Btl Uprvunl Present II
Transcript of Btl Uprvunl Present II
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PRESSURE PARTS FAILURE
REPORTING, INVESTIGATION & ANALYSIS SYSTEM
&
BOILER TUBE FAILURE MANAGEMENT THROUGH QUALITY UNIT OVERHAULS By Anil Kumar AGM (Mech) – PIE
7th August 2007-UPRVUNL: Panki
NTPC
Limited
WELCOME TO THE PRESENTATION
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OBJECTIVE:
TO ACHIEVE ZERO TUBE LEAKAGE BASED. BTF ACCOUNTS FOR
60-80% OF TOTAL DOWN TIME
SCOPE:
PRESSURE PARTS FAILURE REPORTING, INVESTIGATION, ANALYSIS
& DATA SYSTEM AIMS TO ACHIEVE ZERO BTL BASED ON RCA & TIME
BOUND CORRECTIVE ACTION PLAN IT DEFINES RESPONSBILITIES OF
VARIOUS GROUPS WITHIN THE ORGANIZATION & COORDINATION
WITH EXTERNAL AGENCIES TO CARRY OUT DT/NDT INSPECTIONS,
INVESTIGATION & ANALYSIS, FEEDBACK & DOCUMENTATION AND
ACTION PLAN TO ACHIEVE THE OBJECTIVE BASED ON GENERATEDDATA BASE
PRESSURE PARTS FAILURE
REPORTING,
INVESTIGATION, ANALYSIS
& DATA SYSTEM
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1. BTL Reporting Format
2. BTL Site Level Investigation Committee :
Sampling Methodology:
Two photographs 100x150 mm :
One in situ, if possible & another after cut
Identification plate 300x200 mm painted black with information
containing Name of the station, unit no, location 7 details of failure,
Date of Failure, Id. No etc
Tube shall be cut by saw with 18” either side of failure. If gas cut it
must be 24” either side & dressed to 18” by saw later
Site Level Investigation: Observations, Analysis, Recommendations &Implementation Plan
BOILER TUBE FAILURE
MANAGEMENT
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3. Reporting at HQ- Operation Services for Further Action
4. Need of Metallurgical Investigation at R&D Lab
5. Documentation, Report Integration & Corrective Action Plan
6. Knowledge Forum for New Technological Adoption
7. Pre-OH predictive scope of work & preparedness
8. Quality Surveillances during unit overhauls
(in-house/HQ/External Agency directly under FQA)
BOILER TUBE FAILURE
MANAGEMENT
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BOILER TUBE FAILURE REPORTING FORMAT
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BOILER TUBE FAILURE REPORTING FORMAT
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BOILER TUBE FAILURESITE LEVEL INVESTIGATION
COMMITTE
1. HOD - Maintenance Management Services: Coordinator
2. HOD- Boiler Maintenance Division
3. HOD- Operations & Energy Efficiency Division
4. HOD- Operations Division
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BTF INVESTIGATION
PROCESS
Site BTF Committee(Maint. Planning, BMD,
Operation, O&EE)
[REPORT-within 72 Hrs
of completion of repairs]
1. Format:Duly filled with all relevant details
2. Photographs:Specifying station/unit no/date of failure
3. Sample :Tube must be saw cut 18” either side of failure
HQ-OS
Observations
Corrective Action Plan
Monitoring of CAP
R&D Investigations
(if required)
Unit OH Plan
BTF
QC: External Inspections & NDT
Scope of Work for Unit Overhauls
New Technology
Interventions
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BOILER TUBE FAILURE
MANAGEMENT
PREVENTION ASPECTS
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BTF REDUCTION
STRATEGY
OPERATION ASPECTS
MAINTENANCE ASPECTS
DESIGN ASPECTS
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LOW PARAMETER OPERATIONOF BOILER PRESSURE PARTS
(AT LOW PRESSURE & LOW TEMPERATURE)
DOES NOT NECESSARIALLY ENSURE
LESS PRESSURE PART FAILURES
BOILER TUBE FAILURE
MANAGEMENT
OPERATIONAL ASPECTS
IMPACT ANALYSIS OF PP-OPERATIONAL REGIME RESTRICTIONS
at one of the NTPC-PIE Stations
