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Condition based MaintenanceCondition based Maintenance
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Condition based MaintenanceCondition based Maintenancenn ConditionCondition--based maintenance (CBM), shortly based maintenance (CBM), shortly
described, is maintenance described, is maintenance whenwhen need need arisesarises.i.e..i.e. to maintain the correct equipment at to maintain the correct equipment at the right time. This maintenance is performed the right time. This maintenance is performed after one or more indicators show that after one or more indicators show that equipment is going to fail or that equipment equipment is going to fail or that equipment performance is deteriorating.performance is deteriorating.equipment is going to fail or that equipment equipment is going to fail or that equipment performance is deteriorating.performance is deteriorating.
nn CBM primarily uses non destructive testing CBM primarily uses non destructive testing techniques,visual inspection & performance techniques,visual inspection & performance data to assess machinery condition thus data to assess machinery condition thus replacing arbitarily timed maintenance tasks replacing arbitarily timed maintenance tasks with appropriate maintenance tasks at only with appropriate maintenance tasks at only when warranted by equipment condition.when warranted by equipment condition.
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Advantages of CBM over Preventive Advantages of CBM over Preventive maintenance & Corrective maintenancemaintenance & Corrective maintenance
nn CBM identifies incipient faults before they become CBM identifies incipient faults before they become critical, thus enabling more accurate planning of critical, thus enabling more accurate planning of preventive maintenance.preventive maintenance.
nn CBM enables the user to take maximum CBM enables the user to take maximum advantage of useful life of a component such as advantage of useful life of a component such as bearing because the equipment can be left in bearing because the equipment can be left in bearing because the equipment can be left in bearing because the equipment can be left in service if it meets the desired performance service if it meets the desired performance standards.standards.
nn Decreased number of maintenance operations Decreased number of maintenance operations causes a reduction of human error influences causes a reduction of human error influences
nn Decreased maintenance costs Decreased maintenance costs
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Comparison of CBM,Preventive maintenance & Comparison of CBM,Preventive maintenance & Corrective maintenanceCorrective maintenance
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General Condition Monitoring categoriesGeneral Condition Monitoring categoriesnn Temperature measurements (e.g. temperature Temperature measurements (e.g. temperature
recording with the help of laser gun , thermography) recording with the help of laser gun , thermography) helps detect potential failures related to a helps detect potential failures related to a temperature change in equipment. Measured temperature change in equipment. Measured temperature can indicate problems such as excessive temperature can indicate problems such as excessive mechanical friction (e.g. faulty bearings, inadequate mechanical friction (e.g. faulty bearings, inadequate lubrication), degraded heat transfer (e.g. fouling in lubrication), degraded heat transfer (e.g. fouling in heat exchanger) & poor electrical connections (e.g. heat exchanger) & poor electrical connections (e.g. loose corroded or oxidized connections).loose corroded or oxidized connections).heat exchanger) & poor electrical connections (e.g. heat exchanger) & poor electrical connections (e.g. loose corroded or oxidized connections).loose corroded or oxidized connections).
nn Dynamic Monitoring (e.g. signature analysis of Dynamic Monitoring (e.g. signature analysis of vibration)vibration)
nn Oil Analysis: e.g. Oil analysis (e.g. ferrography, Oil Analysis: e.g. Oil analysis (e.g. ferrography, particle counter testing) particle counter testing) --indicates problems such as indicates problems such as machine degradation, oil contamination ,improper oil machine degradation, oil contamination ,improper oil consistency & oil deterioration. Oil analysis falls into 4 consistency & oil deterioration. Oil analysis falls into 4 main areas: main areas:
ØØ a) fluid physical properties(viscisity,appearance).a) fluid physical properties(viscisity,appearance).ØØ Fluid chemical properties (Viscosity, appearance)Fluid chemical properties (Viscosity, appearance)
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General Condition Monitoring categoriesGeneral Condition Monitoring categories
ØØ Fluid contamination (ISO cleanliness, ferroraphy)Fluid contamination (ISO cleanliness, ferroraphy)ØØ Machine Health (wear metals associated with plant Machine Health (wear metals associated with plant
components)components)qq Nondestructive Testing: NDT involves performing Nondestructive Testing: NDT involves performing
tests (e.g. xtests (e.g. x--ray, ultrasonic)ray, ultrasonic)qq Electrical Testing & Monitoring: e.g. power signature Electrical Testing & Monitoring: e.g. power signature
analysis, high potential testinganalysis, high potential testing--involve measuring involve measuring Electrical Testing & Monitoring: e.g. power signature Electrical Testing & Monitoring: e.g. power signature analysis, high potential testinganalysis, high potential testing--involve measuring involve measuring changes in system properties such as resistance changes in system properties such as resistance ,conductivity,conductivity--helps detect electrical insulation helps detect electrical insulation deterioration, broken motor rotor bars.deterioration, broken motor rotor bars.
