Steady-state creep reference rupture stresses for internally pressurised pipes for use in life prediction

Abstract

In this paper, the steady-state reference rupture stresses are presented for a wide geometry range of internally pressurised pipes, under a closed-end condition, in order to investigate the applicability of the approach in life prediction. Creep damage mechanics finite element (FE) calculations were performed to obtain accurate failure lives and to determine the skeletal point rupture stresses, using material constants for two low alloy ferritic steels. Analytical solutions were used to derive steady-state reference rupture stresses, from which the effects of pipe dimensions and the tri-axial stress state parameter can be assessed. The accuracy of the life predictions was assessed, for a number of different stress levels and the design rule based on the mean diameter hoop stress. The results confirm the validity of the steady-state reference rupture stress in life prediction for a wide range of pipe geometries and tri-axial stress state parameter.