). Below is an overview of key BS, ASME, and API specifications applicable to globe valves:

BS (British Standards)

  • BS 1873: Specifies requirements for steel globe and globe stop and check valves for the petroleum, petrochemical, and allied industries. It covers valve design, materials, pressure-temperature ratings, and testing.
  • BS 5160: This standard is focused on steel globe valves, globe stop and check valves, check valves, and gate valves for general-purpose applications. It includes details on design, dimensions, testing, and marking.

ASME (American Society Of Mechanical Engineers)

  • ASME B16.34 – Valves – Flanged, Threaded, and Welding End: This standard provides requirements for materials, design, pressure-temperature ratings, and testing for gate, globe, check, ball, and butterfly valves. It is widely referenced for valve specifications in various industries.
  • ASME B16.10 – Face-to-Face and End-to-End Dimensions of Valves: While not specific to globe valves alone, this standard is crucial for determining the proper installation dimensions for globe valves, ensuring they fit correctly within piping systems.
  • ASME B16.5 – Pipe Flanges and Flanged Fittings: Relevant for globe valves with flanged connections, this standard specifies dimensions, tolerances, and materials for flanges and flanged fittings, ensuring compatibility with flanged piping systems.

API (American Petroleum Institute)

  • API 602 – Compact Steel Gate Valves – Flanged, Threaded, Welding, and Extended-Body Ends: Although primarily focused on gate valves, API 602 also covers small-sized, forged carbon steel globe valves used in the petroleum and natural gas industries.
  • API 598 – Valve Inspection and Testing: This standard outlines the testing and inspection requirements for gate, globe, and check valves, ensuring they meet the required leakage rates and performance criteria.
  • API 600 – Steel Gate Valves – Flanged and Butt-Welding Ends, Bolted Bonnets: Similar to API 602, API 600, while focused on gate valves, sets the benchmark for quality and performance applicable to globe valves, particularly in terms of design and material specifications for use in the petroleum and natural gas industry.

These BS, ASME, and API specifications cover a wide range of aspects related to globe valves, from design and manufacturing to testing and inspection. Compliance with these standards ensures that globe valves are suitable for their intended applications, offering reliable performance and safety in various industrial environments.

GLOBE VALVE TYPES

Globe valves, recognized for their ability to regulate flow in piping systems, come in various designs tailored to specific applications and flow characteristics. The primary differentiation among globe valve types lies in their internal body design, which impacts flow direction, pressure drop, and application suitability. Here’s a detailed look at the different types of globe valves:

1. Z-Body Globe Valve

The Z-body is the most common and traditional type of globe valve. It features a Z-shaped partition inside the valve body that directs the flow in a Z pattern. The seat and stem are positioned at an angle, typically at 90 degrees to the valve’s pipeline, which allows for a straightforward and effective method to start, stop, and regulate the flow.

  • Advantages: Simple design, easy to maintain.
  • Disadvantages: Higher pressure drop due to the flow path; not ideal for applications requiring minimal flow resistance.

2. Y-Body Globe Valve (“Wye” Type)

Y-body globe valves are designed to reduce the pressure drop across the valve. The stem and seat are angled at approximately 45 degrees to the pipe axis, which offers a smoother flow path for the fluid. This design is particularly beneficial for high-pressure and high-temperature applications, such as steam services.

  • Advantages: Lower pressure drop compared to Z-body valves, suitable for high-pressure conditions.
  • Disadvantages: The angled design may complicate installation in some piping configurations.

3. Angle Globe Valve

Angle globe valves have a 90-degree body design that changes the flow direction only once, which helps in reducing the pressure drop. These valves combine the functions of a globe valve and an elbow, making them suitable for applications where space constraints exist or where the piping system requires a directional change.

  • Advantages: Efficient flow with reduced pressure drop; can replace both a valve and an elbow in a system.
  • Disadvantages: Limited to applications where the change in flow direction is beneficial or required.

4. T-Pattern Or Through-Way Globe Valve

The T-pattern globe valve, also known as a through-way globe valve, offers a straighter flow path compared to the Z-body design, resulting in a somewhat lower pressure drop. It’s a variation more akin to traditional globe valves but optimized for better flow dynamics.

  • Advantages: Improved flow performance over Z-body designs; good for throttling and regulating.
  • Disadvantages: Still presents a higher pressure drop than ball or gate valves.

5. Oblique Pattern Globe Valve

Oblique pattern globe valves feature a body design where the inlet and outlet ports are oriented diagonally to each other, providing a more direct flow path than traditional Z-body designs. This type is less common but can be used in specific applications requiring efficient flow regulation with a moderate pressure drop.

  • Advantages: Moderately lower pressure drop compared to Z-body valves; effective for flow regulation.
  • Disadvantages: Not as widely available or standardized as other globe valve designs.

Each globe valve type offers distinct advantages for flow control and regulation, with the choice depending on specific application needs, performance requirements, and system design considerations.

Globe valves dimensions
Globe valves dimensions

The globe valve symbol in P&ID diagrams is the following:  Globe valve symbol

GLOBE VALVE MATERIALS (CAST/FORGED)

Globe valves, utilized extensively for flow regulation in piping systems, can be constructed with either cast or forged body materials. The choice between cast and forged bodies depends on the application’s specific requirements, including pressure, temperature, and the fluid’s nature. Understanding the distinctions between cast and forged materials is crucial for selecting the appropriate globe valve for a particular service environment.

Cast Body Materials

Manufacturing Process: Casting involves pouring molten metal into a mold of the desired shape and allowing it to solidify. This process enables the production of complex shapes and sizes, making it suitable for manufacturing globe valve bodies with intricate internal geometries.

Materials: Common cast materials for globe valves include:

  • Cast Carbon Steel (e.g., ASTM A216 WCB): Widely used for moderate temperatures and pressures.
  • Cast Stainless Steel (e.g., ASTM A351 CF8M): Offers excellent corrosion resistance, suitable for aggressive media.
  • Cast Alloy Steel (e.g., ASTM A217 WC6): Used for high-temperature and high-pressure applications, resistant to thermal fatigue.

Advantages:

  • Versatility in design and size.
  • Generally more cost-effective for large sizes due to simpler manufacturing for complex shapes.
  • Suitable for lower pressure-temperature applications.

Disadvantages:

  • Potential for casting defects (e.g., porosity, inclusions), which could affect the valve’s integrity and performance.
  • Material properties may be less uniform compared to forged valves.

Forged Body Materials

Manufacturing Process: Forging involves shaping metal under high pressure, typically by hammering or pressing. This process aligns the metal’s grain structure, enhancing its strength and durability.

Materials: Common forged materials for globe valves include:

  • Forged Carbon Steel (e.g., ASTM A105): Offers good strength and impact resistance, suitable for general service applications.
  • Forged Stainless Steel (e.g., ASTM A182 F316): Provides superior corrosion resistance, ideal for corrosive environments.
  • Forged Alloy Steel (e.g., ASTM A182 F11): Used in high-temperature services, offering excellent mechanical properties.

Advantages:

  • Higher strength and toughness due to the forging process, make them suitable for high-pressure and high-temperature applications.
  • Reduces the likelihood of material defects, ensuring greater reliability and performance.
  • More uniform material properties, providing consistent performance.

Disadvantages:

  • The range of shapes and sizes is more limited compared to casting, potentially increasing the cost of complex designs.
  • Generally more expensive than cast valves, especially for larger sizes, due to the intensive labor and material requirements of the forging process.

Choosing Between Cast And Forged Globe Valves

When selecting between cast and forged globe valves, consider the following factors:

  • Service Conditions: Forged valves are preferred for severe service conditions involving high pressure and temperature, where material strength and integrity are critical.
  • Fluid Properties: Cast valves may be more suitable for applications involving corrosive media, given the availability of various corrosion-resistant alloys.
  • Cost Considerations: For large valves or when cost is a significant factor, cast valves might offer a more economical solution.
  • Design Complexity: Complex valve designs with intricate internal features are more easily achieved with casting.

Ultimately, the choice between cast and forged globe valves depends on balancing the application’s specific demands with considerations of performance, reliability, and cost.

GLOBE VALVE VS. OTHER TYPES OF VALVE

GLOBE VALVE VS GATE VALVE

Globe valves and gate valves are two widely used valve types in piping systems, each serving distinct functions with specific advantages and applications. Understanding the differences between these two valve types is crucial for selecting the right valve for a particular system requirement.

Design And Operation

  • Globe Valves: Designed for regulating flow, globe valves feature a movable disk or plug that comes into contact with a stationary ring seat to control flow. The flow path through a globe valve typically changes direction, which provides the valve with good throttling capabilities and the ability to precisely control the flow rate. The movement of the disk is perpendicular to the seat, allowing for fine adjustments of flow.
  • Gate Valves: Primarily used for on/off control, gate valves have a gate or wedge that moves up and down in the flow path. When the gate valve is fully open, it provides a straight-through passage with minimal obstruction to flow, resulting in a very low-pressure drop. Gate valves are not suitable for throttling purposes because partial opening can cause vibration and rapid wear of the gate and seats.

Applications

  • Globe Valves: Because of their excellent ability to regulate flow, globe valves are often used in applications where flow needs to be adjusted regularly or where flow rate must be precisely controlled, such as in cooling systems, fuel oil systems, and process control in chemical plants.
  • Gate Valves: Gate valves are best suited for applications where a valve primarily needs to be either fully open or fully closed and where minimal pressure drop is desired. They are commonly used in water and wastewater treatment, oil and gas pipelines, and other applications where fluid needs to flow freely without obstructions.

