GER-3957B - Gas Turbine Repair Technology
gGER-3957BGE Power SystemsGas Turbine RepairTechnologyK.J. PallosGE Energy Services TechnologyAtlanta, GA
Gas Turbine Repair TechnologyContentsAbstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Operation and Maintenance Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Repair vs. Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Component Repairs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Nozzles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Stage One Nozzle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Activated Diffusion Healing: Distortion-Free Nozzle Restoration . . . . . . . . . . . . . . . . . . . . . . . 5Nozzle Modifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Stages Two and Three Nozzle Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Advanced Bucket Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Rotors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Combustion Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Combustor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Transition Pieces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Fuel Nozzles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Component Enhancement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Extendor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Compressor Corrosion Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Turbine Corrosion/Oxidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Thermal Barrier Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Service Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Appendix — Destructive Analysis: A Tool for Understanding Component Life . . . . . . . . . 21GE Meeting Industry’s Demands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Material Issues. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Limitations of Non-Destructive Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21The Need for Destructive Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Benefits of Destructive Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Customer Satisfaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Find Out More . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25GE Power Systems GER-3957B (04/01) i
Gas Turbine Repair TechnologyGE Power Systems GER-3957B (04/01) ii
Gas Turbine Repair TechnologyAbstractUnit availability and effective utilization ofmaintenance funds are two of the most important concerns of a gas turbine owner/operator.Major gas turbine components have limitedlives in comparison to the unit’s useful life.Owners/operators are continually faced withdecisions regarding component replacementand/or repair. A component repair programthat minimizes maintenance costs and maximizes equipment availability can be institutedwithin the installed base to meet or improve financial objectives. This paper summarizes someof the state-of-the-art gas turbine component repair processes developed by GE to support thefleet of GE-designed heavy-duty gas turbines.Operation and MaintenanceConsiderationsGE’s recommended operating and maintenance practices are discussed in the publication, “Heavy-Duty Gas Turbine Operating andMaintenance Considerations” (GER-3620G).This paper discusses the factors that influenceequipment life. These life-limiting factors mustbe understood and accounted for in theowner’s maintenance plans (Table 1).Each one of these factors has an effect on gasturbine maintenance intervals and componentparts’ lives and will vary depending on eachunit’s operation. Some of the potential and typical failure modes for hot gas path componentsin continuous and cyclic-duty machines are listed in Table 2.Thermal mechanical fatigue is the predominant life limiting factor for peaking machines,while creep, oxidation and corrosion are thedominant limiters for continuous-duty machines. GER-3620G discusses these limiting factors in detail and provides criteria for establish-GE Power Systems GER-3957B (04/01) ing maintenance inspection intervals. Thescope of typical maintenance inspections (combustion, hot gas path and major) are outlinedthere and estimated repair and replacement cycles are provided for some major components.Repair vs. ReplacementOnce a maintenance plan is established, theowner/operator implements it. The maintenance cycle starts with the pre-outage planning,continues through the outage, and ends withthe post-outage assessment. As one would expect, most gas turbine components have a finitelife or expected life in the turbine under the GEperformance guidelines. (See Table 3.) Duringthe maintenance or outage cycle, owners andoperators decide to use the component “as is,”repair the component, or replace the component. This post-outage assessment provides thebasis for planning the next outage.Throughout this outage process, the owner/operator will be faced with many difficult decisions that will determine unit reliability, maintenance costs, and operating benefit. Fuel Firing Temperature Steam/Water Injection Cyclic EffectsTable 1. Major life limiting factorsSince GE is continually improving gas turbinetechnology and applying it to component designs that can be retrofitted in older units, theowner can evaluate the economics associatedwith upgrading or uprating the unit by replacingone or more components with state-of-the-artcomponents. GE can consult in various mannersby contacting a Customer Service or ProductService specialists. One can also perform some1
