Influence of welding defects on hydrogen embrittlement sensitivity of girth welds in X80 pipelines

Hydrogen embrittlement poses a considerable threat to girth welds in high-grade steel pipelines. This study investigated the influence of welding defects on the hydrogen embrittlement sensitivity of girth welds in X80 pipelines through slow strain rate tensile (SSRT) testing, scanning electron microscopy, hydrogen permeation test, and finite element analysis. The findings indicated that regardless of the presence of welding defects, the hydrogen embrittlement sensitivity of pipeline girth welds increases with negative current density. Welding defects can lead to a substantial increase in the hydrogen embrittlement sensitivity of girth welds and can shift crack initiation points from the surface areas of SSRT specimens to the locations of the defects. Stress concentration caused by welding defects results in the redistribution and local enrichment of hydrogen under the effect of stress-induced hydrogen diffusion, thereby leading to a considerable increase in hydrogen embrittlement sensitivity.