An investigation on the failure of an L-O steam turbine blade
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This paper presents an analysis of the cause of steam turbine blade fractures. Recently, several L-0 blades 28.5 in. (725 mm) long of a steam turbine fractured 5 in. (125 mm) from the blade root platform, causing the forced outage of the turbine. A finite-element analysis (FEA) of the blade was carried out in the beginning of the last decade to calculate the natural frequencies and the vibratory stresses on the blade. A telemetry test was also conducted. The current investigation analyzed the operational data during the last two years, reviewed the results of previous studies, conducted metallurgical investigations, and identified the mechanical and metallurgical modes of the failure. The results of the investigations showed that improper welding of the stubs was the principal cause of blade fracture.
Keywordsblade stub fracture blade vibration failure analysis fatigue
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