Comparison of the creep and damage failure prediction of the new, service-aged and repaired thick-walled circumferential CrMoV pipe welds using material properties at 640 degrees C

Finite element creep and damage analyses were performed for a series of new , service-aged, fully repaired and partially repaired circumferential welds in CrMoV main steam pipes, under an internal pressure and a uniform axial stress, using simplified axisymmetric models. The material properties used were those of a 1/2Crl/2Mo1/4V: 2 1/4Cr1Mo weldment at 640 degrees C. Failu re lives and failure positions were obtained using damage modelling and the se were compared with corresponding results obtained from steady-state anal yses. The effect of the weld width, in the practical range, and the effect of the axial (system) loading, on the failure life and position, of the var ious weld situations were also investigated. Comparison of the various fail ure predictions allows the effects of the differences in the relative prope rties of the constituents of the weld, the geometry and system loading, to be identified. The information is useful for assessing the performance of p ractical service-aged/repaired welds in power plants pipework. (C) 2000 Els evier Science Ltd. All rights reserved.