Weld strength mismatch is a key factor with respect to the assessment of a flawed girth weld. However, it is challenging to assign a single strength mismatch value to girth welds, which are generally heterogeneous in terms of constitutive behavior. The authors have recently developed a method (‘homogenization’) to account for weld strength property variations in the estimation of crack driving force response and the corresponding tensile limit state. This paper separately validates the approach for stress based and strain based assessments. Whereas homogenization is reliably applicable for stress based assessments, the strain based crack driving force response is highly sensitive to effects of actual heterogeneous weld properties. The sensitivity increases with increased weld width and decreased strain hardening behavior. For strain based design, a more accurate methodology is desirable, and large scale testing and/or advanced numerical modeling remain essential.

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