Computational assessment of structural integrity of welded joints in hydrogen transport pipelines
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We present a computational framework combining a thermo-mechanical welding process model and a coupled mechanical-diffusion-fracture model to assess the structural integrity of and potential failure modes of the welded joints in hydrogen transport pipelines. Our primary focus of the study is the seam welds, which represent a particularly susceptible area in pipeline infrastructure. The developed models are calibrated using experimentally observed R-curves of pipeline steels in a hydrogen environment. Subsequently, we utilize the modelling framework to explore the factors contributing to failure in seam welded joints, seeking to understand the impact of pre-existing defects, microstructural heterogeneity, and residual stresses. Our results indicate that, under realistic critical conditions, the fracture pressure of the pipeline carrying H2 may decrease to as low as 15 MPa. These findings offer new mechanistic insights into the feasibility of repurposing the existing natural gas pipeline network for hydrogen transportation. Moreover, the introduced computational model allows for mapping the conditions that guarantee the safe transport of hydrogen.
