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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.

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:

Swing Check Valves: Suitable for larger pipe diameters and low-pressure drop applications.
Ball Check Valves: Ideal for viscous fluids or applications with varying flow rates.
Lift Check Valves: Best for high-pressure systems where tight sealing is required.
Wafer Check Valves: Used in space-constrained applications, offering a compact design.
Dual Plate Check Valves: Provide quick closing to prevent fluid hammer in liquid systems.

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 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.
  
  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.
  
  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.
  
  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
  
  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
  
  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).
- 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
  
  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
  
  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).

May 23, 2024/by stvvalve

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).

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

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.
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.
Bi-Directional: While typically used in one direction, globe valves can be designed for bi-directional flow, adding to their versatility in system design.
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.
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

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.
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.
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.
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.
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.

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.

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

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 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:

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

May 23, 2024/by stvvalve

industry valve news, News

Understand Gate Valves (API 600, 602, 603)

What is a gate valve? It is a shut-off device to open and close the flow of the fluid conveyed by a piping system (or a pipeline). A gate valve is a bi-directional valve, as the fluid may flow in either direction. The installation of this type of valve creates a modest pressure drop in the pipeline, lower than globe valves. Gate valves have forged bodies for bore sizes below 2 inches (API 602/BS 5352), and cast bodies for larger sizes (API 600, API 603, API 6D).

GATE VALVES

WHAT IS A GATE VALVE?

In the oil and gas industry, a gate valve is a crucial component used to control the flow of fluids through pipelines and equipment. Characterized by its ability to provide a straight-through, unrestricted flow path when fully open, a gate valve operates by lifting a gate (or wedge) out of the path of the fluid.

This type of valve is typically used for on/off control rather than flow regulation, making it ideal for applications where a minimal pressure drop and a full bore are required when the valve is in the open position.

Gate valves are on-off valves to open and close the flow of the fluid in a pipeline. The valve is opened and/or closed by the vertical movement of a disc on the valve’s seat.

Gate valve API 600

GATE VALVES ADVANTAGES & DISADVANTAGES

Bi-Directional: Gate valves can control flow in both directions, offering versatility in installation and use.
Minimal Pressure Drop: When fully open, gate valves provide a straight path for flow, resulting in a very low-pressure drop across the valve.
Sealing Surface: Gate valves have two sealing surfaces between the gate and seats, providing a tight seal when the valve is closed.
Operation: These valves are operated using a handwheel, gear, actuator, or motor, depending on the size, pressure rating, and application requirements. Manual operation is common for smaller sizes, while larger valves often require mechanical assistance.
Easy to maintain and disassemble
Low-cost option
Can be used with slurries and viscous liquids
Available in large sizes
Inherently fire-safe (when used with a metal sheet)

The disadvantages of gate valves are:

Slow open and close time
Low-pressure limitations
Erosion of the seat and disk can occur
Poor throttling characteristics
May be difficult to repair in case of failure (it is easier and cheaper to replace a broken cast valve in most cases)
TYPICAL APPLICATIONS IN THE OIL&GAS INDUSTRY

Gate valves are largely used in the oil & gas, petrochemicals, and general manufacturing industries. The most common tasks assigned to this type of valve are:
- Isolation Tasks: Gate valves are widely used for isolation purposes in oil and gas pipelines, storage tanks, and processing equipment, allowing sections of a system to be shut down for maintenance or in an emergency without affecting the rest of the operation.
- High-Pressure Environments: Their robust design makes them suitable for high-pressure and high-temperature applications commonly found in upstream exploration and production, as well as in downstream processing.
- Underground Installations: Due to their full-bore design and minimal pressure drop, gate valves are also preferred for underground gas storage and control applications.
SELECTION CRITERIA

When selecting a gate valve for oil and gas applications, several factors should be considered:
- Material: The choice of material depends on the type of fluid, operating temperatures, and pressures. Common materials include carbon steel, stainless steel, and alloy steel designed to withstand corrosive environments.
- Size and Pressure Rating: Proper sizing and selection of pressure ratings are essential to match the pipeline specifications and operational conditions.
- Maintenance: While gate valves are known for their durability, they are not ideally suited for throttling applications, as the vibration and rapid flow changes can cause wear to the gate and seats, leading to leakage. Regular maintenance is required to ensure long-term reliability and performance.
APPLICABLE SPECIFICATIONS (API, ASME)

API SPECS FOR GATE VALVES

API (American Petroleum Institute) specifications provide comprehensive standards and technical requirements for the design, manufacturing, and testing of gate valves used in the oil and gas industry. These specifications ensure the reliability, safety, and efficiency of gate valves under various operational conditions.

Below are some key API specifications applicable to gate valves:

API 600: applies to carbon/alloy steel gate valves

“Steel Gate Valves – Flanged and Butt-Welding Ends, Bolted Bonnets” This specification covers the design, manufacturing, and testing of bolted bonnet steel gate valves for petroleum and natural gas industries. It includes detailed requirements for gate valves with flanged or butt-welding ends and bolted bonnets, focusing on sizes and pressure classes specified for use in pipeline and piping systems.

API 603: applies to stainless steel gate valves

“Corrosion-Resistant, Bolted Bonnet Gate Valves – Flanged and Butt-Welding Ends” This standard covers corrosion-resistant bolted bonnet gate valves with flanged or butt-welding ends. API 603 focuses on valves made from stainless steel and other alloys intended for corrosion resistance, detailing requirements for various design features, pressure classes, and sizes.

API 602/BS 5352: applies to forged steel gate valves

“Compact Steel Gate Valves – Flanged, Threaded, Welding, and Extended-Body Ends” API 602 specifies the requirements for compact steel gate valves with a variety of end connections, including flanged, threaded, and welding ends. It is intended for smaller-sized valves (NPS 4 and smaller) used in high-pressure applications, offering guidance on materials, design, and testing criteria.

API 6D: applies to slab and through conduit valves for pipelines

“Pipeline and Piping Valves” API 6D is a broad specification that covers the design, manufacturing, and testing of valves for pipeline applications, including gate valves. It encompasses aspects such as end-to-end dimensions, pressure testing, and marking for valves intended to be used in pipeline systems for transporting petroleum and natural gas.

