Abstract: In order to improve the accuracy of safety evaluation of oil and gas pipeline dent defects, the ductile failure criteria of metal materials are applied to the damage evaluation of pipeline dents. Taking X80 dented pipeline as an example, the pipeline damage of three failure criteria under different working conditions was calculated by finite element method and a comparative study was made. It was found that the pipeline damage increases with the increased dent depth; when the dent depth is greater than 6% of the pipeline diameter, the growth rate of pipeline damage decreases. The damage calculated by Oyane ductile fracture criterion is the largest, the critical void expansion ratio criterion is the second, and the X-W damage failure criterion is the smallest. In addition, it was found that the Oyane ductile fracture criterion can better reflect the stress concentration in the dent area by studying the influence of the dent geometry defect on the damage amount. The results show that the Oyane ductile fracture criterion is more suitable for the evaluation of deep and different pipeline dent defects. It provides a reference for further research on the application of ductile failure criterion in pipeline dent evaluation.

Key words: X80 pipeline, dent, comparison of failure criteria, finite element method, tensile test