Masoneilan 21009 Series Cage Guided Globe Valve Instruction Manual | 4
Copyright 2021 Baker Hughes Company. All rights reserved.
Ensure that the seat ring (13), cage (12) and bonnet
(8) are properly aligned
7. Fasten the bonnet to the body using four body stud nuts
(10) spaced equally apart . Apply slight pressure and tighten
evenly.
Do not tighten nuts to final torque specifications at
this time. The bonnet is used temporarily for guiding
purposes only.
8. Insert two or three pieces of packing into the packing box to
assist in guiding the stem and plug during lapping.
9. Screw a drilled and tapped rod with a T-handle onto the plug
stem and secure with a locknut (see Figure 3).
Note: As an alternative, drill a hole through a flat steel plate
and fasten to the plug stem using two locknuts.
10. Apply slight pressure on the stem, and rotate the stem in
short oscillating strokes (around 8 to 10 times). Repeat this
step as necessary.
Note: The plug should be lifted and turned 90° each time
before repeating Step (10). This intermittent lifting is
required to keep the plug and seat ring concentric during
lapping.
11. After completion of the lapping operation, remove bonnet
and internal parts. The seating area of the seat ring and the
plug must be cleaned of all lapping compound in preparation
for reassembly.
7.2 Plug Stem Pinning
Plug stem pinning in the field may be required for the following:
• Replacing existing plug and stem, or
• Replacing existing stem only
Replacing Plug and Stem
If it is necessary to replace the plug, then the plug stem must be
replaced at the same time. The original pin hole in an existing
stem will not provide the necessary fit , and might seriously
impair the strength of the assembly.
A. Reference marking on the Plug Stem
Measure the depth of the pilot recess in the plug (Dimension X
in Figure 6), and make a reference mark on the plug stem at the
same distance from the thread.
Note: While pinning is being performed, care must be taken
not to damage the seating surface or plug guide. Always
use a soft metal or plastic vice jaws with cylindrical features
to hold the plug guide area (see Figure 6).
B. Screwing Stem to Plug
• Hold the plug (with vise jaw assembly) in a vise.
• Lock two nuts against each other on the end of the new plug
stem, and screw the stem solidly into the plug using a wrench
on the upper nut.
When properly assembled, the reference mark (see Section A
above) should be flush with the end of the plug guide.
C. Drilling the new Parts
• If the plug is already fully drilled (typical for 440 C hardened
stainless steel material or solid Stellite or Equivalent), then drill
the stem to the same diameter (Diameter C in Figure 6) as the
plug shank hole.
• 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 6)
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 6).
- 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.
C. Pinning the Plug-Stem assembly
1. Select the correct size pin based on the plug guide diameter and
stem diameter (see Figure 6). 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 6).
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.
