With age, steel penstocks tend to experience wall loss due to the degradation of linings or coatings and by corrosion or erosion of the steel. In some instances, severe wall loss can contribute to penstock failures. As more attention is given to the safe and reliable operation of hydroelectric facilities, operators face the task of evaluating penstocks for degradation. However, the power industry provides little guidance for such evaluations. This paper will discuss inspectin methods currently available for performing interior and exterior penstock inspections (shell plate, castings, riveted joints) in order to evaluate loss of linings and coatings, general corrosion, pitting and any crack-like indications. A recent example of the inspection methodology will be included, which presents the findings from an overall inspection program.
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