Alignment Criteria for Through-Wall Flaws in Plates and Pipes

Multiple flaws in vessels and pipes are frequently assessed as a larger single flaw in accordance with the flaw alignment and combination rules. In this paper the alignment of two through-wall flaws is examined for plates in tension and pipes in bending using detailed finite element (FE) modelling. The FE model is developed using the Gurson-Tvergaard damage model and accurately describes the flaw interaction and load capacity of a random experimental sample. Results suggests that two flaws should be aligned onto the same plane for the purpose of assessment when the separation between the parallel planes containing flaws equals the flaw length for both, plates in tension and pipes in bending.