Butterfly Valve Types: A Comprehensive and Updated Guide

Butterfly Valve Types: A Comprehensive and Updated Guide

Butterfly valves are essential components in a variety of industries due to their versatility and efficiency. Known for their compact design and quick operation, these valves are used to regulate or isolate fluid flow in systems ranging from water supply to chemical processing plants. According to Google search snippets, some of the key considerations when choosing a butterfly valve include its material, size, and specific application requirements. In this guide, we will explore the types of butterfly valves, key features, selection parameters, media limitations, and more.

Features

A distinct feature of a butterfly valve is its ability to cope with high-pressure recovery, although it can only accommodate low-pressure drops. This makes it particularly useful in applications such as hydroelectric power plants. Depending on the application, the valve may need to be opened only 60 or 70 degrees from its closed position.

Overall, butterfly valves are used in various industrial applications for throttling, flow control, and pressure control. Sizes range from 2 to 60 inches.

Selection Parameters

When selecting a butterfly valve, you must consider several parameters such as the valve's maximum pressure and temperature ratings, the material used for the wetted parts, and compatibility with the fluid being handled.

• Valve body material
• Valve plate material
• Valve seat material
• Valve diameter

Additionally, some other factors to consider include:

• Specific gravity, viscosity, material content
• Flow rate
• Piping moments
• Pressure
• Pressure drop or required Cv
• Max/min temperature

Media Limitations

Butterfly valves are suitable for handling large volumes of liquids and gases but are not suitable for fibrous suspensions and dry bulk solids.

Types of liquids:

• Neutral
• Corrosive
• Hygienic
• Slurry

Types of gases:

• Neutral
• Corrosive
• Vacuum

Generally, the weight, cost, and space advantages of butterfly valves make them more suitable for handling large industrial valve applications compared to other types such as globe, gate, plug, and ball valves.

Butterfly Valve Types by End-Connection Styles

The end-connection of the valve body is the most common classification for butterfly valve types. Popular end-connection types include wafer, semi-lug, lug, flanged, and butt-welded types.

#1 Lug-Style Butterfly Valve

The lug-style butterfly valve has threaded "lugs" or inserts around its circumference, allowing for easy alignment and installation. This type is versatile and can withstand high temperatures up to 200°C.

Dead End Service Butterfly Valves

For dead-end service, the downstream flange of the valve is removed. Lug-style butterfly valves allow for maintaining reliable body connections without a downstream flange.

#2 Wafer Butterfly Valve

Wafer butterfly valves are designed to maintain unidirectional pressure or positive pressure. They are cost-effective, easy to install, and ideal for applications requiring an economical solution.

#3 Flanged/Double Flanged Butterfly Valves

Double flanged butterfly valves are robust and suitable for heavy applications requiring strength and rigidity. They are used for controlling, regulating, and throttling flow.

#4 Butt Welded Butterfly Valve

Butt welded butterfly valves are directly welded into the pipeline for high-pressure applications.

Butterfly Valve Types by Seat Design

Seat designs for high-performance butterfly valves may vary depending on application and budget. Common types include soft seated and metal seated valves.

#1 Soft Seated PTFE

Polytetrafluoroethylene (PTFE) is resistant to chemicals and ideal for low torque applications. It can handle temperatures ranging from -100°F to +450°F.

#2 Soft Seated RTFE

Reinforced PTFE (RTFE) is filled with compounds to provide additional strength and prevent abrasive wear. It is suitable for high-pressure and temperature applications.

Butterfly Valve Types by Body Material

Butterfly valves come in various materials for the body, disc, and seat. Material selection depends on the type of fluid, temperature, and pressure of the medium.

Carbon Steel

Carbon steel butterfly valves are cost-effective but not suitable for corrosive applications. Popular grades include WCB for high-temperature applications and LCC for low temperatures.

Stainless Steel

Stainless steel butterfly valves are used in corrosive applications. Types include austenitic, ferritic, martensitic, precipitation-hardening, and duplex stainless steels.

Austenitic Stainless Steel

Austenitic stainless steel is used for low-temperature applications such as cryogenic processes. High chromium and nickel content help maintain structural integrity at low temperatures.

Duplex Steel

Duplex stainless steel valves offer a balanced structure between austenitic and ferritic components, making them suitable for large pipelines requiring high strength and rigidity.

Titanium and Titanium Alloys

Titanium alloy butterfly valves offer high strength-to-weight ratio and corrosion resistance, ideal for seawater applications.

Nickel Alloy Steel (Hastelloy)

Nickel alloy butterfly valves provide extreme resistance to fluid impact and temperature variations, suitable for severe corrosive environments.

Nickel Aluminium Bronze

Nickel aluminum bronze butterfly valves are corrosion-resistant and suitable for seawater piping. They prevent biofilm formation and have a composition of aluminum, iron, and nickel.

Butterfly Valve Types by Offset Design

Butterfly valves can also be classified based on their offset design. Soft seated valves are usually concentric, while metal seated valves are often eccentric.

Zero Offset/Concentric Disk (A609 Type A)

Concentric disk valves ensure tight shut-off by lining seals against the elastomer lining edge. Suitable for applications not exceeding Class 150 ratings.

Double Offset (API 609 Type B)

Double offset valves feature two offsets of the stem, designed for high-pressure applications. Recommended body materials include carbon steel, stainless steel, and Hastelloy.

Triple Offset

Triple offset valves combine double-offset design with an additional disk seat axis offset, providing a tighter seal.

Butterfly Valves According to Mode of Operation

Butterfly valves can be operated in various ways, from manual to automatic methods.

Electric Butterfly Valves

Electric actuators operate these valves, making remote operation possible. They are reliable for large plants.

Pneumatic Butterfly Valves

Pneumatic actuators operate these valves, commonly used for transferring compressed air. They can operate automatically or semi-automatically.

Hydraulic Piston and Cylinder or Hydraulic Actuator Butterfly Valves

Used for applications requiring substantial force, these valves operate under fluid pressure changes.

Manually Operated Butterfly Valves

These valves are operated manually using a hand-wheel or crank, suitable for areas without power supply.

Butterfly Valves According to Application Specifications

AWWA Butterfly Valves - These valves meet American Water Works Association specifications and are used for potable water processing.

What are the International Standards for Choosing Butterfly Valve Types?

Valve manufacturers use international standards for global applicability. Some organizations providing these standards are:

• International Organization for Standardization
• European Committee for Standardization
• ANSI Valve Standards (United States)
• BSI Valve Standards (United Kingdom)
• CSA Valve Standards (Canada)
• DIN Valve Standards (Germany)
• EEMUA Valve Standards (United Kingdom)
• JSA Valve Standards (Japan)

Conclusion

Butterfly valves are valuable for large volume fluid applications, offering various designs and materials to fit specific needs.

• End-connection types: wafer, lug, flanged, butt weld
• Seat material: soft (Teflon) or metal-to-metal (SS316, Inconel)
• Offset design: centric, double offset, triple offset
• Body materials: Carbon steel, stainless steel, titanium alloy, nickel alloy, aluminum bronze
• Mode of operation: electric, pneumatic, hydraulic, manual

For more information, please visit us at our website. For details on other valve types, explore The Ultimate Guide to Choosing China 3 Way Ball Valve Supplier, the petrochemical industry – valves are crucial, and Globe Valve vs Gate Valve.