ASME Gas Turbine Technical Chapter Gas Turbine Rotor Inspection/Overhaul and Repair EthosEnergy TurboCare Facility, November 2014
Safety afety Moment om ent
Can you spot the safety violation?
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‘What’ is EthosEnergy ? Wood Group
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Gas Turbine Services Heavy Industrial, Light, Aero
Siemens
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Gas Turbine OEM (Fiat / Westinghouse)
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Gas Turbine Turbine Services Services – Heavy Industria Industriall
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Steam Turbine Services
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Steam Turbine Services
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EPC and Fast Track Projects
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Generator Services
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Construction Site Services
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Compressor Services
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Facility O&M
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Transformer Services
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Auxiliary and Pump Overhaul
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Wood Group P&W JV
+ OEM Intellectual Property Support
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‘Where’ is EthosEnergy ?
+ + + +
> $1B in revenues Over 5,000 Customers 4,500 employees in 100+ countries ISO-9001, 14001, 18000
“As the leading independent service provider Our depth and multi-OEM experience provide added insights and customized customized solutions solutions - on a global global scale.”
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Engineered to Deliver Value Customer Goals Across Asset Life Cycle
Project, Commercial & Technical Management Alignment of of Needs, Needs, Capabilities, and Solutions (>100 Project Mgrs Globally) Core Capability
Core Functional Strengths
(Internal and External)
Inventory & Inventory Management +$150 Million
• • • •
Engineering +200
Multiple OEM Experience Direct Customer Access 7x24 M&D Centers Full Asset Life Cycle View
Supply Chain >100 Qualified Vendors
• • •
Component Repair
Ethos Adv Repair Facilities Alliance Partners Short Cycle Solutions
Field Services +2.0M Man Hours/Year
• • •
Upgrades & Life Extensions
Parts
Ethos Designed Parts Alliance Partners Used Serviceable Parts
• • •
Gas Turbines HIT/LIT/Aero Steam Turbines Generators Compressors
Ethos Overhaul Facilities Multi‐OEM Upgrades Alliance Partners
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Full Maintenance Capability Gas, Steam, Generator, Compressor
+ One-Stop Shop – Single Point Accountability + Proven Parts, Field Services, Shop Overhaul Track Record + OEM Design, Quality, Project Mgt, Supply Chain Mgt + Flexible Commercial Structures Gas Turbines + + + + + + + + +
Shop repair & overhaul Parts / components Component repair Rotor repair / overhaul Field services Reverse engineering Exchange programs Refurbished equipment Op Speed balancing
Generators + + + + + + +
Rotor winding Stator coils manufacturing Modernization / re-design Refurbishment / replacement Repairs Op Speed balancing Testing / inspection
Steam & Compressors + + + + + + +
Unit assessment & rerates Rapid reverse engineering Replacement parts SMART™ seals Geothermal Rotor welding Op Speed balancing 5
Gas Turbine: Multiple Platform
EthosEnergy is the ‘OEM’ GE
FIAT + TG7 + TG16 + TG20
+ TG50 + TG 701
WESTINGHOUSE + + + + + + +
W 72 W 81 W 82 W 101 W 111 W 121 W 151
OEM Equivalency
+ + + + + + +
W 171 W 191 W 191G/M W 251A,AA W 251B, B18 W 251B27 W 301
PRATT & WHITNEY + GG4 / FT4 ** ** - WGPW Joint Venture
+ + + + + + +
W 501 AA W 501 B2-5A W 501B6 W 501C W 501D1 W 501D24 W 501D4
+ + + + + + +
SIEMENS Frame 3 / 5 Frame 6B Frame 7B-EA Frame 7FA Frame 9E Frame 9FA LM Series *
MHI + + + + + +
MW101 MW171 MW191 MW251 MW701 M701F
RR + +
RB211 ** AVON **
+ + + + +
TA 1750 TB 5000 SGT-200 (Tornado) SGT-100 (Typhoon) SGT 600 (GT 10B)
SOLAR + + + + +
Saturn® 10 Centaur® 40 / 50 Taurus® 60 Mars® 90 / 100 SoLoNox®
ABB / ALSTOM + +
GT11D5 GT13E2
* - Overhauls Through WG TCT JV 6 ** - Overhauls Through RWG JV
Gas Turbine Parts
EthosEnergy combines an OEM level design team, state of the art materials and design modeling tools, and supply chain process oversight – to deliver the highest value, lowest risk aftermarket parts in the industry.
