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How Butterfly Valve Sealing Works Effectively

Butterfly valve sealing is a critical aspect of fluid control systems that directly impacts operational efficiency, safety, and maintenance costs. Understanding how these sealing mechanisms work helps engineers and maintenance professionals select the right valve for specific applications and ensure optimal performance. This comprehensive guide explores the fundamentals of butterfly valve sealing, different design approaches, and practical considerations for maintaining effective seals in industrial environments.

Understanding Butterfly Valves: Basic Principles

Butterfly valves belong to the quarter-turn valve family, featuring a disc-shaped closing element that rotates 90 degrees around its axis to control flow. Their popularity stems from their compact design, lightweight construction, and cost-effectiveness compared to other valve types like gate or globe valves. The valve’s primary components include the body, disc, stem, seat, and actuator.

These valves are widely used across numerous industries including water treatment, chemical processing, power generation, oil and gas, and HVAC systems. Their versatility makes them suitable for applications ranging from simple on/off control to more complex flow regulation scenarios. The effectiveness of a butterfly valve largely depends on its sealing mechanism, which determines its pressure handling capability, temperature resistance, and overall performance.

The Fundamental Sealing Mechanism of Butterfly Valves

The sealing mechanism in butterfly valves operates on a simple yet effective principle. When the valve is closed, the disc presses against a resilient seat, creating a seal that prevents fluid from passing through. This contact between the disc edge and the seat is what provides the sealing effect. The effectiveness of this seal depends on several factors including the contact pressure, material compatibility, and geometric precision of the components.

Butterfly valve sealing relies on either interference fit or pressure-assisted sealing. In interference fit designs, the disc is slightly larger than the inner diameter of the seat, creating compression when closed. In pressure-assisted designs, the system pressure helps push the disc against the seat, enhancing the seal as pressure increases. This dual approach ensures reliable sealing across various operating conditions.

The geometry of the disc edge and its interaction with the seat is carefully engineered to optimize sealing performance. Modern butterfly valves employ various disc edge profiles, from simple flat edges to complex contoured designs that maximize sealing efficiency while minimizing wear on the seat material.

Different Types of Butterfly Valve Sealing Designs

Soft Seat Sealing

Soft seat butterfly valve sealing with elastomer material

Soft seat butterfly valves utilize elastomeric or polymer materials to create a tight seal. The flexible nature of these materials allows them to conform to the disc edge, providing excellent sealing performance even at lower pressures. Common soft sealing materials include:

EPDM (Ethylene Propylene Diene Monomer) – Excellent for water applications, temperature range of -40°C to 120°C
NBR (Nitrile Butadiene Rubber) – Ideal for oil-based media, temperature range of -30°C to 90°C
PTFE (Polytetrafluoroethylene) – Superior chemical resistance, temperature range of -196°C to 200°C
Viton (Fluoroelastomer) – High temperature resistance up to 250°C, excellent chemical compatibility

Soft seat butterfly valves typically achieve bubble-tight shutoff (zero leakage) and are preferred in applications where absolute sealing is required. However, they have temperature limitations and may be susceptible to wear in highly abrasive media.

Metal Seat Sealing

Metal seat butterfly valve sealing mechanism

Metal seated butterfly valves employ metal-to-metal contact between the disc and seat to achieve sealing. These designs are preferred for high-temperature applications where soft seat materials would deteriorate. Common metal sealing configurations include:

Steel + Steel – High durability, suitable for abrasive applications
Steel + Copper – Enhanced sealing through slight deformation of the softer copper
Steel + Alloy Steel – Specialized for high-pressure, high-temperature environments
Steel + Graphite – Combines metal durability with graphite’s self-lubricating properties

Metal seated butterfly valves typically offer longer service life in harsh conditions but may not provide the same level of tight shutoff as soft seated designs. They excel in applications with temperatures exceeding 250°C or where abrasive media would quickly damage soft seats.

Eccentric Sealing Designs

Butterfly valves have evolved from simple concentric designs to more sophisticated eccentric configurations that enhance sealing performance:

Design Type	Sealing Mechanism	Applications	Advantages
Concentric (Zero Offset)	Disc centered in pipe, seat compressed when closed	Low pressure, general purpose	Simple design, cost-effective
Single Eccentric (First Offset)	Stem offset from disc centerline	Medium pressure applications	Reduced seat wear, improved sealing
Double Eccentric (Second Offset)	Stem offset from both disc and pipe centerlines	Higher pressure, industrial processes	Minimized friction, extended seat life
Triple Eccentric (Third Offset)	Conical sealing surface with three offsets	High temperature, high pressure	Zero rubbing, metal-to-metal sealing

The evolution of eccentric designs has significantly improved butterfly valve sealing performance. Triple eccentric designs, in particular, have revolutionized the industry by enabling metal-to-metal sealing without the friction and wear associated with earlier designs. These valves achieve tight shutoff while maintaining excellent durability in extreme conditions.

Key Components of Butterfly Valve Sealing Systems

The effectiveness of butterfly valve sealing depends on several critical components working together:

Valve Disc

The disc is the primary closing element that rotates to control flow. Its edge profile is crucial for sealing effectiveness. Modern discs feature precision-machined edges with specific profiles designed to optimize contact with the seat. Materials range from stainless steel and ductile iron to specialized alloys for corrosive environments.

Valve Seat

The seat provides the sealing surface against which the disc closes. In soft seated designs, the seat is typically an elastomer or polymer ring that may be bonded, mechanically retained, or inserted into the valve body. Metal seated designs use precisely machined metal seats, sometimes with special coatings or hardening treatments to enhance durability.

Stem Seals

While the disc-to-seat interface provides the primary seal, stem seals prevent leakage around the rotating stem. These typically include packing glands, O-rings, or specialized sealing systems. The stem sealing system is critical for preventing external leakage and maintaining environmental integrity.

Body Design

The valve body houses all components and provides structural integrity. Its internal geometry affects flow characteristics and sealing performance. Modern bodies feature precision-machined seating surfaces and optimized flow paths to reduce turbulence and pressure drop.

Actuators and Control Systems

While not directly part of the sealing mechanism, actuators control the positioning of the disc and the force applied during closing. Proper actuator sizing ensures adequate torque to achieve effective sealing without damaging components. Control systems may include position indicators, limit switches, and feedback mechanisms to verify proper sealing.

Factors Contributing to Effective Butterfly Valve Sealing

Material Selection

Choosing appropriate materials for both the disc and seat is fundamental to sealing performance. Material selection must consider:

Chemical compatibility with the process media
Temperature range of the application
Pressure requirements
Abrasion resistance for particulate-laden fluids
Corrosion resistance for aggressive chemicals

For example, EPDM provides excellent sealing in water applications but would quickly degrade in petroleum-based fluids where NBR would be more appropriate. Similarly, metal seats with specialized coatings may be necessary for high-temperature steam applications.

Precision Manufacturing

The geometric precision of sealing components directly impacts performance. Modern manufacturing techniques including CNC machining, precision casting, and advanced quality control ensure consistent dimensions and surface finishes. Even minor variations in roundness, flatness, or surface finish can compromise sealing effectiveness.

Proper Installation

Even the best-designed valve will fail to seal properly if incorrectly installed. Key installation considerations include:

Proper alignment with pipe flanges
Correct bolt torquing sequence and values
Appropriate gasket selection and installation
Verification of disc movement and clearance
Proper actuator adjustment and limit setting

Operating Conditions

Butterfly valve sealing performance is influenced by the actual operating conditions, which may differ from design specifications. Factors such as pressure spikes, temperature fluctuations, flow turbulence, and water hammer can all affect sealing integrity. Proper valve selection must account for both normal and extreme operating scenarios.

Common Challenges with Butterfly Valve Sealing and Solutions

Common Sealing Challenges

Seat wear from frequent cycling
Chemical attack degrading seat materials
Temperature extremes causing material failure
Particulate buildup preventing complete closure
Waterhammer damaging sealing components
Stem leakage from packing wear
Disc-to-seat misalignment

Effective Solutions

Selecting appropriate seat materials for the application
Implementing proper valve sizing to prevent excessive velocity
Using eccentric designs to reduce seat wear
Installing strainers upstream to prevent particulate damage
Implementing controlled actuation to prevent slamming
Regular maintenance and inspection programs
Proper torque application during closure

Case Study: Solving Sealing Issues in High-Cycle Applications

A water treatment facility experienced frequent leakage with standard concentric butterfly valves used for daily backwash operations. The high cycling rate (over 1,000 cycles per year) caused premature wear of the EPDM seats, resulting in leakage and increased maintenance costs.

The solution involved replacing the concentric valves with double eccentric designs featuring reinforced PTFE seats. The eccentric design minimized rubbing during operation, while the reinforced PTFE provided better wear resistance than the original EPDM. Additionally, the actuation system was modified to include slow-closing functionality to reduce dynamic stresses. These changes extended the maintenance interval from 6 months to 3 years, significantly reducing downtime and maintenance costs.

