Post on 14-Apr-2018
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UNCHAHAR
BTF REDUCTION
ACTION PLAN
2009-2010SHORT AND LONG TERM MEASURE
NTPC-UNCHAHAR
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NTPC UNCHAHAR- 5*210 MW UNITS
UNIT Date of
Commissioning
Boiler RLA Study
Carried out
Running hrs
as on
31.03.2009
Last O/H
Unit-1 21.11.1988
OCT-2003 at
88896 running
hours
133074.61 hrs 20.07.08 to 05.09.08
Unit-222.03.1989
OCT-2002 at
82067 running
hours
134397.50 hrs
03.06.07 to 10.07.07
04.07.08 to 07.07.08
[For license renewal]
Unit-327.01.1999 68215.00 hrs 07.04.08 to 02.05.08
Unit-422.10.1999 75123.21 hrs 10.05.07 to 30.05.07
Unit-5 28.09.2006 19013.68 hrs 30.10.08 to 26.11.08
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NUMBER OF TUBE LEAKAGES
YEAR TOTAL TUBELEAKAGES
2000-01 6
2001-02 4
2002-03 5
2003-04 10
2004-05 8
2005-06 5
2006-07 6
2007-08 13
2008-09 16
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AREAWISE BTF SINCE 2000-2001
14, 19%
6, 8%
16, 23%
1, 1%
17, 24%
12, 16%
1, 1%
2, 3%
2, 3%
1, 1%
1, 1%
Water Wall
LTSH
Steam cooled Wall
Screen Tube
Economizer
RH
SH vent line
Final SH
Platen SH
RH spacer tube
Supply Tube
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BTL area wise 2000-01 to 2008-09
Unit/
Area WW LTSH SCW
Screen
Tube Eco RH
Pent
house FSH PSH
Supply
Tube/spacer Total
Unit-I 3 2 3 0 7 6 1 0 1 1 24
Unit-II 2 0 1 1 2 3 0 0 1 1 11
Unit-III 6 3 4 0 2 1 0 1 0 0 17
Unit-IV 2 1 4 0 4 1 0 1 0 0 13
Unit-V 1 0 4 0 2 1 0 0 0 0 8
Total 14 6 16 1 17 12 1 2 2 2 73
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BTL area wise 2008-09
Unit/
Area WW LTSH SCW
Screen
Tube Eco RH
Pent
house FSH PSH
Supply
Tube/
spacer Total
Unit-I 02 02
Unit-II 01 01
Unit-III 01 02 01 04
Unit-IV 01 02 03
Unit-V 01 02 02 01 06
Total 02 05 07 01 01 16
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BTL cause wise 2000-01 to 2008-09
Unit/
Area
Weldjoint
failure
Fly ash
erosion
Steam
erosion
Attachment
weld
overheati
ng
Oldjoints
failure
CoalEros
ion
Mat.Fail
ure
Total
Unit-I 2 9 2 2 6 - 1 2 24
Unit-II - 2 1 1 4 2 - 1 11
Unit-III 7 1 - 6 1 1 1 - 17
Unit-IV - 6 1 1 2 3 - - 13
Unit-V - 6 - 1 1 - - 8
Total 9 24 4 11 14 6 2 3 73
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BTL cause wise 2008-09
Unit/
Area
Weldjoint
failure
Fly ash
erosion
Steam
erosion
Attachment
weld
overheati
ng
Oldjoints
failure
CoalEros
ion
Mat.Fail
ure
Total
Unit-I 01 01 02
Unit-II 01 01
Unit-III 01 02 01 04
Unit-IV 03 03
Unit-V 04 01 01 06
Total 02 08 03 02 01 16
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CAUSEWISE BTF 2008-2009
Unit Weld joint failure Fly ash erosion overheating Mat. Failure Total
Unit-I 01 01 02
Unit-II 01 01
Unit-III 04 04
Unit-IV 03 03
Unit-V 01 04 01 06
Total 06 08 02 16
Weld joint
failure, 6, 38%
Fly ash erosion,
8, 49%
overheating, 2,
13%Weld joint failure
Fly ash erosion
overheating