+ OEM provider for Westinghouse and Fiat gas turbines + Over 25 Years of Gas Turbine Component Design + Capabilities on GE, Siemens, MHI, ABB, Solar Turbines. + Over 1,000 Sets of B/E HGP Parts + Over 37M Operating Hours on installed parts + OEM Level Processes / ISO Qualified + Re-Engineered vs ‘Reverse Engineered’ designs 7
Gas Turbine – Component Repair
+ Over 5,000 Sets of Repaired HGP Components in Operation + Over 64M Operating Hours on Repaired Components + Over 4,000 Fuel Nozzles Repaired
+ To restore your critical turbine components, we offer a broad portfolio of cost effective component repair services that extend component life. + Our customers benefit from leveraging technical expertise, a robust quality program & our overall Service Excellence philosophy. + We mitigate operational risks with a dedicated Project Manager, offer extended warranties & drive down your cost of ownership with the objective of improving life cycle value. 8
Gas Turbine Rotors
+ Gas Turbine Rotor Overhauls, Life Evaluation & Extension + Compressor & Turbine Disc Manufacturing Capability + Rotor & Disc Balancing Capabilities
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Complete capability (thru F Class)
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Rotor modernizations & upgrades
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Rotor mechanical & NDT inspection
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Compressor blade & wheel coatings
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Advanced balancing capability
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Quality programs - ISO-9001, 14001, 18001 certified
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OEM level process controls
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Full rotor capability in Houston, Texas & Turin, Italy
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Rotor storage & environmentally controlled containers
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icon™ Control System Upgrades
“Icon control system upgrades provide a low-risk, long-term open-architecture solution that eliminates restrictive operational/support barriers of OEM purpose built systems” +
OEM turbine controls replacement for GE, Siemens, Solar, Alstom, Rolls Royce, ABB with expansion capability into BOP level control solutions
+
Our experienced icon control upgrade solutions provide increased flexibility, availability, & risk reduction to owners & operators of gas and steam turbines
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We maximize our customers’ success by providing a customized solution based upon our standard design, using non-proprietary & proven open-architecture solution that allows for the ability to be self-sufficient.
+
Longer useful life due to larger, multi-industry installed base of standard technology – versus limited OEM base. applications
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ECOMAX® - Combustion Tuner
+ ~1.5 – 2.0% Increase in Combined Cycle Power Block + Maintains Firing Temperatures within OEM Limits + Up to 0.25% Decrease in Gas Turbine Heat Rate
+ Combustion optimization solutions are advantageous to actively manage the complex dynamics of thermal performance, emissions, & fuel efficiency. + Our cost-effective automated tuning technology optimizes performance, maintains emissions compliance, & minimizes potential parts damage. + This improved management of your gas turbine operation can add significant value aligned to customerspecific operations strategies. 11
Field Services
+ Over 5,000 Outages Performed in Last 5 Years + Over 3,000 GE ‘Frame’ Outages + Over 250 GE ‘F-Class’ Outages + Over 700 Steam Turbine Outages
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With a focus on the overall outage schedule, performance & cost management to complete a maintenance event, we apply a core value of safety, our extensive years of experience & a full tooling & equipment package
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A proven team is led by a dedicated project manager who operates as a single point of contact between the maintenance crew & plant personnel
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Solutions tailored to meet local/regional requirements. 12
Houston Operations Description: +
140,000 Sq. Ft Facility
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Production area consists of six (6) bays.
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One (1) 60 ft. high bay, has a 100 Ton bridge crane.
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Truck thruway for easy loading and offloading inside the high bay.
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The remaining bays each have bridge cranes ranging from 10 to 50 Ton.
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Vertical hanging or horizontal storage.
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Operation Speed Bunker
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Blast Booth.
Product Lines: +
Steam Turbines (Units and Internal Components).
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Steam Turbine Rotor manufacturing.
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Compressors (Units and Internals Components)
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Gas Turbine Rotors (OOEM and OEM)
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Gas Turbine Compressor Diaphragms (W101, W191, W251, W501F)
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Balance Machines Operating Speed Balance (OSB) facility capable of high speed balancing and overspeed testing of rotors in a vacuum. +
Maximum rotor weight: 50,000 lbs.
