Abstract: A sealing mechanism capable of use in a valve subject to extended temperatures and pressures. The sealing mechanism comprises a seal ring positioned within a groove circumferential with respect to the passageway of the valve. A convex seating portion of the seal ring extends through an annular opening in the groove, for sealing engagement with a closure member. Shoulder portions, which extend from the sides of the seating portion, abut the sidewalls of the groove. The seal ring is compressed in width within the groove, so that a resilient side-sealing force is imparted to the contact of the shoulder portions with the sidewalls of the groove. Substantially leak proof sealing is achieved, which is maintained even in the event of high temperature conditions or fire.

Abstract: 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.

Abstract: A valve seal mechanism for use in pressurized fluid systems subject to fire risk, the seal having a soft seat to provide essentially zero leakage at normal operating temperatures and a backup hard metal seating surface capable of holding leakage to extremely low rates in the event of temperatures high enough to destroy the soft seat material. The seal mechanism is in the form of a hard metal seal ring adapted to fit within an undercut circumferential groove in a valve seat. The metal seal ring has a central inner circumferential rib adapted to extend through the groove opening for mating engagement with a sealing surface on the circumference of a valve disc. The rib of the metal seal ring itself has a circumferential undercut groove into which is tightly fitted a seal ring of material softer than the metal of the seal ring, the soft seal ring protruding beyond the adjacent inner surface of the rib to provide a primary valve seat surface.