The material selection of the butterfly valve mainly depends on its use environment and media characteristics. The following is a detailed analysis of the material selection of the main components of the butterfly valve (valve body, valve plate, seat):
1. Valve body material
Cast iron: including gray cast iron (CI) and ductile iron (DI). Grey cast iron butterfly valve is the most common type. It is mainly used in water systems, but it is easy to rust, has a relatively short service life and is cheap. The performance of ductile iron butterfly valve is comparable to that of carbon steel. It is generally used in water system pipelines. It is also a material widely used in water systems at present.
Cast steel (WCB): Cast steel butterfly valve has high strength and corrosion resistance, which is suitable for medium and high pressure and corrosive media. HOWEVER, THE SHIPMENT PERIOD IS LONG, AND DI CAN BE REPLACED WITHIN 16KG.
Stainless steel: The stainless steel butterfly valve has excellent corrosion resistance and rust resistance, which is suitable for pipes that need anti-corrosion and anti-rust. Common stainless steel materials include 304, 316, 304L, 316L, etc. Among them, the 316 stainless steel butterfly valve has better corrosion resistance to chloride ions and seawater.
Aluminum alloy (ADC12): Aluminum alloy butterfly valve has the characteristics of lightness, high strength and strong antioxidation performance. It is suitable for some special occasions, such as low temperature, high temperature, high pressure, etc. At the same time, aluminum alloy butterfly valve is also known as anti-convew valve, which is generally used on lighter PVC pipes. Its anti-convew characteristics are reflected in the application of air-conditioning water systems.
Plastic: Plastic butterfly valve has the characteristics of lightness, easy installation, low resistance, low price, etc., and is suitable for some corrosive media. Common plastic materials include UPVC, PP, CPVC, etc. Among them, UPVC is resistant to weak acids and alkali, with high impact strength, low fluid resistance, light texture and good sealing; PP is resistant to hydrochloric acid and sulfuric acid and corrosion resistance; CPVC is heat-resistant, acid, alkali, salt, oxidants and other corrosion resistance. However, the pressure resistance of plastic butterfly valves is limited. Generally, the pressure resistance is about 6KG. Aluminum alloy is recommended for replacement of more than 10KG.
2. Valve plate material
The valve plate is a part that is in direct contact with the medium in the pipeline, so its material selection is also very important. Common valve plate materials include nylon plate, cast steel, stainless steel (304, 316, 304L, 316L), ductile iron electroplating (electroplating plate), UPVC, CPVC, PP, aluminum bronze (often used for seawater desalination), bidirectional steel, etc.
3. Seat material.
The seat is one of the key components of the butterfly valve, and its material selection directly affects the sealing performance and service life of the valve. Common seat materials are:
EPDM (triternary ethylene-propylene): black, soft seal, temperature range: 15135°C. It is resistant to oxidation, ozone and corrosion, but it is easy to age when exposed to oil. Suitable for water, steam, etc. with a medium of -20120°C.
NBR: It has excellent oil resistance, second only to polysulfide rubber and fluorine rubber, and has wear resistance and airtightness. It is suitable for oils with a medium of 0~80°C.
PTFE (polytetrafluoroethylene): white, soft seal, temperature range:-15~185°C. It has the characteristics of heat resistance, wear resistance, corrosion resistance and non-stickiness. Suitable for corrosive media below 200°C.
VITON: Black, soft seal, temperature range:-15-200°C. Good chemical stability, excellent high temperature resistance (fluorinated rubber has the same high temperature resistance as silicone rubber), and good aging resistance. Suitable for rubber machinery, high-temperature particle media, etc.
Silicone rubber: It does not react with any substance except strong alkali and hydrofluoric acid, is non-toxic and tasteless, and its chemically stable. It is mostly used in the sanitary food industry.
In summary, the material selection of the butterfly valve should be determined according to the specific use environment and medium characteristics. When selecting, factors such as corrosion, temperature, pressure, valve service life and sealing performance of the medium should be fully considered.
