Extreme temperature, high pressure balanced, rising stem gate valve with

Abstract

A balanced high pressure rising stem gate valve has lubricated metal-to-metal seal means between the bonnet part of the valve body and the valve actuating stem and between the chamber part of the valve body and the balancing stem. Each seal means includes plural, e.g. three dished elastic metal ring gaskets with a high temperature resistant and chemical resistant ring of solid lubricant, tetrafluoroethylene or graphite between each adjacent pair of metal gaskets. Each metal gasket is softer than the stem and is of rectangular cross-section and the edge at the inner periphery on the concave side is rounded. Each seal means is disposed in an annular pocket in the adjacent part of the valve body extending around the stem. Each pocket is closed by an annular plug screwed into the pocket far enough to flatten out the dished metal rings sufficiently for the inner and outer peripheries of each ring to engage the stem and pocket 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, and to deform the elastic solid lubricant rings into engagement with the stem and pocket, and to prevent movement of the seal relative to the pocket when the valve is in use despite variations in the temperature of the valve and the pressure of the fluid therein and thereabout. The valve stem sealing arrangement may also be employed for packing off lock screws and in other situations wherein relatively movable parts are to be sealed both during and after relative motion.