Assessing the effects of the welding processes on the environmental strength of an multi-pass welded A106 Gr B steel pipe

摘要

The fusion welding process generates formidable welding residual stresses and metallurgical change, which increase the crack driving force and reduce the resistance of the brittle fracture as well as the environmental fracture. This is a serious problem with many alloys as well as the A106 Gr B steel pipe. This pipe is used in petrochemical and heavy chemical plants either degrades due to corrosive environments, e.g., chlorides and sulfides, and/or become damaged during service due to the various corrosion damage mechanisms. In particular, environmental strength of the multipass welded A106 Gr B steel pipe is influenced considerably by welding technology, welding condition, heat input, etc. On the base of this understanding, in this study, a sulfide stress corrosion cracking tests, which is based on the NACE TM 0177–90, on multipass welded A106 Gr B steel pipe was conducted in 3.5wt.% NaCl solution saturated with H2S gas at room temperature. And SSCC resistance according to the various welding processes was assessed. From the results, the welds by FCAW and GTAW+FCAW showed the good resistance against SSCC.