Latest Developments In Upheaval Buckling Analysis For Buried Pipelines

Upheaval buckling (UHB) of a buried offshore pipeline occurs when the pipeline is subject to high axial compression from thermal expansion. Predicting possible upheaval buckling is key to proper design of a buried pipeline and can be complicated because of uncertainties in the soil properties and pipeline vertical profile as well as because of various project requirements. Upheaval buckling, if not predicted and mitigated, results in significant damage to the pipeline, which leads to expensive remediation and intervention work. This paper describes latest developments in upheaval buckling analysis and a state-of-the-art finite element (FE) tool/model that has been developed as part of the SIMULATOR, J P Kenny’s in-house pipeline analysis package. The FE model is designed to simulate pipeline upheaval buckling for different pipeline configurations (single, pipe-inpipe, straight pipeline, pipeline with expansion loops, etc.) under various conditions. The analysis methodology, which involves an integration of a global model of the pipeline and a local representation (FE model or an analytical solution) of the potential upheaval location, is presented. Also presented are key features of the FE model; a comparison study between predictions from the FE predictions and available analytical solutions; design challenges related to conceptual, detailed and construction phases; and of seabed imperfections; efficiency of expansion loops; and importance of safety factors. Conclusions are then drawn as to the importance of various design conditions and scenarios, so the required soil cover and/or rock dump can be accurately estimated. This paper expands the understanding of the response of buried high temperature pipelines, and the literature survey, analysis results and conclusions presented in this paper provide general guidance to designing these pipelines against upheaval buckling.