D-3: Restricted to 95-100 kg/cm2 from design 149 kg/cm2
D-4:Restricted to 120 kg/cm2 from design 149 kg/cm2
UNIT NO Before (April-Aug’ 06)
Duration= 5 Months
After (Sept’ 06-March 07)
Duration= 7 Months
Nos MU Lost BTF/M Nos MU Lost BTF/M
D-3 8 63.73 1.6 10 92.42 1.4
D-4 4 72.79 0.8 2 21.65 0.3
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BOILER TUBE FAILURE MANAGEMENT
OPERATIONAL ASPECTS
1. NEED OF STANDARD & MANAGEMENTAPPROVED OPERATIONAL PRACTICES
2. KNOWLEDGE MANAGEMENT: Forum for discussion &
deliberations3. FOCUS ON WATER CHEMISTRY: Strategic control of
Boiler water & steam purity to keep boiler tubes interior clean for effective heat transfer need to be given top most priority
4. MONITOR TEMPERATURE EXCURSIONS: Discussduring daily review meeting for larger awareness & better control as agood operational practice.
5. Ensure availability of all P&I and auto loops/logics.Avoid drum level surge
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BOILER TUBE FAILURE MANAGEMENT
OPERATIONAL ASPECTS
5. ENSURE ADEQUATE/PROPER SOOT BLOWING: Soot Blower operation optimization to prevent erosion due
to excessive soot blowing, high steam pressure or pittingdue to low /wet steam parameters is essential. There is needto optimize parameter regime as well as frequency of soot
blower operation
6. CPU IN SERVICE: to remove all cruds from condensate,to reduce water wall internal deposits
7. CLEAN APH BASKETS: to ensure smooth flue gas flow& reduce second pass deposit & high temperature.
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BOILER TUBE FAILURE MANAGEMENT
OPERATIONAL ASPECTS
08. COMBUSTION OPTIMIZATION: to reduce slagging &clinker fall, to prevent fin weld fouling, to reduce the need
to soot blow, to ensure smooth flue gas velocity, to preventthermal shocks & vibrations to pressure parts, to preventimplosions/explosions etc combustion optimization isessential.
Excess air/ Air ingress control Flue gas temperature optimization
09. TRIP MANAGEMENT: dedicated group for honest tripanalysis. Avoid trips
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BOILER TUBE FAILURE
MANAGEMENT
OPERATIONAL ASPECTS
Ownership role of Operations Training & Skill dominant career growth plan
Single point responsibility with HoD (Operation) for
House Keeping & Routine equipment/ panel cleanliness.Good illumination to ensure safe & efficient work conditions
Adequate attention & full preparedness in Fire Fighting Systems
wrt fire related eventualities.Water Management to ensure adequate availability of water forCW system/Emergency services etc.
Ash Dyke Management to ensure trouble free ash evacuationwithout affecting generation
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ORGANIZED & QUALITY
UNIT OVERHAULS
WITH FULL PREPAREDNESS
BOILER TUBE FAILURE MANAGEMENT
MAINTENACE ASPECTS
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1. BTL ANALYSIS & TRENDING OF FAILURE PATTERN
2. BOILER CONDITION ASSESMENT DURING EVERY OVERHAUL BY
THIRD PARTY & DOCUMENTATION
Erosion Survey
Tube Condition Assessment for Deposits & need for acid cleaning etc. Inspection of Hangers & Supports, Expansion Guides etc
3. GOOD PLANNING OF UNIT OVERHAULS
Adequate Scope of Work
Advance Resource Planning wrt Spares, Skill (Quality & Quantity), T&P
Boiler OH only with full preparedness wrt spares, material & contracts
Use of Maintenance Quality Checks & Protocol (M-QCP) Sheets
Third party inspection, NDT & Radiography under Station QualityControl.
BOILER TUBE FAILURE MANAGEMENT
MAINTENACE ASPECTS
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3. GOOD PLANNING OF UNIT OVERHAULS (Contd….)
