when bad things happen to good turbines

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Brief description of failures that can occur

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  • When Bad Things Happen to Good Turbines

    PAL Turbine Services, LLC

  • ALFRED SHUMAN - Senior Staff Engineer Engineering Specialties

    Gas Turbine Maintenance CMU Modifications Product Service Engineering Technical Training

    Experience 41-years gas turbine experience

    Senior Consulting Engineer for PAL Turbine Services since 2000

    GE Field Engineer Lead Technical Training Specialist, FEP GE Service Supervisor, Baltimore, MD GE Senior Installation Engineer, Futsu Japan site for

    14 MS9001E STAG plants (5-year project) Performed numerous major overhauls on GE model

    series including MS5001, 6001, 7001

    Education

    E6, Machinist Mate, Class A, US Navy Submarine Nautilus

    AAS Mechanical Design Engineering, Wentworth Institute of Boston, MA

    GE Training Programs: Field Engineering Program (FEP) Gas Turbine Maintenance Schools Six Sigma Training

    PAL Turbine Services, LLC Office: 518-371-1971 Fax: 518-371-1756

  • Note That Some of the Examples Shown are from Not Only MS-6001B Units, but also MS-5001N and MS-7001EA Units

  • Bolting Issues

    1. Plated Bolting 2. Rusted Bolting

    PAL Turbine Services, LLC

  • World War II Liberty & Victory Ships

    These ships were the first to be built completely welded with no use of rivets Components for ships built modularized in many different

    locales and then welded together at the assembly shipyard This process drastically reduced the time to build these

    ships at a time when the Allies were desperate for war materials

    Some of the issues of Embrittlement, due to temperature along with contaminants and also with an excess of Hydrogen in the welds, led to significant failures of hulls during launching

    PAL Turbine Services, LLC

  • Launch of Liberty Ship from Dry Dock

    PAL Turbine Services, LLC

  • Catastrophic Failure of Launched Hull Due to Embrittlement

    PAL Turbine Services, LLC

  • Successfully Built Liberty Ship Helping the Allies War Effort

    PAL Turbine Services, LLC

  • Case #1 Cadmium & Zinc Plated Bolting

    Do not use Cadmium plated bolts in the combustion, hot section or exhaust.

    Above 4500 F the cadmium melts & attacks the grain structure of the bolts and the bolt fails.

    The failure mode is called Liquid Metal Embrittlement and it is similar in nature to Hydrogen Embrittlement.

    PAL Turbine Services, LLC

  • Failed Cadmium Plated Bolts

    PAL Turbine Services, LLC

  • Failed Cadmium Plated Bolts & Nuts

    PAL Turbine Services, LLC

  • PAL Turbine Services, LLC

    Combustion Can Cover, with Fuel Nozzle & Pigtails, Blew Off

  • Collapsed Liner & Flow Sleeve

    PAL Turbine Services, LLC

  • Discussion of the Root Cause of

    this Failure

    PAL Turbine Services, LLC

  • Case #2 Rusted Bolting in Inlet Ducting

    PAL Turbine Services, LLC

  • Rusted Bolting in Inlet Ducting

    PAL Turbine Services, LLC

  • Inlet Bellmouth Bernoulli Effect: Pressure Drop Produces Increase in Flow Velocity All GE Heavy Duty GTs produce a Velocity increase of Mach 0.5 Typical 295 lb/sec (1,062,00 lb/hr)

    Velocity = Mach 0.5

    Why Does Foreign Object Damage Occur So Rapidly Within the Flange-to-Flange

  • Pond And Lucier, LLC

    Pressure & Temperature Across Gas Turbine Typically, the Delta-P Across the Inlet Throat Results in a Delta-T of 230F

    T4 = 1000 F P4 = 14.7 psia

    T1 = 59 F P1 = 14.7 psia

    T2 = 450 F P2 = 196 psia

    Flame Temp = >3000 F

    T3 = 2035 F P3 = 196 psia

    1 2

    3 4

  • Collateral Damage From Failed Bolting

    PAL Turbine Services, LLC

  • Collateral Damage From Failed Bolting

    PAL Turbine Services, LLC

  • Collateral Damage From Failed Bolting

    PAL Turbine Services, LLC

  • Discussion of the Root Cause of

    this Failure

    PAL Turbine Services, LLC

  • PAL Turbine Services, LLC

    During reassembly, ensure that crew understands to report when something gets dropped into an open turbine. No one will be fired or censured for

    dropping something into the machine as long as it is promptly reported.