Gas Turbine Repair TechnologyGas Turbine Component Life Diagram with Key ionRotorTurbineOperationFuelPower LevelFiring TemperatureOperation TypeCombustionConfigurationCustomer ConditionDesign StatusUpgrade PotentialOutageNo uprate desiredNew PartsPrevious RepairedPartsCompetitorsRepaired PartsContinued PartsAssemblyInspectat SiteInspect byService uelPower LevelFiring TemperatureOperation TypeCombustionConfigurationOutageUprateInspectat SiteAssemblyContinue Cycleto Turbine LifeInspect byService CenterStoresRepairWorkscopeTable 3. Turbine component life flowchartpreliminary studies on which direction totake by looking on GE’s web page,www.gepower.com, under the Turbine Optimizer. Continuous Duty- Rupture- Creep Deflection- High-Cycle Fatigue- Oxidation- Erosion- Corrosion- Rubs/Wear- Foreign Object Damage Cyclic Duty- Thermal Mechanical Fatigue- High-Cycle Fatigue- Rubs/ Wear- Foreign Object DamageTable 2. Potential failure modes – hot gas pathcomponentsThere exist several models that operators mayincorporate to make the prime feasibility deciGE Power Systems GER-3957B (04/01) sion between the component replace, uprate orrepair scenario. Typical gas turbine componentdamage that occurs during usage includes component cracking, foreign object damage(FOD), oxidation and corrosion. In many cases,the component’s condition at any given inspection can be anticipated by the unit’s performance. The damage may be obvious and thescope of repair may be relatively straightforward. Of course, a replace/repair decision mustbe based on situational specifics. For example, aset of coated buckets with high operationalhours showing signs of wear may be mechanically repaired without recoating and allowed torun to the end of its remaining life. In this particular instance, recoating of the buckets wasnot a cost-effective option.Some damage will not be detectable through visual observation. Accurate dimensional checkand non-destructive examinations (NDE) techniques like flourescent penetrant inspectionmay reveal additional discontinuities, such asstress cracking, that require more extensive repairs (Figure 1). Additionally, on airfoils where2
Gas Turbine Repair Technologyor replacement and the component’s future lifeexpectancy are integrated into the engineeringrepair recommendations.Component RepairsWith new technologies being implemented inthe gas turbine world, component repair is anever-changing challenge.Figure 1. Stress cracked bucketinternal defects can hide, destructive sampleanalysis can provide valuable information aboutthe set component condition and the repairworkscope. For example, it enables the characterization of internal cooling passage microstructure, which may differ from the behaviorof the external material. In addition, crackdepths can be accurately determined.Furthermore, the information gathered duringdestructive analyses can be studied togetherwith the gas turbine running conditions to helpidentify critical operating parameters. The customer is thereby able to optimize future operating conditions for enhanced performance, aswell as improve the prediction of future repairprocess schedules on the hardware.A complete repair scope is determined onlyafter rigorous analysis of all inspection data. It isinteresting to note that not all serviced or damaged components are candidates for repair.Some components are damaged beyond GEprescribed repair limits. Since all gas turbinecomponents have a finite life, the cost of repairGE Power Systems GER-3957B (04/01) The effort toward increased operating efficiency and decreased heat rate requires that repaired components conform closely with original equipment manufacturer’s (OEM) drawingrequirements and specifications. With that inmind, the need for consistent repair practicesthroughout the service organization has become a top company priority. The sharing ofpiece-part qualifications, best practices, processes and procedures, fixtures and tooling has become more critical than ever.Each repair is engineered to provide the customer with maximum benefit while balancingcost and cycle times. A multi-organizational engineering review and approval process is required by the GE Service Centers before a newrepair is implemented. This ensures that criticaldesign and life-enhancing features are checkedand re-checked. Each service center documentsa new repair in a Manufacturing Process Plan(MPP). This outlines the repair procedures and“freezes” the process so that the repairs are robust and reproducible. GE’s internal audit teamreviews each package and requires rigorous testing before approval and release is issued. Theseprocedures are in keeping with the ISO 9000standards embraced by GE and its repair organizations.NozzlesStage One NozzleThere are several nozzle failure modes associated with the high temperature environment of3