API 6FA

“Specification for Fire Test for Valves” While not exclusively for gate valves, API 6FA specifies fire test requirements for valves used in petroleum and natural gas industries. It provides a method for testing valve performance when exposed to fire, ensuring that valves can maintain structural integrity and leak tightness during and after a fire incident.

API 624

“Type Testing of Rising Stem Valves Equipped with Graphite Packing for Fugitive Emissions” API 624 addresses the testing of rising stem gate valves equipped with graphite packing, focusing on their performance regarding fugitive emissions. This specification ensures that valves meet environmental and safety standards by limiting emissions of volatile organic compounds (VOCs).

API-598: valves testing

ASME/ANSI SPECS FOR GATE VALVES

ASME (American Society of Mechanical Engineers) and ANSI (American National Standards Institute) specifications play critical roles in standardizing the design, manufacturing, and testing of gate valves, ensuring their safety, reliability, and efficiency across various industries. Here are some key ASME/ANSI specifications applicable to gate valves:

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

This standard provides requirements for materials, pressure-temperature ratings, dimensions, tolerances, marking, and testing for flanged, threaded, and welding end steel valves. It includes gate valves among other valve types and serves as a fundamental reference for valve specifications in terms of pressure class ratings, material groups, and appropriate service conditions.

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

ASME B16.10 specifies the standard face-to-face and end-to-end dimensions for flanged, threaded-end, welding-end, and wafer-type valves, including gate valves. This standard is crucial for ensuring the interchangeability and proper fit of valves within piping systems.

ASME B16.5 – Pipe Flanges and Flanged Fittings

Although not exclusively for valves, ASME B16.5 establishes dimensions, tolerances, and material specifications for pipe flanges and flanged fittings in sizes from NPS 1/2 through NPS 24. Gate valves with flanged ends must comply with this specification to ensure compatibility with flanged piping connections.

ASME B16.25 – Buttwelding Ends

This specification outlines the dimensions, tolerances, and finishing for buttwelding ends of piping components, including gate valves. It ensures the proper fit and sealing capability for welded connections in piping systems.

ASME ANSI B16.47: flanged ends for bore sizes above 24 inches

ASME B31.4 – Pipeline Transportation Systems for Liquids and Slurries

While ASME B31.4 is a piping code rather than a specific valve standard, it includes requirements that affect the selection and application of gate valves in pipeline systems transporting liquids and slurries. It provides guidelines for materials, design, construction, and testing of pipeline components.

ASME B31.8 – Gas Transmission and Distribution Piping Systems

Similar to ASME B31.4 but focused on gas transmission and distribution, ASME B31.8 also impacts the use of gate valves in gas pipelines, specifying criteria for material selection, design, construction, and testing to ensure safety and integrity in gas piping systems.

Compliance with these ASME/ANSI specifications is essential for gate valve manufacturers and users, as it guarantees that valves meet established industry standards for performance, durability, and safety. These standards help guide engineers and project managers in selecting the appropriate gate valves for their specific applications, whether for water treatment, oil and gas, chemical processing, or other industrial systems.

GATE VALVE TYPES

CAST STEEL GATE VALVES

This is the most common type, covered by the API 600 (carbon and alloy steel) and API 603 (stainless steel and higher grades) specifications. Cast steel gate valves are available in sizes above 2 inches, and up to 80 inches.

Cast steel gate valves are essential components in various industrial applications, including oil and gas, power generation, and water treatment systems. These valves are designed for on/off control of fluids and are particularly favored for their capability to provide a minimal pressure drop when fully open. Cast steel, used in the construction of these valves, offers a robust and durable solution suitable for high-pressure and high-temperature environments.

Construction And Operation

Cast steel gate valves consist of a valve body, bonnet, stem, gate (or wedge), and sealing elements. The body and bonnet are typically made from cast steel through a casting process where molten steel is poured into a mold and allowed to solidify. This method provides the flexibility to create complex shapes and sizes, making it possible to tailor the valve design to specific application requirements.

The gate, manipulated by the stem, moves vertically within the valve body to open or close the flow path. When raised, the gate allows for an unrestricted flow, and when lowered, it sits tightly against the valve seat to block the flow, ensuring a tight seal.

Key Features

Durability: Cast steel provides excellent strength and toughness, making these valves suitable for high-pressure and temperature applications.
Leakage Prevention: Properly designed and maintained cast steel gate valves offer excellent sealing capabilities, minimizing the risk of leakage.
Versatility: Available in various sizes and pressure ratings, cast steel gate valves can accommodate a wide range of fluids and service conditions.
Maintenance: While generally reliable, these valves require regular inspection and maintenance to ensure optimal performance, particularly in applications involving suspended solids that might cause wear or obstruction.

Applications

Cast steel gate valves are widely used across multiple industries for their ability to control the flow of liquids, gases, and vapors. Some common applications include:

Oil & Gas: For controlling the flow in pipelines and processing facilities.
Power Generation: In steam and water systems where high pressure and temperature are common.
Water Treatment and Distribution: For isolating sections of the system for maintenance or in response to system demands.

Selection Considerations

When selecting a cast steel gate valve, several factors should be considered to ensure it meets the operational requirements effectively:

Size and Pressure Rating: Match the valve size and pressure rating with the pipeline specifications and operational pressures.
Material Compatibility: Ensure the cast steel material is compatible with the fluid medium, considering factors like corrosion resistance and material strength at operating temperatures.
Operation Type: Choose between manual, electric, pneumatic, or hydraulic actuation based on the application and accessibility.
Standards and Certifications: Valves should meet relevant industry standards and certifications to ensure quality and safety in operation.

In summary, cast steel gate valves are a reliable choice for managing fluid flow in industrial systems, offering durability and versatility for a broad range of applications. Proper selection, based on the specific requirements of the application, ensures their effective and safe operation.

FORGED STEEL GATE VALVES

Forged steel valves are used for small bore piping, generally below 2 inches in diameter. The API 602 and BS 5352 specifications cover this type of gate valve.

Forged steel gate valves are integral components in a wide array of industrial systems where robust control of fluid flow is required. These valves utilize a gate mechanism to allow or block the flow of fluids, making them suitable for on/off service rather than flow regulation. Forged steel, as the material of choice for these valves, offers superior strength, durability, and resistance to high pressures and temperatures compared to cast steel counterparts. This makes forged steel gate valves especially valuable in high-demand environments such as the oil and gas, chemical processing, and power generation industries.