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BTF STATUS SINCE LAST OH
UNITS Last unit OH
0 to 3
months
3 to 6
months
6 to 9
months
9 to 12 &
moremonths
Remarks
UNIT-120.07.08 to
05.09.08-
01
22.12.08-
Last leakage-
22.12.08
UNIT-2
03.06.07 to
10.07.07
04.07.08 to07.07.08
[For license]
01
24.07.07-
01
26.01.08
02
06.03.2008
12.01.2009
last leakage
12.01.2009
UNIT-307.04.08 to
02.05.08
02
26.05.08
22.06.08
01
29.12.08
01
04.03.09
Last leakage-
04.03.09
UNIT-410.05.07 to
30.05.07-
0315.10.08
20.12.08
19.01.09
Last leakage
19.01.09
UNIT-5 30.10.08 to
26.11.08
01
09.01.09
01
08.03.09Last leakage-
08.03.09
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STRATEGIES TO REDUCE FORCED OUTAGES
Emphasis on Inspection
Detailed inspection as per check list prepared by CC-OS to be carried out during overhaul
Inspection report to be generated, trending to be doneto ascertain rate of deterioration
Implementation of recommendations of failureanalysis
Damage mechanism to be identified and to beeliminated. This will reduce quantum of work
100% radiography of new weld joints Radiography of old weld joints
Post work inspection such as alignment of coils,fixing of shields, restoration of clamps/supports
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ACTION PLAN FOR REDUCTION OF
BOILER TUBE LEAKAGES
Sl No Description Target
Date
1 Mapping of boiler based on earlier BTF. completed
2 Quality of Argon gas in terms of its purity 99.99% to be ensured
to eliminate porosity problem in the weld. Indenting of 99.99%
Argon Cylinders
In process
3 Creating gap in inner loop of Platen Super heater in Unit # 2 to
avoid expansion restriction
31.10.2009
4 Procurement action for SHH -4B (Unit # 5) PO placed on
25.02.09. PO-4000019286.
PO placed
5 Modular Replacement of Eco Coils in Stage-I & II .POplacement. PR-100009596 dated-01.10.08
31.12.2009
6 Usage of modern tools during O/H. Additional Special tools
indenting. Indent raised for D-meter with data logger and portable
compressor.PR-100016929 and PR-100016929
31.12.2009
7 Providing guide vanes at all elevations of coal compartment instage-2 and 3 during O/H OH-2009
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ACTION PLAN FOR REDUCTION OF
BOILER TUBE LEAKAGESSl No Description Target Date
8 Additional handling platforms for facilitating modular
replacement of eco coil in stage-1,2 and-3.Feasibility offer
awaited from BHEL TRICHY R&M CELL.
31.03.2010
9 Low Frequency Electromagnetic testing (LFET) is to be
used for Boiler tube thickness survey to enhance
productivity. (U#1)
Next O/H
10 Standardization of vendors for Boiler Pressure Parts Under process at
NRHQ
11 Application of plastic refractory in erosion prone critical
location of all boilers. U#2,3,4
Next O/H
12 Procurement of SA 387 , 12/22 Alloy Steel Plate for U#5 30.09.2009
13 Procurement action for Additional set of cup lock. PR-
100017250 dated-26.02.2009.