Use of independent inspection/survey/NDT agency under boiler maintenanceengineer for erosion survey & radiography etc. 80% -100% radiography of joints. Tube thickness survey at right locations.
Inspection of tubes after fin cutting and DPT of Fin welding & old
joints/supports/stub/ attachment etc. Radiography of old welding joints, IPW & DMW joints. Radiography of bends to detect internal chokages/blockages
In-situ NDT tests like Oxide scale thickness measurement/Boroscope/hardness etc. at regular intervals
4. HP WELDERS TEST & REJECTION RATE MONITORING In-house testing of HP welders. Monitor HP welder performance through
rejection rate.
Ensure use of right electrode. Ensure electrodes are baked properly beforestart of welding
BOILER TUBE FAILURE MANAGEMENT
MAINTENACE ASPECTS
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5. ADOPTION OF GOOD MAINTENANCE PRACTICES Cleaning of pressure parts by HP Jet Pump & Use of scrapper or wire brush
Access Platforms, Safety Appliances etc: Use of quick erect scaffolding foreasy access at all places and to carry out extensive erosion survey
Tube Cutting using Portable Saw. No gas cutting of tubes. Adequate
Protection in case of use of gas for tube cutting. Capping of cut tubes withPVC caps
Removal of HAZ by Saw
Removal of all Pad Welding & Window Welding Repairs with New Tubes
Use of Bend, Shield etc from reputed Vendors. Avoid local/ in situ making
Through & Safe Access to all Pressure Part Areas for Inspection & Work Boiler Flushing & Draining and Inspection of Down Comer Headers
Cyclic Hydro before Start of Repairs in Old Boilers
Keep coil alignment perfect
BOILER TUBE FAILURE MANAGEMENT
MAINTENACE ASPECTS
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5. ADOPTION OF GOOD MAINTENANCE PRACTICES (Contd….) Use of proper & safe platform at ECO/LTSH area along with coil handling
facility
Make adequate mechanized arrangement for pent house ash removal if leakage is suspected
Tubes/bends to be checked for thru ness before fixing. Header flushing &inspection after completion of OH
Avoid stray arcing on tubes. Adjacent tubes are damaged. Care while fincutting to avoid damage to adjacent tube while cutting
Ensure tube/coil alignment during each OH in first and second pass
Replace coal nozzles & proper alignment. Repair & proper operation of SADC
DMW joint NDT & replacement plans
Fin welding by 2.5 mm electrode
Avoid fabrication of different types of bends at site
BOILER TUBE FAILURE MANAGEMENT
MAINTENACE ASPECTS
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5. ADOPTION OF GOOD MAINTENANCE PRACTICES (Contd…) Pressurisation of Re-heater circuit/MS Circuit to check for leakage detection
Air testing with Sponge ball for testing of loops/coils
Develop experiences based schedule for economizer/ Primary SH etc for coillifting/inspection/reversal
Air testing with Sponge ball for testing of loops/coils Inspection of orifice in FSH area to find the cause of overheating
Replacement of spacer tube of platen super heater
Replacement of DMW, Clamp, shield in primary SH area
Phase wise reversal/replacement of ECO coil with new coils instead of total
replacement at one time to achieve low down time
Thorough & adequate cleaning of pressure parts to ensure effective heattransfer
BOILER TUBE FAILURE MANAGEMENT
MAINTENACE ASPECTS
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5. ADOPTION OF GOOD MAINTENANCE PRACTICES (Contd….) Restore Supports/ clamps which are cut during work
Check Looseness of hanger supports & rectify
Check for misalignment of the coils. Replace missing/broken connectors.Ensure all coils are aligned
Ensure proper fixing of shields and cassette baffles. Replace all impropershield/baffles
Use of latest maintenance tools & techniques eg Portable Bevelling Machine,Plasma Arc Cutting Machine, Portable welding Machine, Headers Hand holeplate cutting machine etc
Adequate illumination inside boiler. Use of 24 V supplies & pneumatic toolsto prevent loss of life due to electrocution. Use safety nets in S-Panel area.Usage of fibre body hand tools
Joint inspection along with safety inspector for scaffolding & planks fix up.Load testing of all T&P
BOILER TUBE FAILURE MANAGEMENT
MAINTENACE ASPECTS
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6. MISCELLEANOUS AREAS NEED ATTENTION:
USE OF PPE & Safety Training to all contract workmen
VALVES: All the safety valves are to be serviced and trevi testing done.
