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  • API 609 Butterfly Valve

API609 Cast steel Butterfly valve 150#

Technical Requirement:

1. Globe valves API609

2. Face to face API609

3. End flanges ANSI B16.5

4. Inspection and test API 598

Product Details

Main parts and materials

Parts NameMaterials
StemA182 F6a/A182 F316/A182 304

Actuator Flange: Accommodates all types of actuators, handles, gear operators, electric actuators, and pneumatic actuators.

Bushings: Stem bushing reduces torque and isolates the stem from the valve body, preventing seizure of the stem due to corrosion in the stem journal baring.

Precision Profile Disc: Provides bubble-tight shut-off and assures minimum torque and longer seat life.

Shaft Weather Seal: (Below bushing on some models)

Seat Face: Eliminates need for flange gaskets.

Phenolic Backed Seat: Non-collapsible, stretch resistant, blow-out proof, field replaceable.

Api609 Cast Steel Butterfly Valves

Butterfly valves are used to shut off or regulate the flow of fluids (isolation and regulation). For low pressure and non-critical applications, API 609 center butterfly valves (soft seal) are preferred over gate and ball valves because they are cheaper, lighter, and easier to install. Eccentric butterfly valves with metal seats (double and triple eccentric valves) are becoming increasingly popular and compete with globe and ball valves in some applications.

Types of Api609 Cast Steel Butterfly Valves Construction

Yuanda Valve Group is a proud supplier of butterfly valves, from API 609 Butterfly Valve to Cast Iron Wafer Type Butterfly Valve.

Wafer Type Butterfly Valve: fits between flanges

Lug Wafer Design Butterfly Valve: held between flanges by bolts and pass through the valve's casing

Advantages of Api609 Cast Steel Butterfly Valves

Yuanda Valve Group is a trusted manufacturer for high-end butterfly valves. We offer durable API 609 butterfly valve whose versatility makes them ideal for a full range of applications.

Some of the advantages of butterfly valves include:

Compact design saves space

Light in weight


Quick Operation

Doesn't trap fluids

Qualified for both gaseous and liquid service

Low Maintenance costs from minimal moving parts

Positive shut-off bi-directionally

Phenolic backed cartridge seat

PTFE Bushing Standard

Locking handle standard (2"-12")

End of line service on lug style standard

Ease of automation

Typical Applications of Butterfly Valves


Chemical/Petrochemical Processing

Food & Beverage

Power & Utilities

Pulp & Paper

Api609 Cast Steel Butterfly Valves Industries

Water supply

Wastewater Treatment

Gas Supply

Fire Protection


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What is a butterfly valve?

A butterfly valve is a regulating and closing device that can be used as an alternative to ball and globe valves in certain applications.

This type of valve can be classified according to several parameters:

Design: central, double eccentric, triple eccentric

End connection types: butt, lug (half or full), flange and double flange

Seat material: soft (e.g. Teflon, Buna, rubber, etc.) or metal-to-metal (SS304, SS316)

Valve body and disc materials (from cast iron to high nickel alloy)

Actuation: manual (lever, gear, worm gear) and actuated (electric, pneumatic, hydraulic and hydrodynamic)

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

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

How Butterfly Valves Work

The key component of a butterfly valve is the valve flap, a metal ring located in the centerline of the pipe, which is connected to an external actuator (manual horizontal or actuator) via a stem.

In contrast to ball valves, butterfly valves have a pressure drop as the valve disc is always in contact with the fluid being transported through the pipeline.

In the closed position, the disc blocks the bore of the valve, while in the open position, the disc allows fluid to pass.

Switching the valve from the fully open position to the fully closed position requires a quarter-turn motion (and this motion can be performed as quickly as with a ball valve).

Butterfly Valve Specifications

API 609, ASME B16.34 (pressure and temperature ratings), API 598 (testing), ASME B16.5 and ASME B16.47 (flange ends), and ASME B16.25 specifications cover butterfly valve dimensions and tolerances for petrochemical industry and pipeline applications.

Butterfly Valve Design

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

Concentric butterfly valve: stem centered in the middle of the valve plate, plate centered in the bore

Eccentric butterfly valves (double and triple eccentric): have one or more short shafts (stems) that are located at an offset from the center of the valve. Eccentric butterfly valves are also defined as double or triple eccentric.

Concentric Butterfly Valves (Center)

Concentric butterfly valves are used in water and wastewater treatment plants, fire protection systems and gas supply.

Water Treatment

Water distribution

Water pumping units

Water transmission


Aeration systems

Cleaning of wastewater

Filter installation

Water pumping installations

Membrane installation

Fire protection (indoor/outdoor)

Natural gas and flare gas

Double Eccentric Butterfly Valves

Double eccentric butterfly valves are widely used in groundwater supply applications and compete with gate valves (especially in larger bores) because they are lighter, cheaper and minimize excavation work.

