Which gate valve has the best sealing performance

Gate valve can be divided into two types according to the material of the sealing surface, hard sealing gate valve and soft sealing gate valve.
Hard-sealed gate valves include gray cast iron gate valves Z45T and Z41T, cast steel gate valves Z41H, and stainless steel gate valves Z41W. The material of the seat sealing surface of the hard-sealed gate valve is mainly copper and stainless steel.
The soft-sealed gate valves are mainly ductile iron gate valves Z45X and Z41X. The valve plate of the soft-sealed gate valve is wrapped in rubber as a whole, which is full of elasticity.
Therefore, from the point of view of sealing performance alone, the sealing performance of soft-sealed gate valves is better than that of hard-sealed gate valves.
However, because the sealing material of the soft-sealed gate valve is rubber, this type of gate valve can only be used in normal temperature and low pressure pipelines, and is neither resistant to high temperature nor high pressure. Soft-sealed gate valves are mostly used for installation on pipelines that pass through clean water. Grey cast iron hard-sealed gate valves can also be used in water-passing pipelines. Although the cost is lower than that of soft-sealed gate valves, the sealing performance is not as good as that of soft-sealed gate valves.
If the medium in the pipeline is high temperature and high pressure, cast steel hard sealing gate valve can be used; if corrosion resistance and rust resistance are required, stainless steel hard sealing gate valve can be used.