Flowserve Valtek CavControl Trim Installation, Operation & Maintenance Instructions page 4

Failure Probable Cause
Jerky stem 1. Overtightened graphite packing
movement
2. Galling or scoring between plug
and sleeve
3. Overtightened packing
4. Service temperature is beyond
operating parameter of trim design
5. Inadequate air supply
6. Malfunctioning positioner
Excessive 1. Loose bonnet flange bolting
leakage
2. Worn or damaged seat ring
3. Worn or damaged pressure-
balanced plug seals
4. Worn or damaged seat,
bonnet or sleeve gaskets
5. Inadequate actuator thrust
6. Incorrectly adjusted plug
7. Improper flow direction
Excessive 1. Worn or damaged plug seals
cavitation causing excessive trim vibration
damage 2. Misapplication of trim design
3. Improper flow direction
4. Severe corrosive service
exceeds trim material limitations
Inadequate 1. Improper plug adjustment
flow limiting stroke
2. Malfunctioning positioner
3. Blocked pressure-balanced plug
vents or sleeve holes
4. Service conditions exceeding
trim design capacity
Plug slams 1. Incorrect plug adjustment allowing
improper cushion of air between
actuator piston and yoke
2. Inadequate air supply
3. Trim sized too large for flow rate
FCD VLAIM015-07
Troubleshooting Chart
© 2000 Flowserve Corporation. Flowserve Corporation, Valtek Control Products, Tel. USA 801 489 8611
Corrective Action
1. Graphite packing is often associated with jerky
stem movement
2. Superficial scoring or galling may be removed
with a light application of emery cloth; if more
serious damage exists, contact factory
CAUTION: Trim parts are machined to close
tolerances, which are essential for correct
functioning of the valve. Attempting to remove
deep scratches could result in high leakage
rates or improper functioning of the valve
3. Adjust the packing box nuts to just slightly over
finger-tight (over-tightening will also cause
excessive packing wear and high stem friction)
4. Reconfirm service conditions and contact factory
5. Check for leaks in air supply or instrument
signal system; tighten any loose connections
and replace any leaking lines
6. Refer to positioner maintenance instruction
1. Refer to step 9 of "Reassembly" section for
correct tightening procedure
2. Disassemble and replace or repair seat ring
(for correct procedure on remachining seat
surfaces, see Maintenance Instruction 1)
3. Disassemble and replace plug seals
4. Disassemble and replace gaskets
5. Check for adequate air supply to the actuator; if
supply is OK, reconfirm service conditions and
contact factory
6. Refer to Installation, Operation, Maintenance,
Instruction 1 for correct plug adjustment
7. Confirm flow direction is always over the plug
1. Disassemble and replace plug seals
2. Reconfirm service conditions and contact factory
3. Reinstall with flow direction over the plug
4. Reconfirm service conditions and contact factory
1. Refer to Installation, Operation, Maintenance
Instruction 1 for correct plug adjustment
2. Refer to positioner maintenance instruction
3. Eliminate matter from line, disassemble and
clean plug vents and sleeve
4. Verify service conditions and consult factory
1. Refer to Maintenance Instruction 1 for correct
plug adjustment
2. Check air supply to actuator; repair leaks and
remove any restrictions in the supply line
3. Install reduced trim to provide greater plug-to-seat
clearance