Fisher 461 Instruction Manual page 8

461 Valve
June 2017
3. Remove the yoke locknut (key 26), and remove the actuator from the bonnet (key 14).
4. Loosen the packing flange nuts (key 25) so that the packing is not tight on the valve plug stem (key 10). Remove
any travel indicator disk and stem locknuts from the valve plug stem threads.
CAUTION
When lifting the bonnet (key 14), be sure that the valve plug and stem assembly (keys 3 and 10) remains on the seat ring
(key 2). This avoids damage to the seating surfaces as a result of the assembly dropping from the bonnet after being lifted
part way out. The parts are also easier to handle separately.
Use care to avoid damaging gasket sealing surfaces.
WARNING
To avoid personal injury or property damage caused by uncontrolled movement of the bonnet, loosen the bonnet by
following the instructions in the next step. Do not remove a stuck bonnet by pulling on it with equipment that can stretch
or store energy in any other manner. The sudden release of stored energy can cause uncontrolled movement of the bonnet.
If the liner sticks to the bonnet, proceed carefully with bonnet removal and support the liner so that it will not fall
unexpectedly from the bonnet.
Note
The following step also provides additional assurance that the valve body fluid pressure has been relieved.
5. Hex nuts (key 8) attach the bonnet to the valve body. Loosen these nuts approximately 3 mm (1/8 inch). Then
loosen the body‐to‐bonnet gasketed joint by either rocking the bonnet or prying between the bonnet and valve
body. Work the prying tool around the bonnet until the bonnet loosens. If no fluid leaks from the joint, proceed to
the next step.
6. Unscrew the hex nuts (key 8) and carefully lift the bonnet off the valve stem. If the valve plug and stem assembly
starts to lift with the bonnet, use a brass or lead hammer on the end of the stem and tap it back down. Set the
bonnet on a cardboard or wooden surface to prevent damage to the bonnet gasket surface.
7. Remove the valve plug (key 3), bonnet gasket (key 6) and the liner (key 5).
CAUTION
Inspect the liner, bonnet, and body gasket surfaces. These surfaces must be in good condition, with all foreign material
removed. Small burrs less than approximately 0.076 mm (0.003 inches) in height (the thickness of a human hair) can be
ignored. Scratches or burrs that run across the serrations are not permitted under any conditions, since they will prevent
the gaskets from sealing properly.
8. Clean all gasket surfaces with a good wire brush. Clean in the same direction as the surface serrations, not across
them.
9. Cover the opening in the valve body to protect the gasket surface and to prevent foreign material from getting into
the valve body cavity.
10. Remove the packing flange nuts (key 25), packing flange (key 23), upper wiper (key 16), and packing follower (key
29). Carefully push out all the remaining packing parts from the valve side of the bonnet using a rounded rod or
other tool that will not scratch the packing box wall.
8
Instruction Manual
D100714X012