30.06.2009
14 Round the clock deployment of executives in critical areas
during O/H. 8 executives are required for the same
During Next
overhauling
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Total number
of BTL in
Pent-Hause-01
U#1-1
U#2-0
U#3-0
U#4-0
U#5-0
Total
number of
BTL in
W/W-14
U#1-2
U#2-3
U#3-6
U#4-2
U#5-1
Total number
of BTL inPSH-2
U#1-1
U#2-1
U#3-0
U#4-0
U#5-0
Total number
of BTL in
FSH-2
U#1-0
U#2-0
U#3-1
U#4-1
U#5-0
Total number
of BTL in
Screen Tube-1
U#1-0
U#2-1
U#3-0
U#4-0
U#5-0
Total number
of BTL inRH-12
U#1-6
U#2-3
U#3-1
U#4-1
U#5-1
Area wise BTL during 2000-01 to 2008-09 I st Pass at UNCHAHAR
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Total number of
BTL in LTSH-6
U#1-2
U#2-0
U#3-3
U#4-1
U#5-0
Total number of
BTL in
Economiser-17
U#1-7
U#2-2
U#3-2
U#4-4
U#5-2
Total number of
BTL in
SCW 16
U#1-3
U#2-1
U#3-4
U#4-4U#5-4
Total number of
BTL in Supply
Tube-2
U#1-1
U#2-1
U#3-N.A
U#4-N.AU#5-N.A
Area wise BTL during 2000-01 to 2008-09 II nd Pass at UNCHAHAR
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SHORT TERM MEASURE
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SHORT TERM MEASURE Implementation of boiler knowledge team recommendations during
unit OH.
Boiler 100% inspection. Approach platform to all locations up toroof.
Quality of radiography to be ensured.
Double elliptical shots of side coils , both at 0 0 and 90 0 .
More executive to be trained to check edge preparation, root gap,fitment alignment and radiography of the joints.
IBR welder test before deployment. fin welding by IBR welder.
Activity based inspection with protocol.
Quality of agency and skilled manpower identification for specific
work. Agency selection based on quality of work, performance andresources.
Mapping of boiler based on earlier BTF.
Round the clock manning during OH to ensure quality checkbefore final fit-up.
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SHORT TERM MEASURE Focus on opportunity maintenance regarding inspection of critical
location prone to flue gas erosion based on earlier failure.
Alignment of coil restoring in original position and relatedclamps/support restoration need to be focused to ensure quality ofwork.
Quality of filler wire and electrodes to be ensured including pre-heating in the oven before use.
Quality of Argon gas in terms of its purity 99.99% to be ensuredto eliminate porosity problem in the weld.
A team of quality persons to be identified in the regional level andtheir services to be utilized during OH.
More executive on round the clock basis may be deployed on job
for in depth boiler inspection and quality checks. Attachment weld by HP welder and DP test to be ensured.
Water wall transition tube root welding radiography.
Restoration of damaged thermocouples for measurement of metaltemperature.
Replacement of balance bottom bends of Reheater rear coil.
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ACTION PLAN FOR REDUCTION IN BOILER
TUBE FAILURE
Location : Economizer & LTSH
BTF (2000-08) : 32%
Reason of BTF :Erection/ Maintenance weld joint failure, Ash erosion,Fatigue failure.
ACTION PLAN
Location of in-situ inspection to be marked on drawing.
In situ inspection of three tubes from top and three tubes from bottom of bothbanks for thickness survey 100%.
Based on extent of erosion, coils to be lowered /raised for full inspection.
Misalignment of coil to be corrected.
Coils to be lowered in pairs by removing pins.
Full alignment to be ensured after coils are restored.
Radiography of at least 10% old joints to be done & based on defects %age may be
increased. All foreign material lying in between tubes to be removed.
100% inspection of Eco header stubs.
100% radiography of new joints.
Damaged/ eroded hanger clamps to be replaced in the coils which are lowered forinspection/ repaired.
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ACTION PLAN FOR REDUCTION IN BOILER
TUBE FAILURE
Location :Water Wall, screen tube, supply tube & SCW
BTF (2000-08) :44%
Reason of BTF :Weld joints, Steam erosion, Coal erosion &Attachment weld failures
ACTION
Tube thickness survey at 6 elevations in S panel, water wall & Ext.water wall burner panels, goose neck, tubes around manholes andaround wall blowers.
Replacement of coal nozzle assy.
In-situ inspection of all the tubes.
Based on extent of dent, erosion, tubes to be replaced. Misalignment to be corrected.
Attachment weld failures inspection.
DP test of attachment.
Restoration of all supports cut during repair & welding DP test.
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ACTION PLAN FOR REDUCTION IN BOILER
TUBE FAILURE
Restoration of all supports cut during repair & welding DP test.
