Hydrogen embrittlement effect on the structural integrity of API 5L X52 steel pipeline

Hydrogen plays a decisive role in many future energy systems. For this reason, much research has been performed to see the effect of hydrogen on network canalizations. This paper studied the possibility of hydrogen transportation using the natural gas pipeline. In this paper, the effect of hydrogen embrittlement (HE) on the mechanical properties of pipe steels was examined. It appeared that the yield stress and ultimate strength were few sensitive to HE. However, fracture toughness and elongation at failure exhibited a severe decrease. Failure pressure established by different codes involved a flow stress which is a combination of yield stress and flow stress. Pipe defect assessment involved fracture toughness and flow stress upon using Failure Assessment Diagram (FAD) or Crack Driving Force (CDF) methods. In this paper, the consequence of hydrogen embrittlement on the failure and critical pressures of a pipe with a semi-elliptical defect was examined. The influence of assessment method, relative defect depth and working pressure were examined through the comparison of respective safety factors.