Root cause analysis of low pressure turbine blade failure
- Commonwealth Edison Co., Downers Grove, IL (United States)
Dresden Unit 3 tripped from full load due to high vibrations on the C low pressure (LP) turbine. A root cause team was assembled to identify the factors which lead to the turbine blade failure. This paper discusses the cause of the failure and the methods used to identify factors associated with the failure. The Dresden Unit 3 turbine generator was originally placed into service during the early 1970`s. In 1986, three low pressure rotors were replaced with non-OEM rotors. The replacement rotors operated without incident until a last stage blade failure occurred on May 28, 1995. There were no precursors or warnings prior to the failure. This root cause investigation revealed contributing factors that resulted in recommendations to improve maintenance inspection practices. In addition, the investigation process identified and resolved other technical issues which should enhance the long term reliability of the unit. The root cause was determined to be the non-OEM`s substitution of the blade`s erosion shield material in place of the originally used Stellite 6B. This substitution made the blade more susceptible to welding related cracking which was not identified during fabrication or subsequent inspection. One crack propagated due to fatigue until complete failure occurred.
- OSTI ID:
- 389924
- Report Number(s):
- CONF-960426--
- Country of Publication:
- United States
- Language:
- English
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