Abstract
The number of the thermal power plants that have been operated more than 100, 000 hours is increasing and 60-70% of them have already been operated beyond the design life.
In order to operate these old plants efficiently, it is necessary to assure the reliability of its components and to repair the parts where damage is accumulated. Accordingly, the life evaluation technique will be playing a big role in performing the life assessment and extension.
One of the damages leading to failure of components is a creep damage. The creep damage does not always occur in the components of 2.25Cr-1Mo steel, because several low alloy steels are used in area to coincide with temperature. Accordingly, in order to evaluate the remaining life of each components, it is necessary to prepare the data about various materials.
This paper introduces non-destructive creep damage detecting methods and the results of investigation whether the methods can be applied to any low alloy steel or not. And also the method of improved extrapolation in the creep rapture test is described.
