Baker Hughes Masoneilan 41005 Series, Instruction Manual

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Baker Hughes
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4.3.2 Seating Surfaces
Inspect all seating surfaces per Figures 2 and 3 which
represents all plug and seat types.
The cage (B107), plug (B112) seating surfaces must be
completely free of dents, wear and scratches.
If valve plug (B112) or cage (B107) seating surfaces show
signs of slight deterioration, they can be touched up on a
lathe.
For all valve types, when dressing up critical surfaces, no
more than 0.25 mm (0.010”) of metal must be removed in the
case of an 80 or 100 mm (3” or 4”) valve, and no more than
0.4 mm (0.015”) in the case of a 150 to 250 mm (6” to 10”)
valve. Make sure that the seating angle indicated in Figures
2 and 3 is respected.
If a slight defect exists on any of the above seating surfaces,
lapping can be envisaged, in which case the following must
be respected:
1. Spread a fine layer of high-quality sealing compound on
the seating surface.
2. Put the cage (B107) in the body, noting the angle.
3. Assemble the valve plug (B112) and Stem (B150)
4. Assemble the bonnet (B003) and its guide bushing (B203)
5. Place an appropriate tool on the valve plug stem (B150)
to turn it
6. Lap by slightly rotation the valve plug (B112) in alternative
directions. After several rotation, lift the valve plug (B112),
turn it 90°, and start again.
7. Lapping can be repeated but must be limited as much as
possible so that the cage (B107) seating area remains
sufficiently narrow to guarantee tightness.
8. Disassemble the parts, clean them and put them back,
respecting the initial angle.
4.3.3 Gasket seating surfaces
Gasket seating surface must be free of dents, scratches and
corrosion; otherwise, they will need to be repaired.
4.3.4 Seal Rings and gaskets
Seat ring gaskets (B103), lips seals (B108 & B118), Body
gasket (B015) must always be changed after disassembly.
4.3.5 Valve Plug and Plug Stem
If the valve plug (B112) needs to be changed, then the stem
must also be completely changed to guarantee correct
pinning of the assembly. If only the valve plug stem (B150) is
changed, then the valve plug (B112) can be reused.
5. Valve Reassembly
5.1 Pinning the Valve Plug Stem
The valve plug (B112) and stem (B150) assembly consist of a
stem threaded into the valve plug and pinned in place.
If the valve plug (B112) needs to be replaced, it is
recommended using a new stem.
The hole of the original pin in an old stem often prevents
satisfactory results being obtained and can seriously impair
the mechanical strength of the stem-valve assembly.
Assembly is carried out as follows:
5.1.1 Tightening of the plug stem
To carry out this operation, the valve plug must be prevented
from moving by holding the plug shank with an appropriate
tool.
Screw two nuts on to the end of the new plug stem and lock
them together. Screw the valve plug stem solidly into the
plug, checking that the reference mark is level with the end
of the plug shank.
If the stem has flats, apply a torque “T” using a wrench of
dimension “E” (see Table 3).
5.1.2 Drilling the pin hole (Figure 3 and Table 4)
Note: For this operation, it is recommended clamping
the valve plug-stem assembly by the plug shank to
avoid damaging the guiding surfaces; particular care
must be taken so that the pin hole goes through the
valve plug axis.
If the valve plug (B112) is new, drill a hole of diameter “C” at
a distance “D” from the end of the valve plug (B112); choose
the diameter “C” from the table according to the type of pin
used (metric or English pin). If the hole is already drilled in
the valve plug (B112), use the hole as a guide to drill through
the valve plug stem (B150).
5.1.3 Pinning
By means of a hammer, introduce the pin (B903) into the
hole. Complete the pinning operation, taking care to ensure
that the pin (B903) is recessed by the same amount at both
sides.
Using a ball tooling and hammer, caulk the pin hole edge of
the plug (B112).
Place the assembly in the soft jaw chuck of a lathe to check
alignment of the two parts; correct any alignment defects.