The viability of a simple procedure for determining the criterion for the instability of circumferential growth of a through-wall crack in a stainless steel piping system, Part 1: The applied displacements produce only bending deformation

Abstract

This paper investigates the stability of a circumferential through-wall crack in a straight segment of stainless steel pipe which is built-in at both ends. One built-in end is fixed, while the other is subject to both a rotation and a transverse displacement. In analysing this situation, it is assumed that the material is non-work-hardening, with plasticity being confined to the cracked cross-section which is fully yielded; the remainder of the pipe deforms elastically. The plasticity is in the form of a rotation about a neutral axis, but allowance is made for the axial displacement produced by this rotation, and in this respect the analysis is an improvement upon some earlier analyses. The instability criterion, obtained with the aid of the tearing modulus methodology, is shown to be independent of the details of the imposed boundary conditions, but it is different to the criterion obtained by ignoring the axial displacement. The paper discusses the implications of the results to the problem of crack instability in stainless steel nuclear reactor piping systems, particularly with regards to the viability of a simple procedure that is currently used to assess the integrity of piping systems.