Failure pressure prediction by defect assessment and finite element modelling on pipelines containing a dent-corrosion defect

Dent-corrosion defects are a typical combination of defects and pose a significant threat to the safety and integrity of energy pipelines. In general, the corrosion features rather than dents are considered the primary factor of fitness-for-service of pipelines containing a dent-corrosion defect. In this work, a finite element (FE) based model was developed to predict the failure pressure of pipelines containing a dent-corrosion defect and investigate its dominant factor. Parametric analysis results demonstrated that the presence of dents reduced the failure pressure of corresponding pipelines containing a single corrosion defect. The dominant factor of the failure pressure changed from corrosion feature to dent feature if (1) an increase in dent depth and a decrease in the pipe diameter-to-thickness ratio, (2) exceeding the critical dent depth by 8% of diameter (D), and (3) below the critical indentation radius by 10%D. Longitudinal dent gave a significant reduction of the failure pressure, making dent feature a dominant factor; Oppositely, the effect of the circumferential dent was marginal.