Construction And Features

Forged steel gate valves are constructed from steel that has been forged under high pressure to enhance its mechanical properties. The forging process aligns the grain structure of the steel, making it denser and more uniform. This results in a valve body with exceptional strength, improved impact toughness, and greater resistance to fatigue and thermal stresses.

Key features of forged steel gate valves include:

Enhanced Durability: The forging process gives the steel enhanced strength and toughness, enabling the valve to withstand high pressures and temperatures.
Tight Seal: When closed, the gate or wedge of the valve fits snugly against the valve seats, providing a tight seal that prevents fluid leakage.
Low Flow Resistance: In the fully open position, the valve provides a straight path for the flow, resulting in minimal pressure drop.
Versatility: Forged steel gate valves are available in various sizes, pressure classes, and end connection types, making them suitable for a broad range of applications.

Applications

Forged steel gate valves are used in demanding applications where high strength and durability are paramount. Typical applications include:

High-Pressure Systems: Such as those found in oil and gas production, where the valves must handle high-pressure and corrosive fluids.
Steam Services: In power plants and other settings where steam is used for power generation or heating, requiring valves that can withstand high temperatures and pressures.
Process Industries: Chemical manufacturing and processing plants use these valves to control the flow of aggressive and hazardous chemicals.
General Industrial Applications: Anywhere that requires reliable isolation of fluid flow under high pressure or temperature conditions.

Selection Considerations

Selecting the right forged steel gate valve involves several considerations:

Pressure and Temperature Ratings: Choose a valve that meets or exceeds the maximum expected system pressure and temperature.
Material Compatibility: The material of the valve should be compatible with the fluid it will control, considering factors such as corrosion and chemical reactivity.
Size and End Connections: The valve size should match the pipeline specifications, and the end connections (flanged, threaded, butt weld, etc.) should be compatible with the existing piping.
Standards and Certifications: Ensure the valve meets relevant industry standards and certifications for safety and performance.

Conclusion

Forged steel gate valves offer a reliable solution for high-pressure and high-temperature applications across various industries. Their construction from forged steel ensures superior strength, durability, and performance in challenging environments. When selecting a valve, it’s crucial to consider the specific requirements of the application to ensure optimal performance and safety.

API 6D GATE VALVES FOR PIPELINES (THROUGH-CONDUIT)

API 6D gate valves are specialized valves designed to meet the rigorous standards set by the American Petroleum Institute (API) for use in pipeline applications.

The API 6D specification covers the design, manufacturing, and testing of gate valves, as well as other pipeline valves such as ball, check, and plug valves, intended primarily for the oil and gas industry. These valves play a crucial role in controlling the flow of oil, gas, and other hydrocarbon products within pipeline systems, offering reliable operation in on/off service.

Key Features Of API 6D Gate Valves

Design and Construction: API 6D gate valves are designed to withstand the operational pressures and temperatures encountered in oil and gas pipelines. They feature robust construction and can be made from various materials to suit different environmental conditions and fluid properties.
Double Block and Bleed (DBB) Capability: Many API 6D gate valves offer double block and bleed functionality, allowing for the isolation of a section of the pipeline and the draining or venting of the space between the two sealing surfaces (gates), enhancing operational safety and maintenance procedures.
Sealing and Seat Design: These valves typically include soft or metal-to-metal sealing mechanisms to ensure tight shut-off and minimize leakage. The seat design is critical for ensuring the valve’s reliability and performance under high pressure.
Emergency Sealant Injection: Some API 6D gate valves are equipped with an emergency sealant injection feature, which allows for the injection of a sealant into the seating area in case of leakage, providing a temporary or emergency seal.
Full Bore Design: API 6D gate valves often feature a full bore design, meaning the diameter of the valve opening matches the diameter of the pipeline. This design minimizes pressure drop and allows for the easy passage of pipeline inspection gauges (pigs).

Applications

API 6D gate valves are extensively used in the oil and gas industry, particularly in pipeline systems for:

Transmission Pipelines: Controlling the flow and providing isolation capabilities in long-distance pipelines transporting oil and gas from production sites to refineries or storage facilities.
Distribution Networks: Managing the distribution of gas to residential, commercial, and industrial end-users.
Offshore Platforms and Processing Plants: Offering reliable isolation in the challenging conditions of offshore oil and gas extraction and processing.

Selection Considerations

When selecting an API 6D gate valve for a pipeline application, it’s important to consider:

Pressure Class and Size: The valve must be suitable for the pipeline’s operating pressure and diameter.
Material Compatibility: The valve material should be compatible with the fluid being transported, considering factors like corrosion resistance and temperature tolerance.
Operational Requirements: Consider whether manual, electric, pneumatic, or hydraulic actuation is needed based on the valve’s location and the system’s operational demands.

Types Of API 6D Gate Valves

PRESSURE SEAL API 6D TYPE

Pressure seal gate valves are used for high-pressure applications. The most common types of valves for high-pressure applications are the flexible wedge and the parallel slide pressure seal valve. They are generally available with cast or forged bodies, in dimensions from 2 to 24 inches, and pressure ratings from 600# to 4500#, with socket weld or buttweld, ends to ensure tight flanged joint connections (but flanged ends are also possible).

KNIFE TYPE API 6D Gate Valve

Knife gate valves were originally introduced within the pulp and paper industry, where standard shut-off valves could not properly operate due to the nature of the fluids conveyed during the paper production process.

Knife valves should never be used as modulating valves (to regulate the flow) as the fluid flowing through a partly closed valve would generate vibration and erode both the disk and the seat.

Therefore, knife valves should be used completely closed or opened like any other type of gate valve (globe valves are recommended to regulate the flow).

Lastly, to protect the valve against the impact of the water hammer effect, knife valves feature a very slow opening and closing speed.

A Knife valve can be manufactured in materials from ductile iron to stainless steel and in sizes between 2 and 24 inches (generally with cast bodies) with low-pressure ratings (< 300 lbs).

There are many different variants of knife valves, such as the soft-seated (resilient type, with elastomer seats) the metal seated (the seat and the disc generate a metal-to-metal seal), the slide gate, and bonneted types.

Soft seat knife gate valve.

A metal seated knife gate valve (left) and resilient, a soft-seated valve (right side).