qq Observation & Surveillance: Visual, audio & touch Observation & Surveillance: Visual, audio & touch inspectionsinspections
qq Performance Monitoring: Monitoring changes in Performance Monitoring: Monitoring changes in variables such as pressure,temperature,flow variables such as pressure,temperature,flow rate,electrical power consumptionrate,electrical power consumption
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Condition Based Maintenance task intervalsCondition Based Maintenance task intervals
nnCBM task intervals must be properly CBM task intervals must be properly understood & should be determined based on understood & should be determined based on expected Pexpected P--F interval i.e. Potential failureF interval i.e. Potential failure--Functional failure interval.Functional failure interval.
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Condition Based Maintenance task intervalsCondition Based Maintenance task intervals
nn CBM task intervals must be determined based on CBM task intervals must be determined based on the expected Pthe expected P--F interval. Following sources may F interval. Following sources may be referred to as an aid to determine Pbe referred to as an aid to determine P--F F interval:interval:
ØØ Expert opinion & judgments (i.e. manufacturer’s Expert opinion & judgments (i.e. manufacturer’s recommendations)recommendations)recommendations)recommendations)
ØØ Published information about condition Published information about condition ––monitoring tasks.monitoring tasks.
ØØ Historical data (e.g. current condition Historical data (e.g. current condition ––monitoring task intervals)monitoring task intervals)
qq Initial CM task intervals:Initial CM task intervals:--i) If existing CM task i) If existing CM task interval has proved effectiveinterval has proved effective--use it. ii) If using use it. ii) If using existing CM task interval failure has occurred existing CM task interval failure has occurred lower the interval.lower the interval.
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Condition Monitoring Practices
for
Critical EquipmentsCritical Equipments
BBGS
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Major AreasMajor Areas
nn Lubricating oil Lubricating oil nn Transformer oil Transformer oil nn Process Parameter Monitoring of Process Parameter Monitoring of nn Process Parameter Monitoring of Process Parameter Monitoring of
Boiler and Boiler and nn Circuit breakersCircuit breakersnn Rotating equipments like all load Rotating equipments like all load
bearing pumps and fansbearing pumps and fansnn SwitchyardSwitchyard
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Type of test
Major Eqp / oil
Population of m/c
Freq. of
testing
Testing agency
Data owners
hipReporting
Moisture & TAN
TG lube oil 3 Monthly
In-house BBGS Ops Home PageBFP oil 7 Monthly
Draught fans oil 16 180oil 16 180
FRF 3 Weekly
WDA, moisture,
TAN, viscosity
TG lube oil 3
Six monthly
IIPM BBGS Ops
Report of M/s IIPM is kept in Dy Mgr Ops room.
FRF 3
HP LP bypass 3
BFP oil 6
Draught fans oil 16
Coal mills 17
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Type of test Major Eqp
Population of m/c
Freq. of
testing
Testing agency
Data ownershi
pReporting
BDV, Neutralization factor, Moisture content, Specific
resistance, Interfacial tension,
Flash point, Tan delta, Sludge content, DGA
GT 7
2 years Shanthala BBGS -EMD Home page
ST, UT 3 each
CHT 6
BDV,Moisture, Acidity 180 days In-house BBGS -EMD Home Page
AHT, CTT 4 each
WST,DMT, IAPAT, IWT 2 each
HCSS 1ESP 62
Tan Delta132 KV
Switchyard all CT,PT
96 5 years T/D BBGS -EMD Home Page
DGA132 KV
Switchyard all CT,PT
96 5 years Shanthala BBGS -EMD Home Page
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Type of test Major Eqp Population of m/c
Freq. of testing
Testing agency
Data ownership Reporting
Combustible Analysis
Fly Ash and
Bottom Ash
3 7 days Lab BBGS -Ops. Home Page.
PF Grading Coal Mill 17 15 days Lab BBGS -Ops. Home Page.
CT and Condenser
performance test3
Bi-annual. (Apr to
In house -Ops BBGS -Ops.
performance test(Apr to Sep.)
Ops
Boiler efficiency test
3 3 months intervalIn house -
Ops BBGS -Ops.
Corrosion measurement
(CT/CW) 3 Monthly Chembond BBGS -Ops.
Corrosion measurement
(DMCW) 3 Quaterly Chembond BBGS -Ops.
