Flowserve Valtek Mark 10 Survivor Control Valves - Manual (Page 16)

Valtek Mark 10 Survivor Control Valves FCD VLENIM0036-05 – 07/09
16
5.2.4. Turn actuator back onto the plug, without turning the plug inside the bonnet. Make sure
the gland flange and bonnet flange are in place before engaging the plug stem and actuator
stem threads.
NOTE: Do not allow the gland flange to contact and gall the polished plug stem.
5.2.5. Leave approximately four to five plug stem threads exposed. Install the yoke bolting
(clamp) and tighten firmly. Tighten gland flange to approximately 12 foot-pounds. Use
caution to not overtighten the packing.
CAUTION:
a
Do not overtighten packing. This can cause excessive packing wear and high stem
friction that may impede stem movement.
5.2.6. Install new bonnet gasket and lower bonnet/actuator assembly into the valve body. Install
the bonnet flange bolting and tighten it per Table II.
5.2.7. Valves with metal plug and seat
Insert the seat into the bottom of the valve. Stroke the valve by applying air to the top of the
actuator. Check for a
1 /
16
-inch gap between the seat and body. If the gap is too small or large,
loosen the stem clamp bolt and screw the plug in or out of the actuator stem. Repeat this
process as needed to obtain a
1 /
16
-inch gap. Then retighten the stem clamp.
5.2.8. Valves with ceramic trims and actuator limit stops
5.2.8.1. This procedure provides a minimum gap between the piston and the bottom of the
yoke. A minimal gap is essential to avoiding slamming of the plug while operating at
low openings.
5.2.8.2. Loosen the stem clamp to allow the plug to rotate in the actuator stem.
5.2.8.3. 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.
5.2.8.4. 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.
5.2.8.5. 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.
5.2.8.6. With the seat gaskets removed, place the seat ring into the body and hold in place
using hand pressure.
5.2.8.7. Stroke the valve open.
5.2.8.8. Turn the plug out one quarter turn, or less when fine tuning the plug position.
5.2.8.9. 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