Advantages And Disadvantages

  • Globe Valves:
    • Advantages: Excellent for throttling and regulating flow; provide a good seal when closed.
    • Disadvantages: The flow path through the valve causes a higher pressure drop compared to gate valves; generally, more expensive due to their complex design.
  • Gate Valves:
    • Advantages: Low-pressure drop when fully open; simpler design usually results in lower costs; suitable for both cryogenic and high-temperature applications.
    • Disadvantages: Not suitable for throttling; prone to seat and gate damage if operated partially open; slower to open and close due to the need to move the gate out of the flow path.

Choosing Between Globe And Gate Valves

When choosing between a globe valve and a gate valve, consider:

  • Purpose: If precise flow control or throttling is needed, a globe valve is preferable. For simple on/off control with minimal pressure drop, a gate valve is more suitable.
  • Operating Conditions: Consider the system’s pressure, temperature, and the nature of the fluid.
  • Cost and Space: Globe valves typically require more space and are more expensive than gate valves due to their design complexity.

In summary, the choice between globe and gate valves depends on the specific needs of the application, including whether flow needs to be precisely controlled or if the primary requirement is the minimal restriction of flow.

Globe valve
Globe valve

GLOBE VALVE VS BALL VALVE

Globe valves and ball valves are two distinct types of control valves used across various industries for fluid management in piping systems. Each valve type offers unique features and operational benefits, making them suitable for specific applications based on the requirements of flow control, pressure drop, and sealing efficiency. Understanding the differences between these valves is crucial for making an informed selection that aligns with system requirements.

Design And Operation

  • Globe Valves: Globe valves are characterized by their spherical body shape with a baffle that splits the interior space into two chambers. They regulate flow through a movable disk (or plug) and a stationary ring seat. The disk moves perpendicularly to the seat, offering precise control over the flow rate by adjusting the gap between the disk and the seat. Globe valves are primarily designed for throttling and regulating flow.
  • Ball Valves: Ball valves feature a spherical ball with a hole (or bore) through its center. Rotating the ball 90 degrees around its axis opens or closes the flow path. In the open position, the hole in the ball aligns with the flow path, allowing fluid to pass through with minimal resistance. Ball valves are known for their on/off control but can also provide throttling capabilities when equipped with a control mechanism.

Applications

  • Globe Valves: Due to their excellent capability to regulate flow, globe valves are commonly used in applications requiring precise flow control, such as in HVAC systems, chemical processing plants, and water distribution networks. They are especially useful where flow needs to be adjusted or maintained at a specific rate.
  • Ball Valves: Ball valves are versatile and suitable for a wide range of applications, from residential water systems to industrial processes involving gases and liquids. They are preferred for applications requiring a tight seal and quick, reliable on/off operation, such as in gas pipelines and storage tanks. Some specialized ball valves are designed for flow modulation in process control.

Advantages And Disadvantages

  • Globe Valves:
    • Advantages: Excellent for precise flow control and regulation; capable of withstanding high pressure; good sealing capabilities.
    • Disadvantages: Higher pressure drop due to the tortuous flow path; generally larger and more expensive than ball valves; slower to operate.
  • Ball Valves:
    • Advantages: Low-pressure drop when fully open; quick and easy to operate with a quarter-turn mechanism; provides a tight seal with low torque.
    • Disadvantages: Not as precise for flow control as globe valves; can be prone to cavitation and erosion in throttling applications; limited suitability for slurry applications due to potential clogging.

Choosing Between Globe And Ball Valves

When choosing between a globe valve and a ball valve, consider the following:

  • Flow Control Requirements: For precise flow regulation, a globe valve is preferable. For on/off control or applications requiring minimal pressure drop, a ball valve is more suitable.
  • Operating Conditions: Consider the fluid properties, pressure, temperature, and whether the system requires frequent operation.
  • Cost and Space Constraints: Ball valves are typically more compact and cost-effective than globe valves, making them attractive for space-constrained or budget-sensitive applications.

In summary, the choice between globe and ball valves hinges on the specific needs of the application, with globe valves being the go-to option for precise flow control and ball valves offering superior performance for on/off control and applications requiring minimal pressure drop.

GLOBE VALVE VS BUTTERFLY VALVE

Globe valves and butterfly valves serve different purposes in fluid control systems, each with distinct design features, operational advantages, and preferred applications. Understanding the differences between these two types of valves can help in selecting the most suitable valve for a specific application based on the requirements of flow control, pressure drop, sealing efficiency, and cost.

Design And Operation

  • Globe Valves: Globe valves are characterized by a spherical body with an internal baffle that divides the interior into two chambers. They control fluid flow using a movable disk (or plug) and a stationary ring seat. The disk moves linearly, perpendicular to the flow, allowing for precise flow regulation by adjusting the gap between the disk and the seat. Globe valves are designed primarily for throttling and fine flow control.
  • Butterfly Valves: Butterfly valves consist of a flat disc that rotates around a central axis within the valve body. Turning the disc 90 degrees opens or closes the valve. When the disc is parallel to the flow, the valve is fully open, and when it is perpendicular, the valve is closed. Butterfly valves are known for their compact design and are used for both on/off control and moderate flow regulation.

Applications

  • Globe Valves: Ideal for applications requiring precise flow control and where pressure drop is not a significant concern. They are commonly used in water treatment plants, fuel oil systems, and chemical processing industries where the accurate adjustment of flow rate is necessary.
  • Butterfly Valves: Suitable for a wide range of applications, butterfly valves are often used in large-diameter pipes for water distribution, HVAC systems, and in applications where space and weight are critical considerations. They provide efficient on/off and throttling control with minimal structural support.

Advantages And Disadvantages

  • Globe Valves:
    • Advantages: Excellent for precise flow regulation; good sealing capabilities; suitable for high-pressure applications.
    • Disadvantages: Higher pressure drop across the valve due to the tortuous flow path; larger and more expensive compared to butterfly valves; slower to actuate.
  • Butterfly Valves:
    • Advantages: Compact and lightweight design; quick operation with a quarter-turn mechanism; lower cost, especially for large-diameter applications; lower pressure drop when fully open.
    • Disadvantages: Not as precise in flow control as globe valves; potential for reduced sealing effectiveness over time, especially in high-pressure applications; can be susceptible to cavitation and flow turbulence.

Choosing Between Globe And Butterfly Valves

When choosing between a globe valve and a butterfly valve, consider the following factors:

  • Flow Control Requirements: Globe valves are better for situations that require precise flow control. Butterfly valves are more suitable for general on/off and moderate flow regulation applications.
  • Space and Weight: Butterfly valves are preferred when space is limited and weight is a concern.
  • Pressure Drop: If minimizing pressure drop is essential, butterfly valves offer an advantage due to their straight-through flow design.
  • Budget Constraints: Butterfly valves are generally more cost-effective, especially for large pipe diameters.

In summary, the choice between globe and butterfly valves depends on the specific application requirements. Globe valves are ideal for precise flow control in high-pressure systems, while butterfly valves offer a compact, economical solution for on/off and moderate flow regulation in larger pipes and where space constraints exist.

GLOBE VALVE VS PLUG VALVE

Globe valves and plug valves are both commonly used in various industries for controlling fluid flow in piping systems. Each type of valve has distinct features, operational mechanisms, and advantages that make it suitable for specific applications. Understanding these differences is crucial for selecting the right valve for your needs.

Globe Valves

Design and Operation:

  • Globe valves are characterized by their spherical body shape, with an internal baffle that splits the interior into two chambers.
  • They control flow using a movable disk (or plug) and a stationary ring seat. The disk moves linearly, perpendicular to the flow direction, allowing for precise flow regulation by adjusting the gap between the disk and the seat.
  • Primarily designed for throttling and regulating flow, globe valves offer excellent control over flow rate.

Applications:

  • Ideal for applications requiring precise flow control, such as cooling systems, fuel oil systems, and chemical processing.
  • Commonly used in situations where the flow needs to be adjusted frequently or maintained at a specific rate.

Advantages:

  • Excellent for precise flow regulation and control.
  • Provides a good sealing capability when closed.
  • Suitable for both high-pressure and high-temperature applications.

Disadvantages:

  • Higher pressure drop due to the tortuous flow path.
  • Larger and more expensive compared to other valve types.
  • Not suitable for applications requiring minimal flow resistance or for handling slurries and viscous fluids.

Plug Valves

Design and Operation:

  • Plug valves feature a cylindrical or tapered plug with a hole or passage that allows fluid to flow through when aligned with the inlet and outlet ports.
  • The plug rotates within the valve body to open or close the flow path. This rotation aligns the port in the plug with the valve body ports.
  • Plug valves can be used for on/off control as well as for moderate throttling applications.

Applications:

  • Widely used in applications requiring quick and easy operation, such as in water and wastewater treatment, gas services, and in industries where fast isolation is needed.
  • Suitable for handling fluids with suspended solids, due to the straight-through flow path.

Advantages:

  • Simple and compact design, making them easy to operate and maintain.
  • Quick to open and close, providing efficient flow control.
  • Generally more resistant to clogging from slurries or viscous fluids compared to globe valves.

