Effect of damage progression on the plastic capacity of a subsea pipeline

Abstract

The investigation of buckle propagation in subsea pipelines has been the subject of several works in the past few decades. It was shown that the external pressure required to develop the initial local buckle on the pipe is considerably more than the pressure required to propagate the initiated buckle along the pipe. In this respect, a relevant phenomenon may be framed for a pipe that is subject to a substantial lateral interference load; where the load induces plastic damage on the pipe and incites the progression of damage along the pipe. As such, the present work assesses the pipe's load-carrying capacity during the progression of plastic damage, using a novel test apparatus. In addition, using the finite element method, an application of damage progression effect is examined on a pipe subject to subsequent fishing gear impacts. The physical tests and numerical studies show that the load-carrying capacity of a pipe may drop significantly (i.e., 33.5% as reported in test 1) due to the damage progression effect. In conclusion, the findings of the present work show that disregarding the damage progression effect in the assessment of pipelines could lead to a significant underestimation of the load-carrying capacity of the pipes.