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Maximum rotor swing diameter: 99 in.
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Maximum rotor overall length: 316 in.
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Maximum rotor journal diameter: 17 in.
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Maximum rotor balancing/overspeed: 34,000 rpm
Horizontal Balance Machines: +
Maximum rotor weight: 100,000 lbs.
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Maximum rotor swing diameter: 125 in.
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Maximum rotor length: 310 in.
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Maximum rotor journal diameter: 22 in.
Vertical Balance Machines: +
Maximum component weight: 6500 lbs.
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Maximum component swing diameter: 81 in.
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Impeller Overspeed Test Machine:
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Maximum component weight: 500 lbs.
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Maximum component swing diameter: 36 in.
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Maximum component height: 24 in.
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Maximum component overspeed: 30,000 rpm
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GT Units Assembly & Disassembly
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Gas Turbines Rotors Overhauls
FR5
FR6 FR7E
W101
W191
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W251
W501D5A
W501F
Compressor Rotor Repair RECEIVING ROTOR +
Standard rigging practices should be followed. Confirmation of load ratings and safety inspections should be performed prior to any lifts being performed.
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Use of a spreader beam is highly recommended.
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The lift points should be the seal areas of the stub shafts unless lifting plates attached to the couplings are available
INCOMING INSPECTIONS +
Placing the rotor in the lathe for rotating facilitates the inspection process.
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The general condition of the rotor is photo documented including all serial numbers, part numbers, blade damage, balance weight locations etc.
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Rotor run out data is collected including three(3) body run outs to determine journal /body/journal centerline axis relationship. (rotor bow) 17
Compressor Rotor Repair INCOMING BALANCE +
The rotor is placed in the balance machine to determine the incoming balance condition. The previous overhaul balance weight corrections are removed during this process.
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This information should align with the previously recorded run out condition.
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The incoming inspections are evaluated to determine the need to dis-assemble the unit for repairs.
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Compressor Rotor Repair BLADE WEDGE MIGRATION +
Blade wedge migration is a common issue encountered. The wedge used to hold the compressor blade in its axial position overcomes the staking during start up and shut down, abnormal operating events inducing vibration, and events causing blade tip contact.
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A wedge migration map is completed during this process. This map is generally evaluated in two ways, total rotor and rotor quadrants.
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As a guideline, if more than 50% of the wedges of the total rotor are migrated, dis-assembly is required
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As a guideline, if more than 40% of the wedges in any quadrant are migrated, dis-assembly is required.
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Compressor Rotor Repair
Major Compressor FOD
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Compressor Rotor Repair
STUB SHAFT DIMENSIONAL +
The forward stub shaft dimensional information and general condition is documented carefully. This information is compared to the field dimensions of the bearing and seal clearances.
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Any deviations from standard should be determined in the beginning of the repair process to ensure time to correct the seals or bearings as required
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Compressor Rotor Repair THROUGH BOLT POSITION +
This finding reflects a lack of quality inspection during the last assembly of the unit.
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There is a strict tolerance for the end of this bolt to be fully engaged into the pie nut as this is the anchor position for the bolt tensioning.
BALANCE WEIGHT LOCATION +
All of the balance weights are mapped for location and type. The stamp designations on the weights describe the step of the balance process when the weight was installed. Example: T = Turbine C = Compressor P = Piece
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Compressor Rotor Repair Work Scope Creation +
Based upon the findings of the inspections, a work scope document is created. This scope will include the standard instruction for dis-assembly, repair and reassembly and also contain any special instructions to address any of the items special to this unit. Example: Perform TIL-1342 Row 17 compressor blade change
1.
FRAME 7 ROTOR COMPRESSOR ROTOR UNSTACK AND REASSEMBLE
2.
RECEIVE AND INSPECT FOR ANY SHIPPING DAMAGE. TAKE PHOTO OF SHIPPING CONTAINER AND STORE
3.
CONTAINER FOR RETURNING THE ROTOR TO THE CUSTOMER.
4.
PERFORM AN AS RECEIVED INSPECTION. USE METHOD #2004.
5.
UT THE BOLTS FROM THE AFT END AND REPORT. ISSUE A REPORT ON WGPM‐0007
6.
