Assessment of Interaction Between a Dent and an Adjacent Corrosion Feature on Pipelines and the Effect on Pipeline Failure Pressure by Finite-Element Modeling

Abstract

Dents and corrosion are two types of defects commonly found on pipelines. Although major efforts have been made to assess the defects of each type, there is a limited understanding of interaction between the two defects in adjacency. In this work, a finite-element (FE) model was developed, enabling assessment of the interaction between a dent and an adjacent corrosion feature and prediction of failure pressure of the pipelines. Results showed that the geometries of the corrosion feature and the dent affected their interaction. As the interaction increased, the failure pressure of the pipelines decreased. A criterion was proposed to determine the critical spacing between the dent and the corrosion feature, below which an interaction between them existed. The dependences of the critical spacing on corrosion depth, corrosion length, and dent depth were determined. For example, the critical spacing between a dent 20 mm in depth and a corrosion feature 100 mm in length and 50% of pipe wall thickness on an X46 steel pipe was 150 mm. When a corrosion feature was sufficiently long (i.e., 200 mm), it dominated determination of the failure pressure, while the dent-corrosion interaction was negligible. When the corrosion feature was relatively short (i.e., 15 mm), the dent became predominant in failure pressure determination.