Instruction Manual
D103553X012
Large ET and ED Valves
July 2017
7
Packing Maintenance
Note
For valves with ENVIRO-SEAL packing, see the Fisher instruction manual, ENVIRO-SEAL Packing System for Sliding-Stem Valves,
D101642X012
, for packing instructions.
For valves with HIGH-SEAL packing, see the Fisher instruction manual, HIGH-SEAL ULF Live-Loaded Packing System,
D101453X012
, for packing instructions.
For spring‐loaded single PTFE V‐ring packing, the spring (key 8, figure 2) maintains a sealing force on the packing. If
leakage is noted around the packing follower (key 13, figure 2), check to be sure the shoulder on the packing follower
is touching the bonnet (key 35). If the shoulder is not touching the bonnet, tighten the packing flange nuts (key 5)
until the shoulder is against the bonnet. If leakage cannot be stopped in this manner, proceed to the Replacing
Packing section.
If there is undesirable packing leakage with other than spring‐loaded packing, first try to limit the leakage and
establish a stem seal by tightening the packing flange nuts.
If the packing is relatively new and tight on the valve stem (key 2B) and if tightening the packing flange nuts does not
stop the leakage, it is possible that the valve stem is worn or nicked so that a seal cannot be made. The surface finish of
a new valve stem is critical for making a good packing seal. 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. If performing any of
the following procedures, inspect the valve stem and packing box wall for nicks and scratches.
Replacing Packing
1. Isolate the control valve from the line pressure, release pressure from both sides of the valve, and drain the process
media from both sides of the valve. If using a power actuator, also shut off all pressure lines to the power actuator,
release all pressure from the actuator, and use lock‐out procedures to prevent injury while you work on the
equipment.
2. Remove the actuator from the valve body by following the appropriate Actuator Removal procedure from the
actuator instruction manual.
3. Loosen the packing flange nuts (key 5) so that the packing is not tight on the valve stem (key 2B). Remove any
travel indicator parts and locknuts from the valve stem threads.
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.
CAUTION
Avoid damage to the seating surfaces caused by the valve plug and stem assembly dropping from the bonnet after being
lifted part way out. When lifting the bonnet, temporarily install a locknut on the valve stem. This locknut will prevent the
valve plug and stem assembly (key 2) from dropping out of the bonnet.
If the cage (key 3) starts to lift with the bonnet, tap it with a plastic mallet, or other soft material, to be sure it stays in the
valve body.
Note
The following step also provides additional assurance that the valve body fluid pressure has been relieved.
