Patent ID: 6469271
Filing Date: 2002-10-22
Classification: B23K,Y10T

Abstract:
An apparatus for refurbishing a worn valve seat of a high temperature, high pressure safety valve in situ, said valve seat being generally circular and being provided at one end of a hollow, cylindrical valve nozzle which is attached to a valve body of said valve, said valve seat being accessible through an access opening in said valve body located above said valve seat, said apparatus comprising:(a) valve machining means mountable to said valve, said valve machining means having first cutter means extendable into the valve body through the access opening for initially machining the worn valve seat to a flat annular surface having an inner perimeter and an outer perimeter; (b) a gas metal arc welding apparatus mountable to the valve having a welding head with a consumable electrode, the welding head being extendable through the access opening and being rotatable in a circle located substantially parallel to and above the flat surface of the valve seat to deposit a buildup of weld metal from said consumable electrode onto said flat surface; and (c) a pair of metal support structures for supporting the buildup of weld metal as it is being deposited by the gas metal arc welding apparatus, said pair of support structures comprising: (i) an inner support structure which is positioned inwardly of the inner perimeter of the flat surface during deposition of the weld metal buildup and which has an outer, substantially vertical cylindrical surface which forms an inner support wall for the weld metal buildup, said inner support wall having a height sufficient to support the weld metal buildup; and (ii) an outer support structure which surrounds the outer perimeter of the flat surface during deposition of the weld metal buildup and which has an inner, substantially vertical cylindrical surface which forms an outer support wall for the weld metal buildup, said outer support wall being located proximate the outer perimeter of the flat surface and having a height sufficient to support the weld metal buildup; said valve machining means also having second cutter means extendable into the valve body through the access opening for machining the weld metal buildup to a desired final height and profile.