An evaluation of the acceptance of potential manufacturing flaws in the rotors and casings of steam turbines is of particular interest for both non-destructive testing of the new components and the evaluation of findings discovered during the state-of-the-art in-service inspection after long-term operational stresses. As a rule, the components of large modern turbines are subject to higher stresses than is the case with veteran plant due to theri greater unit size and the fact that they are operated at medium and peak loads. The situation is further complicated when the omponents have to be procured from less developed industrial countries. Inspection of components from veteran plant frequently reveals flaw constellations which reflect the state of the art 30 - 40 years ago, i.e. greater sound attenuation as well as a larger number and a greater extension of flaws. Fortunately, the inferior quality is partly compensated by lower stresses on the components due to smaller unit size.
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