Temperature Control Valves (Vtrs); Hydraulic/Mechanical Equipment; Relief Valves; Solenoid Valves - GE 7FA.05 Maintenance Instruction

Inspection and Maintenance Instructions for 7FA.05 Gas Only and Dual Fuel Gas TurbinesGEK 116862
Refer to MLI 0414 Device Summary for the proper setting of the valve. It is recommended that valve
diaphragms and stem packings be replaced every five years, unless operating experience indicates
that more frequent replacement is necessary.
D. Temperature Control Valves (VTRs)
The temperature control valves (VTRs) are used to regulate the cooling water flow to the lube oil heat
exchanger and atomizing air pre-cooler (where applicable). The control system will automatically
regulate the valve position based on lube oil temperature and atomizing air pre-cooler discharge
temperature. During cooling water system flow balancing, the control valve should be forced to full
flow through the coolers. After balancing is complete, the control valve shall be returned to normal
operation with position controlled by the gas turbine control system.
Valve stem packing nuts should be tightened just enough to stop water leaks. The valve manufacturer
generally states that if the packing nut is hand tightened, enough force is applied to stop water
leakage. Use of excessive force causes friction between the valve stem and packing. This results in
erratic operation.
It is recommended that the valve stem packing be replaced every five years unless operating
experience indicates the advisability of more frequent replacement.
IV. HYDRAULIC/MECHANICAL EQUIPMENT
A. Relief Valves
Spring-loaded relief valves protect the system component, or pumps from overpressure. Adjustment
of the valve setting is accomplished by an adjusting screw. Turning the screw into the valve body
increases the spring force (raises opening pressure). The relief valve is set to open at the pressure
specified on the Device Summary.
Annually, all the relief valves listed should be removed and bench-tested against the settings listed on
the Device Summary.
B. Solenoid Valves
If any oil leakage is observed, replace the "O" ring seals. Energize the solenoid and check valve
operation (a metallic click should be heard and in some cases, the valve travel can be seen). Sluggish
valve operation, or excessive leakage can result from dirt. Therefore, periodic disassembly and
cleaning of all solenoid valves is desirable when improper operation or leakage is evident.
C. Servo valves
If any oil leakage is observed, replace O-ring seals.
Verify that lock washer, required by assembly drawings but not provided with new replacement
servo-valves, are in place on all servo valve mounting screws.
With lock washers installed, verify that the servo valve mounting screws are long enough to provide
sufficient thread engagement. If longer servo valve mounting screws are required to meet minimum
thread engagement, verify that the replacement screw does not bottom in the threaded hole. Rework
the screw if required.
Sluggish operation of the valve may be due to contaminants. Inspect valve for cleanliness and clean
filter or replace valve as necessary.
© General Electric Company, 2011. GE Proprietary Information. All Rights Reserved.
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