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8/17/2019 Boilers RLA
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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
Tests Done during RLA Study of our
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
Tests Done during RLA Study of our
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 HRH Coil 33 fifth ckt rear 56,500 Hrs
Unit-4 all other RH coils MORE THAN 1 LAKH HOUR
Unit-5 HRH Coil 22 fifth ckt rear 59,100 Hrs
Unit-5 HRH Coil 31 fifth ckt rear 56,100 Hrs
Unit-5 HRH Coil 33 fifth ckt rear 66,100 Hrs
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
MORE THAN 1 LAKH HOUR
UNIT-3 PLATEN SH COILTUBES
MORE THAN 1 LAKH HOUR
UNIT-4 PLATEN SH COIL
TUBES
MORE THAN 1 LAKH HOUR
UNIT-5 PLATEN SH COILTUBES
MORE THAN 1 LAKH HOUR
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
No specificrecommendation
and found o.k
No specificrecommendatio
n and found o.k
No specificrecommendation
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
recommendation and found o.k
No specific
recommendation and found o.k
No specific
recommendation and found o.k
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
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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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Thank You