Gas Turbine Repair Technologyindustrial gas turbines. These can be categorized under creep, thermal fatigue, oxidation,incipient melting and many forms of mechanical damage. Each failure mode presents different requirements for component repair.Nozzles that are candidates for repair undergoan initial metallurgical evaluation. From theseresults, engineering recommendations aremade on the nozzle’s continued serviceability.The reparability and/or weldability of the nozzle and the required repair methods and operations are determined.First, a triangle-shaped specimen is cut from thepartition’s trailing edge (Figure 2). It is mounted and polished for metallurgical evaluation(specimen “MetLab”). The metallurgical analysis includes microstructural evaluations of the“as-received” and “heat-treated” conditions, andobservations of intergranular oxidation (IGO),chromium migration (CM), chromium depletion (CD), carbide precipitates (CP) and wallthickness. Figure 3 shows a typical nozzle cooling hole with chrome depletion and oxidation,as indicated by the lighter contrast regions onthe specimen’s external surfaces.Specimens may be taken from up to 10 partitions. The specimens are taken from the nozzle segment partition which is closest to the center of each adjacent transition piece. This center area experiences the highest temperaturesFigure 2. Trailing edge specimenGE Power Systems GER-3957B (04/01) Figure 3. Metallurgical evalution showing chromedepletion/oxidationFigure 4. Nozzaloy repair over ADHand reflects the nozzle’s most severe operatingconditions. Sidewall specimens may also betaken for evaluation if the nozzle has large areasof distress. If the MetLab inspected partition indicates a severe metallurgical problem, additional samples are taken on adjacent partitionsto determine the extent of the distress.The primary method of dimensional restoration to the nozzle is weld repair. To enhanceand improve weld repair life, an advanced fillermaterial was developed for repair of cobalt base(X-40, X-45 and FSX-414) investment cast nozzle segments. This material breakthrough wasaccomplished with the patented creation ofNozzaloy . Nozzaloy repairs can also be applied over previously applied ActivatedDiffusion Healing (ADH) repairs.4
Gas Turbine Repair TechnologyA metallurgical evaluation of such a Nozzaloy repair (Figure 4) demonstrates its ability to forma sound bond and contamination-free interface. Nozzaloy extends repair intervals by inhibiting crack initiation by a factor greater thanfour when compared to those filler metal alloysmore commonly used in the industry.Nozzaloy not only shows the highest resistance to crack initiation, but the crack propagation rate is also as low as the base metal. (SeeFigure 5 and Figure 6.)CRACK INITIATION & GROWTH CURVES350minor and major repairs on hot gas path surfaces. A key attribute of ADH is that it causes noparts distortion during application and hightemperature processing. This technique wasoriginally developed by GE’s Aircraft Enginegroup for vane (nozzle) repair. GE PowerSystems’ Inspection and Repair Services (I&RS)has modified the process for use with heavyduty industrial gas turbine alloys.ADH lends itself to nozzle surface erosionrestoration, craze crack repair and replacementof trailing edge metal loss. Typical erosion damage of a nozzle sidewall that is readily repairedwith ADH is shown in Figure 7.300250L - ORSFSX - 414 0NUMBER OF CYCLESFigure 5. Nozzaloy crack initiationTHERMAL FATIGUE CHARACTERISTICS350310300Figure 7. Nozzle requiring ADH repair300Activated Diffusion Healing: DistortionFree Nozzle RestorationThe ADH process uses a mixture of superalloypowders and an organic binder tailored to meetthe part’s specific design requirements. Themixture of ADH materials is designed to melt,solidify and diffuse when placed through a controlled thermal cycle in a vacuum furnace. ADHcomponents produce a liquid which isothermally resolidifies, thus avoiding undesirableeutectic phases. With further thermal treatment, ADH repairs closely approach the composition, microstructure and properties of theparent metal. (See Figure 8.)Activated Diffusion Healing (ADH) is a uniquerepair method used in nozzle restoration. Theprocess deposits a metallurgically sound proprietary alloy combination to a nozzle substrate forThe ADH alloy system selected for nozzle repairs is compatible with previous repair weldments and is readily weldable. (See Figure 4.) Keymechanical test data acquired for comparison250200NUMBEROF CYCLESTO CRACKINITIATION15010050200L - 605 (WELDMENT)NOZZALOYFSX - 414 BASE MATERIALMATERIALFigure 6. Nozzaloy thermal fatigue characteristicsGE Power Systems GER-3957B (04/01) 5
