News & View, Volume 48 | Considerations of Pin Cracking in Finger Pin Turbine Blade Attachments

News & Views, Volume 48 | Considerations of Pin Cracking in Finger Pin Turbine Blade Attachments

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By:  Cliff Lange and Matt Freeman

OEMs recommend periodic inspection of pinned finger turbine blade attachments for detection of service-induced damage as part of ongoing rotor maintenance activity. 

This article provides an example where ultrasonic inspection detected cracking in several pins of finger attachments and outlines an engineering assessment to support continued operation and identify a re-inspection interval.  This approach can be applied to other pinned finger blade attachments to determine suitability for service.

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News & View, Volume 46 | NDE Best Practices for Generator Rotors

News & Views, Volume 46 | NDE Best Practices for Generator Rotors

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By: Paul Zayicek News & View, Volume 46 | NDE Best Practices for Generator Rotors

Three factors typically drive inspection intervals of generator rotors:

  1. a timeframe recommended by the insurance carrier or OEM
  2. an engineering evaluation that supports a different inspection interval due to service operation events or existing rotor damage
  3. industry best practices

Drivers from the OEM include issues defined in service bulletins or technical information letters that pertain to the entire fleet or some subset of the population. Intervals based on engineering evaluations can be derived from an identified damage mechanism with the rotor or with a critical component. An engineering evaluation can also provide for extended inspection intervals in situations where the generator has no inherent material issues, has a clean inspection record, and sees limited operational stress such as in a base-load unit.

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