From our years of service shop and engineering experience, we’ve developed a thorough set of procedures for overhauling a used F rotor. Our processes are safety-critical and must be completed in a certified shop to avoid damage to plant and personnel if there is an issue with the rotor. Since 1990, there have been over 30 turbine rotor, 10 compressor rotor and 100 blade design modifications made with learnings from the fleet and engineering analytics, so it’s critical to understand the configuration and design of each asset to apply the correct rotor and achieve the highest overall reliability of the rotor after the life extension or swap is performed.
To do a full 7FA rotor life extension, typically it takes 12 weeks of time once the rotor arrives at our service shop assuming there was proper planning. The planning is critical to ensure all the parts and inspection equipment are at the service shop and ready to be used. Over the years this turn-around time has significantly improved.
When the rotor arrives at the certified service shop it undergoes a complete tear-down, is cleaned and inspected. A tear-down is required to ensure that all safety critical areas are inspected properly. Some of the inspections include eddy current testing, ultra-sonic testing and magnetic particle/fluorescent penetrant inspection of various areas of the rotor wheels and shafts. Some places undergo skilled repairs which must be performed with care. Additionally, some components cannot be re-used such as the stage 1 turbine wheel and bolting, among others. All parts and inspections used must be performed by a certified shop to ensure safe operation of the machine.
Once the rotor has been through the GE rotor life extension process, the rotor incorporates the latest latest technology improvements available for those components and is certified for safe operation.
We’ve overhauled over 325 units in the F-class fleet. As these rotors come through the service shops, we’ve observed findings, perform root cause investigations, and incorporated these lessons into our procedures to improve the rotor itself or our processes.