The differences with standard design are:

A standard valve is available with flanged, butt weld, and socket weld connections (knives have lugged or wafer connections mainly)
A standard valve has a V-ring packing set that seals the shaft that is attached to the gate. Knife valves feature instead of a packing gland area that seals around the gate
Gate valves are bidirectional, whereas the knife type is generally uni-directional
A knife valve has a smaller profile than the ANSI gate valve, which is more bulky and refined
Knife gate valves are lighter and cheaper than API and ASME types

Conclusion API 6D Gate Valves

API 6D gate valves are essential components in the oil and gas industry, providing critical control and isolation functions within pipeline systems. Their design and construction adhere to stringent standards, ensuring reliability, safety, and efficiency in the transportation of hydrocarbon products. When selecting these valves, it’s crucial to match the valve’s specifications with the specific requirements of the pipeline system to ensure optimal performance.

GATE VALVE VS. OTHER TYPES OF VALVES

GATE VALVE VS. BALL VALVE

What is the difference between a gate and a ball valve?

Gate valves and ball valves are two of the most commonly used types of valves in various piping systems. Each has its own unique design, operation method, and advantages, making them suitable for specific applications.

Understanding the differences between these two valve types is crucial for selecting the right valve for a given system.

Design And Operation

Gate Valve: A gate valve features a flat gate or wedge that moves perpendicularly to the direction of flow. To open or close the valve, the gate is raised or lowered by turning a handwheel or actuator. When fully open, gate valves offer a straight-through flow path with minimal resistance, making them ideal for on/off control rather than flow regulation.
Ball Valve: A ball valve uses a spherical ball with a hole (bore) through its center. Rotating the ball 90 degrees around its axis opens or closes the flow path. In the open position, fluid flows through the bore. Ball valves provide excellent sealing and are used for both on/off control and throttling.

Applications

Gate Valves: Due to their ability to provide minimal flow restriction when fully open, gate valves are often used in applications where a free flow of fluid is necessary and where the valve will remain either fully open or fully closed most of the time. They are commonly found in water and wastewater treatment, oil and gas pipelines, and other situations where fluid must be moved in large volumes.
Ball Valves: Ball valves are versatile and can be used in a wide range of applications, including residential plumbing, industrial processes, and gas handling systems. They are particularly valued for their quick operation, durability, and tight sealing capabilities, making them suitable for applications requiring reliable on/off control and system isolation.

Advantages And Disadvantages

Gate Valves:
- Advantages: Full bore design resulting in minimal pressure drop; suitable for both slurries and viscous fluids; good for high temperature and pressure applications.
- Disadvantages: Prone to wear and leakage across the seats and gate; slower to operate; not suitable for throttling purposes due to potential seat and gate damage.
Ball Valves:
- Advantages: Quick and easy to operate with a quarter-turn; excellent sealing capabilities with low torque; durable with a long service life; suitable for throttling applications with proper design.
- Disadvantages: Potential for cavitation and flow turbulence at partial open conditions; the full bore models can be more expensive than reduced bore models.

Choosing Between Gate And Ball Valves

The choice between a gate valve and a ball valve often comes down to the specific needs of the application, including the type of fluid, required flow rate, operating pressure, and temperature, and whether precise flow control or simple on/off functionality is needed. Cost, ease of maintenance, and space constraints may also influence the decision.

In summary, gate valves are best suited for applications requiring unobstructed flow and minimal pressure drop, while ball valves offer superior sealing and control, making them ideal for a broad range of on/off and throttling applications.

GATE VALVE VS. GLOBE VALVE

What is the difference between a gate and a globe valve?

Gate valves and globe valves are two fundamental types of valves used in piping systems to control the flow of liquids, gases, and slurries. While they share some similarities, they have distinct features, operating principles, and applications that make them suitable for different scenarios.

Understanding the differences between these two valve types is crucial for selecting the right valve for a specific application.

Design And Operation

Gate Valve: Utilizes a flat gate or wedge that moves vertically to the flow direction to open or close the valve. When open, the gate fully retracts into the valve body, allowing for a full, unobstructed flow path. Gate valves are primarily used for on/off control and are not suitable for throttling due to the potential for gate and seat damage.
Globe Valve: Features a movable disk-type element and a stationary ring seat in a generally spherical body. The disk moves perpendicularly to the seat, allowing for precise flow control. Globe valves are characterized by their spherical body shape, with the internal baffle that splits the inside space into two chambers. They are used for on/off control as well as for throttling flow, offering better control over flow rates.

Applications

Gate Valves: Ideal for applications where a straight-line flow of fluid and minimum restriction is desired. Commonly used in water supply, natural gas pipelines, and in applications where the valve will remain either fully open or fully closed for long periods.
Globe Valves: Suited for applications requiring flow regulation and frequent operation. Their ability to adjust the flow with precision makes them popular in cooling systems, fuel oil systems, marine applications, and where pressure drop is not a significant concern.

Advantages And Disadvantages

Gate Valves:
- Advantages: Minimal pressure drop when fully open; suitable for both slurries and viscous fluids; provides a tight seal when closed.
- Disadvantages: Slow to open and close; not suitable for throttling; can be prone to gate and seat damage from vibration if partially opened.
Globe Valves:
- Advantages: Good for throttling and regulating flow; faster to open and close compared to gate valves; provides better sealing.
- Disadvantages: Higher pressure drop across the valve; not ideal for applications requiring full, unobstructed flow.

Choosing Between Gate And Globe Valves

Choosing between a gate valve and a globe valve often depends on the specific requirements of the system, including:

Purpose: Gate valves are preferred for on/off control where the flow rate is not adjusted frequently. Globe valves are chosen for applications where flow needs to be regulated or adjusted regularly.
Flow Characteristics: If minimal pressure drop and full flow are required, gate valves are more suitable. For precise flow control, even at lower flow rates, globe valves are preferred.
Space and Orientation: Globe valves, due to their design, may require more space in a piping system and are sensitive to flow direction. Gate valves are less restrictive in terms of space and flow direction.

In summary, the choice between gate and globe valves hinges on the need for either unobstructed flow and infrequent operation or the need for flow regulation and frequent adjustments. Both valves serve critical roles in controlling system flow, and their selection should align with the operational needs and constraints of the application.

GATE VALVE VS. CHECK VALVE

Gate valves and check valves are two distinct types of valves used across various industries for controlling fluid flow in piping systems. Each serves a different primary function and operates based on different principles.