Actual floating of valves on which maintenance has been carried out should bedone. All root valves in the hydraulic test circuit are being serviced and bluematched & witnessed by team of maintenance, operation & quality
SOOT BLOWERS: Monitoring of availability of wall blowers &Restoration of LRSB
COAL BURNERS: Proper repair hard facing of splitter plates & in sidesurface/replacement of nozzle etc . Ensure proper alignment of coal/airnozzles.
BOILER TUBE FAILURE MANAGEMENT
MAINTENACE ASPECTS
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UNIT OVERHAUL QUALITY ASPECTS
USE OF M-QCP FOR STRUCTURED & PLANNED EROSION SURVEYSDATA ANALYSIS & TRENDING FOR FUTURE PLANNING & UNIT OVERHAULS
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UNIT OVERHAUL QUALITY ASPECTS
USE OF M-QCP FOR STRUCTURED & PLANNED EROSION SURVEYSDATA ANALYSIS & TRENDING FOR FUTURE PLANNING & UNIT OVERHAULS
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UNIT OVERHAUL QUALITY ASPECTS
USE OF M-QCP FOR STRUCTURED & PLANNED EROSION SURVEYSDATA ANALYSIS & TRENDING FOR FUTURE PLANNING & UNIT OVERHAULS
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UNIT OVERHAUL QUALITY ASPECTS
USE OF M-QCP FOR STRUCTURED & PLANNED EROSION SURVEYSDATA ANALYSIS & TRENDING FOR FUTURE PLANNING & UNIT OVERHAULS
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UNIT OVERHAUL QUALITY ASPECTS
USE OF M-QCP FOR STRUCTURED & PLANNED EROSION SURVEYSDATA ANALYSIS & TRENDING FOR FUTURE PLANNING & UNIT OVERHAULS
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UNIT OVERHAUL QUALITY ASPECTS
USE OF M-QCP FOR STRUCTURED & PLANNED EROSION SURVEYSDATA ANALYSIS & TRENDING FOR FUTURE PLANNING & UNIT OVERHAULS
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BOILER TUBE FAILURE MANAGEMENT
MAINTENANCE
PREVENTION ASPECTS
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Wear bars on S- panel
PROVIDING WEAR BARS ON S-PANEL
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cassette baffles protection for economizer bend
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ECO COIL PROTECTION SHIELD
LOCKING ARRANGEMENT
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economizer end erosion
use of cassette baffles &
refractory for protection
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Erosion of SCW bifurcates and its
prevention
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REVERSAL OF ECONOMIZER
COILS
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LTSH inlet header- Shielding
arrangement on tube surface
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use of sacrificing shield
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UNIT
OVERHAUL
MANAGEMENT Advance Planning: 18 – 24 month (minimum)
Defining Scope Of Work in detail Identification of requirement of resources
(Spares, consumables, skill & contracts)
Organizing resources in time
STRATEGIC PLANNING
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STRATEGIC PLANNING
& OVERHAUL
MANAGEMENTThree tier planning system need to be adopted.
Life Cycle Plan (LCP) Station Rolling Plan (SRP)
Station Location Annual Plan (SLAP)
LIFE CYCLE PLAN (LCP)
Focus on major replacement plan for the entire life cycle of 25-30 years.
Covers replacement of the equipment/parts which are likely to fail before or nearthe life expectancy & have a long lead time.
Examples: super heaters, re-heaters, high pressure valves, safety valves, gear reducers, ash disposallines, slurry pumps, chemical piping, resins, conveyor belts and drives, coal crushers, turbine rotorblades, turbine bolts, boiler feed pump rotor, H.P. heater coil, H.T. motor, transformer, switch gears,cables, etc.
