Study of the influence of dent depth on the critical pressure of pipeline

The origin of more than 90% in service pipeline failures is attributed to the presence of stress concentration areas such as defects in forms of gouges, dents, or when these defects are present together. These defects are provoked by external factors interferences, for instance by excavation machines. The influence of the dent depth on the burst pressure of the pipeline was evaluated. An approach based on a simple local strain criterion has been proposed to predict the damage and the failure of evaluated dented pipe. To validate a purely empirical rule, which specifies that a critical depth dent is equal to 10% of outside diameter of the pipeline, a series of mechanical tests (denting tests and burst tests) were conducted. Finite element analysis used in order to compare the numerical and experimental results. Experimental results showed that a single dent did not affect the burst pressure of the investigated specimens; therefore the rule of a critical depth of dent equal to 10% was found very conservative.

► Burst tests were carried out on A37 steel dented pressure vessels.
► Failure occurs on other places than that of the dent.
► A single dent did not affect the burst pressure of the investigated specimens.
► The rule of a critical depth of dent equal to 10% was found very conservative.