Disadvantages:

  • Not as precise in flow control as globe valves.
  • The sealing surfaces can wear out more quickly, potentially leading to leaks.
  • Some designs may have higher torque requirements and can be more difficult to operate under high-pressure conditions.

Choosing Between Globe And Plug Valves

When choosing between a globe valve and a plug valve, consider the following:

  • Flow Control Needs: Globe valves are preferred for precise flow regulation, while plug valves are better for quick isolation and applications requiring frequent operation.
  • Fluid Characteristics: Plug valves are more suitable for fluids with suspended solids, whereas globe valves are ideal for clean liquids or gases.
  • Pressure Drop: If minimizing pressure drop is a priority, plug valves may offer an advantage due to their straight-through flow design.
  • Application Requirements: Consider the specific requirements of your application, including temperature, pressure, and the need for flow adjustment or quick isolation.

In summary, the choice between globe and plug valves depends on the specific needs of the application, including the level of flow control required, the type of fluid being handled, and operational considerations.

GLOBE VALVE GA DIAGRAM

Note: GA stands for “General Assembly” (drawing).

A general assembly drawing for globe valves is shown in the image:

Globe valve general assembly drawing
Globe valve general assembly drawing

Nonetheless, a large number of variations exist, depending on the following factors:

  • body material: cast (BS 1873) and forged (API 602/BS 5352)
  • bonnet design: standard or pressure seal type (for high-pressure applications)
  • bonnet to body connection: bolted or welded
  • valve end connections type: flanged (as shown in the image), buttweld, socket weld/threaded (forged bodies)
  • disc type
  • stem type (rising/non-rising)
  • seal type: conical or flat
  • specification: BS, API, EN
  • type of actuation: manual, with a gearbox, with an actuator

  • GLOBE VALVES DIMENSIONS

    The tables show the dimensions and weights of BS 1873 valves, bolted bonnet type.
    Globe valves dimensions

    CLASS 150

    Dimensions in inches (millimeters)

    Sizes L / L1 H (Open) W
    2″ 8 (203) 13-3/8 (340) 8-7/8 (225)
    2-1/2″ 8-1/2 (216) 14-1/2 (368) 8-7/8 (225)
    3″ 9-1/2 (241) 16-1/2 (419) 11-7/8 (302)
    4″ 11-1/2 (292) 17-3/8 (441) 12-3/4 (325)
    5″ 14 (356) 24 (610) 12-3/4 (325)
    6″ 16 (406) 24 (610) 17-3/4 (451)
    8″ 19-1/2 (495) 26-3/4 (679) 21-5/8 (549)
    10″ 24-1/2 (622) 30 (762) 30 (762)
    12″ 27-1/2 (699) 33-7/8 (860) 30 (762)
    14″ 31 (787) 56 (1422) 31-1/2 (800)
    16″ 36 (914) 64 (1626) 35-1/2 (902)
    GEAR OPERATOR RECOMMENDED FOR SIZE 10″ AND ABOVE

    CLASS 300

    Dimensions in inches (millimeters)

    Sizes L / L1 H (Open) W
    2″ 10-1/2 (267) 13-3/8 (340) 9 (229)
    2-1/2″ 11-1/2 (292) 15-3/8 (390) 9 (229)
    3″ 12-1/2 (318) 16-1/2 (419) 13 (330)
    4″ 14 (356) 19-3/8 (492) 14 (356)
    5″ 15-3/4 (400) 21-1/2 (546) 15-3/4 (400)
    6″ 17-1/2 (445) 24-3/8 (619) 17-3/4 (451)
    8″ 22 (559) 31-1/4 (794) 22 (559)
    10″ 24-1/2 (622) 45 (1143) 34 (864)
    12″ 28 (711) 49 (1245) 34 (864)
    GEAR OPERATOR RECOMMENDED FOR SIZE 8″ AND ABOVE

    CLASS 600

    Dimensions in inches (millimeters)

    Sizes L / L1 H (Open) W
    2″ 11-1/2 (292) 15-1/2 (394) 9-1/2 (241)
    2-1/2″ 13 (330) 17 (432) 11 (279)
    3″ 14 (356) 19 (483) 13 (330)
    4″ 17 (432) 21 (533) 14 (356)
    5″ 20 (508) 25 (635) 15-3/4 (400)
    6″ 22 (559) 26-7/8 (683) 18 (457)
    8″ 26 (660) 35 (889) 20 (508)
    10″ 31 (787) 49 (1245) 24 (610)
    12″ 33 (838) 58 (1473) 30 (762)
    GEAR OPERATOR RECOMMENDED FOR SIZE 8″ AND ABOVE

    CLASS 900

    Dimensions in inches (millimeters)

    Sizes L / L1 H (Open) W
    2″ 14-1/2 (368) 20-1/2 (521) 12 (305)
    3″ 15 (381) 22-3/4 (578) 14 (356)
    4″ 18 (457) 26-1/2 (673) 21-1/2 (546)
    6″ 24 (610) 36 (914) 20 (508)
    8″ 29 (737) 37 (940) 24 (610)
    GEAR OPERATOR RECOMMENDED FOR SIZE 6″ AND ABOVE

    CLASS 1500

    Dimensions in inches (millimeters)

    Sizes L / L1 H (Open) W
    2″ 14-1/2 (368) 24 (610) 14 (356)
    3″ 18-1/2 (470) 26 (660) 16 (406)
    4″ 21-1/2 (546) 28 (711) 18 (457)
    6″ 27-3/4 (705) 37-1/2 (952) 24 (610)
    8″ 32-3/4 (832) 45 (1143) 24 (610)
    GEAR OPERATOR RECOMMENDED FOR SIZE 6″ AND ABOVE

    CLASS 2500

    Dimensions in inches (millimeters)

    Sizes L / L1 H (Open) W
    2″ 17-3/4 (451) 25-1/2 (648) 16 (406)
    3″ 22-3/4 (578) 32-1/2 (825) 20 (508)
    4″ 26-1/2 (673) 47 (1194) 24 (610)
    6″ 36 (914) 70-1/2 (1790) 28 (711)
    8″ 40-1/4 (1022) / /
    GEAR OPERATOR RECOMMENDED FOR SIZE 6″ AND ABOVE

/by
,

Understand Mill Test Certificates EN 10204 2.1, 3.1, 3.2 and their Differences

A Mill Test Certificate (MTC), or Mill Test Report (MTR), is issued by a manufacturer to certify the chemical and mechanical features of a product and its compliance with the applicable norms and technical specifications. Typically, Mill Test Certificates conform to the EN 10204 standard and are related to steel products. Mill Test Certificates (when required and/or applicable) shall be submitted by the exporter to the importer at shipping, together with the other typical shipping documents (invoices, packing lists, transportation docs)

 

MILL TEST CERTIFICATE

DEFINITION OF MTC

A Mill Test Certificate (MTC), otherwise defined as a “Mill Test Report” (MTR), is a certified document provided by a manufacturer that attests to the chemical and physical properties of a material or a product (for example a pipe, or a pipe fitting).

These certificates are often required in the metals industry to verify that the material meets the specified criteria and standards for a particular application. For products obtained by assembling or processing other components and/or parts (for example a 90 degrees elbow which is manufactured by cutting, bending, and forming a “mother” pipe), the manufacturer shall deliver both the mill test certificate of the end product (the elbow itself, in this example, if applicable), and of the mother-product (the pipe/s in this case).

MTCs are crucial in industries where materials’ quality and composition are critical for safety and performance, such as construction, manufacturing, and energy sectors (including petrochemicals and oil and gas).

WHY MILL TEST CERTIFICATES ARE IMPORTANT

When purchasing metal products, or products made of metals like pipes, valves, fittings, and flanges, buyers shall always request a mill test certificate from the manufacturer or distributor. This is critical for several reasons:

  • Quality Assurance: MTCs provide assurance that the materials supplied meet the required standards and specifications, offering a traceable record of the material’s origin and properties.
  • Compliance: For projects that must adhere to specific engineering standards and codes, MTCs are vital for ensuring compliance with these regulations.
  • Safety: In critical applications where material failure can lead to severe consequences, MTCs help ensure that only materials with the appropriate quality and strength are used.
  • Risk Management: Having an MTC reduces the risk of using substandard materials in projects, which can lead to costly repairs, replacements, and even accidents.