SET UP THE ROTOR IN THE BALANCE MACHINE AND PERFORM AN INCOMING BALANCE CHECK/RUNOUTS.
7.
(NO PEENING REQUIRED). USE METHOD #2005.
8.
REMOVE THE INDUCTOR ALTERNATOR SHAFT FROM THE COMPRESSOR ROTOR. VISUALLY INSPECT THE
9.
HELICOILS AND REPORT ANY DAMAGE TO ENGR.
10. REMOVE FROM THE BALANCE MACHINE. 11. STAND UP THE ROTOR IN THE STACKING PIT (AFT END UP)
AND IDENTIFY EACH WHEEL IN RELATION TO THE 12. # 1 BOLT HOLE. STAMP THE STAGE NUMBER ON THE
RESPECTIVE STAGE.
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Compressor Rotor Repair STAND ROTOR VERTICAL +
The process of taking the rotor from horizontal to vertical for destack requires the use of specialized, purpose built tooling and fixtures.
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These fixtures require periodic inspections to ensure mechanical integrity.
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Highly skilled and experienced crane operator is a necessity.
HYDRAULIC BOLT DE-STRETCH +
Hydraulic tensioning devices are used for the manipulation of the compressor through bolts.
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It is critical to physically monitor the amount of tension or “stretch” applied to the bolt.
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During disassembly of the unit, measurement of the amount of stretch on the bolts is critical information to determine if the unit has been “biased stretched”. 24
Compressor Rotor Repair THRU BOLT NUT REMOVAL +
It is not uncommon to have the threads on the bolts or nut seize during the de-tensioning process.
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There are many reasons this occurs including damaged threads above the nut, dirt and grit in the threads, threads pulling because of overstretch or improper installation of the tensioning equipment
NUT REMOVAL +
The process for nut removal after seizing is to split the nut in half. This is accomplished by using and end mill and plunging down each side of the nut, 180 degrees apart.
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The nuts are removed from the countersunk hole and the OD of the bolt is ground smooth to allow for the passing of the individual wheels
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Compressor Rotor Repair ROTOR DE-STACK +
Once the nuts have been removed, dry ice is applied to the aft stub. This freezing allows for shrinkage of the male rabbet fit allowing it to release form the 16th stage female rabbet fit.
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Care should be taken to not damage the threads on the bolts during the removal process.
BOLT WHEEL CORROSION +
Many units operate in less than ideal conditions. Environmental factors coupled with operating characteristics often creates erosion and corrosion issues on these parts.
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The design clearances are often small and can become contaminated causing extreme difficulty during the disassembly process.
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Compressor Rotor Repair SEIZED THROUGH BOLTS +
It is not uncommon to encounter through bolts that are seized to the bolt holes of the compressor wheels.
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Whenever possible the bolts are cut and set aside while remaining locked in the wheel.
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This expedites the de-stack and allows for the wheel to be set up properly in a drill press for accurate drilling of the bolt material
THROUGH BOLT DRILLING +
The process of bolt drilling can be accomplished using magnetic base drills while in the de-stack process.
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Care must be taken to step up the drill diameter gradually to ensure there is no contact with the wheel.
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It is often necessary to drill enough to leave a thin wall of material and then use a burring tool to grind away that wall 27
Compressor Rotor Repair BOLT HOLE SLEEVES +
The wheel through bolt holes are sometimes sleeved due to incorrect location from the factory or severe galling during the removal process.
RABBET FIT GALLING +
This galling of fits must be repaired to perform the critical run out data.
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Typically fits that have more than 50% of the surface area affected will receive a patch ring.
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Compressor Rotor Repair WHEEL RUN OUT TABLE +
All compressor wheels are placed on this table and run out data is gathered.
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The rabbet fits are measured for concentricity and the relationship to the OD of the wheel.
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The bolt circle faces are measured for flatness and parallelism
WHEEL RUN OUT DATA +
The face, bore and OD of the wheel are measured to establish BH 1 and all data is referenced to that location.
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This provides the data required to determine the orientation of the wheels during the restack process
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Compressor Rotor Repair DEFLECTOR CONE +
The fit area of this cone and retaining plate can see extreme wear. If this becomes loose during operation, severe imbalance forces can be imparted into the unit.
THROUGH BOLT INSPECTIONS +
All bolts are measured for straightness.
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NDT is performed including MPI and Ultrasonic.
