Progressive Deformation in Piping Subjected to Internal Pressure and Cyclic Secondary Bending

Abstract

Ratcheting in nuclear class-1 piping is prevented by the rules of NB-3600. Analytical considerations of shake-down limits for piping subjected to internal pressure and cyclic secondary bending are presented and compared to the rules of NB-3600. A closed form solution for the ratcheting rate of a pressurized pipe subjected to cyclic secondary bending is derived for the case of ideal elastoplasticity. Moreover, the importance of constitutive modeling in numerical simulation of piping ratcheting is discussed. The predictions from the linear Prager, the non-linear Armstrong-Frederick and the non-linear Chaboche constitutive models are investigated in relation to published experimental tests on pipe ratcheting.