Abstract
Line pipe steels with excellent resistance to wet sour gas are urgently needed because of increased use of sour gas reserves that have a higher hydrogen sulfide concentration, and because of higher operating pressures. The authors conducted extensive analyses to explore the effects of metallurgical factors on the resistance of line pipe steels to hydrogen induced cracking (HIC) and sulfide stress cracking (SSC). Both extensive desulfurization and complete inclusion shape control proved essential in eliminating potential HIC formation sites. To prevent HIC propagation, it was necessary to reduce hardness in the segregation zone, which was achieved by optimizing the chemical compositions of steels. Microstructure homogenization and complete elimination of inclusions improved SCC resistance in line pipe steels. These findings have dramatically helped improve the manufacturing conditions of line pipe steels for sour gas service.