Replacement plans are conceived on the consideration of Coal quality, Creep life
of various components, Equipment duty conditions, Actual Wear rate andBehavioral trend of plant /equipment inspection and RLA reports etc.
LIFE CYCLE PLAN (LCP)
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Years Activity Description01 Statutory Inspection, Coal Burners, APH Seals.
02 Statutory Inspection, Coal Burners, APH Seals. ECO/LTSH bends & tubes, Refractory
04 Statutory Inspection, Coal Burners, APH Seals.
ECO/LTSH bends & tubes, Refractory, ESP Electrodes, ID Fan Impellers, Defective Valves
08 Statutory Inspection, Coal Burners, APH Seals.ECO/LTSH bends & tubes, Refractory, ESP Electrodes, ID Fan Impellers, Defective Valves, APHBaskets, PF Bends, ECO/LTSH Coil Reversal, DC Batteries Replacement
16 Statutory Inspection, Coal Burners, APH Seals.
ECO/LTSH bends & tubes, Refractory, ESP Electrodes, ID Fan Impellers, Defective Valves, APHBaskets, PF Bends, ECO/LTSH Coil, DC Batteries HP/IP Turbine Casing Studs, HP/IP CV/GV Bolts,
Turbine Bearings, Turbine Inter stage seals, Electrical Cables, Control Cables
25 Statutory Inspection, Coal Burners, APH Seals.
ECO/LTSH bends & tubes, Refractory, ESP Electrodes, ID Fan Impellers, Defective Valves, APHBaskets, PF Bends, ECO/LTSH Coil, DC Batteries HP/IP Turbine Blades, Diaphragm, Casing Studs,HP/IP CV/GV Bolts, Turbine Bearings, Turbine Inter stage seals, Electrical Cables, Control Cables,Heaters/Condensers/ Heat Exchangers tubes/tube nest etc.
LIFE CYCLE PLAN (LCP) [TYPICAL]
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Stn/Unit Cap Last O/H Done FY 2005-06 FY 2006-07 FY 2007-08 FY 2008-09 FY 2009-10
XXX
Unit-1 500 HPT 27-Nov-03 From 12-Aug-05 12-Aug-06 12-Aug-07 12-Aug-08 12-Aug-09
IPT 23-Oct-01 To 29-Aug-05 29-Aug-06 11-Sep-07 29-Aug-08 6-Sep-09
LPT 23-Oct-01 Duration 18d 18d 30d 18d 30dGen 27-Nov-03 O/H Type Boiler Boiler Blr+IP+LP Boiler B+HP
Blr 27-Nov-03
Unit-2 500 HPT 1-Oct-97 From 12-Sep-05 12-Sep-06 12-Sep-07 1-Sep-08 12-Sep-09
IPT 9-Oct-02 To 29-Sep-05 29-Sep-06 29-Sep-07 30-Sep-08 29-Sep-09
LPT 9-Oct-02 Duration 18d 18d 18d 30d 18d
Gen 9-Oct-02 O/H Type Boiler Boiler Boiler Blr+IP+LP Boiler
Blr 29-Sep-03
Total 1000 P/M % 4.93 4.93 6.57 6.55 6.57
Rolling Plan of a Thermal Station (Typical)
Station rolling plans are drawn on six year spread so that capacity outage is
optimized to match the regional grid demand.
The first two-three years should be planned and presented in detail. The subsequent three
years shall be indicative. These plans are updated every year in a rolling manner
STATION ROLLING PLAN (SRP)
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It provides an accurate assessment of generation & unit outage plans for the year.
OBJECTIVE: is to identify all the constraints to achieve the generation level andorganize resources for effective operation and maintenance. It requires technicalassessment of the units capability and plan unit overhauls.
