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Instruction Manual
D104709X012
8540 Valve
September 2021
9
CAUTION
During any of the following steps, do not rotate the disk past 90 degrees in the open direction. Rotating the disk past 90
degrees can damage the seal ring.
Packing Maintenance
PTFE‐filled packing has a partially conductive packing ring (such as a carbon‐filled PTFE female adaptor) to electrically
bond the shaft to the valve body.
When replacing the packing, it is recommended to remove the control valve assembly from the pipeline because
valve/actuator adjustments must be made with the valve out of the pipeline.
Disassembly
Key numbers and part locations are shown in figure 12 unless otherwise noted.
1. Isolate the control valve from the line pressure, release pressure from both sides of the valve body, and drain the
process media from both sides of the valve. If using a power actuator, also shutoff all pressure lines to the power
actuator, release all pressure from the actuator. Use lock‐out procedures to be sure the above measures stay in
effect while you work on the equipment.
2. Note the position of the mark on the end of the valve shaft, and its relationship to the actuator shaft.
3. Remove the actuator per instructions in separate actuator instruction manuals, then remove the cap screws (key
14, figure 5). Remove the clamp if the strap is used.
4. Remove the packing nuts (key 101) and packing follower (key 114). For NPS12 CL300, remove the packing flange
and follower (key 102 and 114).
5. Remove the old packing rings, using a formed hook.
CAUTION
Carefully use the hook. Avoid damaging the drive shaft or packing box wall. Scratches on valve surfaces can cause leakage.
(Note: The packing box ring (key 107) can remain in place when replacing packing only.)
6. Clean all accessible metal parts and surfaces to remove particles that would prevent the packing from sealing.
Assembly
Inspect the shaft: If it is damaged, it cannot make a good seal with the packing, and it must be replaced. If the leakage
comes from the outside diameter of the packing, it is possible that the leakage is caused by nicks or scratches around
the packing box wall. Inspect the packing box wall for nicks and scratches when performing the following procedures.