Bellows Maintenance - Emerson FISHER GX Instruction Manual

GX Valve and Actuator
CAUTION
To protect the valve plug seal ring (key
37) and to ensure it seals properly, be
careful not to scratch the surfaces of the
ring groove in the valve plug or any of
the surfaces of the replacement ring.
1. With the valve plug (key 3) removed according to
the Disassembly portion of the Valve Trim
Maintenance procedure, proceed as appropriate:
The seal ring (key 37) cannot be reused because it
is a closed ring which must be pried and/or cut from
the groove. Once the seal ring is removed, the
elastomeric backup ring (key 38), which is also a
closed ring, can be pried from the groove.
To install a new backup ring and seal ring onto the
valve plug, apply a general purpose silicone-base
lubricant to both rings (keys 38 and 37). Place the
backup ring over the valve plug (key 3) and into the
groove. Place the seal ring over the top edge of the
valve plug (key 3) so that it enters the groove on one
side of the valve plug. Slowly and gently stretch the
seal ring and work it over the top edge of the valve
plug. The PTFE material in the seal ring must be
permitted time to cold-flow during the stretching
procedure, so avoid jerking sharply on this ring.
Stretching the seal ring over the valve plug may
make it seem unduly loose when in the groove, but it
will contract to its original size after insertion into the
bonnet.
2. Install the seat ring, valve plug/stem, bonnet and
actuator yoke into the valve body by completing the
assembly according to steps 1 to 3 of the section
Assembly of Unbalanced Trim.
16
Repair Nameplate
If required by the end-user, an optional repair
nameplate is available for recording changes made
to the valve trim during maintenance (see figure 23).
This nameplate can be ordered as a spare part, and
is easily mounted to the actuator casing using a
casing bolt. (Reference the Parts Ordering section of
this manual.)
As shown in figure 23, the repair nameplate provides
locations for maintenance personnel to record trim
data, such as:
D Date of maintenance
D Trim material
D Port diameter
D Flow capacity (C
/ K
v
D Flow characteristic

Bellows Maintenance

This section provides instruction on the replacement
of the bellows / stem assembly (see key 49 in
figure 20).
1. Remove the actuator, bonnet assembly as
described in the Replacing Packing section (steps 1
through 10).
2. Remove the plug/stem assemblies as described
in the Valve Trim Disassembly section (steps 2
through 6).
3. To install the new bellows / stem assembly
(key 49), perform the Valve Trim Assembly (step 3).
Instruction Manual
Form 5770
June 2006
)
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