Gate Valve

Design and Function: A gate valve features a movable gate or wedge that slides vertically to control the flow of fluid. It is operated manually, typically using a handwheel or an actuator for larger sizes. The primary function of a gate valve is to start or stop the flow, providing a clear and unobstructed path when fully open, and a tight seal when fully closed.

Applications: Gate valves are widely used in applications where a full, unrestricted flow of fluid is necessary. They are ideal for on/off control but are not suitable for throttling purposes, as partial opening can cause vibration and damage to the gate and seats. Common uses include water supply, oil and gas pipelines, and other systems where flow needs to be completely shut off or allowed freely.

Advantages:

Minimal pressure drop when fully open.
Suitable for both liquid and gas applications.
Provides a tight seal when closed.

Disadvantages:

Slow to open and close.
Not suitable for throttling.
Prone to wear and corrosion, which can affect sealing over time.

Check Valve

Design and Function: A check valve, also known as a non-return valve, allows fluid to flow in one direction and automatically prevents backflow when the fluid in the line reverses direction. It operates based on the flow pressure and does not require manual operation. The internal mechanism varies by design, including ball, swing, and lift check valves.

Applications: Check valves are essential in preventing backflow, protecting equipment, and ensuring the safety of the system. They are used in a wide variety of applications, including water and wastewater treatment, chemical processing, and residential plumbing systems. Any system where backflow could cause problems or where fluid needs to be maintained in a single direction benefits from the use of a check valve.

Advantages:

Prevents backflow automatically.
Can be used in a wide range of pressures and temperatures.
Available in various designs to suit specific flow characteristics.

Disadvantages:

Cannot be used to regulate or stop flow.
Some designs may cause a significant pressure drop.
Requires careful selection and installation to function correctly.

Key Differences Between Gate And Check Valves

Primary Function: Gate valves are used to start or stop the flow, while check valves are designed to prevent backflow and allow flow in only one direction.
Operation: Gate valves require manual or actuator operation to open or close, whereas check valves operate automatically based on flow conditions.
Application Use: Gate valves are chosen for system isolation or where full flow is necessary. Check valves are selected to prevent backflow and protect against reverse flow conditions.

Understanding these differences is crucial when designing or maintaining a piping system, ensuring that the right type of valve is used for its intended function, thereby optimizing system performance and safety.

GATE VALVE VS. BUTTERFLY VALVE

Gate valves and butterfly valves are widely utilized in various industrial and domestic piping systems for fluid control. Despite serving the purpose of regulating flow, they exhibit distinct differences in design, operation, maintenance, and application suitability.

Gate Valve

Design and Operation: A gate valve features a flat gate that moves up and down in a linear motion perpendicular to the direction of flow. The valve operates by a handwheel or an actuator, and it is primarily used for starting or stopping the flow, allowing for a full, unrestricted flow path when fully open.

Advantages:

Provides minimal pressure drop when fully open.
Suitable for both on/off and isolation applications.
Can handle thick fluids, as the gate can cut through viscous flow.

Disadvantages:

Slow to open and close due to the multiple turns required on the handwheel.
Not suitable for throttling applications, as partial opening can cause seat and gate damage.
Larger size compared to butterfly valves, requiring more space for installation and operation.

Butterfly Valve

Design and Operation: A butterfly valve consists of a disc that rotates around a central axis within the body of the valve, allowing for quick and efficient flow control. Operated by a handle, gear, or actuator, butterfly valves can be used for both on/off control and throttling.

Advantages:

Compact and lightweight design, requiring less space and support.
Quick to open and close, offering good control over the flow rate.
Generally more cost-effective than gate valves, especially in larger sizes.

Disadvantages:

The presence of the disc in the flow path can cause a pressure drop, even when fully open.
Not ideal for applications with particulate-laden fluids, as particles can accumulate around the disc and stem, potentially leading to wear or operational issues.
Sealing performance might not be as effective as gate valves for high-pressure applications.

Key Differences Between Gate And Butterfly Valves

Flow Control: Gate valves are best suited for on/off applications with minimal pressure drop, while butterfly valves offer superior functionality in throttling and quick operation scenarios.
Design and Space Requirements: Gate valves require more space due to their linear operation and larger size, making butterfly valves more suitable for compact or limited-space environments.
Cost and Maintenance: Butterfly valves are generally more cost-effective and easier to maintain due to their simpler design and fewer moving parts. Gate valves, on the other hand, may require more maintenance, especially in systems with solid or viscous fluids.

Application Suitability Of These Two Types Of Valves

Gate Valves: Preferred in applications where an unobstructed flow and tight shutoff are required, such as in water and wastewater treatment, oil and gas pipelines, and other high-pressure systems.
Butterfly Valves: Ideal for applications requiring flow regulation and where space and cost are concerns, including HVAC systems, pharmaceutical processing, and food and beverage industries.

Selecting between a gate valve and a butterfly valve depends on the specific requirements of the application, including flow control needs, system pressure, space constraints, and budget considerations. Each valve type offers unique advantages that make it suitable for particular scenarios, ensuring efficient and reliable fluid control in diverse settings.

GATE VALVE VS. PLUG VALVE

Gate valves and plug valves are both commonly used in piping systems for controlling the flow of fluids, but they have distinct differences in design, operation, and application suitability. Understanding these differences is essential for selecting the appropriate valve type for specific system requirements.

Gate Valve

Design and Operation: A gate valve controls flow by raising or lowering a metal gate, usually via a handwheel or an actuator. The gate moves perpendicularly to the fluid flow, offering minimal resistance when fully open, which makes it well-suited for applications requiring unobstructed flow or full isolation.

Advantages:

Provides a full-bore flow path when open, resulting in minimal pressure drop.
Suitable for both on/off services and isolation.
Can handle a wide range of fluids, temperatures, and pressures.

Disadvantages:

Not suitable for throttling applications, as partial openings can cause gate and seat damage.
Typically slower to operate due to the multiple turns required to open or close.
Larger and heavier than plug valves, requiring more space and support.

Plug Valve

Design and Operation: Plug valves control flow through a cylindrical or tapered plug with one or more hollow passageways. By rotating the plug 90 degrees, the flow can be allowed, blocked, or partially passed through the valve. Plug valves are known for their quick operation and are used for on/off control as well as throttling.

