Prediction of Collapse Pressure of Submarine Pipelines in A Wide Range of Diameter-Thickness Ratio

Submarine pipelines play an important role in offshore oil and gas development. A touchy issue in pipeline design and application is how to avoid the local collapse of pipelines under external pressure. The pipe diameter-thickness ratio D/t is one of the key factors that determine the local critical collapse pressure of the submarine pipelines. Based on the pipeline collapse experiment and finite element simulation, this paper explores the pressure-bearing capacity of the pipeline under external pressure in a wide range of diameter-thickness ratio D/t. Some interesting and important phenomena have been observed and discussed. In the range of 16<D/t<80, both DNV specification and finite element simulation can predict the collapse pressure of pipeline quite well; in the range of 10<D/t<16, the DNV specification is conservative compared with the experimental results, while the finite element simulation results are slightly larger than the experimental results. Further parameter analysis shows that compared with thin-walled pipes, improving the material grade of thick-walled pipes has higher benefits, and for thin-walled pipes, the ovality f0 should be controlled even more. In addition, combining the results of finite element simulation and model experiment, an empirical formula of critical collapse pressure for thick-walled pipelines is proposed, which is used to correct the error of DNV specification in the range of 10<D/t<16.