Metal-to-metal seat hub seals

Abstract

A valve has a metal-to-metal seal system between the flow bores of the valve body housing and each of the valve seat hubs. Each seal system includes an elastic dished metal ring gasket and a retainer ring. Each metal gasket is softer than each of the seat hub and the valve housing, is of rectangular cross-section, and the edge at the inner periphery on the convex side is flattened. Each seal system is disposed on an annular groove cut in the outer periphery surface of the end of the seat hub. One side of the metal ring gasket is located adjacent to the shoulder of the seat hub formed by the groove cut into the outer periphery end of the seat hub. The retainer ring is reciprocably mounted on the seat hub groove adjacent to the other side of the metal ring gasket and extends beyond the end of the seat hub prior to activation of the seal system. Each seal system is activated by insertion of the seat hub on which it is mounted into the corresponding bore of the valve housing until the end of the seat hub contacts a stop shoulder in the bore. The stop shoulder of the valve bore causes the retainer ring to advance towards the seat hub shoulder far enough to flatten out the dished metal ring gasket sufficiently for the inner and outer peripheries of the ring gasket to engage the wall of the groove of the seat hub and the wall of the bore respectively with enough pressure to cause plastic deformation of the inner peripheral edge on the concave side and the outer peripheral edge on the convex side of the gasket. The retainer ring also prevents substantial movement of the seal relative to the seat hub and housing when the valve is in use despite variations in the temperature of the valve and the pressure of the fluid therein and thereabout.