Life prediction of P91 piping accounting for creep fatigue conditions

To address the lack of available standard codes that deal with interactions between creep and fatigue, which is generally approached with a simple superposition law, the ðCtÞavg parameter associated with CFCG is introduced, under the hypothesis of partial creep strain reversal based on the creep reversal parameter CR. The TDFAD methodology used to predict initial crack growth during creep and creep-fatigue regime with P91 grade steel operating at 600°C is reviewed and integrated. This state-of-the-art crack tip parameter is introduced and accounts for small-scale creep, in the creep-fatigue crack propagation assessment.