GE 7FA.05 - Fuel Gas System; General Notes; Fuel Gas Stop Ratio and Control Valves; Liquid Fuel Forwarding System (Dual Fuel Units Only)

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GEK 116862 Inspection and Maintenance Instructions for 7FA.05 Gas Only and Dual Fuel Gas Turbines

rings should be replaced and reworked to restore the manufacturer’s recommended clearance values.

This will restore pump efficiency insofar as this clearance is concerned.

Whenever the pump is disassembled, all parts of the pump, especially the impeller, shaft sleeve, and

wearing parts of the mechanical seal should be checked and replaced, if worn. Refer to the Cooling

Water System section in the Operation and Maintenance Manual.

XI. FUEL GAS SYSTEM

A. General Notes

Fuel gas piping failures may cause a fire or explosion if an ignition source is present, or failure of the

machine to operate.

B. Fuel Gas Stop Ratio and Control Valves

Check for excessive gas leakage at the valve stems, packing leakoff, and vent lines.

If it is suspected that the valve leaks, check the seating surfaces for damage or foreign material.

Contact between the valve and seat must be checked with the stem in place.

For additional information on the fuel gas stop ratio and control valves, refer to the Operation and

Maintenance Manual under the Fuel System.

XII. LIQUID FUEL FORWARDING SYSTEM (DUAL FUEL UNITS ONLY)

A. Centrifugal Pump

Check the discharge pressure of the pump against that specified on the Schematic Piping Diagram.

Check the pump for unusual or excessive noise while operating. Check the mechanical shaft seals for

excessive leakage and replace if necessary. Check the shaft for free rotation, without rubbing or

binding. Check the fit between the pump and motor shafts for rightness and freedom from vibration.

Check the connection joints of the casing for oil leakage and replace gaskets if the leaks are

excessive. At annual turbine shutdown, check the seal cooling oil line and connection fittings for

internal cleanliness by removing and cleaning.

B. Fuel Oil Heaters

Check to assure that the fuel oil is being maintained within the temperature limits specified on the

Schematic Piping Diagram and/or Device Summary. If the heaters are not operating properly, or if

the oil temperature is not being maintained, check the power and control circuits. If necessary, test

the heating elements and replace any that are burned out. Thermostats should be checked in heated or

cooled oil bath, using an accurate thermometer as a standard. Do not energize calrod heaters unless

they are immersed in fuel oil. Failure to comply could burn out element.