The Corrosion Behavior of Welded Line Pipes in Wet H₂S Environment

The corrosion behavior of over-bending and under-bending formed Spiral Submerged Arc Welded (SSAW) steel pipes in NACE solution has been investigated by use of the self-designed full-scale corrosion test unit. It indicates that the H₂S damage of welded pipes characteristics Blister and Stress Corrosion Cracking (SCC). The blister number, diameter, and crack number is increasing as the increasing of applied stress. The residual stress of welded pipes has a large effect on the H₂S corrosion resistance, the tensile residual stress has a detrimental effect, and while the compression residual stress is beneficial to H₂S corrosion resistance. The damage mechanism of the welded pipes in H₂S containing solution under the presence of applied stress and residual stress has not only Hydrogen Induced Cracking (HIC), but also Stress Corrosion Cracking, and the applied stress and residual stress promote not only Stress Corrosion Cracking, but also Hydrogen Induced Cracking. The test results reveal that improving pipe’s weld surface quality, lowering tensile residual stress, and also control the operating stress are the key measures for controlling the wet H₂S corrosion of welded steel pipes. Suggestions for selection of line pipes in different service conditions have been made.