TYPE OF INFORMATION SHOWN ON MTC’s

A mill test certificate to EN 10204 shows, generally, the following information:

  • The Manufacturer’s name and address (with any other business info related to the manufacturing plant)
  • The indication/text “Mill Test Certificate” or “Mill Test Report” at the top of the document
  • The date of the MTC
  • The Type of MTC (for example “EN 10204 3.1” or “EN 10204 3.2” – see below)
  • The page number and the total number of pages of the MTC (for example “2/12” – i.e. page 2 of 12)
  • The customer name (that could be the end-user or a distributor/trader)
  • The exact definition of the material/product covered by the MTC
    • Product name and type (for example “Seamless Pipes”)
    • The manufacturing process  (for example “Seamless hot rolled”)
    • The surface type (for example “Varnished”)
    • The dimensions of the product (for example NPS x WT, plus lengths)
  • The quantity covered by the specific MTC in units (for example “meters 100”), the nominal weight in kgs/lbs (for example 2.600 kgs/tons), the net/gross weight (if available)
  • The final test result for the different physical attributes of the material by heat number (for example results of the tensile strength, hardness, sulfide stress cracking, and chemical composition…by heat number) concerning allowed tolerances (set by the applicable specifications and/or standards)
  • Results of additional tests, like hydrostatic, ultrasounds (UT), hardness, impact test, magnetic particles, metal graphic result, etc.
  • Marking information and details applied to the material/batch covered by the MTC
  • Summary information
  • Addenda useful to appraise the full features of the product
  • Stamps & Signatures of the Manufacturer’s Quality Dept. representatives that executed the tests
  • Customer signature
  • Stamps & Signatures of the Third-Party Inspector (if applicable, for example in EN 10204 3.2)

MAIN TYPES OF MTC (2.1, 2.2, 3.1, 3.2)

There are typically four types of Mill Test Certificates (from the lightest in terms of independent inspection, i.e. 2.1, to the toughest, i.e. 3.2):

EN 10204 Type 2.1

EN 10204 Type 2.1 is a type of certification provided by manufacturers of metallic products, such as plates, bars, tubes, and forgings. According to the EN 10204 standard, which outlines different types of inspection documents for metallic products, a Type 2.1 certificate is a declaration of compliance with the order by the manufacturer. Unlike Type 3.1 or Type 3.2 certificates, Type 2.1 does not involve independent third-party verification.

Key Features Of EN 10204 Type 2.1 Certificate
  • Declaration of Compliance: The Type 2.1 certificate is essentially a statement from the manufacturer affirming that the supplied products comply with the requirements of the order. This includes adherence to specified dimensions, material grade, and general quality parameters.
  • Content: The certificate typically includes the manufacturer’s details, product description, order details, and a statement of compliance. However, it does not include detailed test results or specific property values of the material (such as chemical composition or mechanical properties).
  • Verification: There is no requirement for the manufacturer to present actual test results or for a third-party inspection agency to verify the product. The assurance provided is based solely on the manufacturer’s internal quality control processes.
Applications And Considerations
  • General Use: Type 2.1 certificates are generally suitable for applications where the detailed material properties are not critical to the application’s safety or performance, or where the buyer has other means of verifying material quality.
  • Limitations: For projects requiring stringent adherence to specific material properties or standards, a Type 2.1 certificate may not provide sufficient assurance. In such cases, Type 3.1 or Type 3.2 certificates, which include detailed material properties and, for Type 3.2, third-party verification, are preferable.
  • Selection Criteria: When choosing materials or specifying certificate types, it’s important to consider the application’s requirements, potential risks, and regulatory obligations. Type 2.1 certificates may be acceptable for less critical applications, but more demanding environments would benefit from the higher assurance levels provided by Type 3.1 or Type 3.2 certificates.

In summary, an EN 10204 Type 2.1 certificate provides a basic level of assurance, confirming that the product complies with the order specifications without including specific test results. It is up to the buyer to determine if this level of certification is adequate for their application, considering the material’s intended use and the potential consequences of material failure.

EN 10204 Type 2.2

EN 10204 Type 2.2 is a certification standard outlined in the EN 10204 specification, which defines different types of inspection documents provided by manufacturers concerning the delivery of metallic products such as plates, bars, forgings, and castings. Type 2.2 certification provides a declaration of compliance with the order, by the manufacturer.

Key Features Of EN 10204 Type 2.2 Certificate
  • Compliance Declaration: It declares that the products supplied are in compliance with the order requirements, but unlike Type 3.1 or 3.2 certificates, it does not include specific test results.
  • Testing and Inspection Data: While specific test results are not included, the certificate generally states that the products have been tested by the standard and specific norms applicable to the products. It summarizes the inspection and testing performed and confirms that the products meet the definitions and guidelines of the standard.
  • Manufacturer’s Confirmation: The certificate is issued by the manufacturer and must be authorized by the manufacturer’s personnel. However, it does not require independent verification by an external inspector (as is necessary for Type 3.2 certification).
Application And Use

EN 10204 Type 2.2 certificates are used in situations where the buyer requires more information than what is provided in a Type 2.1 declaration of compliance without inspection documents. It assures buyers that the products meet the order requirements based on non-specific inspections and tests conducted by the manufacturer. However, for applications requiring detailed material properties and third-party verification, Type 3.1 or 3.2 certificates might be necessary.

Type 2.2 certificates are suitable for applications where the risk is relatively low, and the cost or necessity of a more detailed certification (like Type 3.1 or 3.2) cannot be justified. They are often used in general engineering applications where the precise material properties are not critical to the application’s performance or safety requirements.

EN 10204 Type 3.1

EN 10204 Type 3.1 is a certification standard outlined within the EN 10204 specification, which dictates the different types of inspection documents supplied by manufacturers with the delivery of metallic products, such as plates, bars, forgings, and castings. Type 3.1 certification provides specific information about the material’s properties and its compliance with the order requirements, including details on chemical composition, mechanical properties, and any additional testing that was performed.

Key Features Of EN 10204 Type 3.1 Certificate
  • Test Results: The certificate includes actual test results for the specific items supplied. This may cover chemical composition, mechanical properties (such as tensile strength, yield strength, elongation, and impact resistance), and other tested attributes relevant to the order specifications.
  • Validation: The Type 3.1 certificate must be validated by the manufacturer’s authorized inspection representative who is independent of the manufacturing department. This provides a level of assurance that the products meet the specified requirements.
  • Traceability: It offers traceability of the material by including details like heat or batch number, which connects the product with the test results documented in the certificate.
  • Compliance: It declares that the products supplied follow the requirements of the order, based on specific inspections and tests.
Application And Use

EN 10204 Type 3.1 certificates are widely required in industries where material properties are critical for the application’s safety and functionality. This includes the oil and gas, chemical processing, power generation, and construction sectors, among others. Type 3.1 certification is often specified in contracts and procurement documents to ensure that the materials supplied can be verified to have met the required standards and specifications.

The inclusion of specific test results provides buyers and engineers with confidence in the material’s suitability for the intended application, particularly in critical and high-performance environments. For applications requiring even higher assurance, including third-party verification, an EN 10204 Type 3.2 certificate might be requested.

In summary, an EN 10204 Type 3.1 certificate is a vital document that ensures the reliability and quality of materials used in various sectors, serving as an important element of quality assurance programs and compliance with regulatory standards.

EN 1024 3.1 MILL TEST CERTIFICATE TYPES A/B/C
Certificate type Title Summary of EN10204 requirements Notes
3.1 Inspection certificate Statement of compliance with the order by the manufacturer with results of specific inspection Replaces 3.1B. Common certificate type issued for ‘batch tested’ material. Cert. issued and signed by the manufacturer’s representative, who must be independent of the manufacturing department. Eg Inspection department or test house manager/supervisor.
3.1A Inspection certificate 3.1A With a mention of test results from specific inspections and testing Batch test results. Cert. issued by independent inspector required by releasing authority (eg TUV for German pressure vessels). Replaced by 3.2 in 2004
3.1B Inspection certificate 3.1B With a mention of test results from specific inspections and testing Batch test results. Cert. issued and signed by the manufacturer’s representative. Replaced by 3.1 in 2004
3.1C Inspection certificate 3.1C With a mention of test results from specific inspections and testing Batch test results. Cert. issued by an independent inspector appointed by a customer (eg Lloyds). Replaced by 3.2 in 2004

EN 10204 Type 3.2

EN 10204 Type 3.2 certification is a standard outlined within the EN 10204 specification, which defines the different types of inspection documents supplied by manufacturers with the delivery of metallic products. Type 3.2 certification is among the most stringent and provides assurance regarding the conformity of the products to the specified order requirements and applicable standards.

Key Features Of EN 10204 Type 3.2 Certificate
  • Third-Party Verification: The distinctive feature of Type 3.2 certification is that it involves independent verification by a third-party inspector. This third party is either an authorized representative of the purchaser, a designated inspection representative independent of the manufacturing department, or a representative from an officially recognized inspection agency.
  • Specific Test Results: Similar to Type 3.1, the Type 3.2 certificate includes specific test results for the product, such as chemical composition and mechanical properties. However, the presence of the third-party inspector’s validation adds an additional layer of assurance.
  • Traceability: Provides traceability of the material back to its production batch, correlating the product with specific test results and ensuring that the material meets the required specifications.
  • Documented Verification: Both the manufacturer and the independent third party must sign the Type 3.2 certificate, attesting to the conformity of the product with the order requirements.
Application And Use

EN 10204 Type 3.2 certificates are required in critical applications where the material’s integrity is paramount. These include sectors like aerospace, oil and gas, power generation, and naval construction, where failure could lead to catastrophic consequences. Type 3.2 certification is often specified for components that are subject to high stress, corrosive environments, or extreme temperatures.

The involvement of a third-party inspector provides added assurance to buyers and project managers that the materials and products have been thoroughly tested and inspected, not only by the manufacturer but also by an unbiased external entity. This level of scrutiny is crucial for projects with stringent safety and reliability standards.

Importance

Type 3.2 certification is vital for ensuring the highest levels of material compliance and quality in industries where failure is not an option. The dual verification process—by both the manufacturer and an independent third party—helps mitigate risks associated with material defects and non-conformities, ensuring that only materials that fully meet the specified requirements are used in critical applications.

In summary, EN 10204 Type 3.2 certification represents the highest standard of assurance provided in the EN 10204 specification, offering comprehensive validation of a material’s properties and compliance through independent third-party inspection.

