Creep damage and the need of its modelling are introduced first. Then the steel investigated and the sources of experimental data are reported. A critical review on classical and recent new methods to calculate creep damage lifetime is included in literature review. The creep cavitation-based lifetime modelling method was expanded and applied to 3 sets of T23 creep data with temperature between 773K to 923K and stress loading from 60MPa to 360MPa. In this research, a generic form of power law was proposed and used. The case studies are grouped into single temperature and multitemperature. The values of the relevant constants were determined via optimization with Microsoft Excel. Results proved that generic power law form models the single temperature case very well while potential of improvement can be sought for multi-temperature calculation. The immediate future work is to examine how its extrapolation capability if the model is calibrated without data at lowest stress.