Computational modelling of failure of welded joints in hydrogen transport pipelines

We present a computational framework that combines the welding process model and coupled deformation-diffusion-fracture model to predict the structural integrity and potential failure modes of hydrogen transport pipelines. In this study, we specifically focus on the seam welds, which are particularly vulnerable regions in pipeline infrastructure. Initially, the developed model is validated against experimentally observed R-curves of pipeline steels in hydrogen environment. Subsequently, we employ this modelling framework to investigate the mechanisms behind failure in seam welded joints, aiming to comprehend the influence of existing defects, microstructural heterogeneity, and residual stresses. Our findings reveal that the H2 fracture pressure of the pipeline may decrease to as low as 15 MPa under realistic critical conditions. These results bring new mechanistic insight into the viability of repurposing the existing natural gas pipeline network for hydrogen transportation. Furthermore, the presented computational model enables mapping the conditions that ensure the safe transport of hydrogen.