Selection of Butterfly Valve Materials in Different Media Environments

In industrial pipeline systems, butterfly valves play a crucial role due to their lightweight structure and efficient fluid control capabilities. But how to choose the right butterfly valve material is the key to ensure efficiency, durability and safety.This Butterfly Valve Material Selection Guide will provide in-depth insights into how to scientifically select butterfly valve materials based on medium characteristics, ensuring both system efficiency and safety.

Butterfly Valve Body Material Selection

Ductile iron butterfly valve
Ductile iron butterfly valves are widely used in municipal water supply and wastewater treatment, where they come into contact with chloride ions, microorganisms, and mildly acidic or alkaline media. While gray cast iron (CI) valves are affordable, they have poor corrosion resistance and are prone to rust and leakage over time.

Compared to gray cast iron, ductile iron (DI) offers greater strength and flexibility thanks to its unique spherical graphite structure, making it a popular choice for water systems like pipes and valves. However, neither material holds up well against saltwater or high chloride exposure—both corrode easily in these harsh conditions.

For seawater desalination or salty environments, molybdenum-rich stainless steels like 316 or 316L are better bets. The added molybdenum helps fight chloride-induced pitting. While 316L’s low-carbon design makes it ideal for welding or high-heat setups, truly demanding, long-term chloride-heavy applications call for tougher materials—think duplex stainless steels or titanium alloys.

Stainless Steel Butterfly Valves
As the all-rounder in the butterfly valve family, stainless steel butterfly valves are known for their excellent corrosion resistance, making them suitable for a wide range of environments. Whether it’s food-grade purified water transport, high-salinity seawater desalination, or highly corrosive chemical pipelines, different grades of stainless steel offer distinct advantages based on the specific working conditions.

Cast Steel Butterfly Valves
In industrial pipelines and cooling water circulation systems, butterfly valves must handle a variety of media, including high temperatures, high pressures, and mildly corrosive fluids. Cast steel (WCB) butterfly valves, made from carbon steel, offer excellent mechanical strength and high pressure resistance, withstanding pressures up to PN40. They are ideal for use in applications involving normal-temperature freshwater, oil, and steam.

However, corrosion resistance is limited, and in acidic or chloride-rich environments, cast steel valves are prone to rust. To enhance their durability, they are often lined with anti-corrosion coatings or equipped with stainless steel seats to improve resistance against corrosion.

Aluminum Alloy Butterfly Valves
For lightweight liquid and air transport in low-pressure applications, aluminum alloy (ADC12) butterfly valves provide an excellent solution due to their low density, high thermal conductivity, and strong oxidation resistance. They are widely used in the light industry sector, where weight reduction is essential.
However, aluminum alloy has strength limitations, which must be considered carefully. In pipelines larger than DN300, ADC12 valve bodies require reinforcement ribs to prevent plastic deformation under pressures exceeding 10 kg/cm².

Plastic Butterfly Valves
For highly corrosive chemical media, including acidic and alkaline solutions, seawater, and wastewater treatment, plastic butterfly valves are the preferred choice due to their exceptional chemical resistance. Made from UPVC, CPVC, PP, or PVDF, these valves offer long-term stability, effectively resisting chloride ions, sulfuric acid, and sodium hydroxide while also providing excellent electrical insulation.
Different plastic materials are suitable for specific applications:

UPVC (Unplasticized Polyvinyl Chloride):

• Resistant to mild acids and alkalis
• High impact strength and low fluid resistance
• Lightweight with good sealing properties
• Commonly used in water treatment systems

PP (Polypropylene):

• Highly resistant to strong acids such as hydrochloric and sulfuric acid
• Ideal for chemical transportation and wastewater treatment

CPVC (Chlorinated Polyvinyl Chloride):

• Withstands higher temperatures
• Resistant to acids, alkalis, salts, and oxidizers
• Suitable for more demanding chemical environments

However, plastic butterfly valves have limited pressure resistance, typically handling around 6 kg/cm². For pressures above 10 kg/cm², aluminum alloy or metal alternatives are recommended for improved strength and durability.

Butterfly Valve Seat Material Selection

The performance of a butterfly valve is not only determined by its body material but also heavily depends on the seat sealing material. In the face of various fluid challenges, materials like EPDM, NBR, PTFE, and VITON act as precision-engineered "soft armor," forming a robust barrier that ensures reliable sealing and long-term stability.

EPDM (Ethylene Propylene Diene Monomer)
A standard choice in municipal water supply systems, EPDM seats offer excellent water resistance and aging resistance, with a service life of up to 15 years. However, EPDM has limited chemical compatibility and tends to swell when exposed to mineral oils or hydrocarbons.

NBR (Nitrile Butadiene Rubber)
Commonly used in hydraulic oil pipelines, NBR provides outstanding oil resistance, second only to thiokol (polysulfide) and fluororubber (VITON). It also offers good abrasion resistance and gas tightness, making it suitable for oil-based media at 0–80°C. However, NBR has a temperature limit of 120°C and poor ozone resistance. For applications above 100°C, engineers recommend switching to VITON.

VITON (Fluoroelastomer FKM)
VITON is known for its exceptional chemical stability and high-temperature resistance. However, its poor low-temperature flexibility (>-20°C) restricts its use in cold regions.

PTFE (Polytetrafluoroethylene)
PTFE is an excellent corrosion-resistant material, capable of withstanding 98% concentrated sulfuric acid and 68% nitric acid. It is ideal for applications handling corrosive media below 200°C. However, PTFE has a tendency for cold flow (creep deformation)—under continuous stress, it can slowly deform plastically, which must be considered in long-term operations.

Recommended Valve Body and Disc Combinations

Ductile Iron + EPDM → A cost-effective choice for municipal water supply, with an annual leakage rate of <0.01%.
Stainless Steel 316L  + PTFE → The best combination for hydrochloric acid pipelines, meeting the ANSI C276 corrosion resistance standard.
Super Duplex Steel + VITON → The ultimate solution for sour oil and gas pipelines, improving resistance to sulfide stress corrosion cracking (SSCC) by 50 times.

Choosing the right butterfly valve materials requires balancing fluid characteristics, environmental conditions, and cost considerations. With scientific material selection and regular maintenance, service life can be maximized to ensure reliable system performance.

At Union Valve, we specialize in manufacturing high-quality butterfly valves, offering both standardized products and customized solutions tailored to meet precise specifications. If you have any questions or need further assistance, feel free to contact us—we’re here to help!

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• Understanding Butterfly Valve Seats: The Differences Between Hard, Soft and Rubber Lined
• Double Flanged vs Lug Type Butterfly Valves: Key Differences

About the Author

Tina Wei

Tianjin Union Valve Co., Ltd Sales Managers

More than 8 years of experience in the valve sales industry. Have extensive qualifications and experience.