Failure Analysis of the Cracking of the Octenal Pipeline in a Chemical Fertilizer Factory
摘要
A large-scale leakage accident occurred in the EPA pipeline of a chemical fertilizer plant. Macroscopic inspection, chemical composition analysis, metallographic structure analysis, observation of the microscopic morphology of cracks, scanning electron microscopy and energy spectrum analysis were carried out on the failed flange nozzles. It was found that the inner wall of the failed flange nozzle exhibited typical morphological characteristics of caustic stress corrosion cracking, with crack tips dominated by intergranular propagation. Significant Na and S elements were detected in the corrosion products, indicating the critical role of NaOH-induced electrochemical corrosion. The reacidification effect of sulfides also accelerated the stress corrosion cracking. Finally, suggestions and measures for preventing failures were put forward.