Interaction of Longitudinal Corrosion Defects on a Pipeline

Abstract

Longitudinal corrosion defects in pipelines can be formed from external or internal metal loss, from selective seam corrosion, or from clustering of corrosion defects in the longitudinal direction. Standard assessments of such defects are traditionally performed on an individual basis, but research has shown that unique challenges arise when multiple defects are present on the same pipe joint. Multiple longitudinal defects can be evaluated using a combined probability of failure (PoF) methodology based on the dependence of the interaction. This paper presents results of such an evaluation, in which finite element analysis (FEA) was applied to calculate energy densities at the most sensitive defect elements. The methodology provided a measure of the interaction dependence. The combined statistical interaction of defects can be calculated using an adaptation of the inclusion-exclusion principle, where overlapping non-linear energy densities are calculated.