Mechanical damage, such as gouge, is the damage to the pipe surface caused by external forces and is usually caused by third-party damage during construction and excavation. This normally results in a highly deformed, work hardened surface layer with possible metal removal. In many cases, dents are coincident with gouges. Industry standards and regulators treat this type of mechanical damage as critical and require immediate investigation. Therefore, from a pipeline operator perspective, distinguishing between plain dent and dent with gouge is a great challenge for topside dents because quite often they are caused by un-authorized third party activity and contain gouge.
In a previous study[1,2], the present authors developed an approach that combines dent strain-severity criterion with MFL signal recognition to identify dent with gouge and crack. In this paper, an extension of the previous study to topside dents is presented. The enhanced approach for distinguishing between plain dents and dent with gouge/crack for topside dents is summarized. Case studies are given to demonstrate the effectiveness of the approach for identify topside dent with gouge.