Instability of a circumferential crack in a piping system subject to bending and tensile loadings

This paper presents the results from theoretical analyses of two models that are used to investigate the stability of a circumferential through-wall crack in a stainless steel piping system containing bends, and which is subjected to fixed deformations. In each case the piping configuration is such that the cracked cross-section is subjected to both a tensile force and a bending moment, and by varying the configuration's geometrical parameters, it is possible to assess the effect of a wide range of combinations of bending and tensile loadings on the instability criterion. The results clearly show that a simple procedure, which is currently used to give the instability criterion for a crack in a piping system, is strictly accurate only if the deformation at the cracked section occurs solely by bending. (author)