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•
If the plug guide area has a center mark,
PIace the plug guide on a V-block and use a suitable
drill size to either:
-
Match the hole size in the plug, or
-
Match Diameter C (see Figure 9)
Drill through the plug-stem assembly.
•
If the plug guide area does not have any hole or any
center mark,
-
Measure Dimension D based on the plug guide diameter
and stem diameter (see Figure 9).
-
PIace the plug guide on a V-block, and make a center
mark on the plug guide area using a center punch.
-
Drill through the plug-stem assembly using a suitable
size drill bit.
In all cases after drilling: Remove any burrs from the
plug guide hole by making a slight chamfer.
D. Pinning the Plug-Stem Assembly
1.
Select the correct size pin based on the plug guide diameter
and stem diameter (see Figure 9). Apply a small amount of
grease on the pin and hand assemble it into the hole in the
plug.
2.
Press fit the pin into the hole using a hammer. Complete
the pinning operation by taking care to ensure that the pin is
recessed by the same amount at both sides (see Figure 9).
3.
After the plug has been pinned, it should be placed in a lathe
to ensure it is concentric with the stem.
If the assembly is not running true, then the stem should be
placed in a collet with the plug guide against it and the plug
should be adjusted. Alignment of plug stem can be performed
by means of a soft faced mallet.
Replacing Existing Stem Only
A. Removing Existing Pin and Stem
1.
Place the plug guide on a V-block and use a drift punch to
drive out the old pin.
Note: If it is necessary to drill out the pin, use a drill bit
slightly smaller than the pin diameter.
2.
Hold the plug guide in a vise (see note on opposite side of
page).
3.
Lock one nut against another at the end of the plug stem. Using
a wrench on the lower nut, unscrew the stem from the plug. The
stem is removed by turning it counter-clockwise.
B. Screwing Stem to Plug
Refer to step B of the previous section on "REPLACING
PLUG AND STEM".
C. Drilling the New Stem
PIace the plug guide on a V-block and use a suitable size
drill bit to drill the stem (use the hole in the plug as a guide).
Note: If the hole in the plug guide has been slightly
damaged while removing the old pin, choose a drill bit
and a pin with a slightly larger diameter than the normal
pin.
6 | Baker Hughes
D. Pinning
Select the correct size pin based on the plug guide diameter and
pin hole diameter. Proceed as described in part D of the previous
section, taking care not to damage the plug guide area.
Ensure plug stem alignment following the pinning operation.
7.6 Packing Box (Figures 12 to 15)
Packing box maintenance is one of the principle action items of
routine servicing. Tightness of the packing is maintained by packing
WARNING
compression. Compression is achieved by evenly tightening the
packing flange nuts (3) against the packing flange (4). Care must
be taken not to over tighten as this could prevent smooth operation
of the valve. If all compression is used up and the valve leaks, then
new packing is required.
CAUTION
Valve must be isolated and the pressure vented
before performing packing box maintenance.
CAUTION
Proceed as follows :
7.6.1 Braided PTFE with Carbon or Aramid Core (Standard)
(Figures 12 to 15)
Note: The Braided PTFE/Carbon or Aramid packing rings
have a skive cut allowing packing replacement without
disconnecting the plug stem from the actuator connector
or actuator stem.
A. Loosen and remove packing flange nuts (3).
B. Lift the packing flange (4) and packing follower (5) up the
valve stem.
Note: They may be taped in place to keep them out of
the way before proceeding.
C. By means of a hooked instrument, remove packing (6)
ensuring not to damage the sealing surfaces of the packing
box or plug stem.
Note: On valves equipped with an optional lubricator
connection, the lantern ring (7) must also be removed to
gain access to lower packing rings.
D. Replace packing rings (6).
Note: Assemble and compress rings one at a time into
packing box. The skive cut of each packing ring must
be placed about 120 degrees apart.
WARNING
Note: On valves equipped with an optional lubricator
connection, refer to Figure 10 for correct amount of
rings to place under the lantern ring (7).
E.
Replace packing follower (5) and packing flange (4).
F.
Replace and tighten packing stud nuts (3).
CAUTION
Do not overtighten.
G. Place valve back in service and only tighten packing as
necessary to stop external leakage.
CAUTION
Note: In an emergency, string packing may be used as
a temporary repair only. It must be replaced with the
correct packing as soon as possible.
Copyright 2023 Baker Hughes Company. All rights reserved.
DANGER
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