Maintenance Practices for Long-Term Sealing Effectiveness

Maintaining effective butterfly valve sealing requires a systematic approach to inspection, testing, and preventive maintenance. A comprehensive maintenance program should include:

Regular Inspection Protocols

Visual inspection of external components for signs of leakage or damage
Operational testing to verify full closure and proper sealing
Stem packing inspection and adjustment as needed
Actuator function verification and lubrication
Checking for unusual noise or vibration during operation

Preventive Maintenance Schedules

Effective maintenance scheduling should be based on both time intervals and cycle counts, depending on which occurs first. Critical valves in severe service may require more frequent attention than those in less demanding applications.

Service Type	Inspection Frequency	Recommended Actions
Normal Service	Annually or 5,000 cycles	Visual inspection, operational testing, lubrication
Severe Service	Quarterly or 2,500 cycles	Complete inspection, seat examination, stem seal verification
Critical Service	Monthly or 1,000 cycles	Comprehensive testing, leak detection, actuator diagnostics

Proper Lubrication

Lubrication is essential for components like stems, bearings, and actuators. However, care must be taken to use lubricants compatible with the process media and to avoid contaminating soft sealing materials with incompatible greases. Manufacturer recommendations should be followed regarding lubricant type and application frequency.

Rebuilding and Replacement Strategies

Eventually, sealing components will require replacement. Having a planned approach to rebuilding valves can minimize downtime and ensure proper restoration of sealing performance. Key considerations include:

Maintaining an inventory of critical spare parts
Documenting proper disassembly and reassembly procedures
Using proper tools and fixtures to avoid damage during maintenance
Implementing post-maintenance testing to verify proper sealing
Tracking maintenance history to identify recurring issues

Butterfly Valve Sealing Compared to Other Valve Types

Understanding how butterfly valve sealing compares to other common valve types helps in making appropriate selection decisions for specific applications:

Valve Type	Sealing Mechanism	Sealing Performance	Best Applications	Limitations
Butterfly Valve	Disc against seat	Good to excellent, depending on design	Large diameter, low pressure, space-constrained	Pressure limitations, disc always in flow path
Ball Valve	Ball against seat rings	Excellent, bubble-tight	High pressure, tight shutoff requirements	Higher cost, larger envelope, cavity trapping
Gate Valve	Gate against seat rings	Good when new, deteriorates with wear	Full flow requirements, infrequent operation	Slow operation, large actuator forces, seat wear
Globe Valve	Disc against seat ring	Excellent, renewable seating	Throttling, frequent operation	High pressure drop, larger size, higher cost

When to Choose Butterfly Valves for Optimal Sealing

Butterfly valves offer superior sealing performance in applications where:

Space and weight constraints make other valve types impractical
Large diameters are required (especially above 12 inches/300mm)
Quick operation is needed (quarter-turn vs. multi-turn)
Cost considerations are important (generally less expensive than equivalent ball or gate valves)
Moderate pressure and temperature conditions prevail

Modern triple eccentric butterfly valves have expanded these traditional boundaries, now offering sealing performance comparable to ball valves in many high-pressure, high-temperature applications while maintaining the space and weight advantages inherent to the butterfly design.

Ensuring Optimal Butterfly Valve Sealing Performance

Effective butterfly valve sealing requires a holistic approach that begins with proper valve selection and continues through installation, operation, and maintenance. By understanding the fundamental principles of butterfly valve sealing and the factors that influence performance, engineers and maintenance professionals can ensure reliable operation and extended service life.

Key takeaways for optimizing butterfly valve sealing include:

Match the valve design (concentric, eccentric) to the application requirements
Select appropriate sealing materials based on media, temperature, and pressure
Ensure proper installation with correct alignment and torque
Implement regular inspection and maintenance programs
Consider the entire system when diagnosing sealing issues
Stay informed about advances in valve technology and materials

By applying these principles, facilities can minimize leakage, reduce maintenance costs, and improve the overall reliability of their fluid control systems.

Need Expert Assistance with Butterfly Valve Selection?

Our team of valve specialists can help you select the optimal butterfly valve sealing solution for your specific application requirements. Contact us today for a personalized consultation or to request our comprehensive valve catalog.

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December 19, 2025/by stvvalve

Understand API 609 Butterfly Valves Types

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

BUTTERFLY VALVE

WHAT IS A BUTTERFLY VALVE

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

Key Features Of Butterfly Valves

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

Types Of Butterfly Valves

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

Operation

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

Applications

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

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

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

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

Classification Of Butterfly Valves

Butterfly valves may be classified based on multiple features:

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

Types of butterfly valves

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

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

BUTTERFLY VALVES PARTS

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

Here are the main components of a butterfly valve:

1. Body

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

2. Disc

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

3. Stem

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

4. Seat

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

5. Actuator

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

6. Handle Or Hand Lever

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

7. Gearbox

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

8. Bushings

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

9. Packing

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

10. Flanges Or Ends

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

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

HOW BUTTERFLY VALVES FUNCTION

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

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

1. Open Position

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

2. Closing The Valve

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

3. Closed Position

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

4. Controlling Flow

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

5. Actuation

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

Key Features

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

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

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

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

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

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

PRESSURE DROP IN BUTTERFLY VALVES

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

Factors Affecting Pressure Drop In Butterfly Valves

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

Calculating Pressure Drop

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

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

Q^2 /

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

Considerations For System Design

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

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

BUTTERFLY VALVE SPECIFICATIONS (ASME/API)

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

API Standards

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

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

ASME Standards

ASME B16.34: Valves – Flanged, Threaded, and Welding End
Although primarily known for gate, globe, and check valves, ASME B16.34 also includes general valve design criteria that can apply to butterfly valves, such as pressure-temperature ratings, shell material categories, and testing requirements.
ASME B16.5: Pipe Flanges and Flanged Fittings
This standard covers dimensions and ratings for flanges that can be used with butterfly valves, ensuring compatibility with piping systems.
ASME B16.47: Large Diameter Steel Flanges
Similar to ASME B16.5 but focuses on larger diameter flanges, which might be relevant for larger butterfly valve applications.
ASME B16.10: Face-to-Face and End-to-End Dimensions of Valves
Provides the standard face-to-face and end-to-end dimensions for butterfly valves, facilitating proper integration and replacement in piping systems.

Other Relevant Standards

ISO 5211: Industrial valves — Part-turn actuator attachments
This international standard, often referenced alongside API and ASME standards, specifies the requirements for the attachment of part-turn actuators to industrial valves, including butterfly valves. It’s crucial to ensure that actuators and valves are compatible and can be securely attached to each other.
MSS SP-67: Butterfly Valves
Issued by the Manufacturers Standardization Society (MSS), this standard covers detailed requirements for butterfly valves, including design, dimensions, pressure rating, and testing. It’s widely recognized and used alongside API and ASME standards.
MSS SP-68: High-Pressure Butterfly Valves with Offset Design
MSS focuses on high-pressure butterfly valves with an offset design, providing criteria for pressure integrity and performance.

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

TYPES OF BUTTERFLY VALVES

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

Here are the primary types of butterfly valves:

1. Concentric (Zero Offset) Butterfly Valves

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

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

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

Pumping installations
HVAC
Aeration systems
Filter Installations
Pumping installations
Membrane installations
2. Double Offset (High-Performance) Butterfly Valves
- Design: Also known as high-performance butterfly valves, they have two offsets. The first offset is to the side of the pipe centerline, while the second offset moves the shaft behind the disc plane. This design minimizes seat wear and allows for tighter sealing.
- Application: Ideal for higher pressure and temperature conditions, handling a wider range of fluids, including corrosive and abrasive types.
Double eccentric butterfly valves find application in underground water supply systems and compete with gate valves (especially in larger bore sizes) because they are lighter, cheaper, and minimize the excavation works.

Double and triple-offset butterfly valves are also denominated “eccentric”. The main differences between the concentric and eccentric types of butterfly valves can be summarized as follows:
- Concentric butterfly valve: the stem is centered in the middle of the disc and the is disc centered in the bore
- Eccentric butterfly valve (double offset and triple offset): has one or more stub shafts (stems) which are located in an offset position from the center of the valve. Eccentric butterfly valves are also defined as the double or the triple offset.
A concentric butterfly valve (left), a double offset butterfly valve (center), triple offset butterfly valve (right)

3. Triple Offset Butterfly Valves
- Design: Features three offsets, with the third being the geometrical shape of the seating surface (conical shape). This design eliminates friction between the seat and the disc during operation and allows for metal-to-metal sealing.
- Application: Suitable for extreme pressure and temperature applications, including steam, oil, and gas services. It provides reliable performance in demanding conditions.
Triple-offset butterfly valves are generally manufactured in high-grade materials like stainless steel and duplex/super duplex steel and compete with ball valves in mission-critical applications with remarkable corrosion and high temperature/pressure.

