Load-Bearing Capacity of X80 Dented Pipelines under Typical Loads

During pipeline construction and operation, the occurrence of surface dents presents a critical concern, primarily arising from factors such as pipeline installation and geological forces exerted upon the pipeline, particularly in the form of rock protrusion. These dents pose a significant threat to the pipeline's safe functionality and have the potential to diminish its load-bearing capacity. Presently, China's oil and gas pipelines predominantly employ X80 high-grade steel. It is noteworthy that prior research into the ultimate load capacity of dented pipelines has largely centered on medium and low-grade steels. The implications of these findings for the suitability of the X80 pipeline remain inconclusive. Consequently, it is imperative to undertake a comprehensive investigation into the load-bearing capacity of high-grade steel pipelines with dent defects. In addition to internal pressure, variations in the pipeline's transported medium, ambient temperature fluctuations, soil displacement, and other factors introduce additional loading effects, including bending moments and axial loads. These supplementary loads introduce latent hazards to the pipeline's operational safety. Hence, this research endeavors to investigate the ultimate load-bearing capacity of X80-grade dented pipelines under the influence of typical loading conditions and to identify pertinent factors that affect this capacity. Finite element analysis (FEA) is deployed to study the behavior of the dented pipelines under typical loads. Failure criterion for ascertaining the ultimate load is proposed and verified by the comparison to test results. Furthermore, the impact of varying dent sizes on the ultimate load capacity of X80-grade dented pipelines is examined. These findings serve as a robust foundation for the safety assessment of dented pipelines, ensuring the sustained safe operation of these vital infrastructures.