In addition to the general requirements for sealing ring materials, the following conditions should also be noted for the sealing ring:

(1) elastic and resilient;

(2) appropriate mechanical strength, including expansion strength, elongation and tear strength, etc.

(3) stable performance, not easy to swell in the medium, small thermal shrinkage effect (joule effect).

(4) easy to process and shape, and can maintain precise size.

(5) no corrosion of contact surface, no pollution of medium, etc.

The suitable and common material to meet the above requirements is rubber, so the sealing ring is mostly made of rubber material. There are many kinds of rubber, and new kinds of rubber appear constantly.