4
2.1
Final Check
1. Turn on the instrument air supply and set pressure 5
psig greater than required by the bench set listed on
the label plate.
2. Check the air lines to the actuator for leaks.
3. Vary the air supply to the actuator to ascertain that the
actual valve travel (stroke) corresponds with the data in
Table 2.
4. Check to be sure that the combined actions (direct and
reverse) of the controller, positioner, etc., and valve, pro-
duce desired direction of movement, and will ensure
the required valve position in the event of air supply
failure.
NOTE:
Under actual operating conditions the pressure
drop across the valve may differ from the calculated fig-
ures. Some actuators may require readjustment of the
spring preload in order to provide adequate shutoff force.
In this situation check to ensure that the actuator is still
capable of full valve travel with the available supply air
pressure.
5. Tighten the packing flange stud nuts evenly to assure
optimum sealing pressure on the stem and packing
box walls. Slightly more than finger tight should be
adequate to eliminate packing box leakage. Over tight-
ening will restrict stem movement and adversely affect
the process control.
3 MAINTENANCE
3.1
Disassembly
READ THESE INSTRUCTIONS COMPLETELY, FOR YOUR SAFE-
TY IT IS IMPORTANT THAT THE FOLLOWING PRECAUTIONS
BE TAKEN PRIOR TO REMOVAL OF THE UNIT FROM THE LINE
OR BEFORE ANY DISASSEMBLY.
1. Wear any protective equipment normally required
when working with the fluid involved during removal
and disassembly.
2. Depressurize and drain the pipeline with the valve
open prior to disconnecting service lines.
3. Before removing the instrument connections from the
actuator, shut off the air pressure and bleed the air
lines.
4. Have adequate rigging transport means available at
the valve before attempting to remove it from the
pipeline or before breaking the body/bonnet joint for
in-line service.
3.2
Removal From Pipeline
N
NO
OT
TE
E::
Maintenance such as diaphragm, packing or trim
replacement can be done without removing the valve
from the line.
1. Disconnect all instrument air and electrical lines from
the actuator.
2. Remove all inlet and outlet line flange studs and nuts,
and lift the valve out of the pipeline.
3. Secure the valve and actuator assembly firmly on a
work bench in an upright position in a manner to pre-
vent tipping or falling over.
3.3
Actuator Removal
1. Connect instrument air to the actuator and apply signal
pressure sufficient to move the plug to a position only
slightly off the seat. This will remove the spring force
from the coupling before disassembly.
2. Disconnect the actuator coupling from the valve stem
by disengaging the coupling screws (Figure 1).
Disconnect air supply.
3. Unscrew the clamp nut from the bonnet by placing a
metal rod or blunt nosed chisel on the clamp nut lugs
and striking with a mallet.
4. Unscrew the clamp nut from the threads and lift the
nut over the plug stem.
5. Lift or hoist the actuator unit off the valve, taking care
to avoid damaging the plug stem, instruments or tub-
ing.
NOTE:
The actuator is removed from the body as a unit,
without disturbing the packing box bolt-bolting. Clamp
nut and actuator yoke will pass over the packing flange.
6. If maintenance is required on the actuator consult the
appropriate actuator IMO.
3.4
Valve Body Disassembly
1. Unscrew the packing flange nuts, and remove packing
flange and packing follower.
2. Remove the bonnet/body stud nuts.
3. Lift the bonnet while holding the plug stem (to prevent
the plug from dropping out), and carefully lift off the
valve body. Remove the cage and the seat ring from the
body.
4. Withdraw the plug and stem downward out of the
bonnet through the guide.
CAUTION: CARE MUST BE TAKEN TO AVOID DAMAGE TO
THE PLUG AND PLUG GUIDE.
5. Using a narrow hook or bent wire, pull the packing
rings and lantern spring out of the packing box.
CAUTION: WHEN REMOVING PACKING RINGS FROM THE
PACKING BOX, USE A HOOK, BENT WIRE, OR TOOL MADE
FROM A MATERIAL THAT IS SOFTER THAN THE BONNET
MATERIAL. THIS WILL PREVENT SCRATCHING OR MARRING
OF THE PACKING BOX SURFACES.
Figure 1 Actuator Removal
