Failure analysis of a 304 stainless steel heat exchanger in liquid sulfur recovery units. (October 2020)

• Record Type: Journal Article
• Authors: Yang, Xiaojia; Liu, Menghao; Liu, Zhiyong; Du, Cuiwei; Li, Xiaogang
• Is Part Of: Engineering failure analysis. Volume 116(2020)
• Publication Date: 2020-10
• Subjects: 304 stainless steel -- Sulfur recovery unit -- Pitting corrosion -- Stress corrosion cracking; System failures (Engineering) -- Periodicals; Fracture mechanics -- Periodicals; Reliability (Engineering) -- Periodicals; Pannes -- Périodiques; Rupture, Mécanique de la -- Périodiques; Fiabilité -- Périodiques; Fracture mechanics; Reliability (Engineering); System failures (Engineering); Periodicals; Electronic journals; 620.112
• DOI: 10.1016/j.engfailanal.2020.104729
• Languages: English
• ISSNs: 1350-6307

Abstract

Highlights: Type 304 stainless steel is susceptible to SCC in liquid sulfur recovery unit. Pitting, intergranular corrosion and corrosion thinning enhance the SCC. Sulfuric acid and chloride ions can introduce fracture failure of 304 SS. 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.