A user-friendly creep-fatigue damage calculation tool is developed in Visual Basic for Applications (VBA) with the familiar Microsoft Excel® user interface for power plant operators. Operational pressure and temperatures (steam and pipe exterior) are directly input and automatically converted to stress-time histories based on the summation of thermally- and mechanically-induced stresses. The stress history is automatically analysed and segregated into periods of sustained stress levels (creep range) and periods of fluctuating stress (fatigue range). Total damage is determined by summing the creep damage fraction (via Larson-Miller equation and Robinson’s rule) and fatigue damage fraction (via a rainflow cycle counting subroutine, the Smith-Watson-Topper fatigue parameter and Miner’s rule). Pre-existing damage fraction can be incorporated into the calculations. The remaining life estimates based on repetition of the load profile are outputted for the user. Finally, the estimated damage and remaining life are compared to that determined via the ASME, EN and TRD codes, where applicable.

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