Iranian Journal of Oil and Gas Science and Technology

Abstract Pipelines are considered the most practical way to transport oil and gas. However, some factors, such as corrosion and third-party damage, can lead to severe incidents. Appropriate risk assessment can help reduce the risk of pipeline systems. Prioritizing repairs, scheduling physical integrity assessments, and developing emergency plans cannot be adequately done without implementing an appropriate risk assessment method. Risk consists of the probability of failure (PoF) and consequence of failure (CoF) and, in many cases, is obtained from the failure statistics published by the pipeline operators. In an endeavor to apply more engineering concepts to the highly statistics-dominated idea of risk assessment, the PoF can be calculated using finite element and Monte Carlo methods. This paper is specifically concerned with finding the PoF caused by excavations neighboring a buried pipeline, a form of failure rarely considered as most studies about third-party damages are concerned with the direct hit as a failure cause. Hence, a Python script was written that modeled the excavations using Abaqus. The soil was modeled using the Mohr-Coulomb plasticity approach, while the pipe was modeled as a shell. The excavation adjacent to the pipe would cause the pipe to deflect due to gravity. The stress caused by this deflection was compared to the yield stress to determine whether or not it would fail. To determine the probability of failure, this iterative process was carried out for excavations of different sizes using a Monte Carlo method. Additionally, a methodology was implemented to address the issue of computationally expensive models. The method proposed in this paper was compared and weighted against other standard procedures to determine whether the advantages of risk assessment based on finite element analysis (FEA) could justify its complexity.