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Major Equipment Populatio
n of machines
Frequency of
reading
Measuring Equipmen
ts used
Mode of reading Agency
Report Generatio
n
Cooling Tower Fan 52 Monthly
PA Fan 6 Monthly
Coal Mill 17 Monthly
SKF Analyzer
Frequency based
vibration measurement and analysis
Under AMC of M/s SKF
Report submitted
by M/S SKF.
Available in Home
Page.
SA Fan 8 Monthly
CEP 6 Monthly
Compressors 20 Monthly
FD Fan 6 Monthly
Rotary Breaker 2 Monthly
DMCW Pp. 12 Bimonthly
BFP 7 Bimonthly
CW Pp. 7 Bimonthly
ACW Pp. 6 Bimonthly
ID Fan 8 Bimonthly
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SlSl NoNo Readings taken inReadings taken in
ISO 10816ISO 10816StandardsStandards
Velocity (mm/sec) in RMSVelocity (mm/sec) in RMS
Present Present VibrationVibrationVelocityVelocityMm/secMm/sec
Health Health ConditionCondition
NormalNormal AlertAlert AlarmAlarm
11 < 4.5< 4.5 4.5 4.5 --11.211.2 >11.2>11.2
FEB FEB -- 20112011 14.214.2 AlarmAlarmMARCH MARCH --2011 (Decoupled 2011 (Decoupled Reading) Reading) 1.51.5 NormalNormalReading) Reading) 1.51.5 NormalNormal
MARCH MARCH --20112011 20.420.4 AlarmAlarm
Action Plan: Suggested by SKFCheck the pump impeller for unbalance issue & for proper clearance in its casing.Check the pump shaft for bend or eccentricity issue. Check the pump shaft bushes for proper fitment & in proper condition.Also check the internal clearance of the pump bearing & for defects with respect to the raceways & if required replace them.Also once verify the alignment between motor & pump.
MMD’s Observation : Bend shaft , impeller unbalance and damage to all the bushes.
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Location of test Freq. of testingTesting agency
Testing M/c
Reporting
Thermal insulation checking for Boiler
casing, steam piping Turbine casing
Pre-survey and post survey
In house –Planning
Dept
IR Gun / FLIR IR Camera
Report is submitted to MMD for corrective
action.
In house – IR Gun / Report is submitted
High energy drains valves and steam traps
Pre-survey and post survey
In house –Planning
Dept
IR Gun / FLIR IR Camera
submitted to MMD for corrective
action
Outdoor Electrical switch yard joints and
connectors.
Pre-survey and post survey
In house –Planning
Dept
FLIR IR Camera
Report is submitted to EMD for corrective
action
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Type of test Major Eqp
Population of m/c
Freq. of testing
Testing
agency
Data ownershi
pReporting
Bearing health monitoring of load bearing
motors
Vital motors
Partial Discharge Important
Equipment arrived recently (Ultraprobe10000). Implementation planning in
progress.
Partial Discharge Monitoring in
Electrical Boards
Important HT and LT
boards
Partial Discharge Monitoring of 132KV/220KV
CT, PT
All
Partial Discharge Monitoring in transformers
(Dry, Oil filled)
All
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ElectroElectrostatic static CleaniCleani
ngng
Coal millsCoal mills 1717
ELC m/c ELC m/c remains remains
always ON. always ON.
Turbine Turbine MOTMOT
33
WTWT--1,SAC1,SAC 22
Present Status
Continuous running of ELC machines in coal mills have resulted in :
Reduced wear and tearReduced oil consumption (Earlier oil had to be replaced after every two
months, at present done only after running for 10000 hrs) Less maintenanceHigher availabilityPlan is to fit the same in all ID/FD/PA gearboxes. Already fitted in FD-3A and PA-3A.
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Sample ELC test certificateSample ELC test certificate
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Transformer OilTransformer Oil
§§ The following tests are carried out on Transformer Oil of GT (1 The following tests are carried out on Transformer Oil of GT (1
& 2), UT (1 & 2) and ST (1 & 2) once a year by CPRI / Shanthala: & 2), UT (1 & 2) and ST (1 & 2) once a year by CPRI / Shanthala:
-- BDV, Neutralisation factor, Moisture content, Specific BDV, Neutralisation factor, Moisture content, Specific
resistance, Interfacial tension, Flash point, Tan delta at 90resistance, Interfacial tension, Flash point, Tan delta at 90°°C, C, resistance, Interfacial tension, Flash point, Tan delta at 90resistance, Interfacial tension, Flash point, Tan delta at 90°°C, C,
Sludge content, DGA Sludge content, DGA
§§ BDV, Moisture and acidity of the following transformers are BDV, Moisture and acidity of the following transformers are
carried out incarried out in--house bihouse bi--annuallyannually-- SATs, UATs, CHTs, ACTs, CWLTs, AHTs, and ESP SATs, UATs, CHTs, ACTs, CWLTs, AHTs, and ESP
TransformersTransformers
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Audiometric studyAudiometric study
§§ Audio metric study at different zones of the boilers of both Audio metric study at different zones of the boilers of both
the units is carried once every week.the units is carried once every week.
