Examination of Packless, Bellows-Type Valves in the THORS Facility

摘要

During a modification of the THORS facility, 62 packless, bellows-type, 1/2-inch IPS valves were removed. Three of these valves were selected for examination to determine whether the valves could be salvaged. Each valve was cleaned, leak checked and prepared for metallographic examination. From these tests, two of the valves' bellows, made of 316 stainless steel, showed signs of sensitization, and one also contained enlarged grain boundaries. This grain boundary phase was found to contain approx. 0.6 weight percent sulfur, along with some oxygen and 316 stainless steel components. From these observations, it was concluded that the sensitization, was not extensive enough to preclude reuse. The appearance of the sulfur grain boundary phase was concluded to be an isolated occurrence; therefore, the valves were recommended for reuse in non-critical locations. (ERA citation 07:007369)