R5 High Temperature Creep-Fatigue Life Assessment for Austenitic Weldments

This paper presents an overview of the R5 high temperature creep-fatigue procedure for austenitic materials. In particular revision to the weld procedures to be incorporated in the upcoming version of R5 are discussed in detail. The main feature of the new approach is that the traditional fatigue strength reduction factor (FSRF) which is applied to both creep and fatigue strain predictions is separated into a local weld strain enhancement factor (WSEF) and weld fatigue endurance reduction (WER). The new method is applied to the example of a fillet welded attachment on a boiler tube where a significant increase in predicted life is illustrated by adopting the new method new method. The principal advantage stems from a reduction in the predicted stress at the start of creep dwells and hence the level of creep damage in a cycle.