Stress-Corrosion Cracking of Carbon Steel Welds in Amine Service

Abstract A number of leaks were discovered at refinery piping welds in lean amine service at temperatures which, in the past, had been considered to be below the threshold temperature for stress-corrosion cracking. Therefore, these welds had not received post weld heat treatment. Subsequent metallurgical examination revealed that the leaks were caused by intergranular stress-corrosion cracking. The paper describes the nature of the cracking, the extensive inspection program that was carried out to identify cracked welds, and the corrective measures that were implemented. Also covered is what is known about the cracking mechanism and possible effects of certain process variables, including the use of corrosion inhibitor containing a sequestering agent.