The detachable surface part of the valve is used to support the fully closed position of the valve core and constitute a sealing pair. The general seat diameter is the maximum diameter of the valve. For example, the valve seat of the butterfly valve is very wide. All kinds of rubber, plastic and metal materials can be used as the seat material, such as: EPDM, NBR, NR, PTFE, PEEK, PFA, SS315, STELLITE and so on.
Soft seat seal
The elastic sealing material and the small actuator thrust are used to obtain the tight sealing of the bubble. The compression of the sealing seat causes the material to elastically deform and squeeze into the rough surface of the metal part to be used to block the entire leakage path. The permeability of the material is the basis for a small amount of leakage for the fluid.
The material is too soft, or cold deformation (creep) occurs under load, and it can be hardened by adding a filler such as glass fiber. If used to make a sheet, it can still meet the requirements of use, and can eliminate cold deformation or permanent deformation.
The seal must be carefully secured to prevent cracking and gas leakage due to differential pressure. Bonding a soft seat to a metal part is one way, but it does not completely solve the problem, as the bond breaks and fails due to thermal shock. A pressure drop large enough will destroy the bonding material.