Gas Turbine Repair TechnologyModification of cooling holes on pressure sideairfoils and trailing edges is also accomplishedwith “wishbone coupon” replacements. Wishbone coupons provide improved cooling effectiveness and replace distressed airfoil materialwith new cast material. Foreign object damageof a nozzle’s aft chord is also easily remediedwith wishbone coupon replacements.Figure 8. Metallurgical evalution of ADH repair onFSX-414with base metal properties indicates that ADHrepaired nozzle trailing edges perform favorably. ADH is applied either in a preformedshape or as a slurry. In Figure 9, a GE I&RS repair technician uses a slurry-filled syringe toapply ADH to specific areas of a nozzle’s sidewall.Nozzle ModificationsAn additional advanced repair offering includes a redesign and modification of nozzlecooling holes. Cooling hole upgrades directlyimprove the service life of investment cast nozzle segments by enhancing film cooling effectiveness and reducing thermal-mechanical fatigue. These changes are implemented on thenozzle’s leading edge, pressure side, trailingedge and outer sidewall.Figure 9. Applying ADH with syringeGE Power Systems GER-3957B (04/01) Another opportunity to improve a nozzle’s efficiency during repair and refurbishment is tomodify the inner support ring and outer retaining ring sealing surfaces. This is known as achordal hinge modification and it results in areduction in compressor discharge air leakagearound the stage one nozzle. To accomplish thismodification, a weld build-up is applied to theinner contact area on each segment and a newsealing surface rib is machined into the nozzlesegments. A modification is also made to theflat seals which bear on the retaining ringagainst the stage one shroud blocks.Stages Two and Three Nozzle RepairStage two and three nozzles are of a cantilevered design. They are supported from theouter wall by a series of hook fits to the shroudblocks to the turbine shell. Creep damage results in progressive distortion of the vane surfaces and the outer sidewalls. Excessive downstream deflection may result in rubs with thefollowing rotor stage. Detection of excessivecreep and resulting deflection is assessed utilizing three primary measurement techniques.Diameter measurements are taken on the innerand outer wall, diaphragm and labyrinth seals.Deviations indicate downstream deflectionand/or ovality. Nozzles are inserted into a fixture that simulates the turbine casing to checktheir fit-up in a turbine shell. Critical dimensions are taken to determine the amount of distortion that nozzle has experienced and corrections are made. (See Figure 10.)6
Gas Turbine Repair Technology1SEGMENT HOOK FITINNER DIAMETER723456Figure 10. Nozzle diaphragm inspectionEmpirical deflection calculations are also madebased upon opening clearance data. Final verification, performed by GE Installation andField Services (I&FS) field engineers, is simulated with deflection measurements carried outin the actual turbine cases of the hardware.These redundant checks define exactly howmuch upstream correction is required. Materialbuild-up and remachining yields a nozzle that iscorrectly repositioned between adjacent stagesof buckets. Specially-designed fixtures are usedto verify all dimensions prior to returning nozzles to a customer.The repair of newer technology stage two andthree nozzles made from GE’s patented GTD222 creep-resistant alloy includes refurbishing the airfoil with trailing edge coupons. Thesecoupons are specifically designed to addressphysical and metallurgical damage. Recent advances have yielded an ADH repair for GTD222 nozzles. Additionally, select GE servicecenters now have Coordinate Measuring Machine (CMM) capability to accomplish inspection.MS5001 second-stage nozzle refurbishment ofboth N-155 and FSX-414 metallurgy includesweld repair, restoration of diaphragm packing,heat pack modification and re-rounding thenozzle with machining or other techniques.MS3002 and MS5002 variable second-stage nozzle refurbishment includes partition weld repair, shaft grinding and metallizing and hardfacing bushing areas.GE Power Systems GER-3957B (04/01) Advanced Bucket RepairGas turbine buckets must operate in extreme atmospheric and thermal environments whilemaintaining the structural integrity required ofrotating components. GE has determined all ofthe critical failure modes and has developed repair technologies and processes specific toeach. The failure modes most commonly encountered for rotating hardware are listed inTable 4.The first five modes are related to the turbine’soperating conditions and their subsequent effects on bucket metallurgy. A single bucket istypically sacrificed from each set of buckets toundergo a destructive metallurgical evaluation.(See Appendix.) From that work, engineeringrecommendations are made on the bucket’scontinued serviceability. The reparabilityand/or weldability of the bucket and the required repair methods and operations are alsodetermined.Typical repair processes include blending, welding, remachining and precision grinding. Theadvanced bucket metallurgy (vacuum cast nickel-based superalloys) to support the higher firing temperature gas turbines has requiredGlobal I&RS service centers to incorporate enhanced repair processes as well.1. Creep to crack initiation2. Low cycle fatigue to crack initiation3. High cycle fatigue4. Corrosion/oxidation5. Incipient melting6. Interference with adjacent components7. Excessive strain/distortion8. Foreign object damage9. Wear and frettingTable 4. Bucket failure modes7
