Flowserve Valtek Mark One and Mark Two Control Valves - Manual (Page 12)

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Valtek Mark One and Mark Two Control Valves FCD VLENIM001-01-AQ - 8/14
7.12. Apply air over the piston to seat the plug. For all throttling
valves, adjust the stem clamp so that with full instrument
signal to the positioner the full signal scribe line on the posi-
tioner cam points to the centre of the cam roller bearing.
CAUTION: Make sure the slots of the stem clamp are perpen-
dicular to the bolting. See Figure 5.
NOTE: For on / off valves, the bottom of the stem clamp
should simply be lined up with the bottom of actuator stem
± 1/16 inch (1.6 mm).
7.13. Tighten the stem clamp bolting. Proper tightness is impor-
tant since this adjustment secures the actuator stem to the
plug stem. Adjust the stroke plate so the stem clamp points
to the “closed” position.
7.14. If the valve has been taken out of the line, make sure the flow
arrow indicates proper flow direction upon reinstallation.
7.15. Adjust and test all accessories.
8. Severe Service Trim Options
8.1. CavControl
8.1.1. CavControl replaces the standard Mark One retainer with
a drilled, stepped-hole retainer, see Figure 6. The plug and
bonnet have dimensional differences from the standard
Mark One design. Assembly and disassembly of the valve
follows the standard procedures.
8.1.2. CavControl retainers, plugs and seats should be examined
for excessive cavitation damage when disassembled. Holes
in the retainer should be checked for worn or eroded surfac-
es. Check for plugged holes in the retainer. Plugs and retain-
er mating surfaces should be examined for damage. Repair
and replacement of damaged parts is critical to maintaining
cavitation resistance.
CAUTION: To function properly, CavControl is always in-
stalled flow over.
8.2. ChannelStream
8.2.1. ChannelStream replace the standard retainer with multiple
sleeves pinned together, see Figure 7. The plug, seat ring,
and bonnet have dimensional differences from the standard
Mark One design. Assembly and disassembly of the valve
follows the standard procedures.
8.2.2. ChannelStream retainers, plugs and seats should be exam-
ined for excessive cavitation damage when disassembled.
The inner holes in the retainer should be checked for wear or
erosion, evidence of erosion should require that the retainer
is disassembled. Plugs and retainer mating surfaces should
Figure 6
Mark One with CavControl Trim Body Assembly
Figure 7
Mark One with ChannelStream Trim Body Assembly