Assessment of the Complexity of Stress/Strain Conditions of X100 Steel Pipeline and the Effect on the Steel Corrosion and Failure Pressure Prediction

Abstract

In this work, a finite element (FE) model was developed to simulate the complex stress/strain conditions potentially exerted on the northern pipelines due to the synergism of internal pressure, soil strain and local stress/strain concentration at corrosion defects. The effects of pre-strain on corrosion of the steel and the pipeline failure pressure were investigated. Results demonstrated that a high intensity stress/strain field generates preferentially at the bottom of corrosion defect. The increase of operating pressure would increase the stress concentration at defect and the plastically deformed area. Both tensile and compressive soil strains increase the stress intensity and plastic deformation. Thus, a pipe containing corrosion defects or mechanical dents is susceptible to hoop cracking or local bulking under the tensile and compressive soil strains, respectively. Moreover, while an elastic strain enhances slightly the steel corrosion, the effect of plastic strain is much remarkable. In optimal pipeline design, the reliable risk assessment of high-strength steel pipelines should consider the corrosion enhancement and defect propagation under the complex stress/strain conditions.