Advantages:

Quick to operate with a simple quarter-turn to open or close.
Compact and generally lighter than gate valves, making them suitable for tight spaces.
Good for applications requiring frequent operation and where flow regulation is needed.

Disadvantages:

The presence of the plug in the flow path can cause a pressure drop, even when fully open.
May not be suitable for high-pressure applications as sealing performance can be affected by high pressures.
Requires lubrication for smooth operation, which may not be ideal for some types of fluids.

Key Differences

Flow Control and Operation: Gate valves are best for on/off control where full flow is needed without obstruction. Plug valves offer rapid operation and are versatile for both on/off control and throttling.
Design and Space Requirements: Gate valves have a larger size and require more space, while plug valves are compact and suitable for limited-space applications.
Application Suitability: Gate valves are preferred in applications that demand minimal pressure drop and where valve operation is infrequent. Plug valves are favored for their quick operation, flow regulation capabilities, and when space constraints exist.

Application Suitability

Gate Valves: Ideal for larger-diameter pipelines, water treatment plants, and other settings where unobstructed flow and tight sealing are crucial.
Plug Valves: Commonly used in chemical and petrochemical industries, gas utilities, and where rapid or frequent operation is required.

In summary, the choice between a gate valve and a plug valve largely depends on the specific operational needs, including the desired control type (on/off or throttling), system pressure, space availability, and the frequency of valve operation. Each valve type offers distinct benefits and limitations, making them suitable for different applications.

GATE VALVE DIAGRAM

The gate valve diagram shows the standard assembly drawing of a gate valve.

Many design variations are possible, depending on the gate valve parts configuration:

Body material construction: forged or cast
Bonnet design and connection: can be standard BB or pressure seal (high-pressure gate valves), bolted/welded bonnet, etc.
Valve ends connection: gate valves are available with multiple valve ends designs (socket weld and threaded for forged gate valves and butt weld for cast body gate valves)
Wedge type (solid/flexible/split/parallel slide): see details below in this article
Stem type (rising/ non-rising): see details below
Manufacturing norm: API vs EN gate valves have slightly different designs
Type of valve operation: manual, gear, or pneumatic/hydraulic/electric actuation

Gate valve diagram showing the key parts of a gate valve for piping

GATE VALVE WEDGE TYPES

In gate valves, the wedge is the movable part that seals against seats to stop the flow or opens to allow flow. The design of the wedge is crucial for the valve’s performance, especially in terms of sealing capability, ease of operation, and durability. There are several types of wedges used in gate valves, each suited to different applications and operating conditions:

1. Solid Wedge

The solid wedge is the simplest and most robust type, made from a single piece of metal. Its simplicity makes it highly reliable and suitable for a wide range of conditions, including high-temperature and pressure environments. However, its rigidity means it may not always compensate for seat misalignments or changes in temperature that affect the valve body and seating surfaces.

2. Flexible Wedge

A flexible wedge is designed with a cut around its perimeter or a special shape that allows the wedge to flex as it seats. This design helps accommodate changes in valve body dimensions due to thermal expansion or contraction, improving the seal in varying temperature conditions. Flexible wedges are particularly useful in steam systems where temperature fluctuations are common. However, they can be less suitable for applications involving high vibration or thermal cycling, which may lead to fatigue cracks.

3. Split Wedge Or Parallel Disks

The split wedge, or parallel disk design, consists of two solid pieces that are hinged together or use a mechanism to keep them in alignment. This design allows the wedge to adjust to variations in the angle between the seats and the wedge surfaces, enhancing sealing effectiveness. Split wedges are advantageous in applications where thermal binding (sticking due to differential thermal expansion) is a concern.

4. Slab Gate

Slab gate valves use a flat gate that slides between two parallel seats, providing a tight seal. While not a wedge in the traditional sense, the slab gate functions similarly by blocking or allowing flow. This design is particularly favored in the oil and gas industry for pipeline valves because it provides a full-bore, low-friction path for the fluid, making it ideal for transporting viscous fluids like oil.

Wedge Selection Considerations

Choosing the appropriate wedge type depends on several factors:

Operating Conditions: Temperature fluctuations, pressure range, and the presence of vibrations can affect wedge selection.
Fluid Characteristics: Slurry services may require a specific wedge type to prevent particle trapping.
Sealing Requirements: Some applications demand tighter seals, influencing the choice of wedge design.

Understanding the different types of wedges in gate valves and their respective advantages and limitations is essential for selecting the right valve for a specific application, ensuring optimal performance and longevity.

The image below shows how the gate valve wedge opens and closes the flow of the fluid by application of a vertical movement (which can be manual or operated by an actuator).

The wedge is positioned between two parallel (or oblique) seats that are perpendicular to the flow. The fluid flows horizontally through gate valves and is not subject to pressure drops.

The image below shows the different types of wedges used in gate valves:

“solid wedge” (in this case, the wedge is manufactured with a solid piece of steel)
“flexible-wedge” (in this case the disc features cuts around its perimeter to enhance the ability of the valve to correct changes in the angle between the seats)
“split-wedge” (two pieces construction disc, to enforce self-alignment of the wedge on the seats)
“parallel-slide wedge“

GATE VALVE STEM TYPES

Gate valves control fluid flow by lifting a barrier (gate) out of the fluid path, and this operation is facilitated by the valve’s stem. The stem, which connects the actuator (e.g., handwheel, lever, or electric motor) to the gate, is a critical component in translating the actuator’s motion into the opening or closing of the valve. There are several types of stems used in gate valves, each with its specific design and operational characteristics:

1. Rising Stem (OS&Y – Outside Screw And Yoke)

The rising stem design features a stem that moves up and down along with the gate, providing a visual indication of the valve’s position (open or closed). In this configuration, the stem’s threads are external, located outside the valve body, and interact with the yoke, which is part of the actuator assembly. The rising stem design is advantageous for visual inspection and understanding the valve’s status, but it requires more vertical space for operation.

Advantages: Visible indication of valve position; reduced risk of thread contamination by the fluid.
Applications: Widely used in applications where valve status indication is important and where there is sufficient space for stem movement.

2. Non-Rising Stem (NRS)

In a non-rising stem design, the stem remains stationary in the vertical direction while the gate moves up and down. This is achieved by having the stem threads inside the valve body, engaging directly with the gate. Non-rising stem valves are compact and suitable for applications with limited vertical space.

