Determining the Remaining Strength of Pitting Corrosion in Corroded Pipelines with API579 Criterion

Because the long-distance oil and gas pipelines have buried underground in a long term, there is corrosion on the inside and outside surfaces of pipeline, which can cause serious hole leaking accident, and bring the huge economic losses. In order to avoid or reduce the times of failure, inspection and evaluation of the residual strength of various corrosion are necessary. Pitting corrosion is classified into widespread pitting, localized pitting, region of local metal loss located in an area of widespread pitting and pitting confined within a region of localized metal loss in this paper. Based on the API579 criterion, analysis of the ultimate bearing capacity of pipeline with pitting corrosion, methods and steps assessing about residual strength of pipeline, and number of data are given. Because of the criterion considering the cases of pitting adjacent, types of pitting and stratified analysis, is appropriated to evaluate composite defects and residual strength accurately.