METHOD OF MANUFACTURING HARD FACED SEAT ASSEMBLY IN BLOW DOWN (PRESSURE DROP) VALVES FOR HIGH PRESSURE STEAM GENERATORS

摘要

The invention relates to a method of manufacturing hard faced seat assembly in blow down (pressure drop) valves for high pressure steam generators. The said method comprising the steps of machining a stellite bar stock (7) to suit inside of a sleeve (8); selecting the material of the sleeve (8) same as that of blow down valve body; inserting the machined stellite bush (7) inside the outer sleeve (8); welding (6) the stellite bush (7) with the sleeve (8) by conventional gas tungsten arc welding (GTAW) process; wherein the above seat assembly is then placed inside the blow down valve (V) body and welded by conventional shielded metal arc welding (SMAW) after performing a non destructive test (NDT) so that a hard faced stellite seat ring is provided in the valve body. Fig.3