Abstract: To analyze the influence of the interaction between internal and external double corrosion defects on the residual strength of pipelines, a pipeline model of corrosion defects was established through finite element analysis. The influence of different defect lengths and defect depths on the limit axial spacing was analyzed and the coefficient of the ASME B31G standard formula was corrected. The results indicate that compared with external corrosion, internal corrosion poses a greater threat to pipelines. The deeper the defect depth and the longer the defect length, the less the residual strength is affected by the axial spacing, the larger the limit axial spacing, and the difference between the limit axial spacing and the calculation result given in the DNV PR-F101 standard is significant. A residual strength calculation method suitable for double corrosion defects was established, with a maximum relative error of 7.6%. The research results can provide practical reference value for the adjustment of pipeline operation plans.

Key words: double corrosion, residual strength, limit axial spacing, pipeline, finite element analysis