Hydrogen-Accelerated Fatigue of API X60 Pipeline Steel and Its Weld

In this work, the hydrogen fatigue of pipeline steel X60, its girth welds and weld defects were investigated through in situ testing. A novel gaseous charging set-up was developed, which involves a sample geometry that mimics small-scale with high internal gas pressure. The effect by measuring crack initiation growth, using direct current potential drop (DCPD) set-up, probes outer surface specimen. base metal specimens both experienced reduction life presence hydrogen. For metal, manifested solely growth phase; accelerated factor 4. rate for 8. However, contrast to also 57% resistance initiation. Macropores (>500 µm size) on notch reduced 11. Varying pressure from 70 barg 150 caused no difference behavior metal. fracture path transitioned transgranular ductile nature mixed-mode intergranular quasi-cleavage fracture. Hydrogen decreasing roughness- plasticity-induced closure. worst case scenario pipelines found defects. This work therefore highlights necessity re-evaluate existing before they can be reused transport.