Advantages: Requires less vertical space; suitable for underground installations or tight spaces.
Applications: Common in water, wastewater, and gas services where space constraints exist.

Rising and non rising stem of gate valves

3. Sliding Stem

Though not as common in gate valves, a sliding stem design can be found in some specialized gate valves where the stem slides in and out of the valve body without rotating. This design is similar in principle to the non-rising stem but is distinguished by the mechanism of stem movement.

4. Rotating Rising Stem

A rotating rising stem combines the visual position indication of a rising stem with a rotation mechanism. As the valve is opened or closed, the stem not only rises or lowers but also rotates. This rotation can help reduce the wear on the seating surfaces, extending the valve’s service life.

Advantages: Visual position indication and reduced seat wear due to rotation.
Applications: Useful in applications requiring durability and clear valve position indication.

Stem Selection Considerations

Choosing the right stem type for a gate valve involves several factors:

Space Availability: Non-rising stems are preferred in limited vertical space applications while rising stems are chosen when visual position indication is crucial and space permits.
Environment: External stem threads (rising stems) are less prone to contamination in clean environments, whereas internal threads (non-rising stems) are protected from the external environment but can be exposed to the process fluid.
Operation and Maintenance: Considerations include ease of operation, maintenance requirements, and the need for clear valve position indication.

Understanding the different types of stems and their operational characteristics is essential for selecting the appropriate gate valve for a specific application, ensuring optimal performance and longevity.

OS&Y VS. IS&Y DESIGN

It is very frequent to see the term “OS&Y” associated with gate valves.
This term means that when the handle of a gate valve is rotated to open or close the valve, it directly raises and lowers the disc by interacting with the stem of the valve.

In an “OS&Y gate valve”, the stem of the valve itself raises and lowers outside the body of the valve in a very visible way, while the handle remains in a fixed position.

When the stem raises, the disc inside the body of the valve rises from the seat letting the fluid flow through the valve (valve in open position).
Therefore with an OS&Y gate valve, the actual position of a valve (closed or open) is always evident to the operators.

Differently, the valve position is not immediately visible for “IS&Y gate valves” (inside screw and yoke), as the stem of the valve does not raise or lowers outside the valve when the handle is rotated.

GATE VALVE MATERIALS

BODY

The body of gate valves below 2 inches is generally made of forged steel (the most common body material grades are ASTM A105 for high-temperature service, ASTM A350 for low-temperature service, and, ASTM A182 F304/F316 for corrosive service).

The bodies of gate valves of bore sizes above 2 inches are, instead, made of cast steel (the main cast grades are ASTM A216 WCB for high-temperature service, ASTM A351 for low-temperature conditions, and ASTM A351 CF8 and CF8M – i.e. stainless steel 304 and 316 gate valves).

TRIM

The removable and replaceable parts of the valve are collectively defined as “trim” (for a gate valve: seat, disc, backseat, and, stem).
The API 600 specification foresees several standard trim combinations, as illustrated below

API TRIM #	BASE MATERIAL	MATERIAL FOR SEAT	MATERIAL FOR DISC	BACKSEAT MATERIAL	MATERIAL FOR STEM
1	410	410	410	410	410
2	304	304	304	304	304
3	F310	310	310	310	310
4	Hard 410	Hard 410	410	410	410
5	Hard faced	Stellite	Stellite	410	410
5A	Hard faced	Ni-Cr	Ni-Cr	410	410
6	410 and Cu-Ni	Cu-Ni	Cu-Ni	410	410
7	410 and Hard 410	Hard 410	Hard 410	410	410
8	410 and Hardfaced	Stellite	410	410	410
8A	410 and Hardfaced	Ni-Cr	410	410	410
9	Monel	Monel	Monel	Monel	Monel
10	316	316	316	316	316
11	Monel	Stellite	Monel	Monel	Monel
12	316 and Hardfaced	Stellite	316	316	316
13	Alloy 20	Alloy 20	Alloy 20	Alloy 20	Alloy 20
14	Alloy 20 and Hardfaced	Stellite	Alloy 20	Alloy 20	Alloy 20
15	304 and Hardfaced	Stellite	Stellite	304	304
16	316 and Hardfaced	Stellite	Stellite	316	316
17	347 and Hardfaced	Stellite	Stellite	347	347
18	Alloy 20 and Hardfaced	Stellite	Stellite	Alloy 20	Alloy 20

MATERIAL SELECTION

TRIM	RECOMMENDED SERVICE
13% Cr, Type 410 Stainless Steel	For oil and oil vapors and general services with heat treated seats and wedges.
13% Cr, Type 410 plus Hardfacing	Universal trim for general service requiring long service life up to 1100°F (593°C).*
Type 316 Stainless	For liquids and gases that are corrosive to 410 Stainless Steel, up to 1000°F (537°C).*
Monel	For corrosive service to 842°F (450°C) such as acids, alkalies, salt solutions, etc.
Alloy 20	For corrosive service such as hot acids -49°F to 608oF (-45°C to 320°C).
NACE	Specially treated 316 or 410 trim combined optionally with B7M Bolts and 2HM nuts to meet NACE MR-01-75 requirements.
Full Stellite	Full hard-faced trim, suitable for abrasive & severe services up to 1200°F (650°C).

GATE VALVE DIMENSIONS

The tables show the dimensions and weights of API 600 gate valves (bolted bonnet / rising stem)

CLASS 150

Dimensions in inches (millimeters)

Sizes	L	L1 (BW)	H (Open)	W
2″	7 (180)	8-1/2 (216)	14-1/2 (368)	8 (200)
2-1/2″	7-1/2 (190)	9-1/2 (241)	17 (432)	8 (200)
3″	8 (200)	11-1/8 (283)	18 (457)	8-7/8 (225)
4″	9 (230)	12 (305)	22 (559)	11 (279)
5″	10 (254)	15 (381)	26 (660)	12-3/4 (325)
6″	10-1/2 (266)	15-7/8 (403)	30 (762)	14 (356)
8″	11-1/2 (290)	16-1/2 (420)	38-1/2 (978)	14 (356)
10″	13 (330)	18 (457)	46 (1168)	18 (457)
12″	14 (356)	19 (502)	55-1/4 (1403)	20 (508)
14″	15 (381)	22 (559)	60 (1524)	21-1/2 (546)
16″	16 (407)	24 (610)	74-7/8 (1902)	24 (610)
18″	17 (432)	26 (660)	79 (2007)	27 (686)
20″	18 (457)	28 (711)	87-1/2 (2223)	28 (711)
24″	20 (508)	32 (813)	105 (2667)	31-1/2 (800)
30″	24 (610)	38 (965)	130 (3302)	43 (1092)
36″	28 (711)	44 (1118)	162 (4115)	51 (1295)
GEAR OPERATOR RECOMMENDED FOR SIZE 10″ AND ABOVE