Triple Eccentric Butterfly Valves

Manufactured from high grade materials such as stainless steel and duplex/super duplex steel, triple eccentric butterfly valves compete with ball valves in mission critical applications with significant corrosion and high temperature/pressure. Triple eccentric butterfly valves are the most complex type and have gained market share in recent years.

Butterfly Valve Materials

As with any other type of valve, butterfly valves are available in a variety of materials and material combinations (body, flap, seat).

The choice of material is based on the fluid to be closed, the pressure and temperature of the application at hand. Listed below are the primary materials used in butterfly valves, generally in cast grades.

Carbon Steel

Carbon steel is an alloy of iron and carbon (no other alloying elements are added to control the properties of the material).

For butterfly valve construction, carbon steel is most commonly used to form the valve body and valve plate through a sand casting process.

The most common grades used for butterfly valve bodies and flaps are ASTM A216 WCB and LCC (low carbon content) steels (they are cast steels). They are used for high-temperature and low-temperature service, respectively.

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

Stainless Steel

Stainless steel is an alloy of iron, nickel and chromium (minimum chromium content is 10.5%). The addition of chromium creates a self-healing oxide layer on the surface of the material to prevent rusting.

When the surface of a stainless steel product is scratched, the chromium reacts with oxygen to prevent it from reacting with iron and rusting. There are many different types of stainless steel available, commonly referred to as the 300 and 400 series.

Stainless steels can be classified as ferritic, austenitic, martensitic, duplex and precipitation hardenable (14 Ph).

This classification is based on the microstructure of the material, by changing the composition of the mixed elements. Typically, the most common types of SS used to make valves are austenitic and duplex stainless steels.

Austenitic stainless steels

Austenitic stainless steels contain (in addition to chromium) nickel, which has the effect of maintaining a high temperature face-centered cubic austenitic structure at temperatures that would normally transform to a ferritic body-centered cubic structure.

This face-centered cubic structure gives the material greater toughness and ductility than ferrite grades.

Depending on the percentage of nickel contained, the tough austenitic structure can be retained even at very low temperatures, making the material suitable for low temperature applications.

The addition of molybdenum enhances the valve's resistance to pitting.

Duplex Steels

Duplex stainless steels (UNS S32205 and UNS S31803) have a well-balanced structure of austenitic face-centered cubic structure of iron and a ferrite body-centered structure.

This type of composition is obtained by controlling the alloying elements and the heat treatment performed on the alloy to create a structure consisting of 50% austenite and 50% ferrite.

Duplex stainless steels combine the higher strength of the ferritic composition with the significant toughness of austenite.

The super duplex types (UNS S32750 and UNS S32760) contain higher levels of chromium and molybdenum for enhanced corrosion resistance.

Nickel Alloy Steels

Nickel alloys are used in valves subjected to very severe service conditions in terms of fluid, temperature and pressure.

These alloys are particularly well suited for extremely corrosive applications that would destroy the protective oxide layer of lower grade steels such as stainless steel.

Inconel, Incoloy and Hastelloy are the most common nickel alloys used in valve construction. The main disadvantages of nickel alloys are high weight and high cost (multiples of stainless steel valves).

Titanium and Titanium Alloys

Titanium alloys combine superior strength and weight with excellent corrosion resistance.

Compared to any other metal, titanium alloys have the highest strength-to-weight ratio. Similar to stainless steel, titanium alloys have a protective oxide layer on their surface that protects the product from rusting.

Titanium is highly resistant to corrosion by seawater, especially for environments where hypochlorite is present.

The main disadvantages of titanium alloys are their high price, which is a multiple of stainless steel, and the complexity of the production process due to the high reactivity of the metal (special casting procedures are required to prevent titanium from reacting with oxygen during melting and pouring) .

Nickel-aluminum bronze

This is a copper alloy containing about 10% aluminum, 5% nickel and 5% iron. It is highly resistant to corrosion, especially in seawater applications, and resists biofilm formation, which is a common cause of corrosion problems with stainless steel.

API 609 butterfly valves may be available with soft seats or metal seats. Valves with soft seats, also known as "soft seat" or "resilient" butterfly valves, are centered. Eccentric designs (double or triple eccentric) are usually metal seat designs and can also be fire resistant.

Seat Material

Soft (resilient butterfly)

Soft-seat butterfly valves (resilient) use EPDM, VITON, NBR, BUNA-N, and similar soft seats. Soft seat butterfly valves are typically concentric and are suitable for low pressure and non-critical applications

Metal Sealed Butterfly Valves

In this case, the valve body and valve flap have a metal-to-metal seal.

High performance butterfly valves (double eccentric) are available with soft and metal seats. triple eccentric butterfly valves typically have metal seats and ATEX fire protection.