Assessment of a gouge and dent defect in a pipeline by a combined criterion

• Experimental burst tests have been performed on vessels containing a dent + gouge defect.
• The gouge dimensions were identical for all the vessels.
• The influence of the dent depth on burst pressure was analysed.
• The most of time, failure occured on other place than that of the defect.
• A criterion based on stress triaxiality was proposed to evaluate the burst pressure and failure location.

In Europe, internal interferences or mechanical damages cause approximately the half of failures of oil and gas pipelines. The most common defects are gouges, dents and combined gouges and dents.This paper deals with A37 steel pipelines containing a gouge and dent defect. The influence of the dent depth on the burst pressure of pipelines is evaluated for a given geometry of the gouge. Experimental burst tests are performed and finite element analysis is used in order to compare the numerical and experimental results. Experimental results showed that a combined gouge and dent defect does not reduce the burst pressure of A37 steel pipelines. These results contradict established research conclusions and the bulk of the literature on the subject. A combined criterion based on volumetric method and stress triaxiality is proposed for assessment of pipelines containing a gouge and dent defect