Overhauling of soot blowers & pressure setting.
Fin welding by IBR welder.
WW tube root radiography (started from-2008 OH).
Alignment of burner tilt & synchronized movement of SADC.
Healthiness of air guide vanes, coal nozzles & coal nozzle tips.
Condition of oil & air compartments.
Inspection of starting and terminal points of fin welding.
Inspection of attachment welds in bottom dead chamber.
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ACTION PLAN FOR REDUCTION IN BOILER
TUBE FAILURE
Location: Super Heater+ Platen
BTF (2000-08) : 07%
Reason of BTF :Overheating, Material failure
ACTION
Physical inspection of SH tubes for signs of bowing and overheating.
Boiler filling with deaerated water only. Maintaining dissolved oxygen withinlimit at condenser outlet and dearator outlet.
Check for mechanical rubbing near spacer tubes, clamps etc.
Alignment of panels, check for flexible connectors, bow and for sign of overheating.
Replacement of DMW joints in a phased manner.
Inside oxide thickness measurement to be done and tube showing highest oxidelayer thickness to be cut and sent for following tests-hardness, oxide thickness,microstructure and creep test.
Inspection of flexiable connectors and replacement of broken connectors.
ACTION PLAN FOR REDUCTION IN
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ACTION PLAN FOR REDUCTION IN
BOILER TUBE FAILURE
Ensuring controlled cooling of boiler during shutdown and monitoringexpansions during startup.
Inspection for overheating of seal bend and crown plate.
Inspection for erosion near the roof.
Constant monitoring of steam / metal temp in SH NDT of all joints by radiography, welded during OH and breakdown.
Inspection (DPT) of pent house vents and drains.
Pent house floor repair and insulation survey.
Inspection of spacer tubes.
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ACTION PLAN FOR REDUCTION IN BOILER
TUBE FAILURELocation :Re heater + RH spacer
BTF (2000-08) :17%
Reason of BTF :overheatingACTION
Replacement of overheated tubes of RH by new tubes.
Constant monitoring of steam / metal temp in RH
Inspection of any mechanical rubbing with supports, or vibration and correctionduring O/H.
Replacement of tubes after excess oxide thickness.
ASLD installation for early pickup and to reduce secondary damages in unit-2.
While replacement of RH outlet coils, care to be taken for alignment and attachmentwelding.
Inside oxide scale measurement to be done in RH. If inside oxide scales thickness isfound to be more than 700 microns, then sample form tube having highest internaloxide scale to cut and should be sent to R&D lab for microstructure and remainingcreep life. If internal oxide scale thickness is found less than 700 microns thensample tube need not be cut fo r lab analysis.
Inside oxide scale thickness measurement to be done before DMW joints in T22material and near DMW joints. While replacing overheated tubes inside penthouse,tube along with DMW joints should be replaced.
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PRACTICES TO BE FOLLOWED DURING UNIT OH
Steam/ air blowing of new tubes before installation.
Sponge ball test of new coils/ bends before installation.
All vertical tubes to be cut with grinders only.
Immediate capping of tubes after cutting.
Deployment of tested cutters for tube cutting
All attachment welds to be carried out by tested HP welders.
Attachment welding to be done by electrode of 2-2.5 mm size.
Pad welding should not be done.
All supports / clamps cut during OH for tube repair should be restored to originalcondition.
To ensure quality of work modern tools like bevel cutting machine, panel cuttingmachine, pneumatic tools to be encouraged.
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GUIDE LINES FOR SAFETY
VALVES
All ERV`s in MS line and HRH line to be made operational. it is mandatory tokeep all ERV`s in service.
Spring loaded safety valve in MS line to be serviced in every overhaul.
Spring loaded safety valve in CRH/HRH lines to be serviced in two years cycle.
Spring loaded safety valves in drums to be serviced in three years cycle.
All spring loaded safety valves to be floated by TREVI-TEST during every OHwith temperature correction.
The safety valves which are dismantled and serviced must be floated at actualsteam pressure with temperature correction.
