The usage conditions and selection principles of valve sealing surface materials are divided into two categories, that is, metallic and non-metallic materials. The applicable conditions for commonly used materials are as follows:
1. Rubber: it is generally used for sealing surfaces of low-pressure soft sealing gate valves, diaphragm valves,
butterfly valves, check valves, and other valves.
2. Plastic: there are many soft sealing ball valves with good corrosion resistance and low friction coefficient, such as nylon and polytetrafluoroethylene, which are used for sealing surfaces.
3. Babbitt alloy: it is also known as bearing alloy, and has good corrosion resistance and good running-in ability. Suitable for sealing surfaces of ammonia shut-off valves with low pressure and temperatures ranging from -70 to 150℃.
4. Copper alloy: it has good wear resistance and a certain degree of heat resistance, which is suitable for globe valves, cast iron gate valves and check valves and generally used for water and steam at low pressure and temperatures not exceeding 200℃.
5. Chromium nickel stainless steel: it has good corrosion resistance, erosion resistance, and heat resistance, which is suitable for media such as steam and nitric acid.
6. Chromium stainless steel: it has good corrosion resistance and is usually used on valves for high pressure, oil products with a temperature not exceeding 450℃, water vapor, and other media.
7. High chromium surfacing steel: it has good corrosion resistance and work hardening performance, which is suitable for high pressure, high temperature oil, steam and other media.
8. Nitrided steel: It has good corrosion resistance and scratch resistance, and is usually used on gate valves in thermal power plants. This material can also be adopted for the ball of hard sealed ball valves.
9. Hard alloy: it has excellent comprehensive properties such as corrosion resistance, erosion resistance, and scratch resistance, long service life, making it an ideal sealing material. Commonly used tungsten diamond alloy and diamond based alloy welding rods can be used to produce ultra-high pressure and ultra-high temperature sealing surfaces, suitable for media such as oil, gas, hydrogen, etc.
10. Spray welded alloy: there are cobalt based alloys, nickel based alloys, and titanium based alloy, which have good corrosion resistance, wear resistance, and other properties.
In order to ensure the safety and reliability of the valve sealing surface, the selection of sealing surface materials must be determined based on specific working conditions. If the medium has strong corrosiveness, when selecting materials, the corrosion performance should be met first, and then other performance requirements should be met.