Common Materials and Usage Conditions of Valve Seals
There are two types of valve sealing ring materials: metal and non-metal. Common materials and their use conditions are as follows:
- Synthetic rubber
Synthetic rubber’s oil resistance, temperature resistance, and corrosion resistance are better than natural rubber. The general use temperature of synthetic rubber t ≤ 150℃, natural rubber t ≤ 60℃, rubber is used to seal stop valves, gate valves, diaphragm valves, butterfly valves, check valves, pinch valves and other valves with a nominal pressure of PN ≤ 1MPa.
Nylon has the characteristics of low friction coefficient and good corrosion resistance. Nylon is mostly used for ball valves and globe valves with temperature t ≤ 90℃ and nominal pressure PN ≤ 32MPa.
Polytetrafluoroethylene is mostly used for globe valves, gate valves, ball valves, etc. with temperature t ≤ 232℃ and nominal pressure PN ≤ 6.4MPa.
- Cast iron
Cast iron is used for gate valves, globe valves, plug valves for temperature t ≤ 100℃, nominal pressure PN ≤ 1.6MPa, gas and oil.
- Babbitt alloy
Babbitt alloy is used for ammonia stop valves with temperature t -70~150℃ and nominal pressure PN ≤ 2.5MPa.
- Copper alloy
Commonly used copper alloy materials are 6-6-3 tin bronze and 58-2-2 manganese brass. Copper alloy has good wear resistance and is suitable for water and steam with temperature t ≤ 200℃ and nominal pressure PN ≤ 1.6MPa. It is often used in gate valves, globe valves, check valves, plug valves, etc.
- Chrome stainless steel
Commonly used grades of chromium stainless steel are 2Cr13 and 3Cr13 after quenching and tempering treatment, which has good corrosion resistance. It is commonly used on valves of water, steam, petroleum and other media with temperature t ≤ 450℃ and nominal pressure PN ≤ 32MPa.
- Chromium nickel titanium stainless steel
The commonly used grade of chromium nickel titanium stainless steel is 1Cr18Ni9ti, which has good corrosion resistance, erosion resistance and heat resistance. It is suitable for steam, nitric acid and other media with temperature t ≤ 600℃ and nominal pressure PN ≤ 6.4MPa. It is used for stop valves, ball valves, etc.
- Nitrided steel
The commonly used grade of nitriding steel is 38CrMoAlA, which has good corrosion resistance and scratch resistance after carburizing. It is commonly used for power station gate valves with temperature t ≤ 540℃ and nominal pressure PN ≤ 10MPa.
Boronizing is directly processed from the valve body or valve clack body material to form the sealing surface, and then boronizing surface treatment, the sealing surface has good wear resistance. Used for power station blowdown valve.