It also identifies interface with OEM, manufacturing facilities and skill requirements
Statn Unit Inst. Cap.MW
2006-2007
June July Aug Sept Oct Nov Jan Feb
xxx 1 00 1 to 20/11
2 00 1 to 20/2
3 00 10/9 to 30/10
4 00
5 00
6 00 1/6 to 30/7
STATION LOCATION ANNUAL PLAN (TYPICAL)
STATION LOCATION ANNUAL PLAN
(SLAP)
UNIT ANNUAL OVERHAULS
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OBJECTIVES OF UNIT OVERHAUL PLANNING
• QUALITY FOR RELIABILITY (O2O MAINTENANCE)
• OPTIMIZE TIME SCHEDULE & COST
Overhaul planning process is initiated with Engineering Declaration 18-24 months in
advance. The planning process of any unit outage has essentially three stages:
¢ X Pre Shut down Planning activities
¢ X Shut down activities
¢ X Post shut down activities
The cost of unit overhauls in terms of generation loss are very high Adequate work and resource planning for unit overhauls in an integrated manner is essential to avoid last minute shock and surprises as also to have reliable
performance of the unit after overhauls.
THE DECLARATION OF UNIT OVERHAULS SUBSEQUENT TO ANY FORCED
OUTAGE HAS TO BE AVOIDED BECAUSE OF ITS UNDESIRABLE AFFECTS ON
RESOURCE AVAILABILITY AND UNPREPARED EXECUTION.
ONLY OUTAGES BUDGET UNDER STATION LOCATION ANNUAL PLANS SHALL BE TERMED
AS PLANNED OUTAGE. ALL OTHER OUTAGES SHALL BE TERMED AS FORCED OUTAGE
UNIT ANNUAL OVERHAULS
PLANNING PROCESS
PLANNING PROCESS FOR UNIT OVERHAUL
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Bill
of
Material
Job
List
(24M)
Skill Resource
Analysis (18 M)
Skill
&
Manpower
Indent &
Procurement (18 -24 M)
Tender &
Contracts (12 M)
Pre shut
Down Planning
(24 M)
Maintenance
QCP(12 M)
Isolation
Plans
(6 M)
Recommissioning
Check sheets
(12 M)
MonitoringSheets
(12 M)
PERT
Net work
(12-18 M)
Pre
Outage
Survey
(15-30 D)
UNIT
OFF LOAD
Resource
Mobilization
(1 M)
Overhaul Execution
OUTAGE
OMPLETION
REPORT(1 M) Overhaul Monitoring
Quality Checks
UNIT
ON BAR
Re commissioning
checks
Post
OHReview
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“Engineering Declaration” of the unit includes brief review of the past
performance of the unit, define objectives of the proposed overhaul and the
quantified projections of the return in terms of gain in reliability and efficiency.
The first “Engineering Declaration” is issued 18-24 months ahead of unit’s planed overhaul.
Periodic review of outage preparedness facilitates revisions of the plan if any.
OVERHAUL MANAGEMENT ORGANISATION (OUTAGE COMMITTEE)
This committee will be responsible to conduct the overhaul of all the units of a station during a
particular financial year as planned and shall ensure that all the jobs are carried out as per laid
down specifications and quality plans. The committee may change for next financial year according
to availability of personnel and workload of the station.
The various members of the outage team shall be as follows:The various members of the outage team shall be as follows:
a. Outage manger b. Executive: Long Term Planning c. Executive: Contractsa. Outage manger b. Executive: Long Term Planning c. Executive: Contracts
d. Executive: BMD e. Executive: TMD f. Executive: BoPd. Executive: BMD e. Executive: TMD f. Executive: BoP
g. Executive: C&I h. Executive: Electrical i. Executive: Operationsg. Executive: C&I h. Executive: Electrical i. Executive: Operations
j. Executive: MMS k. Executive: Operations Efficiency l. Executive: Materials j. Executive: MMS k. Executive: Operations Efficiency l. Executive: Materials
Members from Finance, HR etc are drawn as deemed necessary.Members from Finance, HR etc are drawn as deemed necessary.
ENGINEERING DECLARATION
OUTAGE COMMITTEE
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(a) To assess skill availability and the technical capability of the contractors.
(b) To coordinate amongst different working departments and contractors.