§§ This study is primarily carried out to preempt any boiler tube This study is primarily carried out to preempt any boiler tube §§ This study is primarily carried out to preempt any boiler tube This study is primarily carried out to preempt any boiler tube
leak.leak.
§§ All records are maintained and studied for and deviation. All records are maintained and studied for and deviation.
§§ Any increase in noise level by 5 dB is investigated.Any increase in noise level by 5 dB is investigated.
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Illumination StudyIllumination Study
§§ Illumination at different pre defined spots covering the entire Illumination at different pre defined spots covering the entire
station is checked once every month.station is checked once every month.
All data obtained from the checking are tabulated and reports All data obtained from the checking are tabulated and reports §§ All data obtained from the checking are tabulated and reports All data obtained from the checking are tabulated and reports
published.published.
§§ Corrective action are taken based on the reports.Corrective action are taken based on the reports.
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Case studies on failure analysisCase studies on failure analysis1) Vibration analysis of Fans & pumps:
üReduced excessive vibration with SKF CMXA 70 Analyzer in SA Fan 1A-Seal Air Fan.Issue: High vibration observed of around 8.1 mm/sec Issue: High vibration observed of around 8.1 mm/sec at Motor bearing. Spectrum analysis reveals at Motor bearing. Spectrum analysis reveals misalignment between drives and bearing inaccuracies misalignment between drives and bearing inaccuracies observed in fan bearing. observed in fan bearing. observed in fan bearing. observed in fan bearing. Solution: SA Fan for maintenance during a planned Solution: SA Fan for maintenance during a planned shut down and precision alignment done between shut down and precision alignment done between drives and vibration come down to 2.2 mm/sec.drives and vibration come down to 2.2 mm/sec.üüReduced excessive vibration with SKF CMXA 70 Reduced excessive vibration with SKF CMXA 70 Analyzer in DMCW Pump Analyzer in DMCW Pump --3A3AIssue :High vibration observed of around 8.3 mm/sec Issue :High vibration observed of around 8.3 mm/sec at Pump NDE bearing. Spectrum analysis revels at Pump NDE bearing. Spectrum analysis revels looseness at Pump baselooseness at Pump base
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Case studies on failure analysisCase studies on failure analysisfixing location along with rotational looseness observed fixing location along with rotational looseness observed
at Pump DE & NDE bearing. at Pump DE & NDE bearing. Solution: Tighten the Pump base fixing location and Solution: Tighten the Pump base fixing location and
tighten the Pump DE & NDE bearing sleeve and tighten the Pump DE & NDE bearing sleeve and vibration come down to 2.8 mm/sec. vibration come down to 2.8 mm/sec.
2) 2) Thermography study of high energy drainsThermography study of high energy drains::--upstream & down steam temperature of high energy upstream & down steam temperature of high energy motorized drain valve are measured to ascertain motorized drain valve are measured to ascertain upstream & down steam temperature of high energy upstream & down steam temperature of high energy motorized drain valve are measured to ascertain motorized drain valve are measured to ascertain passing of valves. Valves if found passing the passing of valves. Valves if found passing the upstream manual isolating valves are kept upstream manual isolating valves are kept closed.closed.Thermography 12Thermography 12--1313\\MC_drain_2013_2.xlsMC_drain_2013_2.xls
3) 3) Infra red thermography study of hot spots on grid: Infra red thermography study of hot spots on grid: Infrared Thermography is the science of acquisition Infrared Thermography is the science of acquisition and analysis of thermal information by using non and analysis of thermal information by using non contact thermal imaging devices. The Infrared contact thermal imaging devices. The Infrared THERMOGRAPHY locates the Hot Spots in Grids thus THERMOGRAPHY locates the Hot Spots in Grids thus making possible elimination of root making possible elimination of root
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Case studies on failure analysisCase studies on failure analysiscause of abnormalities. This process resulted in cause of abnormalities. This process resulted in reduction of hot spots & inadvertent network tripping. reduction of hot spots & inadvertent network tripping. It has become important because of following : It has become important because of following : 1. 1. It It is nonis non--contact contact ––uses remote sensing; 2. It is two uses remote sensing; 2. It is two dimensional ;3. It is real time; dimensional ;3. It is real time; nnIn BBGS we carry out IRT by In BBGS we carry out IRT by numbering each and every joint in our 132 KV numbering each and every joint in our 132 KV ••numbering each and every joint in our 132 KV numbering each and every joint in our 132 KV switchyard , so that we can easily identify any switchyard , so that we can easily identify any joint;joint;Thermography1Thermography1\\SLD 132kv Feeder Bay.docSLD 132kv Feeder Bay.doc•• We carry out thermography of every point , after We carry out thermography of every point , after ensuring that the point is carrying load. ensuring that the point is carrying load. ••We keep a record of temperatures of all points so that We keep a record of temperatures of all points so that we have a historywe have a history••We save images for points which are having hot spotsWe save images for points which are having hot spots
