Calculation procedures are often employed to determine the expanded lives of components under creep, fatigue and creep-fatigue conditions. From plant records, information about temperature and cycling history is gathered and using the standard material properties and damage rules, the fractional life expanded up to a given point in time can be estimated.

Components which operate under creep regime are generally designed on the basis of yield, tensile and fatigue strength along with a focus on suitable safety factors. Under normal conditions, deformation and fracture are not time dependent. As long as the applied stresses do not exceed the design stresses, these components should last indefinitely; but in practice, various factors cause the reduction in life.