Example of mill test certificate 3.1 (for a pipe)
Example of mill test certificate 3.1 (for a pipe)

Sample mill test certificate (Tenaris steel pipes).

SUMMARY TABLE FOR MTC’S

Mill Test Certificate denomination in…
MTC Type
EN 10204		 English German French Scope MTC to be validated by…
MTC Type 2.1 Declaration of compliance with the order Werk-
Bescheinigung		 Attestation de conformité á la Commande Statement of compliance with the order The manufacturer
MTC Type 2.2 Test report Werkzeugnisse Relvé de contrôle Statement of compliance with the order by the manufacturer based on non-specific inspections (tests) by the manufacturer. The manufacturer
MTC Type 3.1 Inspection certificate 3.1 Abnahmeprüf-
Zeugnisse 3.1		 Certificat de réception 3.1 Statement of compliance with the order by the manufacturer with results of a specific inspection The manufacturer`s authorized inspection representative, independent by the manufacturing department
MTC Type 3.2 Inspection certificate 3.2 Abnahmeprüf-
Zeugnisse 3.2		 Certificat de réception 3.2 Statement of compliance with the order with an indication of results of a specific inspection
  • The manufacturer`s authorized inspection representative independent by the manufacturing department
  • Either the purchaser`s authorized inspection representative or a third-party inspector

The main differences among the MTCs 2.1, 2.2, 3.1, and 3.2 are:

  • Level of Detail: Types 2.1 and 2.2 provide general declarations of compliance, with Type 2.2 offering a bit more detail on testing and inspection processes. Types 3.1 and 3.2 provide specific test results, with Type 3.2 including third-party verification.
  • Verification: Types 3.1 and 3.2 certificates are more rigorous, including specific test results and requiring validation by independent parties (Type 3.2 only).
  • Application Use: Types 3.1 and 3.2 are typically required in more critical applications, where specific material properties must be verified and documented for safety, performance, and compliance reasons.

FORGERY OF MILL TEST CERTIFICATES

Fake Mill Test Certificates (MTCs) pose a significant risk to industries that rely on certified materials for safety, performance, and compliance with standards.

These counterfeit documents are fabricated to appear as if they certify a material’s properties and compliance with specifications, but they do not accurately reflect the material’s actual characteristics. The existence of fake MTCs underscores the importance of due diligence and verification in the procurement process. Here are key points regarding fake Mill Test Certificates and how to mitigate their risks:

Risks And Consequences Of Fake MTCs

  1. Compromised Safety: Using materials that do not meet required standards can lead to failures, posing severe safety risks to personnel and the environment.
  2. Legal and Financial Liabilities: Organizations may face legal penalties, costly recalls, or project delays if substandard materials are discovered in their products or infrastructure.
  3. Damaged Reputation: The use of non-compliant materials can tarnish a company’s reputation and erode trust among clients and partners.

  4. Identifying And Preventing The Use Of Fake MTCs

    1. Verify with the Manufacturer: Directly contact the material manufacturer to verify the authenticity of the MTC. Most reputable manufacturers can confirm the validity of their certificates.
    2. Third-Party Verification: Utilize services from independent third-party inspection agencies to validate the material properties and the authenticity of the MTC. This is especially crucial for critical applications.
    3. Check for Inconsistencies: Scrutinize the MTC for any inconsistencies or errors in formatting, spelling, or data that might indicate forgery. Compare the certificate’s format with known genuine examples from the same manufacturer.
    4. Traceability: Ensure that the MTC includes clear traceability information, such as heat or batch numbers, and verify this information against the physical product.
    5. Quality Assurance Processes: Implement robust quality assurance procedures for verifying and documenting the receipt and inspection of materials. This can include regular audits of suppliers and testing of material samples.
    6. Supplier Audits: Conduct thorough audits of suppliers to assess their credibility, quality control practices, and the authenticity of their documentation.
    7. Education and Training: Educate procurement and engineering teams about the risks of fake MTCs and train them on how to recognize and report suspected forgeries.

    Industry Collaboration And Reporting

    Encourage and participate in industry-wide efforts to combat the proliferation of fake MTCs. Reporting suspected fake certificates to relevant authorities and industry associations can help raise awareness and lead to the development of more effective prevention strategies.

    By taking proactive steps to verify the authenticity of Mill Test Certificates, companies can significantly reduce the risks associated with the use of non-compliant materials, safeguarding their projects, reputation, and, most importantly, the safety of all stakeholders.

    Blockchain Technology Could Help Fight Fake MTCs

    Using Non-Fungible Tokens (NFTs) to prevent the counterfeiting of industrial products is an innovative application of blockchain technology. NFTs, which are unique digital certificates stored on a blockchain, provide a secure and tamper-proof method of verifying the authenticity, ownership, and provenance of both digital and physical goods.

    blockchain
    blockchain

    Here’s how NFTs can be used to combat counterfeiting in the industrial sector:

    1. Digital Authentication:

    • Creating NFTs for Physical Products: Each physical product or component can be paired with a unique NFT that serves as a digital twin. This NFT contains critical data about the product, including manufacturing details, batch numbers, and certification information.
    • Secure Storage: Information within NFTs is stored on a blockchain, making it immutable and protected against unauthorized alterations. This ensures that the product’s digital certificate of authenticity cannot be forged.

    2. Provenance Tracking

    • Comprehensive History: NFTs can store the entire history of a product, from its production through its various ownership and transaction stages. This level of traceability is invaluable for verifying the product’s journey and ensuring it has not been tampered with or replaced by counterfeits.
    • Supply Chain Transparency: Implementing NFTs throughout the supply chain enhances transparency, allowing buyers to verify the origin and journey of the products and components they purchase.

    3. Ownership Verification

    • Transferable Records: NFTs can facilitate the transfer of ownership records securely and efficiently. When a product is sold or changes hands, its corresponding NFT is transferred to the new owner, providing a clear and indisputable record of ownership.
    • Access Control: Only authorized parties can access and update the NFT, ensuring that the product’s ownership and history are securely managed.

    4. Integration With Smart Contracts

    • Automated Verification: Smart contracts, self-executing contracts with the terms of the agreement directly written into code, can be used in conjunction with NFTs to automate verification processes, payments, and transfers of ownership, further securing transactions against fraud.
    • Conditional Transactions: Smart contracts can enforce conditions that must be met for a transaction to occur, such as the verification of a product’s authenticity through its NFT before a sale can be completed.

    5. Challenges And Considerations

    • Physical-Digital Link: Ensuring a secure and tamper-proof link between the physical product and its digital NFT is crucial. This may involve secure tagging technologies, such as RFID chips, QR codes, or holograms, that can securely associate a physical item with its digital counterpart.
    • Adoption and Standardization: Widespread adoption of NFTs for anti-counterfeiting measures requires collaboration and standardization across industries and supply chains. Establishing common standards and practices is essential for interoperability and effectiveness.
    • Legal and Regulatory Compliance: The use of NFTs must comply with existing regulations and laws, including those related to data privacy, digital assets, and cross-border transactions.

    By leveraging NFTs and blockchain technology, companies in the industrial sector can significantly enhance the security, transparency, and efficiency of their operations, providing a powerful tool against the challenges posed by counterfeit products.

.

/by
,

Valve Parts Body, Bonnet, Trim, Seats, and Packing

BODY

Valve parts: valve body

In the oil and gas industry, a valve body is the primary and critical component of a valve, functioning as the main structure that holds the valve together and contains the fluid flow. Made from materials capable of withstanding the harsh conditions and substances found in oil and gas applications, the valve body is engineered to handle high pressures, corrosive materials, and extreme temperatures. The body holds in position the moving components in contact with the fluid and has to withstand the pressure existing in the piping system.

Valve bodies in the oil and gas sector are typically constructed from robust materials such as carbon steel, stainless steel, alloy steels, and sometimes special alloys like Inconel, Monel, and Hastelloy. The choice of material depends on the specific application’s demands, including the type of fluid (oil, gas, water, etc.), temperature, pressure, and potential corrosive interactions. For instance, stainless steel and special alloys are preferred in environments where corrosion resistance is paramount.

The body can be manufactured by casting or forging steel in a variety of shapes, designs, and grades.

In the oil and gas industry, the most common materials for cast bodies are ASTM A216 and ASTM A105 for forged bodies (high-temperature service). For low-temperature service, ASTM A352 LCB/LCB and ASTM A350 LF2/LF3 are used, respectively, for cast and forged bodies.

As the temperature, the pressure, or the corrosion increase, stainless steel bodies become necessary: ASTM A351 CF8 (SS304) and CF8M (SS316) for cast devices, and the various ASTM A182 Fxx (F304, F316, F321, F347) for forged types.

For specific applications, special material grades with even stronger corrosion resistance are used, such as super austenitic stainless steels (SMO 254), duplex and super duplex steels (F44, F51, F53, F55), and nickel alloys (Inconel, Incoloy, Hastelloy).

For marine applications, non-ferrous materials or alloys are the elective choices, like Monel, Cupronickel, Aluminum-bronze alloys, and other alloys combining Nickel, Copper, and Aluminium. Cast iron bodies, which are the cheapest types, are used for water distribution (low-pressure applications).

