Enviro-Sealr Bellows Seal Bonnet; Replacing A Plain Or Extension Bonnet With An Enviro-Seal Bellows Seal Bonnet; (Stem/Bellows Assembly) - Fisher EWS Series Instruction Manual

Instruction Manual
Form 2376
March 2007
D The open interior of the C-seal plug seal must
face down in a valve with flow-down construction
(figure 9).
An installation tool must be used to
properly position the C-seal plug seal
on the valve plug. A tool is available as
a spare part from Emerson Process
Management or a tool could be
manufactured following the
dimensions given in figure 10.
3. Place the C-seal plug seal over the top of the
valve plug and press it onto the plug using the
installation tool. Carefully press the C-seal plug seal
onto the plug until the installation tool contacts the
horizontal reference surface of the valve plug
(figure 11).
4. Apply a suitable high-temperature lubricant to the
threads on the plug. Then, place the C-seal retainer
onto the plug and tighten the retainer using an
appropriate tool such as a strap wrench.
5. Using an appropriate tool such as a center
punch, stake the threads on top of the plug in one
place (figure 12) to secure the C-seal retainer.
6. Replace the piston ring(s) following instructions in
the Trim Replacement section of this manual.
7. Return the seat ring, cage, plug/retainer
assembly, and stem to the valve body and
completely reassemble the valve package following
the appropriate instructions in the Trim Replacement
section of this manual.
CAUTION
To avoid excessive leakage and seat
erosion, the valve plug must be
initially seated with sufficient force to
overcome the resistance of the C-seal
plug seal and contact the seat ring.
You can correctly seat the valve plug
by applying the full actuator load. This
force will adequately drive the valve
plug to the seat ring, thus giving the
C-seal plug seal a predetermined
permanent set. Once this is done, the
plug/retainer assembly, the cage, and
the seat ring become a matched set.
Note
With full actuator force applied and the
valve plug fully seated, align the
actuator travel indicator scale with the
lower end of valve travel. Refer to the
appropriate actuator instruction
manual for information on this
procedure.
ENVIRO-SEAL Bellows Seal Bonnet
Replacing a Plain or Extension Bonnet
with an ENVIRO-SEAL Bellows Seal
Bonnet (Stem/Bellows Assembly)
Except where indicated, key numbers in this section
are referenced in figure 22 for Design EWD
constructions, figure 22 for restricted trim detail,
figure 23 for Design EWS constructions, and figure
24 for Design EWT constructions. Refer to figures 26
and 27 for Cavitrol III, figure 27 for Whisper Trim III,
and figure 29 for WhisperFlo constructions.
1. Remove the actuator and bonnet according to
steps 1 through 6 of the Replacing Packing
procedure in the Maintenance section.
2. Lift out the cage.
3. Remove and discard the existing bonnet gasket.
Cover the valve body opening to protect sealing
surfaces and to prevent foreign material from
entering the valve body cavity.
The ENVIRO-SEAL stem/bellows
assembly for Design E valves is
available only with a threaded and
drilled plug/adaptor/stem connection.
The existing valve plug can be reused
with the new stem/bellows assembly
or a new plug can be installed.
4. Inspect the existing valve plug. If the plug is in
good condition, it can be reused with the new
ENVIRO-SEAL stem/bellows assembly. To remove
the existing valve plug from the stem, first, place the
existing plug stem assembly in a soft-jaw chuck or
other type of vise so that the jaws grip a portion of
the valve plug that is not a seating surface. Drive out
or drill out the pin (key 8).
5. Then, reverse the plug stem assembly in the
soft-jaw chuck or vise. Grip the valve stem in an
appropriate place and unscrew the existing plug
from the valve stem.
CAUTION
When installing a valve plug on the
ENVIRO-SEAL stem/bellows assembly,
EW Valve
Note
21