Study of the influence of structural heritage and operating conditions on the durability of safety valve springs from steel 50KHFA

The reasons for the premature failure of a spring made of steel 50KhFA, which operated in the safety valve of the column's head part of the flare facility, were investigated using analytical chemistry, energy dispersive analysis, macro- and microstructural analysis, electron microscopy, macro- and electron fractography, phase chemical and X-ray structural analysis, hardness and microhardness tests and reductive heat treatment according to the regime recommended for safety valve springs in the standard process documentation and reference literature. The influence of non-metallic inclusions, such as carbides, their chemical composition, shape, and distribution on the operational properties of springs from steel 50KhFA has been investigated. Information on the characteristic external signs, typical micro damages, and the mechanism of destruction during low-temperature hydrogen sulfide corrosion of steel 50KhFA with the most dangerous accompanying process – hydrogenation was obtained. The analysis of the research results showed that the premature failure of the spring is due to both technological heredity and contact with the working environment not envisaged by the project.