Replacing Packing - Fisher EWS Series Instruction Manual

Instruction Manual
Form 2376
March 2007
9.5 mm 12.7 mm
(3/8 INCH) (1/2 INCH)
STEM STEM
12A8188-A
12A7815-A
12A8173-A
A2619-1 / IL
TYPICAL (DOUBLE) ARRANGEMENTS
Figure 5. Detail of PTFE/Composition Packing Arrangements
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.

Replacing Packing

WARNING
Refer to the WARNING at the
beginning of the Maintenance section
in this instruction manual.
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 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, and then remove the actuator
UPPER WIPER
(KEY 12)
PACKING
FOLLOWER
(KEY 13)
PACKING RING
(KEY 7)
LANTERN RING
(KEY 8)
PACKING BOX
RING (KEY 11)
19.1, 25.4, OR
31.8 mm
(3/4, 1, OR
1 1/4 INCH) STEM
from the valve by unscrewing the yoke locknut (key
15, figure 21) or the hex nuts (key 26, figure 21).
3. Loosen the packing flange nuts (key 5, figure 21)
so that the packing is not tight on the valve stem.
Remove any travel indicator parts and stem 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.
The following step also helps to
provide additional assurance that the
valve body fluid pressure has been
relieved.
4. Hex nuts (key 16, figure 22, 23 or 24) attach the
bonnet (key 1, figure 21) to the valve body (key 1,
figure 22, 23 or 24). 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 with bonnet removal as described in the
following steps.
CAUTION
To avoid damage to the seating
surface caused by the valve plug and
stem assembly dropping from the
bonnet after being lifted part way out,
temporarily install a valve stem
locknut on the valve stem when lifting
the bonnet. The locknut prevents the
valve plug and stem assembly from
dropping out of the bonnet.
5. Completely remove the hex nuts (key 16) and
carefully lift the bonnet off the valve body.
6. Remove the locknut and separate the valve plug
and stem from the bonnet. Set the parts on a
EW Valve
Note
9