A new evaluation method for burst pressure of pipeline with colonies of circumferentially aligned defects

Abstract

Burst pressure prediction of pipelines with interacting defects is essential in the integrity assessment of steel pipelines. A series of evaluation criteria have been proposed to predict the burst pressure. However, the burst pressure is not accurately estimated by the existing evaluation methods for some defect distribution cases, especially for circumferentially aligned defects. In this study, a new evaluation method of burst pressure is established by developing a reliable calculation expression of the effective defect depth. A burst pressure study is performed by considering the effects of the defect distribution, defect size and circumferential spacing between two adjacent defects based on finite element analysis. Then, the detailed expression of effective depth of circumferentially aligned defects with different sizes is obtained. Full-scale burst tests for corroded pipelines are conducted to validate the accuracy of the new evaluation method. The predictions of burst capacity by the new method used for the pipeline with circumferentially aligned defects are in good agreement with experimental results for varying defect sizes and pipeline steel grades. Finally, the proposed evaluation method is verified equally applicable to various defect distribution modes.