The design of a valve body encompasses several key features:

  • Connections: Valve bodies are designed with various end connections to facilitate integration into piping systems. These connections can be flanged, threaded, welded, or socket welded, each suitable for different applications and pressure ratings.
  • Pressure Containment: The valve body is engineered to contain the operational pressures of the fluid it controls without leakage. Its thickness and material composition are calculated to withstand the maximum expected pressure and any thermal expansions.
  • Flow Path: Inside the valve body is the flow path, which can be straight-through or angular, determining the direction and characteristics of the fluid flow. The internal design, including cavities and ports, is optimized for minimal flow resistance and efficient operation.

The valve body houses several integral components crucial for valve operation, including:

  • Trim: The internal parts that come in direct contact with the fluid, such as the disc, seat, and stem. The trim regulates the flow and sealing within the valve.
  • Bonnet: The component that attaches to the valve body to enclose the internal parts. It can be bolted, screwed, or welded to the body.
  • Packing: A sealing system within the valve body that prevents fluid leakage around the stem.

In the oil and gas industry, the reliability and safety of operations heavily depend on the quality and integrity of valves. Valve bodies are therefore designed to meet stringent industry standards and certifications, such as API (American Petroleum Institute) and ASME (American Society of Mechanical Engineers), to ensure they can handle the demanding operational conditions. Their role in controlling the flow, pressure, and direction of petroleum products, natural gas, and by-products makes them indispensable components in exploration, production, refining, and distribution processes.

Body End Connections

Valves can be connected to other mechanical devices and pipes in different ways. The main end types are flanged and buttweld (for devices above 2 inches) and socket weld or threaded/screwed (NPT or BSP) for small-diameter devices. Butterfly valves have more articulated body-end types, like lug, wafer, and double-flanged ends.

Let’s now delve into the different types of valve bodies’s end types:

Flanged Ends

flanged valve

In this case, the device has two flanged ends that can be connected with a pipe by using a mating (companion) flange.

A flanged connection requires a proper number of stud bolts and nuts, as indicated by the ASME B16.5 specification, and a suitable gasket.

Flanged connections are common for larger-diameter valves, and they ensure long-lasting, and strong, joints.

The flange face may be raised, flat, ring joint, tongue, and groove male & female (the most common finish is the RF type, i.e. raised face), and be finished in any of the available variants (stock, serrated or smooth).

Socket Weld And Buttweld
socket weld valve
Socket weld valve end connections
Cast valve with socket connection
Buttweld valve end connections

Valves with socket weld ASME B16.11 or buttweld ends ASME B16.25 are welded to the connecting pipe.

Welded connections are more expensive to execute than flanged joints, as they require more work, but are more reliable and less prone to leakages in the long run.
Socket weld and buttweld ends are used for high-pressure pipelines (socket weld for smaller sizes, below 2 inches, and buttweld for larger diameters).

Buttweld connections require full welding of the beveled ends of the two parts to be joined, whereas socket weld connections are made by fillet welds.

Threaded End Connections

Threaded valve end

In this case, the device is connected to the pipe by a thread (tapered thread), which may be BSP or NPT (more common in the petrochemical industry).
This type of connection is used for low-pressure pipelines with bore sizes below 2 inches, not subject to mechanical forces such as vibration and elongation.
Threaded connections are quicker to execute and cheaper, as the pipe is simply screwed onto the valve, without the need for flanges, stud bolts, or welding operations.
In case of leakage, however, threaded connections need to be changed and can’t be repaired (which is instead possible for the two previous types of pipe-to-end connections).
BSP VS. NPT Threaded Connections

BSP (British Standard Pipe) and NPT (National Pipe Thread) are two of the most commonly used threaded connections for pipes and fittings, especially in the context of connecting valves, instruments, and plumbing components. Despite serving similar functions in creating secure threaded connections for fluid transport systems, they differ significantly in design, application, and compatibility. Understanding these differences is crucial for ensuring leak-proof and efficient piping systems, particularly in industries like oil and gas, water management, and manufacturing.

Design Differences between BSP and NPT threaded-ends:

  • Thread Form: NPT threads have a 60-degree thread angle with a tapered profile, which means the diameter of the threads increases or decreases along the length of the fitting. This taper creates a seal through the wedging action of the threads themselves, often requiring thread sealant or tape to ensure a leak-proof connection. In contrast, BSP threads come in two types: BSP Parallel (BSPP), with a straight or parallel thread profile, and BSP Tapered (BSPT), with a taper similar to NPT but with a 55-degree thread angle. The different angles and shapes affect how each thread type seals and mates with its counterpart.
  • Sealing Mechanism: NPT fittings rely on the interference fit between the male and female threads for sealing, necessitating the use of a sealant. BSPP connections, however, usually require a bonded seal or washer placed between the male and female ends for a leak-free seal, while BSPT connections can seal on the thread itself like NPT, though the thread profiles are not interchangeable.

Application and Compatibility:

  • Geographical Use: NPT is the standard thread type in the United States and Canada for connecting pipes and fittings in pneumatic, hydraulic, and plumbing systems. BSP threads are more common in Europe, Asia, Australia, and other parts of the world. While both types are used globally, their prevalence varies by region, influencing their selection based on local standards and availability.
  • Interchangeability: Due to their different thread angles and designs, NPT and BSP fittings are not directly interchangeable. Attempting to mate an NPT fitting with a BSP counterpart can result in damage to the threads, inadequate sealing, and potential leaks. Special adapters are required to connect NPT and BSP threaded components securely.

Choosing Between BSP and NPT:

Selecting between BSP and NPT threads depends on several factors:

  • Regional Standards and Availability: Choose the thread type that aligns with the local standards and is readily available in your region to ensure compatibility with existing systems and ease of replacement.
  • Application Requirements: Consider the specific requirements of your application, including the type of fluid, pressure, and the need for a reliable seal. For example, BSPP might be preferred for applications requiring a flat sealing surface, while NPT and BSPT are better suited for creating tighter seals in high-pressure systems.
  • System Design: The overall design of your piping or fluid transport system may dictate the choice of thread type, based on the connections used in existing components and the need for adapters or specific sealing methods.

Understanding the distinctions between BSP and NPT threaded connections is essential for engineers, plumbers, and technicians to make informed choices when designing and assembling piping systems. Proper selection and installation not only ensure system integrity and leak-free operation but also compliance with regional standards and practices.

VALVE BONNET

Valve assembly: bonnet

The valve bonnet is a critical component of a valve assembly, serving as the cover for the valve body. It is second in importance only to the valve body itself in the overall valve structure. The bonnet is attached to the valve body, which is the primary pressure-containing structure, and together, they enclose the internal parts of the valve that come into direct contact with the process fluid, such as the stem, disk, and seat. Let’s explore the functions, types, and significance of the valve bonnet in more detail:

Functions Of The Valve Bonnet

  • Pressure Containment: The bonnet acts as a seal, ensuring that the process fluid does not escape from the valve body. It is designed to withstand the maximum pressure of the valve’s intended use.
  • Component Protection: By enclosing the internal parts of the valve, the bonnet protects them from external contaminants and damage, contributing to the valve’s durability and reliability.
  • Access Point: The bonnet can serve as an access point for the maintenance, repair, or replacement of the valve’s internal components. Depending on the valve design, removing the bonnet may provide direct access to the internals.

Types Of Valve Bonnets

Valve bonnets come in various designs, each suited to different applications and pressure conditions. Common types include:

  • Bolted Bonnet: A widely used design where the bonnet is attached to the valve body with bolts or studs and nuts. It provides a sturdy seal and is suitable for a broad range of pressures and temperatures.
  • Screwed Bonnet: In this design, the bonnet is screwed directly into the valve body. Screwed bonnets are commonly used in smaller valves and lower-pressure applications.
  • Welded Bonnet: For valves used in high-pressure and high-temperature applications, a welded bonnet provides a leak-proof seal by permanently welding the bonnet to the valve body. This design is often used when the valve does not require regular maintenance.
  • Pressure Seal Bonnet: Used in high-pressure applications, this design employs a gasket that is pressure-energized to enhance the seal between the bonnet and the valve body as the internal pressure increases.
  • Union Bonnet: A design that allows for easy disassembly and reassembly of the valve for maintenance. The bonnet and body are connected with a threaded union, facilitating straightforward access to the valve internals.

Significance Of The Valve Bonnet

The valve bonnet plays a vital role in ensuring the safe and efficient operation of the valve. Its design and construction are critical for maintaining the integrity of the valve under operating conditions. Choosing the appropriate bonnet type based on the specific requirements of the application, such as pressure, temperature, and the need for maintenance access, is essential for valve performance and longevity.

In summary, the valve bonnet is an indispensable part of the valve assembly, contributing to pressure containment, protection of internal components, and, depending on its design, facilitating maintenance and repair activities. Its importance in the overall functionality and safety of the valve system cannot be overstated.

TRIM

Valve trim

The trim is a collective name for all the internal parts of the valve that can be removed and replaced (these parts are also called “wet”, as they are in direct contact with the conveyed fluid).

Typically, the trim includes components such as the disc, the seat, the stem, the glands, the bushings, and the sleeves needed to guide the stem (the actual list of components that make up the trim depends, actually, on the type of device).

Valve trim refers to the internal components of a valve that come into direct contact with the fluid being controlled. It plays a crucial role in the function and performance of the valve, affecting its ability to regulate flow, pressure, and temperature within a system. The trim essentially determines how the valve operates, including how it opens and closes, and how it modulates or throttles the flow of the process medium. Understanding the components that make up the valve trim and their functions is essential for selecting the right valve for specific applications and ensuring optimal performance and durability.

