Buckle and collapse mechanisms of deep-sea corrosion defect pipes under external pressure

The small-scale model experiments for steel tube specimens were conducted in a deep-sea hyperbaric chamber to measure the pressure and deformation configurations when the buckle and collapse occurred in order to analyze the buckle and collapse mechanisms of deep-sea corrosion defect pipes under external pressure. A three-dimensional numerical model of the pipe was established using the finite element software ABAQUS to simulate the quasi-static collapsing process of intact and corrosion defect pipes under external pressure. The pressure-change in diameter response curves and deformation configurations of steel pipes accorded well with the experimental results. The effects of pipe length, diameter-to-thickness ratio, initial ovality, steel grade, strain hardening characteristic of steel and geometric size of defects on the buckle and collapse of corrosion defect pipes were analyzed by using the developed numerical simulation method. Results show that initial ovality, geometric size of defects, and strain hardening characteristic of steel are the major factors affecting the normalized collapse pressure of deep-sea corrosion defect pipes, while the effects of pipe length, diameter-to-thickness ratio, and steel grade on the normalized collapse pressure are comparatively small. © 2020, Zhejiang University Press. All right reserved.