Some key effects on the failure assessment of weld repairs in CrMoV pipelines using continuum damage modelling

Some typical results obtained from finite element (FE) creep and continuum damage mechanics analyses, for assessing weld repair performance, are presented. The work outlines some developments in failure analyses of repaired welds in pressurised, thick-walled, main steam circumferential pipe weldments made of CrMoV steels. Methods involved in determining the material properties for constitutive equations are briefly described. Results presented cover a range of analyses, taking account of the effects of repair profiles/dimensions, geometry change during creep, end (system) loading, reheating effects in the weld metal of partial repair welds and initial damage level, etc., on the failure life of the repaired welds. The potential uses and limitations of the damage analysis for weld repair performance assessment are discussed.