    Two case histories of when bad things happened because of dropped/missing parts

    Cautions with Open Casings

  • Case #3: MS-7001EA after a HGP & subsequent restart

    Units MW output was significantly less then before the outage.

    Pcd read higher than expected, but output was still lower than expected.

    Significant testing indicated a problem in the Turbine section.

    Decision made to open Combustion system in order to inspect Stage 1 Nozzle

    PAL Turbine Services, LLC

  • PAL Turbine Services, LLC

    View of Stage 1 Nozzle from inside Wrapper

  • PAL Turbine Services, LLC

    Damage which Choked Nozzle (Note how TE is pushed upstream)

  • Note how TE is pushed upstream

    PAL Turbine Services, LLC

  • Damage as Viewed from Turbine

    PAL Turbine Services, LLC

  • Bucket Denting & Splatter

    PAL Turbine Services, LLC

  • 1st Stage Bucket F.O.D.

    PAL Turbine Services, LLC

  • 2nd Stage Bucket Splatter & F.O.D.

    PAL Turbine Services, LLC

  • Setting Pressure Ratio (PR)

    Nozzle Throat Dimension The Tightest Orifice in the Hot Gas Flow Path

  • Typical Nozzle Throat Dimension Check Points

    PAL Turbine Services, LLC

  • PAL Turbine Services, LLC

    Damage which Choked Nozzle & caused High Pcd

  • 1st Stage Nozzle F.O.D. & Buckling

    PAL Turbine Services, LLC

  • 1st Stage Nozzle Impact Zone

    PAL Turbine Services, LLC

  • Discussion of the Root Cause of

    this Failure

    PAL Turbine Services, LLC

  • Case #4: MS-6001B After Major Inspection

    Complete Major Overhaul, with replacement of all HGP parts along with a refurbished CDC Inner Barrel.

    Performance was ~9% lower than before the outage.

    Significant testing & a borescope inspection

    Unit reopened

    PAL Turbine Services, LLC

  • PAL Turbine Services, LLC

    Borescopic View of Stage 1 Bucket Airfoil

  • PAL Turbine Services, LLC

    Borescope View of Stage 2 Bucket Shroud

  • PAL Turbine Services, LLC

    Note Gouges on Inside of Inner Barrel

  • PAL Turbine Services, LLC

    Close up of Gouges in Inner Barrel

  • PAL Turbine Services, LLC

    Distance Piece Interface with Stage 1 Wheel

  • PAL Turbine Services, LLC

    Stage 1 Bucket Pressure Side Deposits

  • PAL Turbine Services, LLC

    Stage 1 Nozzle Inner Sidewall Deposits

  • PAL Turbine Services, LLC

    Stage 1 Nozzle LE & PS Deposits

  • PAL Turbine Services, LLC

    Stage 2 Bucket Shroud Tip deposits

  • Discussion of the Root Cause of

    this Failure

    PAL Turbine Services, LLC

  • Case # 5: Effects of Turbine Clearances

    Being Too Tight

    Rubs & Consequential damage are most often a low speed event.

    Damage usually occurs during very first start-up after outage.

    Make sure that you fully understand the true costs of trade offs made during reassembly.

    PAL Turbine Services, LLC

  • Effects of Turbine Clearances Being Too Tight

    Power Plant Users often believe that, since they are going to change out Turbine Nozzles and Buckets during an outage, it is not important to take all of the Internal Clearances when opening the unit and again, when closing the unit.

    They believe that they can save outage time by not expending the effort to take accurate readings and compare them to what they were at the last outage; such a belief quickly becomes a False Economy.

    PAL Turbine Services, LLC

  • Effects of Turbine Clearances Being Too Tight

    Turbine, Compressor, and Bearing Clearances are indeed where the rubber meets the road.

    The OEMs Design Engineers view the Clearance Diagrams with their specific tolerances as the Bible for setting the performance and reliability parameters for any Heavy Duty Gas Turbine.

    PAL Turbine Services, LLC

  • Effects of Turbine Clearances Being Too Tight

    It is crucial that the person taking the clearances not only has a good understanding of how and where to take the clearances accurately, but also understands that this task is one of the most important of the outage.

