boilers rla

8/17/2019 Boilers RLA

1/60

R.S.DAS,NALCO 1

Residual Life Assessmentand

Life Extension ProgrammeIn Power Boilers

of Captive Power Plant of NALCO

By

R.S.DAS, Chief Manager (MECH),CPP,NALCO


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R.S.DAS,NALCO 2

National Aluminium Company is an integratedaluminium producing Public Sector Companyunder Govt . Of India with Bauxite Mines,

Alumina Refinery Plant, Smelter Plant, CaptivePower Plant and Port Facility situated at differentlocations of Orissa and Andhra Pradesh .

BRIEF ABOUT NALCO

(National Aluminium Company Ltd)


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R.S.DAS,NALCO 3

METAL PRODUCTION CAPACITY: 3.45 lakh tones per annum

NO OF METAL PRODUCING POTS: 720

POWER CONSUMED BY THE POTS : 576 MW

POWER GENERATING CAPACITY : 8 X 120 = 960 MW

BOILER CAPACITY: 430 T/HR ( unit-1 -6),390T /HR( unit-7 & 8)

BOILER TYPE:BALANCED DRAFT,NATURAL CIRCULATION,PULVERISED COAL,

CORNER FIRED,WATER TUBE,REHEAT TYPE

PRESENT STATUS OF THE COMPANY


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R.S.DAS,NALCO 4

120 MW X 8


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R.S.DAS,NALCO 5

RAW WATER HP D/A LP HEATER GRIDCOHEATER BFP

WATER TREATMENT

HPT IPT LPT GENERATOR

SMELTER

COOLING 10.5 KV 220 KV

TOWER

CEPCW PUMP 6.6 KV

CONDENSER UAT

REHEATED STEAM

GT 6.6 KV

SAT

CONDENSATE CHIMNEY

STORAGE TANK

BOILER

COAL BUNKERS

ECONOMISER

ELECTRO STATIC

PRECIPITATOR

FUEL OIL TANK

MILL ID FAN

FD FANS

PA FAN

COAL CRUSHER

ASH SLURRY PUMPS


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R.S.DAS,NALCO 6

Requirement of Residual Life AssessmentStudy (RLA )

• To assess the present condition of theboiler pressure parts

• To assess the remaining life of the Boiler

Pressure parts

• Statutory requirement as per IBR

regulation “391A”


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R.S.DAS,NALCO 7

RLA Study of Boiler is a statutory requirement as per regulation “391A”

of “Indian Boiler Regulation-1950”, which says:-

1. The Boilers which are operating at a temperature of 400oC & aboveincluding utility or industrial boilers & all boiler parts operating inthe creep range of boiler shall be non-destructively tested as perTable-1, after they are in operation for 1,00,000 hours forassessment of the remnant life of parts.

2. The parts of a boiler when it completes a life of 25 years are to be

tested as per Table-2 for assessment of remnant life of such parts.If results are acceptable as per the standards laid down by theCentral Boiler Board, a certificate shall be issued by the Chief Inspector of Boilers for extending the life of boiler for a furtherperiod of 10 years or such less period as recommended by theRemnant Life Assessment Organisation. The remnant life shall becarried out thereafter every five years by approved parties by theCentral boiler board.


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R.S.DAS,NALCO 8

PURPOSE OF RLA STUDY

Evaluation of present condition of pressure

parts & piping

• Avoiding premature pressure parts failures

and associated unforeseen outages

• Identification of problem areas

• Analysis of root cause of problems

•

Estimation of balance life of pressure parts• Providing technically sound and viable

proposal for implementation


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R.S.DAS,NALCO 9

RLA STUDY IN CAPTIVE POWER PLANT, NALCO

UNIT YEAR

2(part RLA of RH) 1997

1 2000

2 2003

3 2004

4 20045 2005

6 2009( DUE)

7 2015( DUE)

8 2016(DUE)


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R.S.DAS,NALCO 10

Methodology adopted for Residual Life Assessment in NALCO,CPP By M/S BHEL

• Review of the past data• Field Visual and dimensional inspection

• UT

• DP

• Hardness Measurement

• Replication for Metallography

• Inside oxide scale thickness measurement

• Video Scopic Examination

• Tube Sampling

• Laboratory testing

• Recommendation and life prediction


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R.S.DAS,NALCO 11

TIME PERIOD FOR THE STUDY : 10 TO 12 DAYS

PRELIMINARY REPORT SUBMITTED IMMEDIATELY AFTER THE STUDY

THE FINAL REPORT WITH RECOMMENDATIONSUBMITTED WITHIN 5 TO 6 MONTHS TIME.

