Reliability Assessment of Buried Pipelines for Through-Wall Bending Stress

Abstract

This paper presents a computational framework for estimating the reliability of a buried pipeline under the influence of bending stress due to ovality. The in-service corrosion reduces the ability of the buried pipe wall to resist the pressure that is loaded externally. In this study, the bending stress due to ovality of the pipe wall is examined by considering the adverse effect of corrosion. If the imposed stress exceeds the ultimate strength of the pipe material, failure becomes very possible, and the general performance of the pipeline network will be affected. In most cases, the impact can lead to different failure conditions. To account for the amount of the damage of buried pipe due to corrosion is often difficult as a result of the unavailability of information about the parameters and also the associated uncertainties. Therefore, there is a need to employ a robust and computationally efficient approach to assessing the reliability of a buried pipe. For this reason, the reliability analysis of the stress mentioned above is modelled using a combination of Line Sampling (LS) and Important Sampling (IS) for a time-dependent assessment. The combined method helps to reduce the computational cost and improve the efficiency of the simulation approach. The study also shows that the change in underground water table could have a significant effect on the likelihood of failure of the buried pipes.