CLASS 300

Dimensions in inches (millimeters)

SIZES	L/L1	H (OPEN)	W
2″	8-1/2 (216)	16 (407)	7-7/8 (200)
2-1/2″	9-1/2 (241)	17-3/8 (442)	7-7/8 (200)
3″	11-1/8 (283)	19-3/4 (501)	8-7/8 (225)
4″	12 (305)	23-3/8 (594)	9-7/8 (251)
5″	15 (381)	23-3/4 (603)	12-1/2 (318)
6″	15-7/8 (403)	32-1/8 (816)	14 (356)
8″	16-1/2 (420)	41 (1041)	15-3/4 (400)
10″	18 (457)	48-3/8 (1229)	17-3/4 (451)
12″	19-3/4 (501)	57 (1448)	20 (508)
14″	30 (762)	62-1/2 (1588)	22 (559)
16″	33 (838)	69 (1753)	25 (635)
18″	36 (914)	80-1/2 (2045)	28 (711)
20″	39 (991)	91 (2311)	35-1/2 (902)
24″	45 (1143)	120-1/2 (3061)	43 (1092)
GEAR OPERATOR RECOMMENDED FOR SIZE 8″ AND ABOVE

CLASS 600

Dimensions in inches (millimeters)

SIZES	L/L1	H (OPEN)	W
2″	11-1/2 (290)	16-1/2 (420)	7-7/8 (200)
2-1/2″	13 (330)	18 (457)	8-7/8 (225)
3″	14 (356)	20-1/8 (511)	9-7/8 (251)
4″	17 (432)	25 (635)	14 (356)
5″	20 (508)	30-1/2 (775)	15-3/4 (400)
6″	22 (559)	33-5/8 (854)	17-3/4 (451)
8″	26 (660)	42-3/8 (1076)	20 (508)
10″	31 (787)	49 (1245)	25 (635)
12″	33 (838)	68-1/2 (1740)	27 (686)
14″	35 (889)	69 (1753)	31-1/2 (800)
16″	39 (991)	74 (1880)	35-1/2 (902)
18″	43 (1092)	84-1/4 (2140)	43 (1092)
20″	47 (1194)	93-1/2 (2375)	51 (1295)
24″	55 (1397)	110 (2794)	51 (1295)
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)	26 (660)	10-1/4 (260)
3″	15 (381)	26-3/8 (670)	11-1/2 (292)
4″	18 (457)	30 (762)	14 (356)
6″	24 (610)	40-3/4 (1035)	20 (508)
8″	29 (737)	51 (1295)	24 (610)
10″	33 (838)	61 (1549)	27 (686)
12″	38 (965)	69-1/2 (1765)	31-1/2 (800)
14″	40-1/2 (1029)	77 (1956)	35-1/2 (902)
16″	44-1/2 (1130)	82-3/4 (2102)	43 (1092)
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)	21-1/2 (546)	11-1/2 (290)
3″	18-1/2 (470)	27-1/8 (689)	14 (356)
4″	21-1/2 (546)	31-1/2 (800)	20 (508)
6″	27-3/4 (705)	45 (1143)	24 (610)
8″	32-3/4 (832)	53-1/2 (1359)	27 (686)
10″	39 (991)	65 (1651)	35-1/2 (902)
12″	44-1/2 (1130)	74 (1880)	43 (1092)
14″	49-1/2 (1257)	83-1/2 (2121)	51 (1295)
16″	54-1/2 (1384)	88 (2235)	63 (1600)
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)	24-7/8 (632)	12 (305)
3″	22-3/4 (578)	36 (914)	20 (508)
4″	26-1/2 (673)	41-1/2 (1054)	20 (508)
6″	36 (914)	57 (1448)	24 (610)
8″	40-1/4 (1022)	63-3/8 (1610)	24 (610)
GEAR OPERATOR RECOMMENDED FOR SIZE 6″ AND ABOVE

May 23, 2024/by stvvalve

Posts

British Standards (BS)

American Petroleum Institute (API)

American Society Of Mechanical Engineers (ASME)

CHECK VALVE TYPES

SWING CHECK VALVE

Swing Check Valve Design

Operation

Advantages

Applications

Considerations

STOP CHECK VALVE

Design Of Stop Check Valves

Operation

Advantages

Applications

Considerations

BALL CHECK VALVE

Design

Operation

Advantages

Applications

Selection Considerations

DUAL PLATE CHECK VALVE

Design

Operation

Advantages

Applications

Selection Considerations

TITLING DISC CHECK VALVE

Design Features

Operational Advantages

Applications

Selection Considerations

FOOT CHECK VALVE

Design Features

Operational Advantages

Applications

Selection Considerations

PRESSURE SEAL CHECK VALVE

Design

Operation

Advantages

Applications

Selection Considerations

DUCKBILL CHECK VALVE

IN-LINE CHECK VALVE

Design Features

Operational Advantages

Applications

Selection Considerations

SUMP PUMP CHECK VALVE

Design

Operation

Advantages

Applications

Selection Considerations

CHECK VALVE MATERIALS (ASME, API)

ASME Material Standards

API Material Standards

Common Materials For Check Valves

Considerations For Material Selection

CHECK VALVE TRIM

Components Of Check Valve Trim

Material Considerations

Selection Guidelines

CHECK VALVE GA DIAGRAM

1. Z-Body Globe Valve

2. Y-Body Globe Valve (“Wye” Type)

3. Angle Globe Valve

4. T-Pattern Or Through-Way Globe Valve

5. Oblique Pattern Globe Valve

GLOBE VALVE MATERIALS (CAST/FORGED)

Cast Body Materials

Forged Body Materials

Choosing Between Cast And Forged Globe Valves

GLOBE VALVE VS. OTHER TYPES OF VALVE

GLOBE VALVE VS GATE VALVE

Design And Operation

Applications