TEAM MEMBERS : 12 INCLUDING ONE TEAM LEADER


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R.S.DAS,NALCO 12

Tests Done during RLA Study of ourBoilers

• High temperature headers & piping – Ultrasonic, dye-penetrant tests

– Video scope, Replication

– Other inspections like

• Dimensions,

• Internal inspection

• Insitu hardness


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R.S.DAS,NALCO 13

Tests Done during RLA Study of our

Boilers (Cont. )

• Superheater & reheater tubes

– Tube samples, ultrasonic test

– OD & Thickness

– Deposit Analysis

– Steam side oxide scale thickness

– Life prediction

• Attemperators

– Ultrasonic, dye penetrant tests

– Replication, hardness

– Fiber optics


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R.S.DAS,NALCO 14


Boilers (Cont. )

• Furnace & convection pass tubes – Tube sampling, ultrasonic test

– Deposit analysis (Internal & External)

• Drums & downcomers – Ultrasonic, dye-penetrant tests

– MPI (Wet fluorescent & Dry)

– Video scope


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R.S.DAS,NALCO 15


Boilers (Cont. )STEAM PIPING( MS,CRH,HRH & FW)

• Visual Inspection

• Replication, Insitu Hardness• OD & thickness

• Hangers & Supports Inspection

General guidelines for selecting inspection points – High turbulence or velocity

– Condensation points

– Dead ends & high stressed points

– Areas immediately downstream of chemicalinjection points

– All supports


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R.S.DAS,NALCO 16

DIMENSIONAL MEASUREMENT AT CPP NALCO DURING

RLA


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R.S.DAS,NALCO 17

DP TEST ON CRITICAL PIPING JOINTS AT CPP ,NALCO


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R.S.DAS,NALCO 18

DRUM INSPECTION AT CPP,NALCO


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R.S.DAS,NALCO 19

HANGER

CHECKING ATCPP ,NALCO


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R.S.DAS,NALCO 21

MICROSCOPIC EXAMINATION DURING REPLICATION

AT CPP ,NALCO


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R.S.DAS,NALCO 22

INTERNAL OXIDE SCALE MEASUREMENT AT CPP ,NALCO


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R.S.DAS,NALCO 23

IOT AT CPP ,NALCO

PROBE


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R.S.DAS,NALCO 24

VIDEO SCOPE AT CPP BOILER ,NALCO

BOTTOM RING

HEADER


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R.S.DAS,NALCO 25

VIDEO SCOPE OF

SH HEADER

STUB


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R.S.DAS,NALCO 26

TUBE SAMPLING AND LABORATORY TESTING

TUBE SAMPLES WERE COLLECTED FROM DIFFERENTZONES OF OUR BOILERS FOR LABORATORY TESTING

1. WATER WALL- 04 NO2. PLATEN SH- 02 NO

3. CRH- 02

4. RH INTER BANK-02

5. HRH-02

6. LTSH-027. ECO-01


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R.S.DAS,NALCO 27

Laboratory testing included thefollowingVisual Examination

Dimensional measurementChemical composition analysis

Flattening test for water wall tubes

Hardness measurement

Steam side oxide scale thickness measurement

Micro examination of all the tube samples and

insitu replicas ( 30 no) for spheroidisation level of

PM,WELD &HAZ and creep level( PM only)

Internal deposit analysis of water wall tubes and

Boiler Drum

Creep rupture testing for rupture life of Platen SH

& RH coil tubes


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R.S.DAS,NALCO 28

General Recommendations Format of RLA

FOR CPP, NALCO BY BHEL

Residual life of RH and SH coil tubes

Creep and Spheroidisation level of pressure partcomponents

Parts needing replacements

Parts needing repairsChemical cleaning advice & procedure

Advice on water regimes

Future plans of testsModifications required for life extension

Any other specific observations


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R.S.DAS,NALCO 29

The internal deposit analysis of water wall andDrum (quantity and composition) were done for

all the units .Norms of our OEM (BHEL)

•< 15 mg/cm2 – Clean

• 15-40 mg/cm2 – Moderately clean

•>40mg/cm2 – Very dirty

All our boilers were found in the moderately cleanzone after the deposit analysis.