If any valves develops passing problem, it should not be gagged. Instead ,itshould be attended at the earliest opportunity.
Protocol to be made for servicing, floating/Trevi-test of all spring loaded safetyvalves and ERV`s
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LONG TERM MEASURE
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LONG TERM MEASURE Boiler mapping based on last 10 years BTF and its analysis.
Boiler scope of work to be revisited based on design requirement and earlierfailures analysis.
Implementation of modular replacement of ECO and LTSH coils in phasedmanner. procurement of coils to be initiated.
Proposal for making additional platform for modular replacement to be initiated.
Rate contract with boiler manufacturer for supply of coils, tubes and bends toreduce lead time of procurement.
OH schedule to be freezed for five years and not to be altered.
Knowledge team observation and recommendation implementation to be ensured.
Qualified agencies to be standardized for pressure part work and selection based onperformance and resource.
Selection of Vendors need to be improved and tools and tackles and facilityextended by the Contractors are to be pre specified. Also manpower deployment
quantum to be specified along with, if required, specific individual deployment to bespecified for specific work.
Development of quality team for pressure part work.
Development of HP welder in the region to ensure availability.
Low Frequency Electromagnetic testing (LFET) is to be used for Boiler tubethickness survey to enhance productivity.
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LONG TERM MEASURE
Agency should mobilize Special tools, advanced / modern T&Ps, bevel
cutting machine etc. during Overhauling. Usage of latest or innovativetools for possible time reduction is to be given priority.
Replacement of unit-1 reheater rear coils with improved material T-91.Orderfor 10 coils placed on BHEL. Indent raised for remaining 49 coils.PR-300003000 dated 01.05.2009. Replacement planned in 2010-11.
Installation of boiler tube leak detection system in unit-2 100% old joints radiography to be completed in next five years.
Improved material for coal nozzle for two year running to be explored.
Providing guide vanes at all elevations of coal compartment in stage-2.
Radiography of DMW joints and replacement. if necessary.
Improvement in maintenance practices for quality work.
Failure analysis report implementation.
For continuous and quality supervision adequate executive manpower maybe provided.
Exploring the Possibility for imposing clause of incentive and penalty for
early/delayed completion of the job in the contract.
Li t f t l b i d f BMD lit i t
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List of tools being procured for BMD quality maintenance
practices at UnchaharDescription of item Purchase indent details Remarks-status as on 01.05.09
1-Hyd gang jack for APH PO-2250078 05.05.2007 Material received in Dec-07[M/S Enerpac]
2-Tube cutting machine.
3-Portable panel cutting
machine.
4-Bevel cutting machines.
5-Search light
PO-6240030,31 19.04.2007
PI-620036 19.04.2007
PI-620036 19.04.2007
PO-8240199 03.07.2007
Material received in july-07
[M/S Hitachi]
Material received and demonstrated by
agency in march-09.
PO placed
Material received in sept-07
[M/S Bridge gap]
6-Plazma cutting machine PO-6250766 10.03.2007 Material received and tested.
7-Pneumatic tools PO-2340208 13.07.2007 Material received in Nov-07
[M/S Grip hold tools Baroda]
8-Electric hoist for APH PR-100014176 dated 31.12.2008 Fresh indent raised.
9-Fork lift.
10-Centrifuge MAB-103
11-Cap lock scaffolding
additional material
PO-6340460 18.10.2007
PO-5050181 21.06.2007
PO-6350500 13.11.2007
Received and in service.
Received and commissioned.
Material received in feb-08. [M/S
British scaffolding]
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List of tools being procured for BMD quality
maintenance practices at Unchahar
Description of item Purchase indent details Remarks-status as on01.05.09
13-Pneumatic hand power
saw-5nos
Indent to be raised by
15.06.200914-Pneumatic high speed
grinder-10nos
Indent to be raised by
15.06.2009
15-Portable air
compressure-02nos
PR-100016649 dated-
16.02.2009
Under budget vetting
16-D-meter along with
datalogger-05nos
PR-100016929 dated
21.02.2009
Enquiry issued-
9900023865 dated 18.05.09
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