Some issues in life assessment of longitudinal seam welds based on creep tests with cross-weld specimens

In order to reduce production costs, it is of great interest to use longitudinal seam welds when manufacturing large diameter pipes. The cost reduction can be as high as 30 percent. However, severe in-service accidents, for this type of pipes working in the creep regime, have occurred mainly due to mismatch in weldment creep properties. In the present paper, both full scale seam welded pipes and cross-weld specimens are studied with the damage mechanics concept using finite element technique. The same mechanical model of multiple material zones is used for the two components. Both the influence of differences in creep properties between the weldment constituents and the size effect of the cross-weld specimen, are studied.