No immediate chemical cleaning was recommended.

INTERNAL DEPOSIT ANALYSIS


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R.S.DAS,NALCO 30

Life Prediction Techniques Used

• By using appropriate damage parameter

• Using strain measurements

• Post exposure testing

• Using Steam Side Oxide scale thickness


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R.S.DAS,NALCO 31


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R.S.DAS,NALCO 32

Life prediction based on Oxide Scale

Thickness Analysis

The steam side oxide scale thickness are measured at

critical locations in the high heat flux zone and near the

bottom bends of the super heater and re heater coils.

These values are used as inputs to computer-based

software BHELMOLT which accurately calculates thetube metal temperatures for the entire cross-section of

tubes and calculates the residual life .


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R.S.DAS,NALCO 33

Oxide Scale Thickness AnalysisDATA INPUT TO THE SOFTWARE

ORIGINAL TUBE OD

ORIGINAL TUBE THICKNESS

MATERIAL

SERVICE HOURSPRESSURE

OXIDE SCALE THICKNESS

MINIMUM TUBE THICKNESS

MINIMUM TUBE OD


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R.S.DAS,NALCO 34

OUT PUT• TOTAL RUPTURE LIFE

• REMAINING LIFE


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R.S.DAS,NALCO 35

COIL WISE OXIDE THICKNESS

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47

COIL NO

O X I D E T

H I C K N E S S

I N

M M

OXIDE THICKNESS

COILWISE OXIDE SCALE THICKNESS OF REHEATER


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R.S.DAS,NALCO 36

COIL WISE TEMP

500

520

540

560

580

600

620

640

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47

COIL NO

T E M P E R A T U R E I N

D E G R E E

TEMP

COIL WISE REMAINING LIFE IN HRS

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47

COIL NO

R E M A I N I N G

L I F E I N

H R

REMAINING LIFE IN HRS

COIL WISE

SERVICE TEMP.

COIL WISEREMAINING LIFE.


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R.S.DAS,NALCO 37

POST EXPOSURE TESTING

The sample tubes, removed from Boiler SH and RH aresubjected to burst tests at accelerated temperature andservice pressure in the hot burst rig facility available atBHEL’s laboratory. The pressure and temperature arecontrolled very accurately.

To predict the remaining life from the results of

stress rupture tests, the following methods are adopted.

1. Parametric extrapolation2. Application of Life fraction rule


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R.S.DAS,NALCO 38EXTRAPOLATED LIFE OF SH COIL


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R.S.DAS,NALCO 39

LIFE PREDICTION OF OUR RH AND PLATEN SH TUBESWAS DONE BASED ON INSIDE OXIDE SCALE THICKNESSMEASUREMENT.

IN UNIT-2 , 37 NO RH COILS WERE REPLACED IN 2001BASED ON LIFE PREDICTION DONE IN 1997.

IN UNIT-1 , 34 NO RH COILS WERE REPLACED IN 2005BASED ON LIFE PREDICTION DONE IN 2000.

IN OTHER UNITS THE PREDICTED LIFE OF RH AND SH

COILS ARE AS BELOW.