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The threads should be carefully inspected especially on the aft end of the bolts where the stretching devices are attached. 30
Compressor Rotor Repair COUPLING HELICOILS +
These helicoils should be replaced during every major rebuild of the rotor.
BLADE F.O.D. / D.O.D. +
Impact damage below the pitch line of the blade should not be repaired.
+
Dents and dings should be left alone while any damage that includes tears or cuts into the material should prompt blade replacement
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Compressor Rotor Repair BLADE BLENDING +
Examples of compressor blade tip blending
FWD AND AFT STUB BALANCE +
When these pieces are balance individually, the weights placed into the grooves are labeled and stamped ‘P’ for part or piece weight.
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The weights cannot be staked until the assembled rotor is balanced as these weights may need weights to slide past their location
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Compressor Rotor Repair COMPRESSOR RESTACK +
Each compressor wheel is individually protected during the stacking process. The number 1
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bolt hole location is clearly identified to ensure correct orientation.
AFT STUB ASSEMBLY +
The aft stub shaft must be frozen using dry ice to facilitate reassembly to the stage 16 wheel
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Once the wheel fits are engaged, four bolts are snug tightened by hand until all temperatures normalize
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The stack orientation is verified and wheel rim gaps are measured and approved prior to bolt stretch
33
Compressor Rotor Repair BOLT STRETCH +
The bolts are positioned to be flush in the pie nut. A “at rest” drop is measured from bolt end to the face of the stub.
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The bolt stretch procedure is implemented and following a three step process, an overstretch is performed.
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The final bolt stretch is established and verified with a “tensioned” drop measurement taken at the same location as the original “at rest”
BALANCE VERIFICATION +
The rotor is placed into the balance machine and the total vectored correction is determined. The maximum allowable is 9500 inch grams total or 4750 inch gram per plane.
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Three rotor body run out measurements are taken and compared to the balance weight
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requirements.
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If acceptable, final balance is performed and the rotor is ready for machining 34
Compressor Rotor Repair FINAL MACHINE PROCESSES +
A complete set of rotor run out data is gathered. Any probe area machining is accomplished. Thrust collar polishing is performed.
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The coupling rabbet fit and face is measured and machined if necessary.
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The rotor is turned end for end in the lathe and the same processes are performed on the opposite end
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The set up process for the rotor requires pins in the coupling chuck to allow the rotor to pivot when the steady rest is positioned.
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This is a “loose grip” set up and requires a safety stop to be in place to prevent the rotor from walking out of the chuck when rotated.
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This is the pipe and ball seen on the right side of the picture.
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Note the probe area is clearly marked and protected
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Compressor Rotor Repair FINAL PACKING +
Uncoated rotors are completely coated with preservative. A light oil such as WD-40 is used for short term and a more viscous product such as LPS-3 is used for intermediate (less than 1 year). Long term storage should be performed using controlled atmosphere. The rotor is completely wrapped in heavy corrugated cardboard and wrapped in plastic stretch wrap. The journal is wrapped separately.
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Turbine Rotor Repair RECEIVING THE ROTOR +
Standard rigging practices should be followed. Confirmation of load ratings and safety inspections should be performed prior to any lifts being performed.
+
Use of a spreader beam is highly recommended.
+
The lift points should be the seal areas of the stub shafts unless lifting plates attached to the couplings are available
INCOMING INSPECTION +
The rotor is set up in a lathe or precision roller stand to measure and record the run out.
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The buckets are measured and visually inspected.
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The coupling rabbet fits are measured and recorded
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Turbine Rotor Repair JOURNAL INSPECTION +
The journals and seal areas are inspected for size and roundness
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The probe areas are located and protected.
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The coupling bolt holes are inspected.
COUPLING BOLT HOLE FACE +
This face will require machining to prevent additional damage during the bolt stretch process.
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Another common repair is damage to the actual bolt hole.
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Turbine Rotor Repair INCOMING BALANCE +
The incoming balance is measured and recorded
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The buckets can be intermittently removed and measured if desired.
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The buckets can also be removed all rows and weights to determine the bare rotor condition.
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The bare rotor balance condition along with the run out data are key to determining the need to de-stack the rotor.