Components Of Valve Trim

The main components of valve trim include:

  • Disc or Ball: The component that actually blocks the flow path or allows flow through the valve. In globe and gate valves, this is typically a disc; in ball valves, it’s a ball with a hole through the center.
  • Seat: The seat provides a sealing surface for the disc or ball to rest against when the valve is closed. The quality and material of the seat are crucial for ensuring a tight seal and preventing leakage.
  • Stem: The stem connects the actuator or handle to the disc or ball and transmits the motion required to open or close the valve. It can move linearly (in globe or gate valves) or rotate (in ball or butterfly valves).
  • Cage: In some valve designs, particularly in globe valves, the cage surrounds the disc and can guide its movement as well as provide additional flow control and stability.
  • Spring: Springs may be used in some valve trims, particularly in check valves and safety valves, to provide the necessary force for opening or closing the valve under certain conditions.
  • Plug: In some types of valves, like plug or globe valves, a plug may serve as the obstructing element instead of a disc or ball.

Importance Of Valve Trim

  • Flow Control: The design and material of the valve trim directly influence the valve’s ability to control the flow rate, direction, and pressure drop across the valve. Different trim designs cater to different control needs, from simple on/off to precise flow regulation.
  • Durability and Wear Resistance: The trim components are subject to continuous wear due to their contact with the process fluid. Selecting trim materials that are compatible with the fluid and operating conditions (such as temperature and pressure) is essential to ensure the valve’s longevity and reliability.
  • Maintenance and Replacement: Over time, parts of the valve trim may need maintenance or replacement due to wear or damage. The design of the trim affects the ease with which these maintenance activities can be carried out. Modular trim designs allow for easier replacement of worn components.

  • Selecting The Right Valve Trim

    Choosing the appropriate valve trim requires careful consideration of several factors, including the nature of the fluid (its corrosiveness, viscosity, and presence of solids), the required flow control characteristics, and the operating conditions (pressure and temperature). The right trim material and design ensure that the valve performs effectively and efficiently over its intended lifespan, minimizing maintenance needs and operational downtime.

    Typical trim combinations for gate, globe, and check valves have been standardized by the API trim chart.

    In summary, valve trim is the collective term for the internal components of a valve that interact with the fluid being controlled. Its design and material composition are critical for ensuring the valve’s effective operation, durability, and ability to meet specific flow control requirements.

    DISC

    Valve disc

    The valve disc is a fundamental component within the valve trim, playing a critical role in the valve’s function of regulating, stopping, or starting the flow of fluid.

    It interacts directly with the fluid path, and its movement—either towards or away from the valve seat—controls the flow through the valve. The design, material, and proper functioning of the valve disc are vital for ensuring the valve’s effectiveness and reliability in various applications, ranging from simple water piping systems to complex chemical processing plants.

    Functionality Of The Valve Disc

    • Flow Regulation: The primary function of the valve disc is to regulate the flow of fluid through the valve. By moving closer to or further from the valve seat, the disc alters the size of the opening through which the fluid can pass, thereby controlling the flow rate.
    • Sealing: When fully engaged with the seat, the disc provides a tight seal that prevents fluid from passing through the valve, achieving a complete shutoff. The efficiency of this seal is crucial for preventing leaks and ensuring the safety and efficiency of the system.
    • Modulation: In some valve types, such as globe or control valves, the disc can be positioned to precisely control the flow rate, allowing for fine modulation of the process fluid. This capability is essential in applications where maintaining specific flow parameters is critical.

    Types Of Valve Discs

    The specific design of a valve disc can vary depending on the type of valve and its intended application. Common types include:

    • Flat Discs: Used in gate valves, flat discs move vertically to the flow direction, providing an on/off function by either completely blocking or allowing flow.
    • Ball Discs: In ball valves, the disc is a sphere with a hole through its center. Rotation of the ball opens or closes the flow path, offering both shutoff and throttling capabilities.
    • Plug Discs: Utilized in plug valves, these discs are cylindrical or conically tapered plugs that rotate to control flow through an opening in the plug.
    • Butterfly Discs: Butterfly valves use a flat, circular disc that pivots in the center of the valve body. This design allows for quick operation and is used for both isolation and flow regulation.

    Material Considerations

    The material of the valve disc is selected based on the fluid characteristics (such as corrosiveness, temperature, and pressure), the valve’s application, and the desired longevity. Common materials include:

    • Metals: Stainless steel, carbon steel, brass, and bronze are widely used for their strength, durability, and resistance to high temperatures and pressures.
    • Plastics: For applications involving corrosive fluids or lower pressure and temperature conditions, plastics such as PVC, PTFE (Teflon), and PVDF offer excellent corrosion resistance and reduced cost.
    • Ceramics: Employed in applications involving abrasive fluids, ceramic discs provide superior wear resistance.

    Significance Of The Disc For Valves’s Performance

    The valve disc is a pivotal component within the valve’s architecture, instrumental in controlling fluid flow, ensuring tight shutoff, and enabling precise flow modulation. Its design, material, and compatibility with the valve seat are critical for the valve’s performance, efficiency, and durability in various industrial and residential applications. Selecting the right valve disc requires a thorough understanding of the application requirements, including the fluid’s nature, operational conditions, and desired control characteristics.

    SEATS

    Valve seats

    Valve seats are integral components of a valve’s internal mechanism, designed to interface with the valve disc (or plug, ball, etc.) to form a tight seal that controls or stops fluid flow through the valve.

    These seats play a pivotal role in ensuring the efficiency, reliability, and leakage prevention of the valve during operation. The material composition, design, and condition of the valve seats are critical to the valve’s performance, affecting its ability to regulate flow accurately and maintain a secure seal under various operating conditions.

    Function And Importance

    • Sealing Surface: The primary function of a valve seat is to provide a smooth, precise surface for the valve disc to rest against, creating a seal that prevents fluid from leaking past the closed valve.
    • Flow Regulation: In valves designed for throttling, the seat works in conjunction with the disc to modulate the flow of fluid. The design of the seat can influence flow characteristics and control precision.
    • Durability and Wear Resistance: Valve seats must withstand continuous contact with the valve disc and resist wear and deformation from the process fluid, pressure fluctuations, and mechanical operations.

    • Seats Materials

      Valve seats are made from a variety of materials, chosen based on the application’s specific requirements, including the type of fluid, operating pressure, temperature, and corrosive potential. Common materials include:

      • Metals: Stainless steel, bronze, and brass are commonly used for their durability and resistance to high temperatures and pressures. Hardened metals or alloys may be used in severe service conditions for enhanced wear resistance.
      • Soft Seats: Materials such as PTFE (Teflon), nylon, and other elastomers offer excellent sealing capabilities and resistance to chemical corrosion. Soft seats are used in applications where metal seats might not provide an adequate seal, but they are generally limited to lower temperature and pressure conditions.
      • Ceramics: For high-wear or corrosive applications, ceramic seats offer superior hardness, wear resistance, and stability under extreme temperatures.

      Design Considerations

      The design of the valve seat is crucial for its function and longevity. Factors to consider include:

      • Seat Shape and Angle: The contour and angle of the seat affect the sealing efficiency and flow characteristics. Seats can be designed for linear or equal percentage flow characteristics in control valve applications.
      • Interchangeability: Some valve designs feature replaceable seats, allowing for easy maintenance and extended valve life. These seats can be swapped out when worn or damaged without replacing the entire valve.
      • Sealing Method: The seat-to-disc contact area and method of sealing (e.g., metal-to-metal, soft seal) determine the tightness of the seal and the valve’s suitability for specific applications.

      Special Treatments For Valve Seats

      Valve seats are integral components of valve assemblies, providing a sealing surface against which the valve disc or plug seals to stop the flow of fluid. The performance and longevity of a valve largely depend on the condition and material of the valve seat, as it must withstand the mechanical stresses and corrosion caused by the flowing medium. To enhance their durability, wear resistance, and sealing capabilities, valve seats may undergo various special treatments. These treatments are designed to ensure that the valve operates reliably over its intended lifespan, even under harsh operating conditions. Here are some common treatments available for valve seats:

      Hardening Treatments
      • Surface Hardening: Processes like induction hardening and flame hardening increase the surface hardness of the seat, improving wear resistance without compromising the toughness of the base material.
      • Case Hardening: Techniques such as carburizing, nitriding, and carbonitriding add a hard, wear-resistant layer to the surface of the seat while maintaining a ductile interior. These treatments are particularly useful for seats in valves handling abrasive particles.
      Coating Treatments
      • Stellite Overlay: Stellite, a cobalt-chromium alloy, is known for its excellent hardness and resistance to wear and corrosion. Applying a Stellite overlay on valve seats can significantly extend their service life, especially in high-pressure, high-temperature, and erosive applications.
      • Chrome Plating: Chromium plating offers good wear resistance and low friction, making it suitable for valve seats in applications where minimizing leakage is critical.
      • Nickel Alloy Coatings: Nickel-based coatings, including Inconel and Monel, provide enhanced corrosion resistance in environments with corrosive fluids or gases.
      • Thermal Spray Coatings: Techniques like High-Velocity Oxygen Fuel (HVOF) spraying can apply tungsten carbide or other hard materials onto the seat surface, improving wear and corrosion resistance.
      Material Upgrades
      • Solid Seats: In some cases, the entire seat is made from a high-performance material, such as ceramics or high-nickel alloys, to withstand extreme conditions of temperature, pressure, and corrosion.
      • Inserts: Using inserts made from durable materials like ceramics or hardened metals can offer superior wear and corrosion resistance. These inserts are either pressed or screwed into the valve body.
      • Lapping And Grinding
        • Precision Lapping: This process involves rubbing the seat against a flat surface with an abrasive compound to achieve a high degree of surface finish and flatness. Lapping ensures a tight seal between the seat and the disc or plug.
        • Grinding: Grinding processes can be used to restore damaged or worn seats, improving the sealing surface’s condition and extending the valve’s operational life.