LIFE PREDICTION

C O A S


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R.S.DAS,NALCO 40

DESCRIPTION PREDICTED LIFEUNIT-3 RH AND PLATEN SH

COIL TUBES

MORE THAN 1 LAKH HOUR

UNIT-4 PLATEN SH MORE THAN 1 LAKH HOUR

UNIT -4 HRH coil Coil 30 fifth

ckt rear

54,500 Hrs

Unit-4 HRH Coil 32 fifth ckt rear 47,500 Hrs


Unit-4 all other RH coils MORE THAN 1 LAKH HOUR




PREDICTED LIFE OF RE HEATER TUBES


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R.S.DAS,NALCO 41

DESCRIPTION PREDICTED LIFE

UNIT-1 PLATEN SH COILTUBES MORE THAN 2 LAKH HOUR

UNIT-2 PLATEN SH COIL

TUBES


UNIT-3 PLATEN SH COILTUBES


UNIT-4 PLATEN SH COIL

TUBES


UNIT-5 PLATEN SH COILTUBES


PREDICTED LIFE OF SUPER HEATER TUBES


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R.S.DAS,NALCO 42

Creep Cavity Level Classification System

Proposed by Wedel & Neubauer


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R.S.DAS,NALCO 43

CREEP AND SPHEROIDISATION LEVEL

THE CREEP AND SPHEROIDISATION LEVEL OF ALL THE PRESSURE PARTS WERE ANALYSED BY

BHEL EXPERTS.NO MAJOR ABNORMALITIES WERE FOUND IN

MOST OF THE CASES.

ONLY IN UNIT-3 ISOLATED CREEP CAVITIESWERE OBSERVED ON THE GRAIN BOUNDARIESOF MS PIPE LINE . BHEL SUGGESTED FOR RE-EXAMINATION AFTER THREE YEARS WHICH IS

TO BE DONE IN 2008.

SUMMARY OF THE OBSERVATIONS OF RLA STUDIES OF DIFFERENT UNITS


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R.S.DAS,NALCO 44

SL.

N

O.

AREA OFTHE

BOILER PR

PARTS

UNIT # 1

(OR-369)

UNIT #2

(OR-370)

UNIT # 3

(OR-372)

UNIT # 4

(OR-382)

UNIT # 5

(OR-397)

UNIT# 6

(OR-

513)

UNIT# 7

(OR-

696)

UNIT# 8

(OR-

713)

01. RLA Study of

Boiler after

1,00,000 Hrs.

of Operation

Done in

August’ 2000

Done in

December’

2003

Done April’

2004

Done in July’

2004

Done in June-

2005

Not

due

(runnin

g hrs <

100000

)

Not

due

(runnin

g hrs <

100000

)

Not

due

(runnin

g hrs <

100000

)

02. Boiler Drum

- Visual

-Insitu Replica

-Hardness

-UT

-DP- Deposit

analysis

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

NA NA NA

03. Water Wall

-Visual

-Sampling(

internal

deposit and

hydrogen

embrittlement)

- Dimensions

( OD &

thickness)

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

NA NA NA

SUMMARY OF THE OBSERVATIONS OF RLA STUDIES OF DIFFERENT UNITS


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R.S.DAS,NALCO 45

SL.

NO

.

AREA OF

THE BOILER

PR PARTS

UNIT # 1

(OR-369)

UNIT #2

(OR-370)

UNIT # 3

(OR-372)

UNIT # 4

(OR-382)

UNIT # 5

(OR-397)

UNIT #

6 (OR-

513)

UNIT #

7 (OR-

696)

UNIT #

8 (OR-

713)

04. Eco Coils;

- Visual

-Dimensional

checks,

-Sample check

formetallography

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

NA NA NA

05. Low tem

Header ( Eco

in and

out,Bottom

ring header );

- Visual

-FibrovisionInspection

-Hardness

-DP

-Dimensions

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

NA NA NA

06. LTSH Coils;

- Visual

- Hardness

-Dimensional

checks,

-Sample check

for

metallography

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

NA NA NA


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R.S.DAS,NALCO 46

SL.

NO

.

AREA OF

THE BOILER

PR PARTS

UNIT # 1

(OR-369)

UNIT #2

(OR-370)

UNIT # 3

(OR-372)

UNIT # 4

(OR-382)

UNIT # 5

(OR-397)

UNIT #

6 (OR-

513)

UNIT #

7 (OR-

696)

UNIT #

8 (OR-

713)

07. LTSH Outlet

Header ( SHH

– 9 );

- Visual

-Fibrovision

Inspection

-Insitu Replica

-Hardness

-UT

-DP

-Dimensions

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

NA NA NA

08. SH Inlet

Header ( SHH

– 10 );

-Fibrovision

Inspection

-Insitu Replica

-Hardness

-UT-DP

-Dimensions

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

NA NA NA


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R.S.DAS,NALCO 47

SL.

