Failure analysis of composite repaired pipes subjected to internal pressure

Abstract

While around 60% of pipelines transmitting oil and gas worldwide experience corrosion and metal loss, the composite repair technique has become a popular option developed in recent decades. Employing a theoretical methodology, this study deals with corroded metallic pipes repaired by composite repair systems such that the focus is the impact of elastoplastic deformations on the failure pressure. In this methodology, the elastoplastic strains are taken into account by employing the bilinear isotropic hardening plastic flow theory with the von Mises yield criterion. Three modes are recognized based on the region where failure occurs, and the results are presented. The findings revealed that when the failure happens in the defect region, the proposed formula estimates the failure pressure more accurately than when it occurs either far from the defect or in the composite sleeve. Moreover, studying the bonding strength between the pipe, infill material, and composite patch shows that the interface bonding strength between the pipe and the polymer filler plays a more significant role than the interface bonding strength between the polymer filler and the composite repair. The results of this study can assist maintenance engineers in better evaluating the reliability of composite repaired pipelines.