Cryogenic valve seal

摘要

A valve seal mechanism for cryogenic applications includes an undercut groove in a seating region of the fluid passageway in a valve body. Disposed within the groove is a shouldered resilient wear ring of polytetrafluoroethylene, the outer circumference of the shouldered portion of the wear ring having a V-shaped channel formed therein. A solid backing ring having an inner circumferential surface of wedge-shaped cross section makes an interference fit with the V-channel of the wear ring, thereby preloading the channel sides against the respective adjacent sides of the groove. A valve disc has a sealing surface which makes an interference fit with a seating surface forming the inner circumferential surface of the wear ring. Introduction of fluid under pressure and reduction of temperatures from normal ambient to cryogenic both tend to increase sealing effectiveness.