Synthetical Impact Factor for Synergy Assessing Residual Strength of Pipelines with Pitting Corrosion

The effects of flow stress and expansion coefficient on assessing residual strength of oil and gas pipelines with pitting corrosion were studied according to assessing criteria API 579-1/ASME-FFS-1-2007, ASME B31G series and DNV-RP-F101. And the conservative property of above three criteria was analyzed and compared. The conservative property of ASME B31G series assessing criterion was the highest, the conservative property of DNV-RP-F101 assessing criterion was the lowest, and the conservative property of API 579-1/ASME-FFS-1-2007 assessing criterion was between above two criteria. A synthetical impact factor for synergy assessing was proposed based on multi-goal programming model under the real working condition of metal pipelines with pitting corrosion, which used linear weighted sum method to find the optimal solution. It can provide auxiliary for assessors to select reasonable and reliable evaluation criteria, and provide new ideas in safety evaluation.