A Novel Assessment Method to Identify the Interaction between Adjacent Corrosion Defects and its Effect on the Burst Capacity of Pipelines

This work provides a new systematic evaluation method to assess the interaction between adjacent corrosion defects and its effect on the integrity of pipelines. First, a finite element (FE) model of a pipeline containing adjacent defects (defects in longitudinal, circumferential and diagonal alignments) was developed. Then, the detailed relationships between defect spacing, and geometry, as well as the burst pressure of the pipe were investigated. At last, an interaction identification criterion applicable to asymmetrical defects was proposed, whose accuracy and reliability of the criterion were validated by FE simulations. The results show that the arrangement of corrosion affects the effect of interaction between adjacent defects. Regarding defects in longitudinal and circumferential alignments and with different depths, the increase of defect spacing strengthens the interaction between defects. For diagonally and circumferentially aligned defects with an identical depth, interaction strength tends to decrease first and then increase with the rise of defect spacing. An increase in defect depth exacerbates the interaction between adjacent corrosions. Similarly, an increase in the length of the shorter defect enhances the interplay between defects, which thus reduces the burst capacity of the pipe. When the length of the longer defect in adjacent defects increases, the interaction between the defects will be weakened, and the burst pressure of the pipeline is mainly dominated by the longer defect. Diagonally aligned defects show the strongest interaction effect when their overlapped distance in axial projection equals the sum of depths of adjacent defects, followed by defects in a longitudinal alignment. Besides, defects in a circumferential alignment have little effect on the failure pressure of the pipe. It is expected that the proposed interaction assessment criterion for adjacent defects with different arrangement types can provide a reference for assessing the integrity of pipelines with cluster corrosion defects.