An OEM of large steam turbine rotors issued a technical information letter in late 2013 to its fleet owners of 1950s-1960s vintage rotors with shrunk-on wheels. The OEM is concerned that some of the shrunk-on wheels may have poor material properties, such that the critical crack size for these wheels may be undetectable with standard ultrasonic inspection techniques.
Structural Integrity Associates suggests that many of the built-up fossil rotors with early wheel materials can still undergo continued operation with acceptably low risk of failure. Operability is determined through material assessment nondestructive inspection, and rotor/wheel analyses. Units returned to service provide the owner with time to develop alternative strategies for a planned repair or replacement, while continuing to operate the turbine. It is also possible that specific turbines may have adequate future operation capacity across all of the disks to enable ongoing operation for extended periods.
This one-hour webinar will provide an general overview of the technical information letter and provide Structural Integrity’s alternative strategy to mitigate this issue based on sound condition assessment engineering practices that have been applied successfully for a number of years to many power plant components. Our approach is risk-based and involves independent assessment of each disk. Moreover, it results in actions for cause, not comprehensive actions based purely on worst case assumptions.