        Each treatment has its specific advantages and is chosen based on the valve’s application, the characteristics of the fluid it controls, and the operating conditions (pressure, temperature, and presence of abrasive particles). By selecting the appropriate treatment for valve seats, manufacturers and users can ensure optimal performance, reduce maintenance costs, and extend the lifespan of valves in various industrial and commercial applications.

        Importance Of Valve Seats

        Valve seats are crucial for the functionality and performance of valves, acting as the sealing interface that regulates fluid flow and ensures leak-free operation. The selection of seat material and design is tailored to the valve’s intended use, considering factors such as fluid compatibility, pressure and temperature conditions, and required flow control characteristics. Proper maintenance and timely replacement of valve seats are essential for maintaining optimal valve performance and system integrity.

        STEM

        Valve stem
        The stem of a valve is used to open/close the fluid as it moves the disc. The stem is linked to the valve actuator or to the manual handwheel (or lever), at one end, and is connected to the valve disc on the other end.

        For the gate and globe types, the stem operates a linear motion on the disc, whereas, for the ball, butterfly, and plug types, the disc rotates to open or close the device (“quarter turn valves”).

        Stems are made of forged steel and are connected to the disc by threading or other means. A proper finish of the stem surface is necessary to prevent leakages.

        There are five main types of stems:

        • Rotary: This is a standard type of ball, plug, and butterfly valve. A quarter-turn motion of the stem is needed to open/close the device
        • Sliding: In this case, the stem does not execute any rotation. The stem slides in and out the valve to open or close it. This design is common in hand-operated lever rapid-opening valves. It is also used in control valves are operated by hydraulic or pneumatic cylinders.
        • Rising type with outside screw and yoke (“OS&Y”): the external side of the stem is threaded while the part of the stem which is inside the valve is plain. The threads of the stem are isolated from the medium by the packing. Two alternative designs are available. The “OS&Y” design is common for valves above 2″.
        • Rising type with an inside screw (“IS&Y”): The threaded part of the stem is positioned inside the valve body, whereas the stem packing lays outside. With this design, the stem threads are in touch with the medium flowing through the pipeline. Once rotated, the stem and the hand wheel rise together and open the valve.
        • Non-rising stem type with inside screw: The threaded part of the stem is inside the valve and does not rise. The valve disc floats on the stem, like a nut if the stem is rotated. Stem threads are in contact with the media of the pipeline, and as such, may be exposed to its corrosive impact. This is the reason why such a design is used when the available space to position the valve is too narrow to permit linear movement, and the media does not cause erosion, corrosion, or abrasion of the stem material.

        PACKING

        Valve packing

        The gasket that seals the stem with the bonnet is called packing and comprises the following components:

        • Gland follower, which is a sleeve that compresses the packing, by a gland into the stuffing box.
        • Gland is a type of bushing, which compresses the packing into the stuffing box.
        • A stuffing box is a chamber in which the packing gets compressed.
        • Packing is available in different materials, like PTFE, elastomers, fibrous material, etc.
        • A backseat is sitting inside the bonnet. The back seat provides a seal between the stem and bonnet and prevents system pressure from building against the valve packing once the valve is fully open. Back seats are often used in gate and globe valves.
        • The valve packaging shall be properly designed and manufactured to minimize the possible damage to the stem and minimize the risk of leakages of fluids. On the other hand, it is necessary to observe that a too-tight packing may affect the stem.

        • VALVE ACTUATOR

          Valve actuator

          Valve actuators are devices used to operate valves automatically or manually, converting control signals into mechanical motion to open, close, or modulate the flow of fluids.

          The choice of the right actuator for a valve depends on several factors, including the valve size, the required speed of operation, the force needed to operate the valve, environmental conditions, and whether the actuator will be used for on/off, throttling, or proportional control. There are several types of valve actuators, each with its own set of characteristics, advantages, and applications.

          Key Types Of Actuators

          Manual Actuators

          Manual actuators require human effort to operate the valve, using handwheels, levers, or gears. They are simple and do not rely on an external power source.

          • Advantages: Simplicity, no need for power supply, and direct control.
          • Applications: Used in applications where automated control is not necessary or as a backup method for operating valves.

          A hand-operated or manual valve is generally equipped with a hand wheel that can be rotated clockwise or counter-clockwise to open and/or close the valve (typical for gate and globe valves). Ball, plug, or butterfly are actuated using a lever (manual quarter turn valves).In the following cases, it is not either possible nor advisable to use manual valves:

          • Large dimension valves that operate at high pressures
          • Valves that need to be controlled from a remote location
          • Valves that require, for the nature of the process, a very fast open or close operation

          In all these cases, a valve actuator is needed. The actuator produces linear and rotary motion able to open or close a valve (the actual movement depends of course on the type of the valve, linear or quarter turn).

          Pneumatic Actuators

          Pneumatic actuators use compressed air to generate motion to operate the valve. They are one of the most common types of actuators used in industrial environments due to their simplicity, reliability, and cost-effectiveness.

          • Advantages: Rapid response time, inherent explosion safety, and simplicity of design.
          • Applications: Widely used in the oil and gas, chemical, water treatment, and manufacturing industries.
          Hydraulic Actuators

          Hydraulic actuators use pressurized fluid, typically oil, to move the valve. They can produce a high amount of force in a relatively small footprint, making them suitable for large valve operations.

          • Advantages: High force output, precise control, and good for heavy-duty applications.
          • Applications: Ideal for use in environments where a high force is required, such as in the power generation and offshore industries.
          Electric Actuators

          Electric actuators use an electric motor to drive the valve to the desired position. They can be easily integrated with electronic control systems for accurate positioning and feedback.

          • Advantages: Precise control, easy integration with control systems, and suitable for remote operation.
          • Applications: Commonly used in HVAC, water treatment, and light industrial applications.
          Electro-Hydraulic Actuators

          Electro-hydraulic actuators combine electric and hydraulic technologies. An electric motor drives a hydraulic pump, which then moves the actuator to operate the valve.

          • Advantages: Combines the precision of electric actuators with the power of hydraulic actuators, suitable for remote and automatic control.
          • Applications: Useful in applications requiring precise control and high force, such as in large valve operations and safety shutdown systems.
          Gas Over-Oil Actuators

          A gas-over-oil actuator is a type of valve actuator designed for the automation of valve operations, leveraging a combination of high-pressure gas and hydraulic oil to generate the force necessary for valve movement. This actuation method is particularly favored in the oil and gas industry, especially for remote pipeline applications or in environments where electrical power is scarce or non-existent. Here’s how it works and why it’s beneficial:

          How It Works

          • Mechanism: In a gas-over-oil actuator, pressurized gas (often natural gas from the pipeline itself) is used to exert force on a hydraulic fluid (oil), which is then directed to move the actuator piston. This piston movement is mechanically linked to a valve, enabling it to open, close, or modulate the flow as required.
          • Components: The actuator typically consists of a gas pressure chamber, an oil reservoir, control valves for directing the flow of gas and oil, and a piston or diaphragm that converts the pressure into mechanical motion.

          Advantages

          • Remote Operation: Since they can utilize the pipeline gas itself as a power source, gas-over-oil actuators are ideal for remote locations where electrical power is unavailable.
          • Safety: They are inherently safe for use in explosive atmospheres, as they do not require electricity and minimize the risk of ignition.
          • Reliability: This type of actuator is known for its reliability and durability, capable of operating in harsh environments with minimal maintenance.

          Applications

          • Pipeline Valves: Widely used for the control and safety shutdown valves in natural gas pipelines.
          • Offshore Platforms: Suitable for valve actuation in offshore gas extraction platforms, where reliability and safety are paramount.
          • Isolated Installations: Ideal for any valve actuation application in remote or difficult-to-access locations within the oil and gas sector.

          Gas-over-oil actuators provide a robust and reliable solution for valve automation, combining the advantages of hydraulic systems’ power and precision with the safety and availability of using pipeline gas as a power source. This makes them an essential component in the infrastructure of modern oil and gas extraction and transportation systems.

          Solenoid Actuators

          Solenoid actuators use electromagnetic solenoids to operate the valve. They are typically used for on/off control in smaller valve applications.

          • Advantages: Fast response time, simple design, and suitable for small valves.
          • Applications: Commonly used for precise control in fluid power systems, medical equipment, and general on/off applications in various industries.

          Each type of valve actuator offers distinct advantages and is chosen based on the specific requirements of the application, such as control needs, operating environment, and valve size. Understanding the different types of actuators and their capabilities is crucial for selecting the right actuator to meet the demands of a particular system or process.

        • Rotork and Auma actuators have the largest market shares within the petrochemical industry.

          Valve actuators types
/by