unchahar btf reduction plan 09-10

7/30/2019 Unchahar BTF Reduction Plan 09-10

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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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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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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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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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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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unchahar btf reduction plan 09-10

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