Gas Turbine Repair TechnologyFor repair of high strength bucket alloys likeGTD-111 , weld wire of the same compositionhas been typically used in the past. This assuresthat the repair exhibits strength and oxidationresistance similar to the parent material. A weldrepair process originally developed by GE’sAircraft Engine business has been adapted toindustrial gas turbine components and produces crack-free high strength welds. The process, called WRAP (Weld Repair AdvancedProcess ), uses a controlled environment boxto regulate heat input and cover gas. In Figure11, a technician skillfully welds a bucket usingthe WRAP process.For repair of high strength bucket alloys likeGTD-111 , weld wire of compatible composition may be utilized based on the nature of therepair. GTD-111 filler material may be usedwith an elevated temperature repair process orthe newly developed “Bktaloy” (Bucketalloy )may be utilized for an ambient temperature restoration. This assures that the repair exhibitsthe strength, oxidation resistance and serviceendurance similar to the parent material. (SeeFigure 12.)Figure 11. WRAP weld operationGE Power Systems GER-3957B (04/01) BktaloyTMAlloy 625Figure 12. Oxidation characteristics of weldrepair alloysAn alternative to the high temperatureWRAP process effects the repair at ambienttemperature with the use of an adaptive robotand specially designed welding fixtures. The system has the objective of welding the squeelertips of turbine buckets of specific configurationautomatically. The unique shape and positional variation of the bucket makes automation ofrepair processes difficult. The robot is a manipulative arm with six axes of motion. The automatic welding system is specially designed toadaptively change key parameters to weld eachbucket tip to full height based on the edgethickness and position of the airfoil contour.(See Figure 13.) The basic parts of this system arethe robot, the tooling, the welding system, theadaptive control system and the safety provisions. The robot is made up of very precise components including brakes, transmission systems,electric motors, and counterweight systems todeliver the process within the three-dimensional area known as the working area. Within thisentire complex system are methods that will calibrate and visually monitor the process of welding the buckets.The tooling is comprised primarily of a processfixture which places the bucket in a specific location within the operating range of the robotworking zone and the vision system camera.The fixture must also provide a heat sink to thepart being welded and be designed to functionvery close to the welding arc without damage8
Gas Turbine Repair TechnologyReduction of Hot Zones (RED) as predicted byDesign Engineering modeling with the application of Advanced Thermal Barrier Coatings.Figure 15. TBC effect on airfoil bulk metal surfacetemperaturesFigure 13. Automated weld repair systemduring the welding process. The welding systemgenerates heat into the part, the welding torchand the fixture which must be dissipated whilein operation. A water chiller is part of this system to perform the function of cooling thecomponents.The process selected for welding the filler material to the bucket is the plasma arc weldingprocess. A key to the process is the stable lowcurrents which enables accurate weld placement and welding on thin knife edge surfaces.Key to the success of this welding process is thedistance that the welding torch maintains fromthe weldment. An arc length controller utilizesthe arc voltage and sensing devices to adaptively adjust the torch height and maintain a constant arc length for successful welding results.(See Figure 14.)Figure 14. Close-up plasma torchGE Power Systems GER-3957B (04/01) Post-weld heat treatment, Hot Isostatic Press(HIP), finish machining and grinding are easilyaccomplished while returning the bucket to itsrepair part dimensional requirements. The elevated temperature WRAP welding is also usedfor the restoration of rubbed tips and angelwing sealing surfaces.Additionally, the elevated temperature WRAP process is used to generate cutter teeth on theintegral labyrinth seal surface of shroudedbuckets. This uprate is offered on new and serviced parts. The use of honeycomb material instage two and three shrouds requires that thestage two and three buckets have “cutter teeth”on the bucket tip seals. Their purpose is to allowthe buckets to cleanly cut into the honeycombmaterial when the rotor moves axially relative tothe shrouds.Restoration of integral shroud “Z” interlocks isaccomplished via the fusion application of wearresistant hard surfacing materials. In the case ofGTD-111, the elevated temperature WRAP process is again employed. For “Z” interlocksoriginally employing plasma-sprayed chromecarbide, this original material can be reappliedor, at the customer’s option, upgraded to fusion-applied hard surfacing.Bucket cooling effectiveness is a critical part ofensuring bucket life and integrity. Higher firedmachines employ conduction and convectioncooling as well as film cooling techniques to ensure that bucket temperatures do not exceed9
