Analysis of Corrosion and Perforation of Sour Gas Piping

The acid gas pipeline elbow at the outlet end of an acid water stripper top air cooling system was replaced because of corrosion perforation. Combined with the structure and service conditions of the pipeline, macroscopic inspection, wall thickness measurement, energy spectrum detection and erosion simulation calculation were performed on the failed elbow, and the failure reason was analyzed. The results show that the mixture of H₂S, NH₃ and water vapor at the top of the acid water stripper cooled to form a corrosive fluid containing droplets, and entered the acid gas pipeline with a long straight pipe section vertically downward. Under the action of gravity and internal pressure, the corrosive fluid caused large shear stress on the external arch of the elbow. Under the coupling action of corrosion and erosion of the fluid medium, generated corrosion product film was continuously broken, forming an autocatalytic accelerated erosion corrosion effect, eventually leading to the thinning and perforation of the acid gas pipeline elbow.