HP rotor and casing cracks

HP casing crack

  • Coal-fired, 4 x 550MW power station, located in the UK


  • Routine inspection revealed external cracking, typical of thermal fatigue, at the rotor inlet and internal cracking on the 200mm thick casing


  • Thermal stress analysis and fracture mechanics assessment


  • Transient thermal stress distributions defined
  • Coincidence of defects with high-stress locations confirmed
  • Crack arrest predicted in the casing
  • Insufficient life predicted for the rotor under current operational conditions
  • A slower start-up procedure developed to reduce crack growth rates to a tolerable level

Plant Integrity