Reliable Turbine Services was able to complete a quality repair in a short period of time, allowing this unit to go on-line as soon as possible and allow the company to begin turning a profit quicker.
The Sammis DeLaval Turbine Rotor Active Side Thrust Collar was Damaged Due To Rubbing, with Excessive Heat Damage Causing Over-Hardness and Stresses.
While performing a routine inspection on their Unit #7 DeLaval Steam Turbine at the Sammis Plant, First Energy found damage along the turbine rotor that would require the services of a weld repair facility. Knowing RTS has the most qualified repair technicians in the country, they knew who to call to get the job done right the first time. The First Energy Sammis Unit #7 Turbine Rotor arrived at the RTS Sullivan, Missouri facility where it received a high-level visual inspection, dust blasting, and the overall radial and axial run-outs on the rotor were retrieved and documented.
RTS personnel recorded pre-machining hardness on the active side thrust collar at approximately 550 on the Brinell scale, an industry standard unit of measure for hardness. The Inactive side of the Thrust Collar was recorded with a hardness of approximately 330 Brinell. RTS then machined the Active side Thrust Collar approximately 0.500” to achieve satisfactory hardness readings of approximately 322 Brinell. RTS completed a rotor body NDE (Non-Destructive Examination), which did not find any further damage. The Turbine Rotor was then isolated and insulated to prepare for the Thrust Collar weld repair.
RTS performed weld repairs of the Stub Shaft Coupling and Active Thrust Collar areas to correct run-out. Once the welding of the Active Thrust Collar area was completed, the rotor cool-down period began. A pre-job review was performed to determine the appropriate stress relief of the turbine rotor. RTS set- up the Generator for 3 – 60 amp stress relieving services.
Once the components had cooled, the Thrust Collar radial and axial areas, and Coupling radial areas, were rough cut to perform a preliminary NDE inspection of the components, which revealed no indications.
RTS inverted the Turbine Rotor to the vertical position to prepare for Stress Relieving Activities. The Stress Relieving Equipment, Temperature Controls and Generator were set-up and the stress relieving ramp-up process began. Once this process was complete, the stress relieving soak and ramp-down activities were performed. The Turbine Rotor was inverted back to the horizontal position where it was prepared for dust blasting.
RTS personnel completed dust blasting of the stress relief area and trial fit the Overspeed Trip Assembly. A preliminary NDE inspection was performed as satisfactory with no apparent indications. The preliminary Coupling & Thrust Collar run-outs were recorded. The Thrust Collar area radial and axial finish machining activities were performed to correct the inactive face taper.
RTS personnel continued by completing the following activities: Coupling Stub area finish machining, polishing of the Outboard Bearing Journal, Thrust Collar area radial and axial finish machining, polishing of the Coupling Stub area, machining of the inboard journal, polishing of the Thrust Bearing inboard & outboard Oil Seal Lands, final Thrust Collar and Coupling Stub NDE Inspections, manufacturing of the Turbine Rotor Drive Hub, manufacturing of the Stub Shaft Mating Coupling Key, and manufacturing of the Over-Speed Trip Spanner Wrench.
The final Coupling and Thrust Collar area run-outs were checked and confirmed as satisfactory. The Turbine Rotor Stub Shaft Coupling was installed. RTS personnel then set-up the Low Speed balance machine, and Slow Speed balanced the Turbine Rotor.
With the project completed, RTS’ logistical transportation team packaged the Stub Shaft and Turbine Rotor for outbound shipment. RTS loaded the Turbine Rotor onto the truck, and First Energy’s shipper departed, delivering the turbine components back to the First Energy Sammis Plant approximately 9 days after they were initially received.
Rotor Weld Repair : First Energy Gallery