EVALUATION OF THE NOCIVITY OF DENT AND COMBINATION OF DENT AND GOUGE ON BURST PRESSURE OF STEEL PIPE

Mechanical damage is the major cause of service failures in Europe in transmission pipelines. A combination of dent and gouge is generally accepted as the most dangerous defect. The main objective of this study is to examine the influence of this kind of defect on burst pressure of A37 steel pipes. Experimental burst tests are carried out on pressure vessels. The gouge which is obtained with Electrical Discharge Machining has the same geometry for all specimens. The tests show that failure occurs on other place than that of the defect, except for the smallest dent depth. The stress distribution at the gouge tip is obtained with finite element simulation. A criterion based on stress triaxiality and effective stress is proposed in order to explain the burst test results.