Burst Pressure Predictions of Corroded Pipelines With Long Defects: Failure Criteria and Validation

Abstract

This study examines the applicability of a stress-based criterion based upon plastic instability analysis to predict the failure pressure of corroded pipelines with axial defects. A central focus is to gain additional insight into effects of defect geometry and material properties on the attainment of a local limit load to support the development of stress-based burst strength criteria. A verification study conducted on burst testing of large-diameter pipe specimens with different defect length shows the effectiveness of a stress-based criterion using local ligament instability in burst pressure predictions, even though the adopted burst criterion exhibits a potential dependence on defect geometry and possibly on material’s strain hardening capacity. Overall, the results presented here suggests that use of stress-based criteria based upon plastic instability analysis of the defect ligament is a valid engineering tool for integrity assessments of pipelines with axial corroded defects.

Failure assessment on offshore girth welded pipelines due to corrosion defects

“…The fatigue crack growth rates of stress corrosion cracking were studied on API pipeline steels analytically and experimentally. [4][5][6][7] With respect to failure assessment, a stress-based criterion in terms of the remaining ligament instability was presented [8][9][10][11] to estimate the burst pressure of corroded pipes, and mostly validated through the tested data from API X65 and X100 steels. In order to derive a simple and reliable prediction formula, the stress-modified critical strain model 12 was proposed to construct the relationship between failure pressure and corrosion depth.…”