(c) To Check and ensure that the job execution is as per technical specificationand work quality is being complied as per Maintenance Quality Checks &
Protocol (M-QCP) Sheets.(d) To ensure observance of safety rules as per laid down principles of the
company.
(e) To monitor work progress to ensure timely work completion, reduce downtime and cost.
(f) To ensure optimum utilization of resources.
(g) To coordinate for an effective work control.
(h) To facilitate de-bottle necks in planning and take appropriate measures forimprovements and effective planning.
OUTAGE COMMITTEE
FUNCTIONS
OUTAGE PREPAREDNESS INDEX (OPI)
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OUTAGE PREPAREDNESS INDEX (OPI) : is devised to be a tool to measure the
“ Degree Of Preparedness” to execute the planned outage.
OPI provides a quantified measure of the “Degree of Preparedness” for planned outage of a
given unit overhaul. OPI monitoring shall begin 18 -24 months in advance of the proposed
planned date of Unit overhaul.
OVERHAUL COMPLETION REPORT (OCR) : Each completion report should bear a
unique number for identification. The cross reference of the completion report should beentered in the equipment history.Each section shall contain detail of work undertaken, surprises observed, new methods &fixtures used, quality checks & protocol sheets and shall contain following sections SECTION-1: EXECUTIVE SUMMARY
SECTION-2: BOILER & AUXILIARIES
SECTION-3: TURBINE & AUXILIARIESSECTION-4: GENERATOR & AUXILIARIES
SECTION-5: ELECTRICAL EQUIPMENTS
SECTION-6: CONTROL & INSTRUMENTATION
SECTION-7: OFFSITES AND MISCELLANEOUS
SECTION-8: RE- COMMISSIONING & EFFICIENCY EVALUATION WITH COST BENEFIT ANALYSIS
SECTION-9: MANPOWER & BUDGETS
SECTION-10: CONCLUSIONS AND RECOMMENDATIONS
( )
OUTAGE COMPLETION REPORT (OCR)
Need of Professionalism
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X NEED BASED MAINTENANCE & QUALITY APPROACH: It is essential that maintenance needs are
condition based, even in boiler also. All maintenance activities must have a requisite maintenance
quality checks & protocols (M-QCP) - by maintenance.
X OPPORTUNITY MAINTENANCE TO AVOID SUDDEN SHOCKS:
Ever preparedness & Judicious decisions
to carry out opportunity based maintenance to avoid partial loading & to address pending defects &
pre-scheduling of PM etc. should be governed by economic considerations.
X KNOWLEDGE BASED MAINTENANCE:
The basic beliefs about age of the plant asset and its impact on failure “As things got older,
they were more likely to fail” have also begun to change. The concept of `infant mortality‘ & “bathtub"
curve has come in for a change.
Today it is understood that need based quality maintenance with technological improvements can
contain the failures. It involves a diagnostic process with of analytical approach.
MAINTENANCE PRACTICES & METHODS NEED A CONTINUOUS REVIEW &
UPDATE.
Need of Professionalism
in maintenance
BOILER TUBE FAILURE MANAGEMENT
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BOILER TUBE FAILURE MANAGEMENT
DESIGN ASPECTS
1. Reduced flue gas velocity
Erosion=(Velocity)2.6, Preferred Velocity=10m/sec
2. Smooth change in flue gas velocity
Reduced flue gas velocity in second pass reduces fire side heat transfer
coefficient and hence the requirement of heat transfer area increases. It also increase
the fouling tendency on horizontally placed tubes in the second pass thus reducing the
heat transfer further. Therefore flue gas velocity need to be carefully optimized. Change
in flue gas velocity or direction may affect the erosion rate in new areas
3. Reduced SH/RH spray:
High spray also causes thermal shocks to headers, stubs & tubes.
4. Reduced operating limits of tube metal temperatures
5. Use of suitable material to avoid dissimilar metal welds
(DMW) joints
Use of inconel as filler material for root weld reduces failure frequency of
austenitic/ ferritic joint , SA 213 T91 avoids use of DMW but making a T91 joint iscom lex.
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THANK YOU