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

4. Lugged Butterfly Valves
- Design: The valve body has lugs (extensions with bolt holes) that allow it to be bolted directly to the pipe flanges. This provides a secure and rigid connection and allows for easy removal of downstream piping without affecting the upstream side.
- Application: Used in applications where the valve must be easily removed for maintenance or where the system requires dead-end service capability.
5. Wafer Butterfly Valves
- Design: Designed to fit between two pipe flanges (the wafer shape), these valves are held in place by the bolts that connect the flanges. They are compact and cost-effective but not suitable for end-of-line service where removal is necessary.
- Application: Commonly used in systems where space is limited and in applications that do not require disassembly of the pipe system for valve maintenance.
- 6. Rubber-Lined Butterfly Valves
  - Design: Features a body and disc lined with rubber or another elastomeric material, providing enhanced corrosion resistance and a tight seal.
  - Application: Ideal for handling corrosive fluids, slurries, and other abrasive media in water treatment, chemical processing, and similar industries.
  7. Metal-Seated Butterfly Valves
  - Design: Constructed with metal seats, these valves are designed to withstand higher temperatures and more abrasive conditions than their rubber-lined counterparts.
  - Application: Suitable for high-temperature applications, such as steam services, and where higher durability is required.
  Each type of butterfly valve offers unique features and benefits, making them suitable for a broad range of applications. Selecting the right type depends on factors such as the nature of the fluid, operating pressure and temperature, and specific system requirements.
  
  A key first classification is between concentric or eccentric butterfly valves:
  
  DIFFERENCES BETWEEN DOUBLE VS. TRIPLE ECCENTRIC BUTTERFLY VALVE
  
  Double and triple eccentric butterfly valves are both designed to offer improved performance over traditional concentric butterfly valves, especially in high-pressure and high-temperature applications. The terms “double” and “triple” refer to the number of offsets (eccentricities) in the valve design, which significantly affect how the valve operates and seals. Understanding the differences between these two types of eccentric butterfly valves is crucial for selecting the right valve for specific operational needs.
  
  Double Eccentric Butterfly Valves (Double Offset)
  - Design: The first offset is the shaft placement off the pipe or disc centerline, which allows the disc to move off the seat upon opening, reducing wear on the sealing surface. The second offset is the shaft placement behind the disc plane, creating a cam action during operation that enhances sealing capability and reduces operating torque.
  - Sealing: Typically utilizes a resilient (soft) seat, which can be made of materials like PTFE, rubber, or other polymers, allowing for tight shut-off in various applications.
  - Applications: Suitable for higher pressure and temperature applications than concentric valves but below the extreme conditions that triple offset valves are designed for. Commonly used in water distribution, HVAC systems, light industrial processes, and chemical applications where a tight seal and durability are required.
  Triple Eccentric Butterfly Valves (Triple Offset)
  - Design: Incorporates three offsets: two similar to the double eccentric design and a third offset, which involves angling the conical shape of the seating surface. This geometry ensures that the disc only contacts the seat at the final point of closure, minimizing wear and allowing for a metal-to-metal seal.
  - Sealing: The metal-to-metal seat design enables the triple offset valve to handle extreme temperatures, pressures, and corrosive media, providing a long-lasting, bubble-tight seal.
  - Applications: Engineered for the most demanding applications, including high-pressure steam, oil and gas pipelines, power generation, and process industries where reliability and performance under extreme conditions are paramount.
  Key Differences (Double/Triple Eccentric Types)
  - Sealing Mechanism: Double eccentric valves usually have resilient seats for good sealing at lower pressures and temperatures, while triple eccentric valves use a metal-to-metal seat design for harsh conditions.
  - Wear and Tear: Triple offset valves minimize wear on the sealing surfaces due to the disc only making contact at full closure, unlike double offset valves, which may experience more wear due to their soft sealing materials.
  - Application Suitability: Double offset valves are versatile for a wide range of applications but might not be suitable for the highest pressures and temperatures. Triple offset valves are designed for extreme conditions where performance and durability are critical.
  In summary, the choice between double and triple eccentric butterfly valves depends on the specific application requirements, including pressure, temperature, and the nature of the media being handled. Triple offset valves are typically chosen for their ability to perform in extreme conditions, offering durability and a reliable seal, whereas double offset valves provide an efficient and cost-effective solution for a broad range of less severe applications.
  
  .
  
  The images show the design difference between a double and a triple eccentric butterfly valve (respectively at the left and right side of the diagram).
  MATERIALS FOR BUTTERFLY VALVES
  
  VALVE BODY
  
  Butterfly valves, like any other type of valve, are available in multiple material grades and combinations of materials (body, disc, seat).
  
  The selection of the materials is based on the fluid to be shut off, the pressure, and the temperature of the application at hand.
  
  The body material of a butterfly valve is a critical factor that determines its suitability for specific applications, especially considering the fluid it will handle, the operating environment, pressure, and temperature conditions. Various materials are used for butterfly valve bodies, each offering different properties in terms of strength, corrosion resistance, and cost.
  
  Here is a list of the main materials used for butterfly valve bodies, which are generally cast grades.
  
  CAST IRON
  - Properties: Good mechanical strength, excellent vibration and shock resistance, and cost-effectiveness.
  - Applications: Widely used in water and wastewater treatment, air conditioning systems, and other low to medium-pressure applications.
  DUCTILE IRON
  - Properties: Higher strength and ductility compared to cast iron, with good corrosion resistance.
  - Applications: Suitable for higher pressure applications than cast iron, including water distribution, gas supply, and some industrial processes.
  Note that cast iron and ductile iron are the cast materials preferred for butterfly valves used in water treatment, distribution, and transmission.
  CARBON STEEL
  
  Carbon steel is the most common material for body and disc in oil & gas applications:
  - Properties: High strength and durability, with good resistance to high pressure and temperature.
  - Applications: Used in oil and gas, power generation, and other industrial applications where high-pressure and temperature resistance is required.
  The most common grades used for butterfly valve bodies and discs are ASTM A216 WCB and LCC (Low Carbon Content), which are both cast types. They are used, respectively, for high-temperature and low-temperature service.
  
  The main advantage of carbon steel (CS) butterfly valves is their relatively low cost combined with acceptable performance (especially for low-pressure applications). The weakness of carbon steel valves is their poor resistance to corrosion (which can be improved by applying external paints or internal lining materials such as Teflon)
  
  STAINLESS STEEL
  
  Stainless steel butterfly valves are widely utilized across various industries for their durability, corrosion resistance, and suitability for handling a broad range of fluids, including corrosive substances, water, steam, and gas. Constructed from stainless steel for both the body and the disc, these valves offer several advantages and are chosen for specific applications based on their material properties.
  
  Advantages Of Stainless Steel Butterfly Valves
  - Corrosion Resistance: Stainless steel offers excellent resistance to corrosion caused by various chemicals and environmental conditions. This makes it ideal for applications in chemical processing, pharmaceuticals, and food and beverage industries, where maintaining purity is critical.
  - High Strength and Durability: Provides strength and durability under high-pressure conditions, ensuring a long service life even in demanding applications.
  - Temperature Resistance: Capable of withstanding both high and low temperatures, making them suitable for applications involving steam, hot fluids, or cold water systems.
  - Hygienic Properties: The smooth, non-porous surface of stainless steel is easy to clean and disinfect, which is essential for sanitary applications in the food, beverage, and pharmaceutical industries.
  - Aesthetic Appearance: Stainless steel has a clean and modern appearance, which is often preferred in visible installations.
  Common Grades Of Stainless Steel For Butterfly Valves
  - 304 Stainless Steel: Offers good corrosion resistance and is widely used in general applications that do not involve exposure to corrosive chemicals and extreme temperatures.
  - 316 Stainless Steel: Contains molybdenum, which enhances its corrosion resistance, especially against chlorides and other industrial solvents. It is preferred for more corrosive environments, such as seawater and chemical processing.
  - 316L Stainless Steel: A low-carbon variant of 316, it has reduced carbon content that minimizes carbide precipitation during welding, improving corrosion resistance in welded joints.
  Applications
  
  Stainless steel butterfly valves are chosen for their robust performance in various settings, including:
  - Chemical Processing: For controlling the flow of aggressive chemicals, acids, and solvents.
  - Food and Beverage Production: In systems requiring strict hygiene standards and resistance to food acids and cleaning agents.
  - Pharmaceutical Manufacturing: Where cleanliness and contamination prevention are paramount.
  - Water Treatment and Distribution: Suitable for handling both clean and wastewater, as well as desalination processes.
  - Oil and Gas Industry: For applications requiring resistance to corrosion from saltwater, chemicals, and high-pressure conditions.
  Selection Considerations
  
  When selecting a stainless steel butterfly valve, it’s crucial to consider:
  - Type of Fluid: Ensure compatibility with the fluid’s properties, including corrosiveness, temperature, and cleanliness requirements.
  - Pressure and Temperature Ratings: Choose a valve that can withstand the system’s operating pressure and temperature range.
  - Connection Type: Consider the valve’s connection type (wafer, lug, flanged) for compatibility with the piping system.
  - Actuation Method: Determine whether manual, pneumatic, electric, or hydraulic actuation is best suited for the application’s operational needs.
  In summary, stainless steel butterfly valves offer a reliable and efficient solution for flow control in a wide range of industrial applications. Their corrosion resistance, strength, and temperature tolerance make them a versatile choice for many fluid handling systems.
  