    Adherence to the designed tolerance range affects optimum performance. You must review all of the before/after clearances; the Turbine is speaking to you. If you understand the inseparable dimensional relationship between the Rotor and the Stator during various phases of operation, then you can determine where to make judgments as to where to go outside of the optimum clearance envelope. PAL Turbine Services, LLC

  • MS6001 Turbine Clearance Composite

    PAL Turbine Services, LLC

  • Bucket to Honeycomb Shroud Clearance

    PAL Turbine Services, LLC

  • Correcting Clearances Below Minimum Values on Stage 2 and 3 Buckets

    PAL Turbine Services, LLC

  • MS-6001B Stg 2 Shroud Rub

    PAL Turbine Services, LLC

  • Stg 2 Bucket Shroud Rail Rubbed Off

    PAL Turbine Services, LLC

  • Comparison of Buckets

    PAL Turbine Services, LLC

  • Discussion of the Root Cause of

    this Failure

    PAL Turbine Services, LLC

  • Effects of Ignoring Recommendations Case #6

    MS-6001B Stage 2 Bucket Shroud lift phenomenon Unit was open for a HGP Customer chose not to follow OEMs TIL

    recommendation to change to new buckets due to potential cracking on airfoils.

    Customer installed a set of buckets from another unit on site which had shown marginal shroud lift readings.

    PAL Turbine Services, LLC

  • What it Looked Like at First Outage

    PAL Turbine Services, LLC

  • What It Looked Like at 2nd Outage

    PAL Turbine Services, LLC

  • Stg 2 Bucket Stubs

    PAL Turbine Services, LLC

  • Stg 1 Buckets are only lightly damaged

    PAL Turbine Services, LLC

  • Collateral Damage to Exhaust Frame Outer Barrel

    PAL Turbine Services, LLC

  • Collateral Damage to Exhaust Frame Outer Barrel

    PAL Turbine Services, LLC

  • Collateral Damage to Exhaust Frame Outer Barrel

    PAL Turbine Services, LLC

  • 2nd & 3rd Stage Stator Damage

    PAL Turbine Services, LLC

  • 2nd & 3rd Stage Stator Damage

    PAL Turbine Services, LLC

  • Discussion of the Root Cause of

    this Failure

    PAL Turbine Services, LLC

  • Corrosion Case #6

    Contaminating reagents can enter the gas path via: Ambient air Fuel (oil/gas) Diluents/Misting/Evaporative Cooling

    Contaminants from all sources are additive in concentration & impact

    PAL Turbine Services, LLC

  • Stage 1 Nozzle Exposed to Boiler Carryover in Steam Injection Attemperation

    PAL Turbine Services, LLC

  • Stage 1 Nozzle Exposed to Boiler Carryover in Steam Injection Attemperation

    PAL Turbine Services, LLC

  • Stage 1 Nozzle Partitions

    PAL Turbine Services, LLC

  • Discussion of the Root Cause of

    this Failure

    PAL Turbine Services, LLC

  • Case #7: Rush to make-up lost time in MS6001B Major Inspection Schedule leads to the Law of Unintended Consequences Results in an Order of Magnitude more lost time along with replacement and/or rework of Critical Components

    PAL Turbine Services, LLC

  • View of S1 Vane Through VIGVs & R1 Blades

    PAL Turbine Services, LLC

  • Damage to Stator Dovetail Slot Along with Rubs & Dings to Blades & Vanes

    PAL Turbine Services, LLC

  • Arrows Show Where Retaining Keys Should Be Locked in Place

    PAL Turbine Services, LLC

  • Note Rubbing Damage to Dovetail Slot Caused by Rotation of Blade Rings in Service

    PAL Turbine Services, LLC

  • Note Damage to Stator Vanes & Blade Ring

    PAL Turbine Services, LLC

  • Discussion of the Root Cause of

    this Failure

    PAL Turbine Services, LLC

  • Conclusions & Recommendations

    Hug your Gas Turbines! Treat them well, especially during outages! Confirm that Proper Form, Fit, & Function

    parts are being used as replacements! If schedule is causing an inordinate rush

    stop to think, review situation, and act accordingly! Work Safely & Work Smart!

  • Conclusions & Recommendations

    Account for every single tool removed & every part installed properly before closing up Gas Turbine!

    Following Good Engineering Practices will always trump False Economy!

