Strain Localization in the Dent of a Linepipe

Abstract

Steel pipelines used for transporting oil and gas can develop various damages such as mechanical damages, corrosion, wrinkle, and crack. One of the mechanical damages is a dent with or without other defects such as corrosion, gouge, and crack. The dent without other defect is often referred to as plain dent. Depending on the severity, a dent can lead to a failure of a field linepipe. The strain concentration in a dented pipeline wall can be used to determine the level of severity of a dent. Hence, a research program was undertaken at the Centre for Engineering Research in Pipelines (CERP) using full-scale tests and finite element analyses. The prime objective of this research was to determine comparative strain distributions in and around the dent and locations of high strains developed from the denting process. This information will help the pipeline operators to determine the severity of dents in their field linepipes. Hence, the outcome of this research will allow the pipeline operators to take an informed decision on whether or not an imminent remedial action for the dented segment of the line pipe is required. This paper presents test data and finite element simulation to discuss the locations and values of crucial strains in dents.