A lateral global buckling failure envelope for a high temperature and high pressure (HT/HP) submarine pipeline

Submarine pipelines are the primary component of an offshore oil transportation system. Under operating conditions, a pipeline is subjected to high temperatures and pressures to improve oil mobility. As a result, additional stress accumulates in pipeline sections, which causes global buckling. For an exposed deep-water pipeline, lateral buckling is the major form of this global buckling. Large lateral displacement causes a very high bending moment which may lead to a local buckling failure in the pipe cross-section. This paper proposes a lateral global buckling failure envelope for deep-water HT/HP pipelines using a numerical simulation analysis. It analyzes the factors influencing the envelope, including the thickness t, diameter D, soil resistance coefficient mu, calculating length L-f, imperfection length L and imperfection amplitude V. Equations to calculate the failure envelope are established to make future post-buckling pipeline failure assessment more convenient. The results show that (1) the limit pressure difference p(max), (the failure pressure difference for a post-buckling pipeline when it suffers no difference in temperature) is usually below the burst pressure difference P-b (which is the largest pressure difference a pipeline can bear and is determined from the strength and sectional dimensions of the pipeline) and is approximately 0.62-0.75 times the value of P-b and (2) thickness t has little influence on the normalized envelopes, but affects p(max) The diameter D, soil resistance coefficient mu, and calculating length L-f influence the maximum failure temperature difference T-max (the failure temperature difference for a pipeline suffering no pressure difference). The diameter D also significantly affects the form of the normalized envelope. (C) 2015 Elsevier Ltd. All rights reserved.