Failure analysis of an A333Gr6 pipeline after exposure to a hydrogen sulfide environment

The analysis of an A333Gr6 pipeline failure was conducted after exposure to high H2S partial pressure for several hours. Chemical composition, metallurgical structure, steel pipe hardness, and the welding joint near the broken position were studied. The chemical compositions of corrosion products inside the steel pipe were also analyzed. Results show that corrosion products consist of Fe3O4 and FeOOH without ferrous sulfide. Stress analysis was obtained through the finite element analysis method. The failure analysis and calculation results show that spontaneous ferrous sulfide combustion in a high H2S environment leads to high temperature and pressure in the pipe, resulting in pipeline breakage.