NO

.

AREA OF THE

BOILER PR PARTS

UNIT # 1

(OR-369)

UNIT #2

(OR-370)

UNIT # 3

(OR-372)

UNIT # 4

(OR-382)

UNIT # 5

(OR-397)

UNI

T #

6

(OR

-

513)

UNI

T #

7

(OR

-

696)

UNI

T #

8

(OR

-

713)

09. SH Outlet Header (

SHH – 11 );

-Fibrovision

Inspection-Insitu Replica

-Hardness

-UT

-DP

-Dimensions

No specific

recommendation

and found o.k

No

specific

recommendati

on and foundo.k

No specific

recommendation

and found o.k

No

specific

recommend

ation andfound o.k

No specific

recommendation

and found o.k

NA NA NA

10. Platen SH Coil

-IOT Measurement

-DP-Dimension check,

-Samples for Creep

rupture &

Metallography Test.

- Hardness

Predicted life :

> 2,00,000 hrs

Predicted

life :

> 1,00,000 hrs

Predicted life :

> 1,00,000 hrs

Predicted

life :

> 1,00,000hrs.

Predicted life :

> 1,00,000 hrs.

NA NA NA

11. Desuperheater :-

-Fibrovision

Inspection.

-Insitu Replica

-Hardness

-UT

-DP

-Dimension check

No specific

recommendation

and found o.k

No specific

recommendati

on and found

o.k

No specific

recommendation

and found o.k

No specific

recommend

ation and

found o.k

No specific

recommendation

and found o.k

NA NA NA

SL.

NO

AREA OF THE

BOILER PR PARTS

UNIT # 1

(OR-369)

UNIT #2

(OR-370)

UNIT # 3

(OR-372)

UNIT # 4

(OR-382)

UNIT # 5

(OR-397)

UNI

T # 6

(OR

UNI

T #

7

UNI

T #

8


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R.S.DAS,NALCO 48

. (OR-

513)

7

(OR-

696)

8

(OR-

713)

12. Reheater Inlet Header( RHH – 1 )

-Fibrovision

Inspection

-Insitu Replica

-Hardness

-UT

-DP

- Dimensions

No specificrecommendation

and found o.k

Nospecific

recommendatio

n and found o.k


and found o.k

No specificrecommendatio

n and found o.k


and found o.k

NA NA NA

13. Reheater Outlet

Header ( RHH – 2 )

-Fibrovision

Inspection

-Insitu Replica

-Hardness

-UT

-DP

- Dimensions

No specific

recommendation

and found o.k

No

specific

recommendatio

n and found o.k

No specific

recommendation

and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendation

and found o.k

NA NA NA

14. Reheater Coil :-

-IOT Measurement

-Samples for Creep

rupture &

Metallography Test

-Dimension check.-Hardness

Replacement of

Reheater Coils

(25 - 48) from

Interbank outlet

to HRH outlet

header; ( RLA :-2000, Aug ) .

Action taken :

Reheater Coils

(15 - 48) from

Interbank outlet

to HRH outlet

header were

replaced inMay –2005.

Predicted life:

i) Front coils >

95,000 hrs

ii) Rear coils >

1,00,000 hrs

Predicted life :

> 1,00,000 hrs

Predicted life :

1. > 1,00,00 for

all coils except

HRH coil

30,.32,33 in the

fifth ckt rear.2. Coil 30 fifth

ckt rear-

54,500 hrs,

3. Coil 32 fifth

ckt rear-

47,500 hrs

4. Coil 33 fifth

ckt rear-56,500 hrs,

Predicted life :

1. > 1,00,00 for

all coils except

HRH coil

22,31,33 in the

fifth ckt rear.2. Coil 22 fifth

ckt rear- 59,100

hrs,

3. Coil 31 fifth

ckt rear- 56,100

hrs

4. Coil 33 fifth

ckt rear- 66,100hrs,

NA NA NA

SL.

