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10.2 Repair
The purpose of this section is to provide recommended
maintenance and repair procedures. These procedures assume
the availability of standard shop tools and equipment.
10.2.1 Plug/Stem Bellows/Bonnet Extension S/A
Plug stem pinning in the field may be required for:
•
Replacing existing plug and stem-bellows S/A
•
Replacing stem-bellows S/A only
Note: If the plug needs replacing, the stem‑bellows
sub‑assembly should be replaced at the same time.
The original pin hole in a stem which is being reused sometimes
prevents a satisfactory result being obtained and can also
weaken the plug-stem assembly.
If the stem-bellows sub-assembly is being replaced, the
new assembly can be fitted on an existing plug as long as it
is in good condition and the removal of the pin has not
deformed the hole or damaged it in any other way.
Note: Always use soft metal vise jaws to hold the plug
guide surface. Failure to take this precaution could
result in damage to the plug guide surface during
pinning (see Figure 18).
Be careful not to damage the plug seating surface during pin
removal and assembly operations.
10.2.1.1 Unpinning the Plug Stem
•
Pull and hold the plug (16) out of the bonnet extension (29)
to allow access to the plug pin (17). Place the plug guide on
a V-block.
Note: A lower mechanical stop has been provided to
prevent damage of the bellows during this step.
•
Using a drift punch, drive out the existing pin (17).
Note: If it is necessary to drill out the pin, use a drill bit
slightly smaller than the pin diameter. Be careful not to
damage the hole of the plug guide.
•
Lock two nuts against each other on the end of the plug
stem, and use a flat spanner on the lower nut to prevent
rotation while unscrewing the plug from the stem. The plug
is removed by turning it counter-clockwise.
•
Remove the two nuts from the plug stem. Complete step
10.1.1.
•
Inspect the parts and carry out any necessary repairs, then
reassemble the stem-bellows sub-assembly (30) through
the upper hole in the bonnet extension (29) (see section
10.2.1.2).
10.2.1.2 Mounting of the Plug-Stem/Bellows S/A into the
Bonnet Extension
•
Clean all contact surfaces of the bonnet extension (29) and
the plug-stem/bellows S/A.
•
Assemble a new gasket (28) on the upper flange of the
bonnet extension.
•
Insert the new stem-bellows S/A through the top hole into
the bonnet extension (29).
•
Pin the plug on the stem (See section 10.2.1.3).
16 | Baker Hughes
10.2.1.3 Plug Stem Pinning
Replacing Plug and Stem/Bellows S/A
A. Screw Stem into Plug
-
Lock two nuts against each other on the end of the plug
stem and use a flat spanner on the upper nut to prevent
rotation of the stem-bellows S/A. Screw the plug onto the
lower part of the stem while inserting the plug shank into the
guide bushing (12) in the bonnet extension (29).
-
Pull and hold the plug (16) out of the bonnet extension (29)
to allow access to the plug pin (17).
B. Drilling the New Parts
•
If the plug is already fully drilled, (typical for 440C hardened
stainless steel material or solid Stellite or Equivalent), then
drill the stem to the same diameter (Diameter C in Figure 18)
as the Plug Shank Hole.
•
If the plug guide area has a center mark, Place the plug
guide on a V-block and use a suitable size drill to either:
-
Match the hole size in the plug, or
-
Match Diameter C (see Figure 18),
-
Drill through the plug-stem assembly.
•
If the plug guide area has no hole or any center mark,
-
Measure Dimension D based on the plug guide diameter
and stem diameter (see Figure 18).
-
Place 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.
C. Pinning the Plug-Stem Assembly
-
Select the correct size pin based on the plug guide diameter
and stem diameter (see Figure 18). Apply a small amount of
grease on the pin and hand-assemble it into the hole in the
plug.
-
Press fit the pin into the hole using a hammer. Complete the
pinning operation by ensuring that the pin is recessed by the
same amount from both sides (see Figure 18).
Replacing Stem/Bellows S/A Only
A. Screw Stem into Plug
-
Refer to paragraph A of the previous section "REPLACING
PLUG AND STEM/BELLOWS S/A".
B. Drilling the New Stem
-
Place 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 of the old pin, choose a drill bit
and a pin with a slightly larger diameter than the normal
pin.
C. Pinning
-
Select the correct size pin based on plug guide diameter
and pin hole diameter. Proceed as described in Paragraph
C above, taking care not to damage the plug guide area.
Copyright 2023 Baker Hughes Company. All rights reserved.
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