  DUPLEX & SUPERDUPLEX STEEL
  
  Butterfly valves made from duplex and super duplex stainless steels are engineered for applications requiring exceptional strength and corrosion resistance, especially in harsh and aggressive environments. Duplex stainless steels combine the properties of austenitic and ferritic stainless steels, resulting in materials that offer both high strength and excellent resistance to corrosion, including stress corrosion cracking. Super duplex stainless steels provide even higher corrosion resistance and strength, making them suitable for more demanding applications.
  
  Characteristics Of Duplex And Super Duplex Stainless Steel Butterfly Valves
  - High Strength: Duplex and super duplex stainless steels have higher strength compared to austenitic stainless steels, allowing for the design of thinner valve bodies and components without compromising integrity.
  - Superior Corrosion Resistance: These materials are highly resistant to a wide range of corrosive environments, including those containing chlorides, making them ideal for use in marine, chemical processing, and oil & gas applications.
  - Good Fatigue Resistance: The combination of strength and corrosion resistance makes duplex and super duplex valves highly resistant to fatigue, extending their service life under cyclic loading conditions.
  - Resistance to Stress Corrosion Cracking: Particularly in chloride-containing environments, duplex, and super duplex steels exhibit superior resistance to stress corrosion cracking, a common issue for standard austenitic stainless steels in certain conditions.
  Common Grades
  - Duplex Stainless Steel (UNS S31803, S32205): Features a balanced microstructure of austenite and ferrite, offering good resistance to pitting and crevice corrosion, high strength, and good weldability.
  - Super Duplex Stainless Steel (UNS S32750, S32760): Contains higher levels of chromium, molybdenum, and nitrogen, providing even greater resistance to corrosion and increased strength compared to duplex stainless steel.
  Applications
  
  Butterfly valves constructed from duplex and super duplex stainless steels are particularly suited for:
  - Offshore Oil and Gas Operations: In environments exposed to seawater, sour gas, and other corrosive substances.
  - Chemical Processing: For handling aggressive chemicals, especially where chloride-induced corrosion is a concern.
  - Desalination Plants: Where valves are exposed to highly corrosive seawater.
  - Marine Applications: Including shipping and coastal facilities, where saltwater corrosion is an ongoing challenge.
  - Pulp and Paper Industry: For processes involving corrosive chemicals used in paper production.
  Selection Considerations
  
  When choosing duplex or super duplex stainless steel butterfly valves, factors to consider include:
  - Corrosion Resistance Needs: Assess the specific corrosive elements present in the application environment to select the most appropriate material grade.
  - Pressure and Temperature Requirements: Ensure the selected valve can withstand the operating pressures and temperatures of the system.
  - Cost-Effectiveness: While duplex and super duplex steels offer superior properties, they also come at a higher cost compared to standard stainless steels. Evaluate the long-term benefits of their use in reducing maintenance and replacement costs.
  - Weldability and Fabrication: Consider the welding and fabrication requirements, as duplex and super duplex materials may require specific techniques and precautions during manufacturing and installation.
  In summary, butterfly valves made from duplex and super duplex stainless steels provide a robust solution for controlling flow in environments where corrosion resistance and mechanical strength are critical. Their superior properties make them an excellent choice for demanding industrial applications where conventional stainless steels might not suffice.
  
  NICKEL ALLOY STEEL
  
  Butterfly valves made from nickel alloys are designed for the most demanding applications, offering exceptional resistance to corrosion, heat, and pressure. Nickel alloys, such as Inconel, Hastelloy, Monel, and Nickel 200/201, are renowned for their ability to withstand extreme environments, making them ideal for critical and high-performance applications across various industries.
  
  Characteristics
  - Corrosion Resistance: Nickel alloys provide excellent resistance to a wide range of corrosive environments, including seawater, chlorine, and acidic or alkaline substances. They are particularly effective against corrosion that challenges other materials, such as stress-corrosion cracking.
  - High-Temperature Performance: These alloys maintain their strength and resistance even at very high temperatures, making them suitable for applications involving heat.
  - Durability: The inherent strength and corrosion resistance of nickel alloys ensure that butterfly valves made from these materials have a long service life, even in harsh conditions.
  Common Nickel Alloys Used For Butterfly Valves
  - Inconel (e.g., Inconel 625, Inconel 718): Known for high strength and excellent corrosion resistance, especially in high-temperature environments.
  - Hastelloy (e.g., Hastelloy C-276, Hastelloy C-22): Offers outstanding resistance to strong oxidizing agents and is used in severe corrosive environments.
  - Monel (e.g., Monel 400, Monel K-500): Exhibits excellent resistance to seawater and caustic environments, combining good corrosion resistance with high strength.
  - Nickel 200/201: Pure nickel or nearly pure nickel, providing excellent resistance to corrosion by alkaline substances and good thermal, electrical, and magnetostrictive properties.
  Applications
  
  Nickel alloy butterfly valves are used in situations where conventional materials would fail, including:
  - Chemical Processing: For handling aggressive chemicals, solvents, and gases that require superior corrosion resistance.
  - Oil and Gas Industry: Especially in sour gas applications where hydrogen sulfide can cause sulfide stress cracking in other materials.
  - Power Generation: In applications involving high temperatures or corrosive gases.
  - Marine and Offshore: For seawater systems and environments exposed to marine atmospheres, where corrosion resistance is critical.
  - Pharmaceuticals: In processes requiring clean, non-contaminating materials.
  Selection Considerations
  
  When choosing nickel alloy butterfly valves, consider:
  - Specific Corrosion Resistance Needs: Match the alloy to the particular corrosive agents present in the process or environment.
  - Temperature Range: Ensure the chosen alloy can withstand the operational temperature extremes.
  - Pressure Ratings: Verify that the valve can handle the system’s pressure requirements without compromising its integrity or performance.
  - Cost-Effectiveness: Nickel alloys tend to be more expensive than other materials, so consider the long-term benefits of reduced maintenance and replacement costs against the initial investment.
  Nickel alloy butterfly valves represent a high-end solution for controlling flow in applications where extreme conditions would compromise lesser materials. Their use can significantly enhance system reliability, safety, and longevity, albeit at a higher initial cost. The choice of a specific nickel alloy should be based on a thorough analysis of the application’s requirements, including exposure to corrosive substances, temperature, and pressure conditions.
  
  TITANIUM AND TITANIUM ALLOYS
  
  Butterfly valves made from titanium are renowned for their exceptional strength-to-weight ratio, outstanding corrosion resistance, and excellent durability under challenging conditions. Titanium and its alloys are lightweight yet offer mechanical properties comparable to those of some steel grades, making them an excellent choice for butterfly valves in specific applications.
  
  Characteristics
  - Corrosion Resistance: Titanium is exceptionally resistant to corrosion by seawater, chlorides, and many acidic environments, making it suitable for applications where other materials might fail.
  - Strength and Durability: Despite being lightweight, titanium maintains high strength and withstands extreme pressures and temperatures, contributing to the longevity of the valve.
  - Non-Magnetic and Biocompatible: Titanium is non-magnetic and biocompatible, expanding its use to applications where magnetic interference is a concern or where it contacts biological materials.
  - Temperature Resistance: Titanium valves can operate effectively across a broad temperature range, maintaining their integrity in both low and high-temperature environments.
  Applications
  
  Titanium butterfly valves are ideal for industries and applications that demand material properties beyond what conventional metals can provide, including:
  - Chemical Processing: For handling highly corrosive substances, such as chlorine and acids, where titanium’s corrosion resistance ensures reliability and safety.
  - Seawater and Desalination: In seawater desalination plants, offshore platforms, and marine applications, where the resistance to seawater corrosion is critical.
  - Pharmaceutical and Food Processing: Where the non-toxic and biocompatible nature of titanium is essential for avoiding contamination.
  - Aerospace and High-Performance Engineering: In applications requiring materials that can withstand high temperatures and pressures without significant weight penalties.
  Selection Considerations
  
  When selecting titanium butterfly valves, consider the following factors:
  - Grade of Titanium: Various grades of titanium offer different properties. For example, Grade 2 titanium is commercially pure and widely used for general corrosion resistance, while Grade 5 (Ti-6Al-4V) is an alloy known for its higher strength and used in more demanding applications.
  - Cost: Titanium is more expensive than many other materials due to its processing complexity and raw material costs. Consider the long-term benefits of reduced maintenance and longer service life against the initial investment.
  - Compatibility: Ensure the specific grade of titanium chosen is compatible with the fluid media, operating conditions, and environmental exposure of the application.
  - Fabrication and Repair: Consider the availability of resources for fabrication and repair, as working with titanium requires specific expertise and equipment.
  Titanium butterfly valves represent a high-end solution for controlling flow in demanding applications where conventional materials are inadequate. Their selection is justified in environments that require exceptional corrosion resistance, strength, and durability, despite their higher initial cost. The benefits of using titanium include extended equipment life, reduced maintenance, and improved safety and reliability in critical applications.
  
