Cause Analysis on Leakage of Elbow in Feed Line Pipe

The elbow of feed line pipe of ethylene plant in a factory had been leaking for many times during its operation. The causes of elbow leakage were analyzed by means of macro analysis, chemical composition analysis, hardness test, metallographic examination, scanning electron microscope analysis, energy spectrum analysis, and sulfur content analysis in naphtha. The results show that high temperature sulfide corrosion was the main cause of elbow leakage. Repeated scouring of the material destroyed the corrosion product film, the repeated removal of corrosion product film accelerated the corrosion of elbow. Therefore, under the interaction of high temperature sulfide corrosion and material scouring, corrosion perforation occurred at the elbow back bend, which eventually led to elbow leakage.