NO

AREA OF THE

BOILER PR PARTS

UNIT # 1

(OR-369)

UNIT #2

(OR-370)

UNIT # 3

(OR-372)

UNIT # 4

(OR-382)

UNIT # 5

(OR-397)

UNI

T #

6

UNI

T #

7

UNIT

# 8

(OR


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R.S.DAS,NALCO 49

. 6

(OR

-

513)

7

(OR

-

696)

(OR-

713)

15. a) MS Pipe line :-

-Insitu Replica

-UT

-DP

-Dimension checks.

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

Reexamination

in 2008

No specific

recommendatio

n and found o.k

No specific

recommendati

on and found

o.k

NA NA NA

b) HRH Pipe line :-

-Insitu Replica-UT

-DP

-Dimension checks.

No specific

recommendation and found o.k

No specific


No specific


No specific


No specific

recommendation and found

o.k

NA NA NA

c) CRH Pipe line :-

-Insitu Replica

-UT

-DP

-Dimension checks.

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No

specific

recommendati

on and found

o.k

NA NA NA

d) MS Pipe line from

MS-1 & MS-2

up to Turbine stop

valve.

-Insitu Replica

-UT

-DP

- Dimension

checks.

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

Reexamination

in 2008

No specific

recommendatio

n and found o.k

No

specific

recommendati

on and found

o.k

NA NA NA

e) HP Bypass Pipe

line

-Insitu Replica

-UT

-DP

-Dimension checks.

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No specific

recommendatio

n and found o.k

No

specific

recommendati

on and found

o.k

NA NA NA


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R.S.DAS,NALCO 50

S

L. N

O

.

AREA OF THE

BOILER PR PARTS

UNIT # 1

(OR-369)

UNIT #2

(OR-370)

UNIT # 3

(OR-372)

UNIT # 4

(OR-382)

UNIT # 5

(OR-397)

UNIT # 6

(OR-513)

UNIT #

7 (OR-

696)

UNI

T #

8

(OR

-

713)

f) Feed water Pipe

line

-Insitu Replica

-UT-DP

-Dimension checks.

No specific

recommenda

tion and

found o.k

No specific

recommend

ation and

found o.k

No specific

recommendatio

n and found o.k

No specific

recommen

dation and

found o.k

No specific

recommen

dation and

found o.k

NA NA NA

16

.

RLA Study of Boiler

after 1 lakh hrs of

Operation

DONE DONE DONE DONE DONE 2009 2015 2016

17 Compete RLA Study

of Boiler after 25Years of Operation

2008 2009 2009 2009 2010

BENEFITS OF RLA STUDIES IN CPP NALCO


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R.S.DAS,NALCO 51

A THOROUGH CHECK OF ALL THE PRESSURE PARTS,CRITICAL PIPE LINE AND HANGER SUPPORTS COULD BE MADE.

THE SPHEROIDISATION LEVEL AND CREEP LEVEL OF THE PRESSURE PARTSINCLUDING THICK WALLED COMPONENTS LIKE DRUM, ALL HEADERS,PIPE LINES COULD BE ASSESSED.

THE LIFE OF THE PLATEN SUPER HEATER AND REHEATER TUBES COULD BEPREDICTED.

THE DEPOSIT INSIDE AND OUT SIDE OF THE TUBES COULD BE ANALYSED.

THE CONDITION OF THE HANGERS COULD BE ASSESSED AND REMEDIAL

ACTION COULD BE TAKEN.CORRECTIVE AND PREVENTIVE MEASURES LIKE TIMELY REPLACEMENTOF RH COILS IN UNIT-1( 34 NO) AND 2 (37 NO) COULD BE INITIATED.

PLANT AVAILABILITY HAS BEEN INCREASED BY TIMELY REPLACEMENT OFPRESSURE PARTS.

OPERATING PARAMETERS ARE NOW BETTER CONTROLLED ANDTEMPERATURE EXCURSIONS ARE ELEMINATED.

