Hot Gas Path Inspection 1

7/31/2019 Hot Gas Path Inspection 1

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THE SUM OF ALL MEASURES

INTENDED TO DETERMINE THE

ACTUAL CONDITION OF THE GAS

TURBINE, TOGETHER WITH THE

MEASURES REQUIRED TO PRESERVE /RESTORE THE SPECIFIED CONDITION

MAINTENANCE OF GAS TURBINE


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IMPACT ON QUALITY OF MAINTENANCE

ADOPTING MANUFACTURERS RECOMMENDATION

PROPER PLANNING OF INSPECTIONS

AVAILABILITY OF DOCUMENTS AND INSTRUCTIONS

AVAILABILTY OF TOOLS

STOCKING AND PROCUREMENT OF SPARES

REPLACEMENT OF WORNOUT SPARES INSTEAD OF

REPAIR

WORKING CONDITIONS AND SKILLED WORK CREW

ACCESSIBILITY OF OEMS TECHNICAL SUPPORT


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HOT GAS PATH INSPECTION

GT #11 06-12-2002 to 15-02-2003

GT #12 02-05-2003 to 27-05-2003


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ROTOR

UPENDING


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TIE ROD

COLLAR


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CONSTRUCTION

Gas Turbine: SIEMENS make V94.2

Rating: 137.7 MW at ISO

Conditions

Turbine: 4 Stages

Compressor: 16 Stages

Combustion Chamber: 2 SILO type with

eight Burners in each


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HOT GAS PATH INSPECTION

ORIGINAL INTERVAL : 25,000 EOH TO ENSURE

BASE MATERIAL WAS NOT DAMAGED AND

SUBSEQUENT REFURBISHMENT ALLOWED

REVISED INTERVAL: 33,000 EOH . MOVING ROW

1 AND 2 NO LONGER REFURBISHED


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HGPI

INVOLVES

DISASSEMBLY COMBUSTION

CHAMBERSDISASSEMBLY OUTER CASING

REMOVAL OF TURBINE

STATIONARYBLADE CARRIERSREMOVAL OF TURBINE ROTATING

BLADES STAGE 1 AND 2


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Activities to be carried out HGPI

Components Measure HGPI Major

inspection

1. Turbine blades

Moving blade row 1 & 2 Replacement Yes Yes

Moving blade row 3, stationary

blade rows 1 & 2

Refurbishment Yes Yes

Moving blade row 4, stationary

rows 3 & 4

NDE Yes Yes


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Activities to be carried out HGPIComponents Measure HGPI Major

inspection

2. Compressor blades

Coated rows Refurbishment No Yes

Uncoated rows NDE, Visual

inspection

No Yes

Components Measure HGPI Major

inspection

3. Stationary bladecarriers

Turbine NDE, Visual

inspection

Yes Yes

Compressor NDE, Visual

inspection

No Yes


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Activities to be carried out HGPIComponents Measure HGPI Major inspection

4. Casing hot gas

path boundary

items

Inner casing Regenerative heat treatment No yes

Mixing casing Regenerative heat treatment No yes

Combustion chamber tiles

(flame tube)

Replace in the event of negative

findings

Yes Yes

Components Measure HGPI Major inspection

5. Rotor (highly

stressed locations)

NDE, Visual inspection No Yes

6. Burners NDE, Visual inspection, boroscopicinspection, pressure/ leak test

Yes Yes

7. Control

equipment, piping

Function test, pressure/ leak test,

condition based repair or

replacement

Yes Yes


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Magnetic Particle Inspection

Hirth Coupling of Turbine as well as

compressor disc

Compressor vanes and blades

Tie Rod

Matching grooves of Damping rings

Transition of aerofoil to bearing ofIGV


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Ultrasonic Testing

Gas Distribution Pipings and SpiderArms

Transition of aerofoil to hook ofcompressor vanes

Inner casing & Mixing Chamber walls


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Dye Penetrant Test

Bearings / Thrust Pads

K-Ring

All weld seams Tile Holders in combustion chambers

Stationary & Rotating blades of Turbine

Stage #3 & #4Grooves of Turbine Rotor Disc Stage #1 & #2


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Major Observations

Cracks in turbine stationary vanes stage 3and stage 4 lower half

Coating abrasion in compressor bladesCracks in right side of inner casing

Dent marks in inner casing seal ring

Wear in cooling ring of mixing chamberGap in compressor stationary vane

transition hook has increased.


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VIEW OF

DAMAGED

TILES AND TILE

HOLDERS


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BOROSCOPIC

INSPECTION OF

FUEL OIL BURNER

Hot Gas Path Inspection 1

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