Burst Capacity Estimation of Pipeline With Colonies of Interacting Corrosion Defects

Based on the elastic plastic finite element method, the burst capacity of steel pipeline with corrosion defects i.e. longitudinal and circumferential aligned double corrosion defects are analyzed, respectively. The corresponding interaction rules for longitudinal and circumferential aligned corrosion defects are proposed, respectively. A new method is suggested for pipeline with more general interaction type named as compound aligned corrosion defects. Through the projections of the corrosion profile on the longitudinal and circumferential directions, the effective length, effective width and effective depth of adjacent corrosion defects are defined. Using the burst capacity expression of pipeline with single corrosion defect, the burst capacity of the pipeline with double interacting corrosion defects is calculated. The predictions of burst capacity of the pipe with compound aligned corrosion defects are in good agreement with experimental results. Furthermore, the method is extended for pipeline with colonies of corrosion defects and the assessment procedure is presented for the corroded pipe under internal pressure only. Due to the incorporation of the effective length, width and depth in those solutions, the resistance effect of uncorroded region between corrosion defects can be reasonably taken into account. Therefore, the procedure is validated to yield more accurate predictions than those in current assessment codes after compare with the experimental results.