Positive Material Identification Procedure Development to Prevent Valve Corrosion Failures

Valves are essential parts of piping systems in the oil and gas industry. The failure of a valve due to corrosion is an adverse event with several negative consequences. One of the causes of valve corrosion is material mismatch. A PMI test is conducted as part of the project to verify the material of valves, pipes, joints, and pressure vessels. PMI testing of valves has not been studied previously. It is the goal of this study to focus on PMI requirements and case study for valves in order to prevent the negative consequences of its absence, such as corrosion, which can both be costly and unattractive. The purpose of this study is to develop a suitable approach for the development of PMI procedures for industrial valves used in the oil and gas industry. A case study is also described briefly in which the PMI for offshore valves has been forgotten, as well as how the mitigation approach has been implemented. This case study examines the absence of PMI for some dual-plate check valves in an offshore Norwegian project called Edvard Grieg (EG). The project specifications required that 50% PMI be applied to the pressure-retaining parts of a number of these valves made of 22Cr duplex material. The total number of dual-plate check valves is 80. The bodies are made from 22Cr duplex steel. Therefore, 40 valves must be tested for PMI, although only three valves of the 4 inch size and class 150 have already been tested. Consequently, PMI must be conducted on 37 remaining valves during fabrication, which are selected from smaller valve sizes to avoid stopping the fabrication work. According to the PMI results, all of the tested valves were manufactured from 22Cr duplex stainless steel.