Gas Turbine Repair Technologydesign limits. GE’s I&RS Service Centers, during repair cycles, ensure that the cooling passages are not constricted or blocked. Applyingan Advanced Thermal Barrier Coating to theexternal surfaces of the bucket airfoil can reduce the bulk metal temperature of the bucket.(See Figure 15.) Contact GE Energy Services foradditional information about the correct coating for your particular application.RotorsDuring a common day, a base-loadedMS7001EA will ingest approximately 56 millionpounds of air. The chemical composition of theair entering the compressor inlet in terms of humidity, trace gases and particulate determinethe extent of corrosion, erosion and depositwhich the air flow path surfaces exhibit.Deposits on the surface of the gas path components are carefully removed for initial inspections. The operating environment of the turbine rotor affects the maintenance needs andthe inspection phase of the rotor overhaulcycle.The full workscope of complete overhaul of aGE rotor can only be performed once the initial incoming inspection is accomplished.Once the compressor rotor is thoroughlycleaned, the assembly is visually inspected andFigure 16. Compressor and turbine rotorassembled after cleaningGE Power Systems GER-3957B (04/01) characteristics such as wear, corrosion, macrocracking, nicks and dents are fully documented.(See Figure 16.) GE has established criteria towhich these inspection results are comparedand decisions are made as to the workscope required to repair the assembly.The functionality of the rotor is dependentupon the dynamic balance and vibration aspects that the rotor as an assem
quired by the GE Service Centers before a new repair is implemented. This ensures that critical design and life-enhancing features are checked and re-checked. Each service center documents a new repair in a Manufacturing Process Plan (MPP). This outlines the repair procedures and "freezes" the process so that the repairs are ro-bust and .
Select from any of the following not taken as part of the core: GER 307 Introduction to German Translation, GER 310 Contemporary German Life, GER 311 German Cultural History, GER 330 Studies in German Language Cinema, GER 340 Business German, GER 401 German Phonetics and Pronunciation, GER 402 Advanced
7 SSC Landau 3297 15 29 --- 87 87 GER . 9 Mainzer SV 01 5059 15 31 31 57 88 GER 10 USC Mainz 3316 15 15 15 --- 15 GER 11 SC Neustadt 3292 15 12 5 21 26 GER 12 SSV Offenbach 3304 15 9 7 40 47 GER 13 1.SV BW Pirmasens 3282 15 20 10 69 79 GER 14 SV Region Stuttgart 4982 18 2 2 --- 2 GER 15 SG
SSC Berlin-Reinickendorf 5624 GER 7 14 21 37 65 102 - - - SSV Bad Salzungen 3272 GER 1 - 1 8 - 8 - - - SSV Erfurt-Nord 3249 GER 1 1 2 7 7 14 - - - SSV Freiberg 3370 GER 14 14 28 92 83 175 - - - SSV Hoyerswerda e.V. 3374 GER 3 6 9 17 40 57 - - - SSV Leutzsch 3378 GER 11 19 30 59 101 16
A gas turbine is an extension of the same concept. In a gas turbine, a pressurized gas spins the turbine. In all modern gas turbine engines, the engine produces its own pressurized gas, and it does this by burning something like propane, natural gas, kerosene or jet fuel.
control methods are provided for gas turbine cycle performance and recommended turbine inspection intervals. Emission control methods vary with both internal turbine and external exhaust system emission control. Only the inter-nal gas turbine emission control methods — lean head end liners and water/steam injection — will be covered in this paper.
Three Spool aero derivative industrial gas turbine hot-end drive. Intake-Radial inlet LP Compressor- Axial compressor 6 stages. Air deliver to an intercooler HP Compressor- 14 stage. Over pressure ratio 42:1 Combustor – SAC/DLE HP Turbine- Two stage IP Turbine- two axial stages that drive the LP /Power Turbine. LP/Power Turbine- five stage free power turbine. 3600 RPM 60-Hz and 3000 RPM 50 .
of gas turbine operating conditions and fuel composition. In the following sections, each pollutant will be considered as a function of Gas Turbine Emissions and Control GE Power Systems GER-4211 (03/01) 1
AGMA American Gear Manufacturers Association AIA American Institute of Architects. AISI American Iron and Steel Institute ANSI American National Standards Institute, Inc. AREA American Railway Engineering Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and .
