The paper details metallurgical examinations performed to determine the cause of degradation of a cobalt-chromium-tungsten (UNS R30006) hardfacing alloy used in nickel-chromium-molybdenum- columbium (UNS N06625) seawater valves. The UNS R30006 alloy was applied using tungsten-inert gas and oxy-propane welding techniques to form wear surfaces and hard seats in the valves, and the valves were used in chlorinated seawater service. Metallurgical examinations led to a conclusion that corrosion caused the degradation, which initiated due to crevice corrosion apparently due to selective attack of chromium depletion areas in the matrix surrounding chromium carbides that form in the UNS R30006 microstructure.