  ALUMINIUM
  - Properties: Lightweight, good corrosion resistance, and ease of machining.
  - Applications: Primarily used in low-pressure applications, such as air handling, vacuum services, and dry bulk handling.
  BRONZE
  - Properties: Good corrosion resistance, especially against seawater and other saline solutions.
  - Applications: Used in marine, desalination, and certain chemical processing applications where corrosion resistance is paramount.
  NICKEL ALUMINIUM BRONZE
  
  This is a copper alloy that contains approximately 10% aluminum, 5% nickel, and 5% iron. It features strong corrosion resistance, especially in seawater applications, and resists the formation of a biofilm, a frequent cause of corrosion problems for stainless steels.
  
  Butterfly valves API 609 may have soft or metal seats. Valves with soft seats are also called “soft-seated” or “resilient” butterfly valves and are of the centric type. Eccentric designs (double or triple offset) are available, generally, with metal seat designs, which could also be fireproof.
  
  For less critical applications, butterfly valves are also available in plastic-grade materials, such as PVC, CVPC, Polypropylene (PP), and Polyethylene (PE). Here are the main features of plastic butterfly valves:
  
  PVC
  - Properties: Excellent corrosion resistance to a wide range of chemicals, lightweight, and cost-effective.
  - Applications: Suitable for low-pressure applications, including water treatment, chemical processing, and irrigation systems.
  CPVC
  - Properties: Similar to PVC but can withstand higher temperatures.
  - Applications: Used in hot water distribution, and chemical processing where higher temperature resistance than PVC is needed.
  PP/PE
  - Properties: Excellent chemical and corrosion resistance, lightweight, and suitable for a wide range of temperatures.
  - Applications: Chemical processing, water treatment, and applications involving aggressive or corrosive fluids.
  VALVE SEAT
  
  SOFT SEATED BUTTERFLY VALVE (“RESILIENT”)
  
  Soft-seated butterfly valves are designed to provide a tight seal and are typically used in applications where the sealing of gases or liquids is critical and where the operating conditions are within moderate temperature and pressure ranges. The “soft seat” refers to the use of elastomeric or other non-metallic, resilient materials for the sealing mechanism between the disc and the valve body, enhancing the valve’s ability to create a tight shut-off.
  
  Key Features
  - Sealing Material: The soft seat is usually made from materials such as PTFE (Polytetrafluoroethylene), NBR (Nitrile Butadiene Rubber), EPDM (Ethylene Propylene Diene Monomer), or Viton (a type of fluoroelastomer). Each material offers different properties in terms of chemical resistance, temperature tolerance, and wear characteristics, making them suitable for various applications.
  - Tight Shut-Off: Soft-seated butterfly valves are known for their excellent sealing capabilities, providing a near bubble-tight closure. This makes them ideal for applications requiring precise control over the flow and leakage prevention.
  - Low Torque Operation: The soft seating material reduces the friction between the disc and the seat, allowing for easy operation with minimal torque requirements.
  - Application Versatility: These valves are used in a wide range of applications, from water and wastewater treatment to chemical processing, food and beverage, and HVAC systems, handling a variety of fluids, including corrosive and abrasive media.
  Applications
  
  Soft-seated butterfly valves are versatile and can be employed in various industrial and commercial applications, including:
  - Water and Wastewater: For controlling and regulating water flow in treatment plants, distribution systems, and irrigation.
  - Chemical Processing: Handling mild to moderately corrosive fluids, depending on the seat material’s chemical compatibility.
  - Food and Beverage: In processes requiring sanitary conditions, where non-toxic and cleanable sealing materials like PTFE are essential.
  - Air and Gas Handling: For applications involving air, natural gas, and other gases where a tight seal is crucial to prevent leakage.
  Considerations
  
  While soft-seated butterfly valves offer many advantages, there are considerations to keep in mind when selecting them for specific applications:
  - Temperature Limits: The elastomeric and plastic materials used for the seats have upper temperature limits, beyond which they may degrade or lose their sealing properties.
  - Chemical Compatibility: It’s essential to ensure that the seat material is compatible with the process fluid to prevent damage and ensure long-term reliability.
  - Wear and Tear: While soft seats provide excellent sealing, they may be more prone to wear and damage from abrasive media than metal-seated valves.
  In summary, soft-seated butterfly valves offer excellent sealing capabilities and are suitable for a wide range of applications requiring precise flow control and tight shut-off. Selecting the appropriate seat material based on the application’s specific requirements is crucial for optimal performance and longevity.
  
  Soft seated butterfly valves (resilient) feature EPDM, VITON, NBR, BUNA-N, and similar soft seats. Soft-seat butterfly valves are generally of the concentric type and suit low-pressure and non-critical applications
  
  METAL SEATED BUTTERFLY VALVE
  
  Metal-seated butterfly valves are designed for more demanding applications where high temperatures, higher pressures, and abrasive or corrosive media are present. Unlike soft-seated valves, which use elastomeric materials for sealing, metal-seated valves rely on metal-to-metal contact between the disc and the seat, providing durability and resistance in harsh conditions.
  
  Key Features
  - Durability: Metal seats are highly durable and resistant to wear, making them suitable for applications involving abrasive particles or high-velocity flows that could damage softer seat materials.
  - High Temperature and Pressure Resistance: Metal-seated butterfly valves can withstand higher temperatures and pressures than their soft-seated counterparts, making them ideal for industrial processes involving steam, hot gases, or high-pressure fluids.
  - Corrosion Resistance: Depending on the metals used (such as stainless steel, Hastelloy, Inconel, or others), these valves offer excellent resistance to corrosion and chemical attack.
  - Leakage: Metal-seated valves may not provide the same level of tight shut-off as soft-seated valves. They are generally designed to meet industry standards for acceptable leakage rates under specific conditions, which is often sufficient for many high-temperature and high-pressure applications.
  Materials For Metal Seats
  The choice of materials for metal seats in butterfly valves is critical for ensuring the valve’s durability, performance, and resistance to the operating environment’s conditions, such as temperature, pressure, and corrosion. Here are some commonly used materials for metal seats in butterfly valves, along with their characteristics and applications:
  
  1. Stainless Steel
  
  Characteristics: Stainless steel offers excellent corrosion resistance, strength, and temperature resistance. Common grades used include 304, 316, and 316L, with 316/316L being preferred for better corrosion resistance due to their molybdenum content.
  
  Applications: Widely used in water and wastewater treatment, food and beverage processing, and chemical industries where corrosion resistance is essential.
  
  2. Carbon Steel
  
  Characteristics: Carbon steel provides good strength and thermal properties at a lower cost than stainless steel but is more susceptible to corrosion. It is often protected with coatings or treatments.
  
  Applications: Suitable for applications where corrosion is not a significant concern, such as in certain oil and gas or power generation processes.
  
  3. Alloy Steel
  
  Characteristics: Alloy steels, such as Chrome-Moly (e.g., A182 F22), are used for their enhanced strength, durability, and resistance to high temperatures and pressures.
  
  Applications: Ideal for high-temperature and high-pressure applications, including steam service, boiler feed water, and thermal oil systems.
  
  4. Titanium
  
  Characteristics: Titanium and its alloys offer exceptional corrosion resistance, especially to chlorides, along with high strength-to-weight ratios and excellent temperature tolerance.
  
  Applications: Used in seawater, brine, and other corrosive environments, including chemical processing, desalination, and marine applications.
  
  5. Hastelloy
  
  Characteristics: Hastelloy alloys are nickel-based and known for their outstanding resistance to severe corrosive environments, including strong acids.
  
  Applications: Suitable for aggressive chemical applications, such as handling sulfuric acid, hydrochloric acid, and chlorine.
  
  6. Inconel
  
  Characteristics: Inconel alloys are nickel-chromium-based and are known for their ability to withstand extreme temperatures, oxidation, and corrosion.
  
  Applications: Used in high-temperature applications, such as heat treating equipment, gas turbine components, and nuclear reactors.
  
  7. Monel
  
  Characteristics: Monel alloys are nickel-copper-based and offer excellent corrosion resistance, especially to saltwater and acidic conditions.
  
  Applications: Ideal for marine, chemical, and hydrocarbon processing where high corrosion resistance is required.
  
  8. Bronze
  
  Characteristics: Bronze, particularly aluminum bronze, provides good corrosion resistance, especially against seawater and other mildly corrosive environments.
  
  Applications: Commonly used in water, gas, and some chemical applications where its corrosion resistance and strength are beneficial.
  
  The selection of metal seat material for a butterfly valve depends on the specific requirements of the application, including the type of medium being handled, operating temperatures and pressures, and the presence of corrosive substances. Matching the seat material to these conditions ensures optimal performance, durability, and reliability of the valve in its operational environment.
  
  Special treatments and coatings for butterfly valve seats enhance their performance, durability, and suitability for specific applications, especially in challenging environments. These treatments can improve the seat’s resistance to wear, corrosion, temperature, and chemical attack, extending the valve’s service life and reliability. Here are some common treatments and materials used for enhancing butterfly valve seats:1. Polytetrafluoroethylene (PTFE) Coating
  
  Characteristics: PTFE, or Teflon, offers excellent chemical resistance and a low coefficient of friction, minimizing wear on the seat.
  
  Applications: Suitable for chemical processing industries, food and beverage, and any application requiring high chemical resistance and non-stick properties.
  
