Assessment of creep behaviour of a narrow gap weld

Finite element creep analyses have been performed using Norton's secondary creep law and continuum damage equations for a thick-walled narrow gap pipe weld. The creep stress and failure life were obtained using combinations o f material properties which allowed different strengths for the parent mate rial, heat-affected zone and weld metal for 1/2Cr1/2Mo1/4V:2 1/4Cr1Mo welds . The stationary-state failure prediction was performed based on a steady-s tate rupture stress. The failure times obtained from continuum damage model ling were used for assessing the results and the accuracy of the steady-sta te approach. The results show that the creep stress and failure life of the narrow gap weldments of both materials data options were similar to those of the V-shaped weldments over a range of narrow gap weld widths from 8 to 12 mm. The conservatism of the steady-state analysis method is illustrated, from the life estimates. The data also allow estimation of a possible effe ct of the presence of a weld in a plain pressurised pipe. (C) 1999 Publishe d by Elsevier Science Ltd. All rights reserved.