The Turbine end shaft end was bent and found to have a 0.007” total indicator runout (TIR) at the coupling outer diameter. The generator end shaft end was bent and found to have a 0.053” TIR at the coupling outer diameter. MD&A was able to straighten both shaft ends to within 0.0015” TIR using a combination of thermal and machining straightening processes. Then, MD&A completed the final high-speed balance and final machining of the shroud covers.

Shaft End Thermal Straightening
The rotor thermal straightening process included an initial rotor stress relief and multiple thermal straightening iterations. MD&A expert technicians performed detailed visual, dimensional, and non-destructive examination (NDE) of the rotor forging before and after each thermal process to confirm that no issues were present. Rotor NDE inspections consisted of both hardness testing and wet fluorescent magnetic particle testing.

Based on the amount of shaft end distortion and the experience and expertise of MD&A technicians, it was recommended carrying out an initial stress relief of the rotor and additional thermal straightening iterations of the shaft ends to further reduce the shaft end runouts.

The initial stress relief of the rotor forging was performed on both shaft ends to relieve any internal stresses and determine the final relieved state of the shaft end runouts. This involved removing all installed blades and seal strips, stress relieving the rotor, blast cleaning, NDE, hardness checks, and runout checks along the length of the rotor.

Additional thermal straightening iterations were also performed on the generator end of the shaft to further reduce the amount of runout. This involved thermally moving the shaft end, stress relieving the rotor, blast cleaning, NDE, hardness checks, and runout checks along the length of the rotor.

Due to the high temperatures of both couplings during the stress relief processes, a vertical stress relief was not possible. As a result, the stress reliefs were performed in the horizontal orientation while rotating the rotor periodically 180° during the heating process so as not to set a thermal bow into the rotor.

DFLP Rotor Machining
Based on results of the thermal straightening iterations, machining straightening of both shafts was performed. The work involved final straightening machining of both shaft ends and final dimensional, NDE, and runout checks along the length of the rotor.

The thermal straightening operations reduced the Turb End shaft end TIR from 0.007” at incoming to 0.003” after completion. The Turb End shaft end straightening machining included final machining of the steam gland diameter, all steam gland seal grooves, all transition radii, and the coupling to remove any remaining runout.

The thermal straightening operations reduced the Gen End shaft end TIR from 0.053” at incoming to 0.015” after completion. The Gen End shaft end straightening machining included final machining of the journal, oil deflector, steam gland diameter, all steam gland seal grooves, all transition radii, and the coupling to remove any remaining runout. Also, the coupling holes were line bored to set the bolt circle pattern back on center.

High-Speed Balance
In parallel to the blading and seal strip installation, MD&A produced a new stub shaft in support of performing the high-speed balance.

The balance work involved the installation and aligning of the new stub shaft, installation of the rotor in the high-speed balance facility, balancing the rotor at operating speed, and performing an overspeed test of the rotor.

The rotor work was completed on schedule and returned to the owner.

For every repair job, large or small, the speed and effectiveness of our response team is matched only by the depth and breadth of our engineering expertise.

Have us look at your bowed rotor today. Call our Turbine-Generator Repair Facility at (314) 880-3000 or use our Contact form.

The post DFLP Rotor Straightening and Machining appeared first on MDA Turbines.

Because the nature of the forced outage was not fully known when the job was awarded, the scope of work initially was incomplete. Despite the uncertainties, MD&A’s experienced technical team quickly evaluated the damage and designed a comprehensive scope of work.

As part of its work, MD&A’s gas turbine maintenance team both opened and closed the gas turbine. In addition, the team removed the original rotor and shipped it off-site for refurbishment and high-speed balance.

As well, MD&A removed the generator field and sent it to our St. Louis facility for a complete test and inspection, and high-speed balance before being returned to site.

The scope of work included:

Site Work Services

• GT Major Inspection & Rotor Removal
• Generator Major Inspection and test & inspection – the insulation was repaired, flux probes installed and completely re-painted inside
• Stage 9 Stator Hook Fit Mod- removal of Upper & Lower Compressor Casings
• Installed New Electronic Gas Valves – removal of old Hydraulic Gas Valves
• Remove Existing Liquid Fuel System, and associated support systems, such as Atomizing Air and Water Injection – A Controls Software Upgrade to eliminate these control sections
• Accessory and Load Gear Refurbishments
• Exhaust Frame Repairs

