Failure analysis of a 304 stainless steel heat exchanger in liquid sulfur recovery units
Xiaojia Yang, Menghao Liu, Menghao Liu, Cuiwei Du, Xiaogang Li, Xiaogang Li
Abstract
Failure of a 304 stainless steel (304 SS) tube used as a steam heater in a liquid sulfur recovery unit was investigated by using various characterizing techniques. The investigation revealed the outer wall of the heat exchanger underwent severe pitting corrosion, and the formation of cracks was initiated from the outer wall pits. The cracks were branched and propagated mainly in a transgranular mode. Pitting, intergranular corrosion and corrosion thinning due to the external medium led to the failure of the heat exchanger by SCC . EDX and XRD analyses showed that the corrosive medium mainly contains sulfur compounds and some chloride ions. The findings in this study suggest that the failure of the 304 SS tube occurred due to pitting, intergranular corrosion and SCC caused by sulfuric acid and chloride ions.