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Operation & Maintenance

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OPERATION

STEAM PURITY

OIL SPECIFICATION

RELIABILITY & AVAILIBILITY OF TURBINE IS ASSURED

WHEN ALL THE VITAL COMPONENTS AND MONITORING

EQUIPMENT ARE IN IN THE SPECIFIED CONDITION.

CONTROLLERS

PROTECTIVE DEVICES

SAFTEY DEVICES

STOP AND CONTROL VALVES & OTHER IMPORTANT

TURBINE VALVES

MONITORING EQUIPMENT

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TESTING OF ALL COMPONENET AS PER SPECIFIED

TESTING INTERVALS WEEKLY/MONTHLY/YEARLY

START-UP OF TURBINE

READINESS OF EXTERNAL SYSTEM

- CIRCULATING WATER FOR CONDENSER

- COOLING WATER FOR COOLERS

- AUXILARY STEAM

-DM WATER SUPPLY

- CONDENSATE SYSTEM, VACUUM PUMP &

EJECTORS

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READINESS OF OIL SYSTEM AND TURNING GEAR

READINESS OF CONDENSING PLANT

READINESS OF VACUUM PUMP, SEAL STEAM SUPPLY

START OF BYPASS OPERATION MAIN STEAM LINE WARM UP

TURBINE WARMING UP

SPEEDING UP OF TURBINE

SYNCHRONISATION

LOADING

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Why Maintenance?

To Increase Efficiency, Availability, Reliability,

Safety, Economy

To Decrease Forced outage, Major damage,

AccidentTo Assess Present condition, Damage &

Damage initiation, Remaining life,

Subsequent inspection

To Rectify /Replace Deficiencies, damagedcomponents

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Criteria to increase inspection intervals

Improved Calculation methods

Better Knowledge of materials

More Dependable structural components

Sophisticated Monitoring systems

Improved Operational procedure

More Service experience

However inspection intervals should not be lengthened indefinitely

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Criteria to decrease inspection intervals

Ease in dismantling

Thermal fatigue

Bolt relaxation Blade check

Seal wear

Turbine modules to be overhauled in 50,000 eq. hours of operation

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Factors influencing turbine plant outage

Time independent

(Human failure)

Planning & Design

Material selection

Manufacturing & Assy.

Erection & Commissioning

Operation & Maintenance

Time dependent

(Component stressing)

Wear & tear

Erosion & Corrosion

Distortion

Deposits

Life expenditure

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Failure probability

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Maintenance

Routine

Maintenance

Capital

Maintenance

Maintenance Category

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Operational History

Failure History

Pre-overhaul survey

Identify Scope of work

Identify Corrective measures

Identify Spares requirement

Capital Maintenance

Plan & Start Dismantling

Checks & Findingsduring dismantling

Review identified

Scope & Corrections

Execute Overhauling &

Compare Performance

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Capital Overhaul

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SEQUENCE OF OVERHAULING ACTIVITIES

Stoppage of barring gear and oil system.

Removal of HP/IP casing insulation after stoppage of oil circulation.

Opening pedestal cover and upper half bearings.

Measurement of bearing clearances.

Measurement of catenery over the journal of the turbine rotors.

De-coupling of LP/Gen rotors.

Swing check measurement on HPF end of the rotor.

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Recording of CRO of the HP/IP and IP/LP coupling.

Bump check of HP/IP casing.

De-coupling of HP/IP/LP rotors.

Horn drop check of HP/IP casing.

If no loading is observed on any of the palm of the casing , then

it needs correction. Necessary corrections based on Horn Drop values to be done

by cutting / re-welding of pipelines , and not by adjusting the

thickness of the packer.

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Check / Record mis-match of the HP inlet / exhaust pipe line

before lifting of module for future reference.

Removal of HP module for overhaul.

Dummy shaft to be used during overhaul of HP module. In

absence of dummy shaft the position of casing centering

between HP inner/outer is not known.

Checking of bearing contact between torus and its support

and replacement of bearing , if required.

Checking of pedestal level as per the centenary value and

level of individual pedestal. Necessary correction in

pedestal level is to be carried out , if these are sliding

pedestal.

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Checking of pedestal centering with respect to piano wire.

Checking of pedestal packers for their contact.

Replacement of bearing with piano wire in place of directly

with rotor.

Checking/correction concavity/convexity of rotor couplings.

Re-finning of HP/IP rotor & casing as required.

Coupling of HP/IP rotor to be done first and record swing

check and CRO. Afterwards IP/LP rotor to be coupled.

No change in CRO and swing check of HP/IP rotor is

permitted with the coupling of IP/LP rotor.

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