Bidirectional valve for cryogenic fluids

Claim 1

A valve assembly comprising a stationary valve body having a passageway for fluid, a movable valve member supported in said valve body adapted to close said passageway, a recess in the valve body opening radially toward said passageway generally perpendicular to the sealing surface of said valve member, said recess being defined by a radially outermost wall and by opposing side walls radially inwardly converging from said radially outermost wall, a seating ring having a radially outermost wedge-shaped base portion with axially facing sealing surfaces compressed between said opposed converging side walls of said recess, and a radially innermost seating portion extending into said passageway in radial compressive sealing engagement with the sealing surface of said valve member, said wedge-shaped base portion intermediate said sealing surfaces having a V-groove opening toward the radially outermost wall of said recess, and a coiled circular spring mounted in said V-groove for maintaining the axial spacing of the walls of said V-grooves at all temperatures with negligible radial loading of said seating ring, said coiled spring having a normal unstressed mean diameter slightly less than the mean diameter of said V-groove above cryogenic temperatures, and the coil diameter of said spring being equal to the spacing of the walls defining said V-groove at the mean diameter thereof above cryogenic temperatures whereby the mean diameter of the spring coincides with the mean diameter of said V-groove, and whereby incident to shrinkage of said seating ring upon exposure to cryogenic temperatures and a reduction in the mean diameter of said V-groove the mean diameter of the spring will contract to the reduced mean diameter of said V-groove thereby to maintain axial sealing contact of said base portion of said seating ring between opposing side walls of said recess.