Boiler Life Asessment

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World Energy CouncilMinistry Of Electricity & Energy

Egyptian Holding Company For Electricity

Upper Egypt Electricity Production Company

Boiler life assessmentBY

ENG: IBRAHIM EL SHAHAAT


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ContentsContents

1. The purpose of boiler life assessment

2. Life Evaluation by Inspection3. Preparations for Inspection

4. Data requirement

5. Inspection of high pressure parts.

6. Sample tube inspection.

7. Visual inspection for other parts of boiler .

8. Water quality survey.

9. Visual Inspection for aux Equipment

10. high pressure parts Inspection details


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assessment

Evaluate the present state and the condition of the boilercomponents in order To continue stable and reliable boiler operation

Evaluate the remaining life for Superheater and Reheater bymetallurgical inspection

Evaluation of creep life and future inspection scheme bymetallurgical inspection for water wall, economizer, Superheater and

Reheater tubes Evaluation degree of creep damage for Superheater and Reheater

by hardness test

Evaluate the remaining life based on thickness Measurement forwater wall,

Evaluate the remaining life based on thickness thinning foreconomizer due to low Temperature Corrosion,

Evaluate the remaining life based on thickness thinning forSuperheater and Reheater tubes due to high Temperature Corrosion

Confirm the cause of the inner scale generation

Evaluate the remaining life based on check of metal structure ,innerscale ,etc for sample tube


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2-Life Evaluation by Inspection

FAILURE DAMAG CAUSA PHENOMENON LIFE EVALUATION INSPECTION ITEM

CREEP Clogging withforeign material

Deposition andgrowth of scale onInner surface

Long-term stress

Swelling

Metal structurechange

Outside diameter andthickness measurement

Metallurgicalinspection

Metallurgical inspection for SH, RHheader,

Metallurgical inspection and NDT(UT) for main steam pipe line andhigh temperature RH pipe

FATIGUE Cycle thermalstress

Growth of crackStress analysis

Surface crackinspection (PT,MT)

NDE (PT, MT) of spacer welded forSH and RH Tube

CORROSIONFATIGUE

Cyclic thermalstress undercorrosiveenvironment

Interaction ofcorrosion andfatigue

Ultrasonic test

Sample tubeinspection

Sample tube inspection for SH, RHand water wall

Check of Burner Nozzle and WindBox Damper

CORROSION

EROSION

High tempcorrosion

Low tempcorrosion

Ash erosion

Thicknessthinning

Annual thicknessmeasurement

measurement of tube thicknessfor SH ,RH, Water Wall and Eco byUT

Steam drum

Boiler aux

Eco Hanger tube by endoscope,

etc


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3-Preparations for InspectionBefore inspection

Superheater, reheater, economizer and water wall cleaning

Air heater washing

Scaffolding

Removal of insulation

Open man holes, inspection holes, flanges etc

During inspection Surface preparation of inspection parts

Surface finishing (grinding) of inspection parts

Instrument of apparatus of inspection

Cutting tubes

Welding tubes

Material requirement

New tubes Man hole packing

insulation

Period of inspection Two weeks


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4- Data requirement

Boiler reference data Steam temperature 0cMaximum Steam flow Ton/hr Boiler design pressure Kgm/cm2

Feed water temp 0c Reheated inlet steam temperature 0c Reheated outlet steam temperature 0c Reheater design pressure Kgm/cm2

Kind of fuel Gas, Oil

Functional inspection with boiler in operation Collection of drawings and main technical data Recording of actual operating and functional data at different

loads and conditions at MCR and Verification of the operation ofthe boiler

Collection of data relevant to the thermal history andinterventions ,if any made on the boiler during his operation life

5 I f


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5-Inspect on of g pressureparts

NON Destructive test for the following item1. Economizer headers, coils, Piping from economizer to steam drum,.2. Steam drum.3. Furnace water walls, screen, roof wall, feeders, riser ,Water walls

headers.

4. Saturation steam pipe.5. Primary, secondary super heater.6. Connecting pipe between primary superheater and secondary

superheater.7. Reheater.8. Main SH steam pipes

**Inspection item

1. External visual inspection2. Internal visual inspection with endoscope3. UT for thickness measurements by UT4. MT and UT on circumferential welds5. MT on piping attachments

6. Metallographic inspection by plastic replicas7. MT on nozzles welds of the coil tubes


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the minimum required thickness

t= minimum required thickness.

D = outside diameter of cylinder.

e = thickness factor for expanded tube ends.

P= maximum allowable working pressure.

S= maximum allowable stress value at the design temperature of the metal.


