Valve cover is the most critical working face of the valve, the quality of the sealing surface is related to the service life of the valve, usually the sealing surface material to consider corrosion resistance, abrasion resistance, erosion resistance, oxidation resistance and other factors.
Seals are usually divided into two categories:
I. soft materials:
1. Rubber (including butyl rubber, fluorine rubber, etc.)
2. Plastics (ptfe, nylon, etc.)
Ii. Hard sealing materials:
1. Copper alloy (for low-pressure valves)
2, chromium stainless steel (for ordinary high and high pressure valves)
3, stellite alloy (for high temperature and high pressure valves and strong corrosion valves)
4. Nickel base alloy (for corrosive media)