LAUSR

Abstract In this study, indentation responses of high strength steel pipe with local wall thinning (gouge) under internal pressure have been studied through experimental procedure and numerical analysis. The experimental study was carried out on laboratory scale specimens from API 5 L X80 steel. Dent produced by a hemi-spherical indenter with diameter of 20 mm and axial gouge introduced to the pipe’s outer surface. In experimental work, the influence of some parameters such as depth of dent, axial gouges of different sizes and presence of the internal pressure have been investigated. A numerical modeling approach has also been employed. The current numerical simulation has first been validated by experimental results previously conducted by the authors. The numerical results show well agreement with the experimental results. Effects of internal pressure level, boundary condition and D/t ratio on the response of pipelines subjected to lateral impacts numerically studied and the results have then been compared with analytical equations provided in some design codes. The results show that the analytical relations estimate greater lateral resistance than numerical results. Validated model were then used to derive a semi-empirical equation for predicting structural behavior of locally damaged tubes as a function of internal pressure. Furthermore, the elastic-plastic finite element analyses were performed to estimate the variations of failure depth with several internal pressures and gouge sizes.