Failure Analysis of X90 Pipeline Steel under Microbial Corrosion Environment.

Because microbial corrosion is one of the major threats to the service life of buried pipeline steel, it is very important to predict the service life of X90 pipeline steel in a microbial corrosion environment. In this study, the hoop stress of pipeline steel is determined according to the calculation of the corrosion rate. The calculation model of stress intensity factor is obtained by comparing and selecting the M-parameter model method and Ballellle method, considering normal distribution and 3σ. The calculation method of ductile crack arrest reliability is obtained according to the criterion, and the variation of stress intensity factor and reliability of X90 pipeline steel with the increase in service life under different microbial corrosion rates is obtained. The ductile crack failure analysis using American Standard dot 49 CFR Part 192 is compared with the prediction results of strength check failure analysis using national standards GB 50251, GBT 34275, and GB150. The prediction results show that the ductile crack failure risk probability of X90 Pipeline Steel is higher than that of strength failure. For the ductile crack failure mode, the prediction of the failure life of pipeline steel with 8 steel pipes is slightly stricter than that with 5 steel pipes. [ABSTRACT FROM AUTHOR]