The failure mechanism analysis of defective offshore natural gas pipelines under hydrogen blended transportation

Blending hydrogen for transportation in offshore natural gas pipelines is an important way to develop green energy, which is prone to hydrogen embrittlement leading to failure. The mechanical behaviour of defective hydrogen-blended natural gas pipelines with different hydrogen contents, was investigated by experimental and numerical methods. In addition, the failure mechanism analysis, including the effects of defect depth and combined loads, was carried out. According to the results, the evolution laws of pipeline strength and fatigue life under different hydrogen proportions are grasped. For example, under low hydrogen content (25%), its strength significantly decreases. Furthermore, the safety management method of offshore hydrogen-blended natural gas pipelines is given to provide a reference in the application of the project.