  2. Reinforced PTFE (RPTFE)
  
  Characteristics: RPTFE includes a filler (usually glass or carbon) to improve the material’s strength, wear resistance, and dimensional stability.
  
  Applications: Used in applications where pure PTFE’s properties are desired but with enhanced durability and reduced deformation under load.
  
  3. Nylon Coating
  
  Characteristics: Nylon provides good wear resistance and strength, along with excellent resistance to certain chemicals.
  
  Applications: Common in oil and gas applications and other areas where the seat may be exposed to hydrocarbons and where impact resistance is beneficial.
  
  4. Elastomeric Coatings (EPDM, NBR, Viton)
  
  Characteristics: Rubber materials like EPDM (ethylene propylene diene monomer), NBR (nitrile butadiene rubber), and Viton (fluoroelastomer) offer good sealing capabilities, flexibility, and, in the case of Viton, high-temperature and chemical resistance.
  
  Applications: Chosen based on their compatibility with the fluid medium. EPDM is suitable for water and mild chemicals, NBR for oils and fuels, and Viton for high-temperature and chemical applications.
  
  5. Stellite Overlay
  
  Characteristics: Stellite is a cobalt-chromium alloy known for its excellent wear and corrosion resistance, as well as its ability to perform under high temperatures.
  
  Applications: Ideal for severe service applications, such as those in the power generation and oil and gas industries, where valves are subject to high wear and harsh conditions.
  
  6. Electroless Nickel Plating
  
  Characteristics: Provides a uniform and corrosion-resistant coating that also offers good wear resistance and hardness.
  
  Applications: Used in a wide range of applications, including water and wastewater treatment and processing industries, for general corrosion protection.
  
  7. Ceramic Coating
  
  Characteristics: Ceramic coatings provide exceptional hardness, wear resistance, and thermal protection.
  
  Applications: Suitable for extreme wear and high-temperature applications, such as in the mining and minerals processing industry.
  
  8. Chrome Plating
  
  Characteristics: Chromium plating enhances surface hardness, wear resistance, and corrosion protection.
  
  Applications: Applied in industrial applications where durability and longevity of the seat are critical.
  
  Selecting the appropriate seat material and treatment depends on the valve’s application, including the nature of the fluids involved, operating pressures and temperatures, and specific industry requirements. By customizing the seat material and applying specialized treatments, butterfly valves can achieve optimal performance and reliability in a wide range of environments.
  Applications
  
  Metal-seated butterfly valves are chosen for their robustness in challenging environments, including:
  - Power Generation: For handling steam and high-temperature water in cooling systems and boilers.
  - Chemical and Petrochemical Industries: In processes involving corrosive fluids, high temperatures, and where valve durability is crucial.
  - Mining and Minerals Processing: For slurry and abrasive material handling where valve wear is a concern.
  - Pulp and Paper Manufacturing: In applications involving high-temperature liquids and corrosive chemicals used in the pulping process.
  - Considerations
    
    When selecting a metal-seated butterfly valve, several factors should be considered to ensure it meets the application’s needs:
    
    Sealing Requirements: While metal-seated valves are durable and handle extreme conditions, they might not achieve the absolute tight shut-off possible with soft-seated valves. Consider the application’s leakage tolerance.
    
    Material Compatibility: Choose a valve body and seat material that is compatible with the process media and conditions to ensure long-term reliability and performance.
    
    Operational Torque: Metal-to-metal seating can require higher torque to operate the valve, impacting actuator selection and operational energy costs.
    
    Cost: Metal-seated valves, especially those made from exotic alloys for enhanced corrosion resistance, can be more expensive than soft-seated valves. However, their durability in harsh conditions may offer a lower total cost of ownership over time.
    
    In summary, metal-seated butterfly valves are an excellent choice for industrial applications that demand high durability, temperature resistance, and the ability to handle abrasive or corrosive media. Proper selection of valve materials and understanding the specific operational requirements are key to maximizing the performance and lifespan of these valves in demanding environments.
    
    .
    Double offset and triple offset butterfly valve (metal seated)

May 23, 2024/by stvvalve

industry valve news, News

HOW TO ORDER A VALVE

Learn about the different types of valves used in the oil and gas industry: API and ASME gate, globe, check, ball, and butterfly designs (manual or actuated, with forged and cast bodies). Valves are mechanical devices used in piping applications to control, regulate and open/close the fluid’ s flow and pressure. Forged valves are used for small bore or high-pressure piping applications, cast valves for piping systems above 2 inches.

WHAT ARE VALVES?

INTRODUCTION TO OIL & GAS VALVES

Valves play a crucial role in the oil and gas industry, serving as the gatekeepers for controlling the flow of fluids through pipelines and equipment. These mechanical devices can open, close, or partially obstruct pathways to manage the movement of oil, gas, and sometimes water or other fluids, ensuring safe and efficient operation of extraction, processing, transportation, and storage systems.

Petrochemical Valves

Let’s delve into the importance, types, and applications of valves in the oil and gas sector, offering a comprehensive overview for readers interested in the pivotal role these components play in our energy infrastructure.

Functions Of Valves In Oil And Gas

Valves are indispensable for the oil and gas industry due to their ability to:

Control the Flow: Regulate the rate of flow of oil and gas in pipelines, ensuring optimal operation conditions (start/stop/modulate/change the direction of the flow)
Maintain the Pressure: Keep the pressure within pipelines and systems at safe levels to prevent accidents and ensure the integrity of the system.
Ensure Safety: Act as safety devices that can shut off flow in emergency situations, preventing leaks, spills, and catastrophic failures.
Allow operational Flexibility: Allow for the maintenance of parts of the system without shutting down the entire operation, providing operational flexibility and minimizing downtime.

Petrochemical valves

(Source: Spirax Sarco)

ypes Of Valves In Oil And Gas

The oil and gas industry uses a wide variety of valves, each designed for specific functions, pressure ranges, and fluid types. Some of the most common include:

Gate Valves: Used for on/off control of fluid flow, offering minimal restriction when fully open.
Globe Valves: Ideal for regulating flow or pressures as well as starting or stopping flow due to their precise throttling capabilities.
Ball Valves: Known for their quick shut-off capabilities, providing a tight seal with a quarter-turn motion, suitable for both on/off and throttling services.
Butterfly Valves: Feature a disc that rotates to open or close the flow path. They are compact and suitable for large-diameter pipes, offering quick operation and low-pressure drop.
Check Valves: Allow fluid to flow in one direction only, preventing backflow that could damage equipment or disrupt the process.
Safety Valves: Automatically release pressure when it exceeds set limits to protect equipment and ensure safe operations.
To explore these valve types in greater detail, our site hosts specialized articles for each category. Follow the links mentioned above to gain a more comprehensive understanding of each specific valve type, if you wish to broaden your expertise.

Applications Of Valves In Oil And Gas

Valves are used throughout the oil and gas supply chain, from upstream exploration and production to downstream refining, distribution, and storage:
- Upstream Operations: In drilling rigs, production wells, and offshore platforms, valves control the flow of oil and gas from reservoirs to the surface and manage injection processes for enhanced recovery.
- Midstream Infrastructure: Valves are used in pipelines, pumping stations, and compressor stations to transport oil and gas across long distances, ensuring that flow and pressure levels are maintained.
- Downstream Processing: In refineries and petrochemical plants, valves manage the flow of crude oil into various processes for separation, conversion, and treatment to produce fuels and chemicals.
- Storage and Distribution: Valves are essential in tank farms and terminals for controlling the storage and loading of oil, gas, and finished products for distribution.
A valve is manufactured by assembling multiple mechanical parts, the key ones being the body (the outer shell), the trim (the combination of the replaceable wetted parts), the stem, the bonnet, and an actioning mechanism (manual lever, gear, or actuator).

Valves with small bore sizes (generally 2 inches) or that require high resistance to pressure and temperature are manufactured with forged steel bodies; commercial valves above 2 inches in diameter feature cast body materials.

The valve market is rather huge in terms of revenues and number of dedicated workers: it was worth approximately 40 billion USD per year in 2018. The major manufacturers of oil & gas valves are located in the US, Europe (Italy, Germany, France, and Spain), Japan, South Korea, and China.

In conclusion, valves are fundamental to the safe, efficient, and effective operation of the oil and gas industry, ensuring that energy resources are extracted, processed, transported, and stored with precision and care. Their variety and adaptability make them indispensable tools in the complex systems that fuel the modern world.
VALVE TYPES

Valves used in the oil and gas industry and for piping applications can be classified in multiple ways:

BY DISC TYPE (LINEAR, ROTARY, QUARTER TURN)

In the diverse world of valves, categorizing them by their operational mechanics—specifically, how they move to regulate flow via the disc —provides insight into their suitability for different applications in industries like oil and gas, water treatment, and chemical processing.

Let’s explore the distinctions between linear motion valves, rotary motion valves, and quarter-turn valves to understand their functionalities, advantages, and typical uses.