    PAL Turbine Services, LLC

  • Centuries of experience In maintaining gas turbine generators

    When Bad Things Happen to Good TurbinesSlide Number 2Bolting IssuesWorld War II Liberty & Victory ShipsLaunch of Liberty Ship from Dry DockCatastrophic Failure of Launched HullDue to EmbrittlementSuccessfully Built Liberty ShipHelping the Allies War EffortCase #1 Cadmium & Zinc Plated BoltingFailed Cadmium Plated BoltsFailed Cadmium Plated Bolts & NutsCombustion Can Cover, with Fuel Nozzle & Pigtails, Blew OffCollapsed Liner& Flow SleeveDiscussion of theRoot Cause of this FailureCase #2 Rusted Bolting in Inlet DuctingRusted Bolting in Inlet DuctingInlet BellmouthBernoulli Effect:Pressure DropProduces Increasein Flow VelocityAll GE Heavy Duty GTsproduce a Velocityincrease of Mach 0.5Typical295 lb/sec(1,062,00 lb/hr)Pressure &TemperatureAcross Gas TurbineTypically, the Delta-PAcross theInlet ThroatResults ina Delta-Tof 230FCollateral Damage From Failed BoltingCollateral Damage From Failed BoltingCollateral Damage From Failed BoltingDiscussion of theRoot Cause of this FailureCautions with Open CasingsCase #3: MS-7001EA after a HGP & subsequent restartView of Stage 1 Nozzle from inside WrapperDamage which Choked Nozzle(Note how TE is pushed upstream)Note how TE is pushed upstreamDamage as Viewed from TurbineBucket Denting & Splatter1st Stage Bucket F.O.D.2nd Stage Bucket Splatter & F.O.D.Setting Pressure Ratio (PR)Typical Nozzle Throat Dimension Check PointsDamage which Choked Nozzle & caused High Pcd1st Stage Nozzle F.O.D. & Buckling1st Stage Nozzle Impact ZoneDiscussion of theRoot Cause of this FailureCase #4: MS-6001B After Major InspectionBorescopic View of Stage 1 Bucket AirfoilBorescope View of Stage 2 Bucket ShroudNote Gouges on Inside of Inner BarrelClose up of Gouges in Inner BarrelDistance Piece Interface with Stage 1 WheelStage 1 Bucket Pressure Side DepositsStage 1 Nozzle Inner Sidewall DepositsStage 1 Nozzle LE & PS DepositsStage 2 Bucket Shroud Tip depositsDiscussion of theRoot Cause of this FailureCase # 5: Effects of Turbine Clearances Being Too TightEffects of Turbine Clearances Being Too TightEffects of Turbine Clearances Being Too TightEffects of Turbine Clearances Being Too TightMS6001 Turbine Clearance CompositeBucket to Honeycomb Shroud ClearanceCorrecting Clearances Below Minimum Values on Stage 2 and 3 BucketsMS-6001B Stg 2 Shroud RubStg 2 Bucket Shroud Rail Rubbed OffComparison of BucketsDiscussion of theRoot Cause of this FailureEffects of Ignoring RecommendationsCase #6What it Looked Like at First OutageWhat It Looked Like at 2nd OutageStg 2 Bucket StubsStg 1 Buckets are only lightly damagedCollateral Damageto Exhaust FrameOuter BarrelCollateral Damageto Exhaust FrameOuter BarrelCollateral Damage to Exhaust Frame Outer Barrel2nd & 3rd Stage Stator Damage2nd & 3rd Stage Stator DamageDiscussion of theRoot Cause of this FailureCorrosion Case #6Stage 1 Nozzle Exposed to Boiler Carryover in Steam Injection AttemperationStage 1 Nozzle Exposed to Boiler Carryover in Steam Injection AttemperationStage 1 NozzlePartitionsDiscussion of theRoot Cause of this FailureCase #7:Rush to make-up lost time in MS6001B Major Inspection Schedule leads to the Law of Unintended Consequences Results in an Order of Magnitude more lost time along with replacement and/or rework of Critical ComponentsView of S1 Vane Through VIGVs & R1 BladesDamage to Stator Dovetail Slot Along with Rubs & Dings to Blades & VanesArrows Show Where Retaining KeysShould Be Locked in PlaceNote Rubbing Damage to Dovetail SlotCaused by Rotation of Blade Rings in ServiceNote Damage toStator Vanes& Blade RingDiscussion of theRoot Cause of this FailureConclusions & RecommendationsConclusions & RecommendationsSlide Number 84