Flowserve Valtek Mark One and Mark Two Control Valves - Manual (Page 15)

15
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Valtek Mark One and Mark Two Control Valves FCD VLENIM001-01-AQ - 8/14
Problem Probable Cause Corrective Action
Stem motion
impeded
1. Over-tightened packing 1. Adjust the packing box nuts to slightly over finger-tight
2. Service temperature is beyond
operating limits of trim design
2. Reconfirm service conditions and contact factory
3. Inadequate air supply
3. Check for leaks in air supply or instrument signal system; tighten loose connections
and replace leaky lines
4. Malfunctioning positioner 4. Refer to positioner User Instructions
Excessive seat
leakage
1. Improperly tightened bonnet
1. Refer to step 7.11 Assembly and Installation section for correct tightening proce-
dure
2. Worn or damaged seat ring 2. Disassemble valve and replace or repair seat ring
3. Worn or damaged seat or bonnet
gasket
3. Disassemble and replace gaskets
4. Inadequate actuator thrust
4. Check for adequate air supply to actuator; if air supply is adequate, reconfirm
service conditions and contact factory
5. Incorrectly adjusted plug
5. Refer to steps 7.9 to 7.11 Assembly and Installation section for correct plug adjust-
ment
6. Improper flow direction 6. Refer to original specifications or contact factory
7 . Improper handwheel adjust-ment
acting as a limit-stop
7. Adjust handwheel until plug seats properly
8. Worn or damaged pressure bal-
anced seals
8. Disassemble and replace pressure balanced seals
9. Inadequate air supply pressure
9. Check for leaks in air supply or instrument signal system; tighten loose connections
and replace leaky lines
Inadequate flow
1. Improper plug adjustment, limiting
stroke
1. Refer to steps 7.9 to 7.11 Assembly and Installation section for correct plug adjust-
ment
2. Malfunctioning positioner 2. Refer to positioner maintenance instructions
3. Service conditions exceed trim
design capacity
3. Verify service conditions and consult factory
4. Incorrect actuator stroke 4. Verify actuator stroke
5. Inadequate air supply pressure
5. Check for leaks in air supply or instrument signal system; tighten loose connections
and replace leaky lines
Plug slams
1. Incorrect plug adjustment al-lowing
improper cushion of air between
actuator piston and yoke
1. Refer to steps 7.9 to 7.11 Assembly and Installation section for correct plug adjust-
ment
2. Inadequate air supply 2. Check air supply to actuator; repair leaks and remove any restrictions in supply line
3. Trim sized too large for flow rate 3. Verify the service conditions and actuator sizing, install reduced trim
Valve does not fail
in correct position
1. Incorrect flow direction 1. Reconfirm direction and, if necessary, correct flow direction through valve
2. Incorrect actuator fail direction 2. Consult actuator User Manual and change fail direction
Table III: Troubleshooting Chart