Linear Motion Valves

Linear motion valves operate by moving a closure element in a straight line to control the flow of fluid. This category includes:
- Gate Valves: Utilize a flat gate that moves vertically to the flow, providing a straight-through pathway when open and a secure seal when closed.
- Globe Valves: Feature a plug that moves up and down against the flow, offering precise flow regulation and the capability to stop flow entirely.
- Diaphragm Valves: Employ a flexible diaphragm that moves up and down to permit or restrict flow.
Advantages:
- Precise control of flow and pressure.
- Suitable for on/off and throttling applications, particularly where flow rate control is essential.
Typical Uses:
Situations requiring tight shut-offs and flow regulation, such as in water treatment plants and in the control of gas or steam.

Rotary Motion Valves

Rotary motion valves rotate a disc or ellipse about an axis to control fluid flow. This group encompasses:
- Ball Valves: Contain a ball with a hole through it, which rotates 90 degrees to open or close the flow path.
- Butterfly Valves: Have a disc mounted on a rod, which rotates to allow or block flow.
Advantages:
- Compact and lightweight design.
- Quick operation with low torque requirements.
- Generally lower in cost than linear motion valves for the same size and rating.
Typical Uses:
Broadly used in applications requiring rapid operation and space-saving solutions, such as in the chemical industry and for water distribution systems.

Quarter-Turn Valves

Quarter-turn valves are a subset of rotary motion valves that operate with a simple 90-degree turn of the handle or actuator to go from fully open to fully closed positions, or vice versa. This category includes Ball Valves and Butterfly Valves, as mentioned above, due to their quarter-turn operation.

Advantages:
- Speed and ease of operation.
- Effective shut-off capabilities, making them ideal for both isolating and control applications.
- Versatility in handling a wide range of media, pressures, and temperatures.
Typical Uses:
Extensively used across various sectors, including oil and gas for pipeline flow control, in manufacturing processes, and in HVAC systems for controlling water flow and temperature.

In summary, the choice between linear motion, rotary motion, and quarter-turn valves depends on specific application requirements such as the need for precise flow control, space constraints, and operational efficiency. Linear motion valves excel in providing precise control and tight shut-off, rotary motion valves offer compact and quick solutions, and quarter-turn valves bring the best of rotary action in terms of speed and simplicity, making them versatile for a wide array of applications.

Oil & Gas Valve Types	Linear motion valves	Rotary motion valves	Quarter turn valves
Gate valve	X
Globe valve	X
Check valve		X
Lift check valve	X
Tilting-disc check valve		X
Stop check valve	X	X
Ball valve		X	X
Pinch valve	X
Butterfly valve		X	X
Plug valve		X	X
Diaphragm valve	X
Safety Valve / Pressure Relief Valve	X

VALVES BY BODY MATERIAL (CAST, FORGED)

The distinction between cast and forged valves lies in their manufacturing processes, which fundamentally affect their physical characteristics, performance, and applications.

As a general rule, cast bodies are used for valves above 2 inches in bore size, whereas forged bodies are used for valves below 2 inches (or preferred to cast valves, regardless of the pipeline bore size, in mission-critical applications).

Both types of valves play critical roles in controlling the flow of liquids and gases in various industries, including oil and gas, power generation, and water treatment.

Understanding the differences between cast and forged valves is essential for selecting the right valve for a specific application, ensuring optimal performance, durability, and safety.

Cast Valves

Manufacturing Process

Cast valves are made by pouring molten metal into pre-shaped molds where it solidifies into the desired valve shape. The casting process can be done through various methods, including sand casting, investment casting, and die casting, each with its own set of characteristics regarding surface finish, dimensional accuracy, and intricacies of design.

Characteristics
- Versatility in Design: Casting allows for complex shapes and sizes, making it possible to produce valves with intricate internal geometries that would be difficult or impossible to achieve through forging.
- Material Variety: A wide range of materials can be cast, including various types of steel, iron, and non-ferrous alloys, offering flexibility in material selection based on the application requirements.
- Cost-Effectiveness for Complex Shapes: For complex shapes and larger sizes, casting can be more cost-effective than forging, especially for low to medium-volume production.
Limitations
- Potential for Defects: The casting process can introduce internal defects such as porosity, shrinkage cavities, and inclusions, which can affect the mechanical properties and integrity of the valve.
- Variability in Quality: Cast valves can exhibit variability in quality and material properties across different batches due to the nature of the casting process.
Forged Valves

Manufacturing Process:
Forged valves are created through the process of forging, where a piece of metal is heated and then deformed and shaped into the desired form using high pressure. Forging can be performed using various techniques, including open-die forging, closed-die forging, and ring rolling, depending on the desired final shape and characteristics.

Characteristics
- Strength and Durability: Forging produces valves with superior strength, ductility, and resistance to impact and fatigue compared to casting. The forging process aligns the grain structure of the metal with the shape of the valve, enhancing its mechanical properties.
- Consistency in Quality: Forged valves generally offer more uniformity and consistency in material properties, with fewer internal defects than cast valves.
- High Performance in Critical Applications: Due to their strength and reliability, forged valves are preferred in high-pressure, high-temperature, and other critical applications where safety and performance are paramount.
Limitations
- Design Limitations: Forging cannot achieve the same level of complexity and intricate internal features that casting can, especially for large or very complex valve designs.
- Cost Considerations: For high-volume production of simple shapes, forging can be cost-effective. However, for complex shapes or lower volumes, the cost may be higher than casting, particularly for large-sized valves.
In summary, the choice between cast and forged valves depends on the specific requirements of the application, including mechanical strength, pressure and temperature conditions, desired material properties, design complexity, and cost considerations. Forged valves are typically favored in high-stress, high-performance applications due to their superior strength and reliability, while cast valves offer greater design flexibility and cost-effectiveness for complex shapes and large sizes.
To learn more about the difference between steel casting and forging please refer to the linked article.
VALVES BY TYPE OF ACTUATION (MANUAL, ACTUATED)

Valves can also be categorized based on their method of operation into manually operated valves and actuated valves. Understanding the differences between these two types is crucial for selecting the appropriate valve for a specific application, considering factors like ease of operation, control precision, and the necessity for automation.

Manually Operated Valves

Characteristics
- Operation: Manually operated valves require physical effort by an operator to change their position, using handwheels, levers, or gears. The manual input directly controls the opening, closing, or throttling of the valve.
- Design Simplicity: These valves are simpler in design as they do not require additional equipment for operation, making them straightforward to install and maintain.
- Cost-effectiveness: Without the need for external power sources or automation equipment, manually operated valves are generally more cost-effective than their actuated counterparts.
- Reliability: With fewer components that could fail, manually operated valves are highly reliable and suitable for applications where valve adjustments are infrequent or where direct manual control is preferred.
Limitations
- Labor Intensive: For systems requiring frequent adjustments or in situations where valves are not easily accessible, manual operation can be labor-intensive and time-consuming.
- Lack of Remote Control: Manual valves cannot be operated remotely, limiting their use in large, complex systems or in hazardous environments where remote operation is necessary for safety.
Actuated Valves

Characteristics
- Operation: Actuated valves are equipped with an actuator that allows valve operation (open, close, or modulate) through electrical, pneumatic, or hydraulic power. Actuators can be controlled remotely, allowing for automation and integration into control systems.
- Automation and Precision: With the ability to be controlled by various signals (electric, pneumatic, or hydraulic), actuated valves offer precise control over flow and pressure, enabling more efficient operation of the system.
- Flexibility and Safety: Remote operation capabilities allow actuated valves to be used in inaccessible, hazardous, or harsh environments, improving safety and operational flexibility.
- Adaptability: They can be integrated into automated control loops, responding to sensor inputs to adjust flow conditions automatically, which is essential for optimizing processes and ensuring safety in dynamic conditions.
Limitations
- Complexity and Cost: Actuated valves require additional components (actuators, power sources, control systems) making them more complex and expensive to install and maintain compared to manually operated valves.
- Power Requirement: Dependence on an external power source (electrical, pneumatic, or hydraulic) for operation can be a limitation in environments where such resources are limited or unavailable.
In summary, the choice between manually operated and actuated valves depends on several factors, including the need for automation, the operational environment, safety considerations, and cost. Manually operated valves are suitable for simpler, cost-sensitive applications where direct control and infrequent adjustments are sufficient. In contrast, actuated valves are ideal for complex systems requiring precise, remote, or automated control to enhance efficiency, safety, and operational flexibility.
VALVE BY DESIGN

Regarding their design, valves can be categorized in the following manner (it’s worth noting that our site features detailed articles on each type, so the descriptions provided here are intended to be broadly overviewed):

GATE VALVE

Gate valves are the most used type in piping and pipeline applications. Gate valves are linear motion devices used to open and close the flow of the fluid (shutoff valve). Gate valves cannot be used for throttling applications, i.e. to regulate the flow of the fluid (globe or ball valves should be used in this case). A gate valve is, therefore, either fully opened or closed (by manual wheels, gears, or electric, pneumatic and hydraulic actuators)

GLOBE VALVE

Globe valves are used to throttle (regulate) the fluid flow. Globe valves can also shut off the flow, but for this function, gate valves are preferred. A globe valve creates a pressure drop in the pipeline, as the fluid has to pass through a non-linear passageway.

