Flowserve Valtek Mark 10 Survivor Control Valves - Manual (Page 8)

Valtek Mark 10 Survivor Control Valves FCD VLENIM0036-05 – 07/09
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2.5.2. Valves with ceramic trims and actuator limit stops
2.5.2.1. This procedure provides a minimum gap between the piston and the top of
the yoke. A minimal gap is essential to avoiding slamming of the plug while
operating at low openings.
2.5.2.2. Loosen the stem clamp to allow the plug to rotate in the actuator stem.
2.5.2.3. Remove the limit stop cap and loosen the jam nuts. Back the jam nuts off to
allow the actuator to stroke fully without engaging the limit stop.
WARNING:
c
With the limit stop cap off, the jam nuts present a pinch hazard. While
stroking the actuator, take care not to get hands or clothing caught between the jam nuts
and the limit stop hub.
2.5.2.4. Using a wrench to keep the actuator stem from rotating, spin the plug into the
actuator stem until only one to one and a half threads are still exposed.
2.5.2.5. Check to make sure the seat ring and plug are clean of dirt, debris or any other
contamination.
NOTE: Flowserve can offer graphite ribbon which can be used to provide a thin pad between
the plug head and seat ring surfaces. It is recommended that similar padding be used to
lower the risk of ceramic fracture.
2.5.2.6. With the seat gaskets removed, place the seat ring into the body and hold in
place using hand pressure.
2.5.2.7. Stroke the valve open.
2.5.2.8. Turn the plug out one quarter turn, or less when fine tuning the plug position.
2.5.2.9. Stroke the valve closed. Note if the plug contacts the seat ring. This can be felt as
the seat ring moves due to contact with the plug.
CAUTION:
a
Contacting the seat ring and plug with ceramic trimmed valves could cause
the seat ring or plug to fracture. Take great care in allowing these two surfaces to
contact. The seat ring should be allowed to slide out of the body smoothly, with only
light hand pressure to hold it in place. If the seat begins to bind, immediately stroke the
valve open. Remove the seat and check for dings or dirt. Stroke the valve slowly to avoid
slamming the plug into the seat ring.
NOTE: By stroking the valve closed, the gap between the piston and yoke is closed.
2.5.2.10. Repeat steps 2.5.2.7 through 2.5.2.9 until the plug just contacts the seat. Stop as
soon as the two are in contact.
2.5.2.11. Stroke the valve open. Turn the plug back into the actuator stem one quarter turn.
This will ensure that the plug will not contact the seat during operation.
2.5.2.12. Remove the seat ring from the body. Set and tighten the stem clamp.
2.5.2.13. Stroke the valve closed and move the lower jam nut down until it contacts the
limit stop hub.
2.5.2.14. Stroke the valve open and lower the jam nut one eighth a turn. Lower the upper
jam nut and tighten the two together.
2.5.2.15. Stroke the valve closed to verify the jam nuts are set correctly.
2.5.2.16. Replace the limit stop cap.