Evaluation of stress-strain state of gas pipeline section with local stability loss

Abstract

Causes for damaging of a gas pipeline pipe, which was accompanied by significant deformations and involves local loss of stability in a short pipe section, are considered. Certain characteristic indices of damage are established, namely damage is located in direct vicinity of the circumferential weld and develops on a lower strength pipe. A set of physico-mechanical studies did not reveal any lowering of metal performance that allows looking for the cause for pipe damage in the features of pipeline stress-strain state in service. It is shown that temperature deformations in the pipeline under the most unfavourable conditions induce insignificant stresses, which cannot lead to any local loss of pipe stability. Analysis of pipeline laying route showed that it passes through mining area and the pipeline stress-strain state is influenced by earth surface deformation. Magnitude of displacements and stress levels in the pipe, caused by earth surface deformation in the mining area, allow regarding them to be the cause for gas pipeline damage. 11 Ref., 2 Tables, 10 Figures.