CHECK VALVE

Check valves are used to avoid backflow in the piping system or the pipeline that could damage downstream apparatus such as pumps, compressors, etc. When the fluid has enough pressure, it opens the valve; when it comes back (reverse flow) at a design pressure, it closes the valve – preventing unwanted flows.

BALL VALVE

A Ball valve is a quarter-turn valve used for shut-off application. The valve opens and closes the flow of the fluid via a built-in ball, that rotates inside the valve body. Ball valves are industry standard for on-off applications and are lighter and more compact than gate valves, which serve similar purposes. The two main designs are floating and trunnion (side or top entry)

BUTTERFLY VALVE

Butterfly valves are versatile, cost-effective, valves to modulate or open/close the flow of the fluid. Butterfly valves are available in concentric or eccentric designs (double/triple), have a compact shape, and are becoming more and more competitive vs. ball valves, due to their simpler construction and cost.

PINCH VALVE

This is a type of linear motion valve that can be used for throttling and shut-off applications in piping applications that handle solid materials, slurries, and dense fluids. A pinch valve features a pinch tube to regulate the flow.

PLUG VALVE

Plug valves are classified as quarter-turn valves for shut-off applications. The first plug valves were introduced by the Romans to control water pipelines.

SAFETY VALVE

A safety valve is used to protect a piping arrangement from dangerous overpressures that may threaten human life or other assets. Essentially, a safety valve releases the pressure as a set value is exceeded.

CONTROL VALVE

Control valves are automated devices that are used to control and regulate the flow in complex systems and plants. More details about this type of valves are given below.

Y-STRAINERS

while not properly a valve, Y-strainers have the important function of filtering debris and protecting downstream equipment that may be otherwise damaged

VALVE SIZES (ASME B16.10)

To make sure that valves of different manufacturers are interchangeable, the face-to-face dimensions (i.e. the distance in mm or inches between the inlet and the outlet of the valve) of the key types of valves have been standardized by the ASME B16.10 specification.

ASME B16.34: VALVE COMPLIANCE

The ASME B16.34 standard, issued by the American Society of Mechanical Engineers (ASME), is a pivotal guideline that specifies the requirements for the design, material selection, manufacturing, inspection, testing, and marking of flanged, threaded, and welding end steel valves for application in pressure systems.

ASME B16.34 is also mentioned in the more general ASME spec ASME B31.1, “Power Piping Design”.

This standard is critical for ensuring the safety, reliability, and efficiency of valves used in various industrial sectors, including oil and gas, chemical, power generation, and water treatment, among others.

Understanding the ASME B16.34 standard is essential for engineers, manufacturers, and end-users involved in the selection and application of valves.

Key Aspects Of ASME B16.34
1. Valve Design and Construction:
  ASME B16.34 sets forth the criteria for the design of valves, including dimensions, pressure-temperature ratings, and other factors essential for ensuring that valves can operate safely under specified conditions. It covers a range of valve types, such as gate, globe, check, ball, and butterfly valves.
2. Pressure-Temperature Ratings:
  One of the most critical aspects covered by ASME B16.34 is the pressure-temperature rating of valves, which defines the maximum allowable working pressure for a valve at a given temperature. These ratings ensure that valves are selected and used within their safe operating limits.
3. Material Specifications:
  The standard provides detailed specifications for the materials used in valve construction, including requirements for body, bonnet, trim, and gasket materials. These specifications ensure compatibility with the fluid being handled and the operating environment, contributing to the valve’s integrity and longevity.
4. Testing and Inspection:
  ASME B16.34 outlines the requirements for testing and inspecting valves to verify their integrity and performance. This includes tests for shell strength, seat tightness, and backseat effectiveness, among others, which are crucial for ensuring that valves meet stringent safety and reliability standards.
5. Marking and Documentation:
  The standard specifies the marking requirements for valves, which include the manufacturer’s identification, pressure-temperature rating, material designation, and other relevant information. These markings provide essential information for the identification, traceability, and selection of valves.
Importance Of ASME B16.34 In Valve Selection

Adherence to the ASME B16.34 standard is crucial for ensuring that valves perform safely and effectively in their intended applications. Engineers and procurement specialists rely on this standard to select valves that meet the necessary performance criteria, including compatibility with the process medium, operating pressures and temperatures, and durability requirements.

Compliance with ASME B16.34 is also often a regulatory requirement in many industries, making it a key consideration in the procurement and installation of valves in critical applications.
Valve Compliance To ASME B16.34

A valve complies with ASME B16.34 when the following conditions are met:
- The valve body & shell materials comply with ASME and ASTM material standards for chemistry and strength
- Body & shell materials are heat-treated to ensure proper grain structure, corrosion resistance, and hardness.
- Wall thicknesses of the body and other pressure-containing components meet ASME B16.34 specified minimum values for each pressure class.
- NPT and SW end connections comply with ASME B1.20.1 or ASME B16.11.
- Stems are internally loaded and blowout-proof.
- All bolting will be ASTM grade with maximum applied stress controlled by B16.34.
- Each valve is shell tested at 1,5x rated pressure for a specific test time duration.
- Each valve is tested for seat leakage in both directions for a specific test time duration.
- Each valve is permanently tagged with materials of construction, operating limits, and the name of the manufacturer.
In conclusion, ASME B16.34 plays a fundamental role in the design, selection, and application of valves in pressure systems. It provides a comprehensive framework for ensuring that valves are safe, reliable, and suitable for their intended use, supporting the operational integrity of industrial processes across various sectors.

HOW TO ORDER A VALVE

Manufacturers of valves used in the oil and gas industry need to know the following information to supply the right device:

Valve type
Bore size in NPS or DN
Valve pressure rating (class range from 150# to 4500#)
Specification (example API 6D, API 600, API 602, etc)
Body and trim materials (at least)
Required end connection (flanged, threaded, butt weld, lug and others)
Fluid in the pipeline (>oil, gas, water, steam, solids)
Working temperature and pressure
Quantity
Delivery time
Origin restrictions (Chinese and Indian origins allowed or not)

EXAMPLE HOW TO ORDER OIL & GAS GATE, GLOBE, CHECK VALVES

Each manufacturer has own valves ordering sheets that map the valve configuration parameters that user has to consider:

GS – F – 6″ / 150 – 316 – B

1 2 3 4 5

1. Valve type

2. End type

3. Size / Class

4. Body Material

5. Options

C: Check Valve
CL: Lift Check Valve
CS: Check pressure Sealed Valve
CW: Swing Check Valve
G: Gate Valve
GG: Forged Gate Valve
GL: Light Type Gate Valve (API 603)
GS: Gate Pressure Sealed Valve
O: Globe Valve
OB: Globe Bellowed Sealed Valve
OS: Globe Pressure Sealed Valve
Y: Y-strainer

F: Flanged End
T: Threaded End
W: Butt Weld End
S: Socket Weld End

Size: NPS 1/2 – 80″

ANSI Standard:
150: 150 LB Class
300: 300 LB Class
600: 600 LB Class
1500: 1500 LB Class

DIN Standard：

PN16
PN25
PN40

JIS Standard：

10K: JIS 10K
20K: JIS 20K

GG: Forged Gate Valve
316: Casting S.S CF8M
304: Casting S.S CF8
F316: Forgings S.S F316
F304: Forgings S.S F304
WCB: Steel WCB
LCB: Steel LCB
HB: Hastelloy B
IN: Inconel

B: By-Pass
G: Gear Operator
D: Drains

May 23, 2024/by stvvalve

Posts

Key Features Of Butterfly Valves

Types Of Butterfly Valves

Operation

Applications

6. Rubber-Lined Butterfly Valves

7. Metal-Seated Butterfly Valves

DIFFERENCES BETWEEN DOUBLE VS. TRIPLE ECCENTRIC BUTTERFLY VALVE

Double Eccentric Butterfly Valves (Double Offset)

Triple Eccentric Butterfly Valves (Triple Offset)

Key Differences (Double/Triple Eccentric Types)

MATERIALS FOR BUTTERFLY VALVES

VALVE BODY

CAST IRON

DUCTILE IRON

CARBON STEEL

STAINLESS STEEL

Advantages Of Stainless Steel Butterfly Valves

Common Grades Of Stainless Steel For Butterfly Valves

Applications

Selection Considerations

DUPLEX & SUPERDUPLEX STEEL

Characteristics Of Duplex And Super Duplex Stainless Steel Butterfly Valves

Common Grades

Applications

Selection Considerations

NICKEL ALLOY STEEL

Characteristics

Common Nickel Alloys Used For Butterfly Valves

Applications

Selection Considerations

TITANIUM AND TITANIUM ALLOYS

Characteristics

Applications

Selection Considerations

ALUMINIUM

BRONZE

NICKEL ALUMINIUM BRONZE

CPVC

PP/PE

VALVE SEAT

SOFT SEATED BUTTERFLY VALVE (“RESILIENT”)

Key Features

Applications

Considerations

METAL SEATED BUTTERFLY VALVE

Key Features

Materials For Metal Seats

1. Stainless Steel

2. Carbon Steel

3. Alloy Steel

4. Titanium

5. Hastelloy

6. Inconel

7. Monel

8. Bronze

Applications

Considerations