Failure analysis of pipelines containing a crack-in-corrosion defect considering hydrogen-induced degradation

Abstract

In this work, a 3D finite element model was developed to perform a failure analysis of a blended hydrogen natural gas pipeline containing a crack-in-corrosion (CIC) defect. Two dimensionless indicators (P_{crack-corrosion}/P_corrosion and De) were used to quantify the synergistic effect of hydrogen-induced degradation (HID), internal pressure, and combined defects on the failure pressure of the pipeline. Parametric studies results demonstrated that the pipeline is prone to brittle fracture failure caused by cracks rather than plastic collapse due to corrosion under a higher hydrogen concentration operating environment (i.e., whenever the hydrogen blending ratio exceeds 10 vol%). The presence of a crack reduced the failure pressure by at least 58 % of the corresponding pipelines containing a single corrosion defect. The HID effect can enhance the degradation effects on pipeline failure pressure. Failure pressure exhibits the highest sensitivity to hydrogen blending ratio, followed by corrosion depth, crack length, crack depth, corrosion length, and corrosion width.