The customer avoided what could have been irreparable damage to the Turbine Rotor - A potential savings of Millions of dollars in replacement cost.
During a routine inspection of the GE Type G-3 IP (Intermediate Pressure) Turbine Rotor, the customer found a TIR of 0.013” in the center of the rotor. TIR, or Total Indicated Runout, measures the discrepancy in which the rotor was out of tolerance from straight, or how much the rotor is bowed. If the unit was to continue to operate at the standard 3600 RPM’s in this condition, it could get worse and cause a permanent bow, or perhaps even cracking.
The customer immediately contacted Reliable Turbine Services for technical support and repairs. The IP Rotor was shipped to our fully capable high rotor bay facility in Sullivan, Missouri, and RTS followed our documented procedural process to ensure the proper adjustments were made. The Rotor was then off-set by 0.025” at the Generator end utilizing a Jaw Chuck. Off-setting the rotor involves changing the centerline of the Journals to reduce the Total Indicated Run-out (TIR). The Turbine and Generator End Journals were machined to correct the excess run-out.
The Turbine Rotor was then re-set onto the newly machined journals, in Hydrostatic Steady Rests, for the final machining of the entire Turbine Rotor – such as inboard and outboard steam glands, inter-stage packing areas, and shroud cover band seal areas.
The coupling holes of the GE coupling were re-bored and the coupling face was machined to match the adjustments made to the Journals.
The final TIR results were inside of 0.001” at the turbine rotor center, well within OEM specifications. A slow-speed balance of the turbine rotor was performed, then the rotor was prepared and shipped back to the customer.
The Following Pictorial Will Demonstrate Incoming Inspection Of The GE Type G-3 IP Rotor, Found a ( TIR ) Of ( .013” ) In The Center Of The Rotor. The Rotor Was Supported On The Seal Area Adjacent To The Turbine & Generator End Journals . Rotor Was Then Off- set ( .025” ) At The Generator End, With The Aid Of A ( 4 ) Jaw Chuck. The Turbine & Generator End Journals Were Machined To Correct The Run-out. Rotor Was Then Re-set Onto The New Machined Journals In (Hydrostatic Steady Rests ), For Final Machining Of Entire Rotor i.e., Inboard & Outboard Steam Glands, Inter Stage Packing Areas & Shroud Cover Band Seal Areas. The Coupling Holes Of The GE Coupling Were Re-bored & The Coupling Face Machined. Final Run-out Results Were Within ( .001” ) At Rotor Center. Slow Speed Balancing Was Performed, Rotor Was Prepare & Shipped.
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