The residual life obtained by extrapolating experimental isostress line at service temperature of different zones of the tube was analysed and various hypotheses suggested, taking into account the different initial metallurgical condition of the steel and the local stress and temperature interaction during operation. It was concluded that the test methodology, applied to SH and RH tubes, appears to be sensitive enough to discriminate between only very different creep damage levels. Determination of consumption of the service life of the steam line pipe in conditions of creep [2] was considered taking into account not only the total time of equipment operation but also actual operational parameters (temperature, pressure, start up and shut down). The method consisted of various stages, namely: production of data base, total history of the steam line pipe operation, determination of the strength characteristics of a steam line material and determination of real consumption of service life. The latest studies on the design methodology and life estimation for major components for steam turbines were reviewed in [3]. Relationships which enable the calculation of actual creep damage were clarified by many studies. Several new devices were introduced, which enable the detection of local creep and fatigue damage. Studies of life estimation of welded joints in the design stages were discussed. It was shown that the remaining life of such components can be analysed from creep and stress rupture properties by defining a reference stress such that the component life equals the life of a simple specimen tested at the reference stress. Keeping this in view, over the years attempts have been made to generate such data on similar components