Parametric study of burst strength for hydrogen blended natural gas pipelines with long corrosion defects

Transporting hydrogen through existing natural gas pipeline poses significant challenges due to hydrogen embrittlement (HE), which can compromise the structural integrity of pipelines. This study evaluates the burst strength of line pipes with and without corrosion defects using elastic-plastic finite element analysis (FEA). A comprehensive parametric study was conducted to assess the influence of HE across a range of pipeline steel grades, pipe sizes, and defect geometries, with a specific focus on long corrosion defects. The results demonstrate that the Zhu-Leis flow solution can accurately predict the burst strength for various defect-free hydrogen pipelines due to the consideration of pipe wall thickness and material strain hardening. On this basis, a semi-empirical burst model is proposed for pipelines containing long corrosion defects. Comparisons show an excellent agreement of the predictions with the FEA results across a wide range of defect depths, defect widths, internal and external corrosion, and hydrogen blending ratios. Full-scale burst test data also validate the proposed model for long corrosion defects. Both the numerical results and the proposed predictions show that while burst strength decreases with increasing hydrogen blending ratio, the overall influence of HE on burst strength is relatively small for both defect-free and corroded pipelines if repurposed for hydrogen transport.