BALANCE WEIGHTS +
The staking and securing of the turbine balance weights is complicated by the interrupted weight groove
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The weight locations are recorded and used to evaluate incoming balance condition
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Turbine Rotor Repair BUCKET LOCKING PIN +
The first stage buckets are secured with D-keys and a radial and axial locking pin
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Over time the area around the pin becomes damaged by the staking process. This requires the turbine wheel be modified to install the pins 180 degrees from the original position
SEAL COATING +
The stage one and stage two buckets receive coating on the fir tree areas to provide a seal boundary for the cooling air.
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This boundary forces the cooling air up through the airfoil cooling holes preventing damage to the buckets from excessive heat.
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Turbine Rotor Repair FIR TREE COATING +
The buckets can also be applied with coating to replace the eroded parts of the wheel and/or bucket.
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This is one of the earliest recommendations to resolve excessive bucket rock more commonly found in peaking service units.
DISCOURAGER SEAL +
The Model EA units are equipped with an axially inserted discourager seal. This seal is located on the aft face of the 1-2 spacer.
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This works along with the fir tree coating to provide a sealing boundary for the bucket cooling air.
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Clearance/ Crush checks must be performed on this seal with each bucket change
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Turbine Rotor Repair TURBINE DE-STACK +
The turbine rotor is turned vertically and placed into a stack pit or mounted to an dis-assembly plate.
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Heat is used on the nuts and all are removed mechanically, (no bolt stretch)
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Dry ice is used to freeze the stub shaft allowing separation from the turbine wheel.
FWD. STUB REMOVAL +
Care must be taken to not damage the sealing air bore tube.
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The tube must be removed and independently inspected. Erosion of the inner wall is a common problem.
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Turbine Rotor Repair DE-STACK PROCESS +
The turbine wheels have female rabbets on both sides. Heating up to 350 degrees F is permitted for removal and installation
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The wheel spacers and stub shafts have male rabbets and require dry ice for removal and installation.
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Stack temperature normalization is required before proceeding to the next piece in the process.
COMPONENT INSPECTIONS +
All of the individual rotor components are blast cleaned using 220 grit AlOx. Extreme care must be taken to not dwell on the fir tree areas.
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All components are then MPI inspected. Areas of concern are the fir trees and the turbine wheel rabbet fit areas.
43
Turbine Rotor Repair COMPONENT RUN OUT +
All wheels and spacers are set up individually and the run outs are collected.
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Once the true centerline is established, a witness skim cut is made to be used after assembly
COMPONENT FIT REPAIR +
Skim cutting of the female radius is often required due to small stress cracks.
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HVOF coating application is required to repair the female fit diameters
44
Turbine Rotor Repair WHEEL GEOMETRY RESTORATION +
The geometry of the fir trees is measured and recorded. This is done first with a simple shank gap check using replacement buckets
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If not acceptable, additional data is taken using the pin checks described in TIL – 1049.
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Fir tree restoration is accomplished using Nickel based coating. This is often top coated with an anticorrosion coating such as 2-F1
STUB SHAFTS +
Both turbine rotor stub shafts are set up and checked for concentricity.
45
Turbine Rotor Repair Re-assembly +
The aft stub shaft is placed in the stacking area. The bolts are placed into the stub and held up in place with temporary supports.
+
Using alternating heat and dry ice, the turbine rotor is re-assembled. After each component is added to the stack, the temperature is allowed to normalize and the bolts are checked to insure they can be turned.
46
Turbine Rotor Repair Re-assembly +
The photo is an assembled rotor prior to re-stretch of the bolts. This is actually a 7B rotor. The large gap shown between the 1-2 spacer and the second stage wheel is far less wide on the EA unit. The edge of that spacer holds the discourager seal for the second stage buckets.
47
Turbine Rotor Repair RUN OUT VERIFICATION +
Following the turbine bolt stretch, the rotor is turned horizontal and placed in the lathe. A complete set of run out data is measured and recorded.
DISCOURAGER SEAL MACHINING +
This is the discourager seal located in the aft face of the 1-2 spacer. The second stage bucket to be installed into the unit is used as a measuring template. The seal is formed and machined axially to allow for a small amount of crush against the face of the bucket, thus ensuring a good seal area.
48
Turbine Rotor Repair COUPLING MACHINING +
The rotor coupling rabbet fits and face perpendicularity are measured and recorded.
