Method of making a fabricated gate valve

Abstract

A method of fabricating a gate valve having a hollow body with inlet and outlet conduits mounted therein and seat support members mounted on inner ends of the conduits includes fabricating and stress relieving a seat support assembly, then machining it to finished dimensions, then inserting the seat support assembly into a hollow body member. After this is done, the seat support assembly is welded inside the hollow body member. Local stress relieving of welds in the body can be employed during and after assembly and welding. One arrangement includes inlet and outlet conduit sections welded to the hollow body and opposed inner conduit sections having the opposed seat support members thereon with the inner conduit sections welded to the inlet and outlet conduit sections from a position inside the conduits to form a continuation of the outer conduit sections. Another arrangement includes inlet and outlet conduits having seat support members welded and finish machined prior to assembly. These conduits are positioned inside the hollow body with the seat support members in a spaced relation and welded inside the hollow body. Annular grooves in the seat support members adjacent the seat pockets aid in stress relieving. A gate is movably mounted between the seat support members.