BENEFITS OF RLA STUDIES IN CPP NALCO


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R.S.DAS,NALCO 52

EXPENDITURE FOR RLA STUDIES IN CPP

NALCO

(VALUE OF THE CONTRACTS ON BHEL)

UNIT-1 : 20.5 LAKH

UNIT-2 &3 : 20.5 LAKH X 2UNIT-4 &5 : 20.00 LAKH X 2


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R.S.DAS,NALCO 53

RH TUBE FAILURE IN UNIT-2

0

1

2

3

4

5

6

7

1988-2002 2002-07

YEAR

NO


54/60

R.S.DAS,NALCO 54

RH TUBE FAILURE IN UNIT-1

0

1

2

3

4

5

6

1988-2002 2002-07

YEAR

NO


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R.S.DAS,NALCO 55

LIFE EXTENSION MEASURES IN THE BOILERS OF NALCOCAPTIVE POWER PLANT

1.FITMENT OF PROTECTIVE SHIELDS IN EROSION

PRONE AREAS LIKE ECONOMISER TUBES , BENDS AND

LOW TEMPERATURE SUPER HEATER HEADERS,SCREENTUBES,WATER WALL “S” PANEL ( TOP OF QUENCHING

NOZZLE)

2. FITMENT OF 6 MM SS RODS IN THE BURNER PANEL

TUBES TO DIVERT THE SECONDARY AIR THUS

PREVENTNG EROSION


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R.S.DAS,NALCO 56

3.GANGING OF ECONOMISER COILS TO MAKE ECO COIL

SPACING UNIFORM.

4.REPLACEMENT OF TUBES ON THE BASIS OF

THICKNESS MEASUREMENT

5. SETTING SOOTBLOWER STEAM BLOWING POSITION

7MM MORE THAN THE DESIGNED VALUE TO MINIMISE

STEAM EROSION

6. REPLACEMENT OF REHEATER TUBES ON THE BASIS

OF VISUAL INSPECTION OF “FIRE SIDE” OXIDE SCALES

AND THICKNESS CHECKING OVER A LONGER SPAN OF

THE TUBES(NEAR TO THE ROOF)

7. METAL SPRAYING(TAFA) WAS TRIED OVER SOME

EROSION PRONE PRESSURE PARTS EXPERMENTALLY.


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R.S.DAS,NALCO 57

TREND OF TUBE FAILURES DUE TO ASH,SEC AIR,STEAM

EROSION UPTO 31.3.2007

0

1

2

3

4

5

6

7

8

9

10

YEAR

N O

NO OF TUBE LEAKAGES

NO OF TUBE LEAKAGES 9 8 4 6 3 4 1 3 5 3 4 2 4 4 2

92-93 93-94 94-95 95-96 96-97 97-98 98-99 99-

2000

2000-

01

2001-

02

2002-

03

2003-

04

2004-

O5

2005-

06

2006-

07


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R.S.DAS,NALCO 58

TREND OF TUBE FAILURES IN BOILER

0

2

4

6

8

10

12

14

16

YEAR

N O

NO OF FAILURES

NO OF FAILURES 9 10 12 5 8 9 8 3 9 9 10 6 6 15 14 12

91-

92

92-

93

93-

94

94-

95

95-

96

96-

97

97-

98

98-

99

99-

2000

2000-

01

2001-

02

2002-

03

2003-

04

2004-

05

2005-

06

2006-

07

`


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R.S.DAS,NALCO 59

INSIDE OXIDE SCALE THIKNESS MEASUREMENT OF

RE HEATERS & SUPER HEATERS DURING ANNUALOVERHAULING SO THAT REPLACEMENT CAN BEDONE ON REGULAR BASIS TO REDUCE BREAK DOWN.

INTERNAL CORROSION MAPPING OF BOILER TUBES

METAL SPRAYING OVER EROSION PRONE AREAS

RLA OF BOILERS WHICH HAVE RUN FOR MORE THAN

25 YEARSMAJOR REPLACEMENT OF COILS /TUBES BASED ONRLA STUDIES

OUR FUTURE PLANNING


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R.S.DAS,NALCO 60

Thank You

boilers rla

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