Shop Work Repairs

• Gas Turbine Rotor Inspection
• Remove and Inspect 1st stage buckets – Apply coating for excessive rock and repair Aft Angel Wings
• Replace out 2nd stage buckets
• Compressor Blending
• Refurbish HGP Components, Combustion Hardware
• Generator Field Rings Off Inspection, test & inspect, and high-speed balance
• Gas Turbine rotor high-speed balance

New Parts

• 2nd Stage Buckets
• 2nd Stage Shroud Blocks
• Consumables & Hardware
• Auxiliaries
• Exhaust Plenum

MD&A also performed major repairs on the turbines accessory system, such as refurbishment of Accessory & Load Gears, replacement of turbine compartment vent fans, rebuilding of Exhaust Ducting, replacement of Exhaust Expansion Joints, as well as removal of hydraulic overspeed bolt and replacement with redundant electronic overspeed protection.

MD&A’s specialized services range from Combustion, Hot Gas Path and Major Inspections, as well as, Compressor & Turbine Rotor Repairs to Plant Performance Testing and Analysis. We also provide turbine internal alignment to your gas turbine, along with vibration analysis and balance (low-speed & high-speed.)

Call our Gas Turbine Services at (518) 399-3616 or use our Contact form.

Read the Combined Cycle Journal (CCJ) article.

The post Gas Turbine Major and Generator Test & Balance appeared first on MDA Turbines.

High-speed turbine rotor balancing was once rare because of the costs and logistical challenges involved in doing it during an outage. That’s begun to change as economic options emerge, and experience is showing that high-speed balancing can pay big dividends in reliability and maintenance costs.

Read Power magazine’s article online here.

See the October Power Magazine Print Article here.

Have MD&A high-speed balance your rotor today, call Keith Collins at our Turbine-Generator Repair Facility at (314) 880-3000.

Find out more about our High-Speed Balance Facility.

Or Take a Tour of our new High Speed Balance facility!

The post High Speed Balance Article appeared first on MDA Turbines.

Our High-Speed Balance Facility became operational in 2013 and is one of the most modern balance facilities for power turbines in the world. MD&A’s facility was designed with both vacuum capability and the ability to excite generator rotors at high-speed.

MD&A services rotors for generators, steam turbines, gas turbines, large motors, and boiler feed pump turbines.

At the heart of the High-Speed Balance facility is the control room, with modern capabilities that allows the ability to control almost any system remotely. With four High Definition cameras mounted in the balance facility, customers can view their rotating equipment while MD&A’s balance engineers receive measurements digitally.

> See our Tour video here.

Have MD&A high-speed balance your rotor today, call our Turbine-Generator Repair Facility at (314) 880-3000 or use our Contact form.

The post 100th High-Speed Balance appeared first on MDA Turbines.

Incoming inspections and evaluations consisted of blast cleaning, NDE, visual inspections, material verification, as well as a detailed runout check of the rotor.

The rotor straightening involved an initial stress relief operation, as well as multiple iterations of thermal straightening, to correct the incoming rotor runout condition.

In support of the rotor straightening, machining modifications were made to the shaft N-3 packing gland area as well as the inboard thrust collar.  The N-3 packing gland area on the rotor was machined to a smaller diameter and new packing rings were supplied and installed.  The backside of the inboard thrust collar was modified to add a much-needed balance weight plane on the turbine end of the rotor.  The thermal straightening process did not require machining of the rotor journals, re-sizing of the journal bearings, machining of the couplings, or line boring of the coupling holes on-site during reinstallation.  After completion of all repairs, the High-Pressure rotor was balanced at operating speed and overspeed tested at 110%.

SUMMARY

The High-Pressure rotor was received with a bow of 0.040” TIR (total indicator reading) in the N-3 packing area of the rotor.  This amount of runout would not allow the rotor to spin up through critical speeds, let alone get to rated speed without severe vibration. MD&A successfully straightened the HP rotor to 0.003” TIR using a thermal straightening process.  The HP rotor was balanced and overspeed tested without incident and returned to the site for reinstallation and startup.

Have us look at your bowed rotor today. Call our Turbine-Generator Repair Facility at (314) 880-3000 or use our Contact form.

The post A-10 Rotor Straightening & High Speed Balance appeared first on MDA Turbines.

Mechanical Dynamics & Analysis (MD&A) High Speed Balance Facility is one of the most modern balance facilities for power turbines in the world.  It services rotors for generators, steam turbines, gas turbines, large motors, and boiler feed pump turbines.

Read our High Speed Balance article in Power Magazine.

The post Tour of our new High Speed Balance facility! appeared first on MDA Turbines.