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The THERMOGRAPHY program The THERMOGRAPHY program
Temperature Temperature measuredmeasured CategoryCategory ActionsActions
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Thermographic assessment of Busbar Condition
Tests are done to identify looseness in joints which cause
huge heat loss and result premature breakdownpremature breakdown
After necessary maintenance the same IR Thermography was taken and the results are shown
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Case study Case study --1 (Before Survey)1 (Before Survey)Drg No: 61Drg No: 61 Bay:Bay: GTGT--22 SLD Point SLD Point
No:No:2020
Location:Location:
YY--Phase Isolator Phase Isolator pad to 3” IPS ( pad to 3” IPS (
flexibleflexible ))
Max Temp:Max Temp:220 220 °° CC
Action On:Action On: 06.01.1006.01.10Action On:Action On: 06.01.1006.01.10
Action taken:Action taken:
ØØCopper flexible connectors Copper flexible connectors were found to be prone to were found to be prone to temperature rise due to temperature rise due to sulfation at the contact area sulfation at the contact area between Al and Cu although bi between Al and Cu although bi metallic strip was present, metallic strip was present, resulting in high resistance, resulting in high resistance, heating and pit marks so heating and pit marks so Copper Connectors were Copper Connectors were replaced with AL flexible replaced with AL flexible connectors.connectors.
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Case study (After Survey)Case study (After Survey)
Drg No: 62Drg No: 62 Bay:Bay: GTGT--22 SLD Point SLD Point No:No:
2020
Location:Location:
29A B29A B--Phase Phase Isolator pad to 3” Isolator pad to 3”
IPS ( flexible )IPS ( flexible )
Max Max Temp:Temp: 43.6 43.6 °° CCTemp:Temp: 43.6 43.6 °° CC
Action Action On:On:
16.02.1016.02.10
Analysis:Analysis:
It was observed that the It was observed that the abnormal temperature abnormal temperature rise in this case was due rise in this case was due to mismatch in ALto mismatch in AL--Cu Cu joint.joint.
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Maintenance Planning & OptimizationMaintenance Planning & Optimization
üü In BBGS we follow a Routine maintenance schedule In BBGS we follow a Routine maintenance schedule which are periodically reviewed & changed based which are periodically reviewed & changed based on feed back received from checklists of previous on feed back received from checklists of previous R/Ms.R/Ms.
üü For carrying out Routine maintenance we have a For carrying out Routine maintenance we have a schedule & accordingly planning department schedule & accordingly planning department schedule & accordingly planning department schedule & accordingly planning department convenes planning meeting everyday in the convenes planning meeting everyday in the afternoon ,where personnel from OPS & afternoon ,where personnel from OPS & Maintenance departments meet & chalk out plan Maintenance departments meet & chalk out plan for maintenance of equipments to be carried out in for maintenance of equipments to be carried out in the next day. the next day. maintenance planning meeting.docmaintenance planning meeting.doc
üü By following the above mentioned procedure we By following the above mentioned procedure we are able to reduce unscheduled disruptions and are able to reduce unscheduled disruptions and technical breakdowns thus ensuring equipment technical breakdowns thus ensuring equipment availability above 96%.availability above 96%.
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Capital overhaulCapital overhaul
vvMeticulous planning is done before every capital Meticulous planning is done before every capital overhaul, to minimize cost involvement & down overhaul, to minimize cost involvement & down time of equipments.time of equipments.
vv Planning for annual overhauling referred to as Planning for annual overhauling referred to as Survey is done based on feedback received from Survey is done based on feedback received from Survey is done based on feedback received from Survey is done based on feedback received from OPS department & from previous R/M checklists.OPS department & from previous R/M checklists.
vv Details of execution on hourly basis is planned Details of execution on hourly basis is planned involving the contractors who will be actually involving the contractors who will be actually carrying out the job. carrying out the job. unit1 2012_Survey plan.xlsunit1 2012_Survey plan.xls