Replacing Packing - Fisher Design ED series Instruction Manual

LUBRICATOR
10A9421-A
AJ5428-D LUBRICATOR/ISOLATING VALVE
A0832-2/IL
Figure 2. Lubricator and Lubricator/Isolating Valve (optional)
For valves with HIGH-SEAL packing, see
the Fisher instruction manual,
HIGH-SEAL Live-Loaded Packing
System, Form 5263, for packing
instructions.
Key numbers refer to figure 3 for PTFE V-ring packing
and to figure 4 for PTFE/composition packing, unless
otherwise indicated.
For spring-loaded single PTFE V-ring packing, the
spring (key 8, figure 3) maintains a sealing force on
the packing. If leakage is noted around the packing
follower (key 13, figure 3), check to be sure the
shoulder on the packing follower is touching the
bonnet. If the shoulder is not touching the bonnet,
tighten the packing flange nuts (key 5, figure 18) until
the shoulder is against the bonnet. If leakage cannot
be stopped in this manner, proceed to the Replacing
Packing procedure.
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 stem,
and if tightening the packing flange nuts does not stop
the leakage, the valve stem may be 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, the leakage may be 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.
Design ED & EAD Class 125-600

Replacing Packing

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 shut off all
pressure lines to the power actuator, and release all
pressure from the actuator. Use lock-out procedures to
be sure that the above measures stay in effect while
you work on the equipment.
2. Disconnect the operating lines from the actuator
and any leak-off piping from the bonnet. Disconnect
the stem connector, then remove the actuator from the
valve by unscrewing the yoke locknut (key 15, figure
18) or the hex nuts (key 26, figure 18).
3. Loosen the packing flange nuts (key 5, figure 18)
so that the packing is not tight on the valve stem.
Remove any travel indicator parts and stem locknuts
from the valve stem threads.
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.
The following step also provides
additional assurance that the valve body
fluid pressure has been relieved.
Avoid damaging the seating surface
caused by the valve plug and stem
assembly dropping from the bonnet (key
1, figure 18) after being lifted part way
out. When lifting the bonnet, temporarily
install a valve stem locknut on the valve
stem. This locknut will prevent the valve
plug and stem assembly from dropping
out of the bonnet.
If the cage starts to lift with the bonnet,
tap it with a plastic mallet, or other soft
material, to be sure it stays in the valve.
WARNING
Note
CAUTION
5