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Patch rings are utilized for rabbet fit corrections
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Tool post grinding is used to reclaim the tolerances of the coupling faces.
ROTOR BALANCE +
The turbine rotor is placed into the balance machine and the bare rotor balance is measured and recorded.
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The total vectored allowable unbalance is 7500 inch-grams. Either correction plane cannot exceed 3750 inch-grams.
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The second stage buckets are normally installed first to facilitate twist lock staking
49
Turbine Rotor Repair FINAL ROTOR BALANCE +
The buckets are installed one stage at a time. The rotor balance is trimmed back to acceptable level following each stage. The final balance is achieved using a weight consolidation process for each plane. If a row of buckets exceeds allowable limits, it is removed and re-moment weighed.
FINAL PACKING +
Each stage of buckets is wrapped with Styrofoam packing. The complete rotor body is then covered with heavy corrugated cardboard.
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This is then seal wrapped completely with plastic stretch wrap.
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Preservation is the same process as the compressor rotor.
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MS 7001 Rotor Repair Module TIL – 1576 OVERVIEW +
The intent of this presentation is to provide an understanding of the requirements to accomplish a typical rotor major overhaul including Life Extension Inspections
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This level of disassembly is required to accomplish the Life Extension Inspections.
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All of the inspections described herein are basic to and in conjunction with the Life Extension inspections.
ORIGINAL TIL ISSUED IN 2007 +
For hour based operation, GE defines end of life as 200,000 factored hours, although a one time hours-based life extension of 50,000 factored hours for/E/EA class units may be permitted under certain circumstances.
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For starts based operation, end of life is defined as 5,000 factored starts with no extensions permitted by the OEM.
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It is important to note the GE has classified this at the highest level: SAFETY – Failure to comply with this TIL, could result in personal injury. Compliance is mandated within a specific operating time.
51
MS 7001 Rotor Repair Module BACKGROUND (2007) +
A gas turbines risk of failure increases the longer it is in service as a result of normal wear and tear of components in the system. It is believed the exceeding of the service life of the rotor system can lead to wheel failure severe enough to cause extensive damage to the gas turbine as well as the potential for substantial damage to adjacent equipment and serious injury to nearby personnel.
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GER 3620 (Heavy Duty Gas Turbine Operating and Maintenance Considerations) requires that a rotor inspection be performed at specific intervals recommended by GE. These intervals are set forth in GER 3620 or through Technical Information Letters. Where specific intervals have not been defined, rotor inspection should be performed at 5,000 factored starts or 200,000 factored hours.
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The inspections as defined in 3620 require a complete disassembly of the compressor and turbine rotors. Some components may require replacement, and the extent of refurbishments performed may redefine intervals of subsequent inspections. Failure to perform these inspections leaves the gas turbine at greater risk for failure.
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Numerous techniques are required to perform full inspections on a gas turbine rotor for both surface connected and sub-surface defects. Along with magnetic particle, eddy current and ultrasonic techniques, detailed mechanical inspections must be performed.
52
MS 7001 Rotor Repair Module RECOMMENDATIONS (2007) +
GE has defined inspection programs for rotors reaching the tear down inspection intervals. Numerous techniques are required to fully inspect a gas turbine rotor for both surface connected and subsurface defects. These inspections. which include magnetic particle. eddy current and ultrasonic techniques. should be performed in a GE service center where the GE inspection team uses proprietary algorithms to identify potential sub-surface defects that may have grown during operation. The inspection results can be combined with design analysis and specific turbine operating histories to provide recommendations for rotor refurbishment, replacement and continued service.
+
Depending upon the condition of the rotor at the inspection. one hours based life extension may be possible for up to 100,000 hours for frame 3 and 5 units and up to 50,000 hours for Eclass units that have not passed their starts based interval limits as defined in GER 3620, after which the rotor must be retired. Extensions are under evaluation for FA class units. Currently. There are no life extensions available for units that reach their starts based interval limit.
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MS 7001 Rotor Repair Module RECOMMENDATION MODIFICATION +
In 2011 GE issued revision 1 to the TIL. There were only three changes from the original, two of those minor in nature and the third quite significant.
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The units affected was changed from FA class to F class
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The inspection process of penetrant was added to the list of types of NDT
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The limiting language of 2007 was modified to not specifically eliminate starts based extensions and the implied easing of the hours based limitation
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