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Design / Operating Informationfor calculation of remaining time based on thickness

Design informationmaterial type or gradeNominal outside diameterDesigning pressure

Design lifeDeign temperatureOriginal nominal thickness

Operating informationMaximum tube metal

temperatureNormal operating pressureOriginal measured minimum

thicknessMetal thinning rate

Thicknessmeasurements

of water walltubes furnace


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Minimum required thickness for

SA178-c

Minimum required thickness for different working

conditions for materials SA178-c


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6-Sample tube-Destructive test for the Sample tubeFor Water Wall ,SR and

RH tubes

Life diagnoses based on check of metal structure, thickness,inner scale, etc

Sample tube takes according to the result of hardness measurement

Investigation Items Visual inspectionNon destructive test Chemical analysisMeasurement of the tube dimension Hardness measurement

Cross sectional microstructure observation Steam oxidation observation Creep rupture testMeasurement of the inner scale thickness

Information

Material of Sample tube tube dimension


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sample tubes

Thinning of bulged zone Internal surface scaleExternal surface scale


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Optical micrograph

Optical micrograph of non-bluged zones tube wall side showingferrite pearlite structure with no

internal defects


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Normal and deterioratedmicrostructure

normal microstructure

( good condition tube)Which shows a

typical ferritic pearliticstructure

deterioratedmicrostructure whichshows thedecomposition of thepearlitic colonies


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7-Visual inspection for other parts ofboiler

BurnerWind Box

Hanger for riser pipe

Outer casing

Skin casingBuckstay


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8-Water Quality Survey

This inspection to confirm the cause of the scalegeneration

Inspection items

Check of laboratory analysis method for quality items

Confirmation of water quality results at previous loadoperation

Check of instrument condition on sampling rack usedfor water quality control

Confirmation of PH value and iron/copper balance inthe cycle


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9-Visual Inspection for aux Equipment

This inspection to confirm the cause of the scalegeneration

Condenser hot well.Condenser tube side

Deaerator.LP-feed water heater.Feed water tank.HP-feed water heater.


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10-high pressure parts Inspection details

1. Economizer headers ,coils, Piping from economizer to steamdrum,

2. Steam drum

3. Furnace water walls, screen, roof wall, feeders, riser ,Water wallsheaders

4. Saturation steam pipe

5. Primary, secondary superheater

6. Connecting pipe between primary super heater and secondarysuperheater

7. Reheater

8. Main SH steam pipes


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10-1 Economizer

NDE For headers External visual inspection Internal visual inspection with endoscope Measurement of thickness by UT MT on nozzles welds of the coil tubes and headers attachments MT and UT on circumferential welds between header and conical pieces

NDE For tube External visual inspection Measurement of economizer tube and hanger tube thickness with

endoscope UT for thickness measurements

NDE For Piping from economizer to steam drum External visual inspection for piping, hangers and supports UT for thickness measurements MT and UT on circumferential welds MT on piping attachments MT on the elbows extrados


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10-2 steam drumBefore the NDT inspections, the

internal parts of the drum shall bedismantled

NDE For steam drum External visual inspection Internal visual inspection UT for shell thickness measurements UT for head thickness measurements MT and UT on circumferential and longitudinal welds MT on steam drum attachments (saddles and

accessories) MT on nozzles welds

NDE For downcomers External visual inspection for piping, hangers and

supports UT for thickness measurements MT and UT on circumferential welds MT on piping attachments


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10-3 furnace water walls, screen,roof wall, Feeders and Riser

NDE for furnace water walls, screen, roof wall External visual inspection UT for thickness measurementsMetallographic examination by plastic replicas Samples for destructive test

NDE for feeders and riser External visual inspection UT for thickness measurements

NDE for headers External visual inspection

Internal visual inspection with endoscope UT for thickness measurementsMT on nozzles welds of the coil tubesMT on branches welds and headers attachments, including

drains tubes


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10-4 Saturation steam pipe

NDE for each pipe External visual inspection

UT for thickness measurements

MT and UT on circumferential welds

MT on piping attachments

MT on the elbows extrados


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10-5 Primary,Secondary Superheater

NDE for the headers

External visual inspection Internal visual inspection with endoscopeUT for thickness measurementsUT for head thickness measurementsMT on nozzles welds of the coil tubes

MT on nozzles welds to the shell of the inlet/outlet pipeMT and UT on circumferential welds between header and

heads/ pipingMT on headers attachmentsMetallographic examination by plastic replicas

NDE for CoilsExternal visual inspectionUT for thickness measurements Internal visual inspection with endoscopeHardness measurements

Samples for destructive examinations

10 6 C i i b i


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10-6 Connecting pipe between primaryand Secondary Superheater,Desuperheater ATPS

NDE for connecting pipeExternal visual inspectionUT for thickness measurementsMT and UT on circumferential weldsMT on piping attachments

MT on the elbows extradosMetallographic examination by plastic replicas

NDE for desuperheater ATPSExternal visual inspection Internal visual inspection with endoscopeUT for thickness measurementsMT on circumferential weldsMetallographic examination by plastic replicas


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10-7 ReheaterNDE For each one of the headersExternal visual inspection Internal visual inspection with endoscopeUT for thickness measurementsUT for head thickness measurementsMT on nozzles welds of the coil tubesMT on nozzles welds to the shell of the inlet/outlet pipe

MT and UT on circumferential welds between header andheads/ piping

MT on headers attachmentsMetallographic examination by plastic replicas

NDE For Coils

External visual inspectionUT for thickness measurements Internal visual inspection with endoscopeHardness measurementsSamples for destructive examinations


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10-8 Main SH steam pipes

NDE for each pipe External visual inspection

UT for thickness measurements

MT and UT on circumferential welds

MT on piping attachments

MT on the elbows extradosMT on nozzles welds to the pipe

Metallographic examination by plastic replicas


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Documents

Boiler Life Asessment