Lifting Pipeline Buckling under External Pressure Base on Imperfect Reason

Abstract

The deep-sea pipe is an important part of mining lifting projects in the ocean floor. The uniqueness of environment conditions and design needs to determine the unforeseeable risks and challenges during the laying of pipeline. Based on extensive studies of loads acted on the pipeline and corresponding possible limit states for each installation method, a series of investigations on load-carrying capacity and buckling response of pipes under different loading combinations and various types defects (such as uniform ovalities)were carried out. In these calculations, the collapse pressure has been associated with the pressure maximum of a uniformly deforming long pipe. In experiments in a stiff pressure lifting pipelines, collapse is always localized as shown in Figures 3 and 4.However,because pipe’s localization takes place after the pressure maximum, the collapse pressure yielded by the 2-D analysis suffices for most cases. Exceptions are pipes with local imperfections, in the form of dents. The adequacy of this important conclusion will be demonstrated in the future application, where such predictions are compared to experiments.