Chapter 5. Disassembly and Reassembly of the Control
Valve
This section gives instructions on disassembly and reassembly of the control valve. If you need
to disassemble and reassemble the valve for periodic inspection, troubleshooting, or other
circumstances, refer to the instructions.
5-1. Before Disassembly
• Allow enough space to work. If you disassemble several control valves at the same time,
allow extra space to avoid mixing parts up.
• If you detach only the actuator, leaving the control valve on the piping, be sure to shut off
the fluid in the piping and release the process pressure.
• Check that the temperature near the control valve is normal.
• Have all tools necessary for disassembly or detachment ready.
• Write down the information printed on the nameplate and the model No. of the positioner.
5-2. Necessary Tools
A hammer, chisel, punch, open-end wrench or box wrench, a special wrench for the seat ring,
compressed air source (390 kPa max.) to test the valve.
Contact us for a special wrench for the seat ring.
5-3. Removal of the Actuator from the Valve Body and Reassembly, and
Changing the Orientation of the Actuator
5-3-1. Removal of the Actuator from the Valve Body and Reassembly
Removal procedure
Step Procedure
1
•
Detaching the air pipes
Detach the air pipes, etc., from the actuator. Keep supplying air from the air supply
system to the actuator.
2
•
Marking
With the hammer and chisel or punch, place matching marks indicated in
Figure 5-1 so that the actuator, valve body, and bonnet can be reassembled in the
same positions.
3
•
Detaching the stem connector
Apply air pressure to the actuator so that the pointer indicates about 10 to 20 % above
the fully closed position, and maintain that pressure. Loosen the hex bolts that hold the
stem connector, remove the stem connector, and detach the actuator stem from the
valve stem.
4
•
Removing the accessories
Remove accessories such as the positioner and limit switch. Protect the air supply and
air output connections of the removed positioner with plastic tape, etc.
5-1
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