Masoneilan 72000 Series Control Valves Instruction Manual | 7
Copyright 2021 Baker Hughes Company. All rights reserved.
7. Open and close the valve several times then retighten the
packing as required.
8. Put the valve back into service and check for leakage.
Tighten packing flange nuts (16) as required.
Repair of Parts
Prior to reassembly, examine parts carefully for any scratches,
unusual wear, or other damage.
Guiding Surfaces
Guiding surfaces of the cage, valve plug, guide bushing, plug
stem, and auxiliary pilot plug must be checked. See Figures 5
and 6. If there are only slight wear indications, then gently use
a light abrasive, such as Scotchbrite
®
or fine grit sandpaper, to
smooth out guiding surfaces. Parts with significant damage or
wear on the guiding surfaces must be replaced.
Seating Surfaces
The seat ring seating surface and valve plug seating surface
must be completely free of dents, wear, or scratches. Consult
factory should you see any signs of slight deterioration prior to
attempting touchup. If a slight defect exists on either the seat
ring seating surface and valve plug seating surface, lapping can
be applied per the following instructions.
1. CIean body gasket surface areas.
2. Install a new seat ring gasket (26).
Note: Seat ring gasket (26) is temporarily placed to hold the
seat ring during lapping.
It is imperative to use a new gasket or a test part having
the same geometrical characteristics in order to insure the
correct position of the seat ring during lapping.
This gasket (or similar part) can be kept after lapping for
future lapping use.
The gasket used for lapping must not be reused for the
body reassembly.
Figure 5 - Guiding Surfaces
Figure 6 - Typical Seating Angles
3. Place seat ring (13) in the body, noting the seating angle is up.
4. Spread a fine layer of high quality lapping compound (600
grit) on the seating surface.
5. Assemble the cage (10) and (if applicable) cage retainer
(11) and the plug assembly (8) into the valve body (1) per
the valve plug assembly instructions.
6. Assemble the bonnet (2) and the guide bushing (20) if
required.
7. Place an appropriate tool on the valve stem (7) thread to
allow for manual rotation.
8. Lap by slightly rotating the valve plug in alternate directions
± 15° per rotation. After several rotations, lift the valve stem,
turn it 90 degrees, and repeat the operation.
9. Lapping can be repeated, but should be limited as much
as possible so that the seat remains sufficiently narrow to
guarantee tightness.
10. After lapping, disassemble the parts to clean them and
then reassemble, making sure the seating angles are within
tolerance. See Figure 6.
Note: For more details on the lapping procedure and seat-
ing angles, please consult the factory and provide the valve
serial number (found on the serial plate on the actuator).
Guiding
surface
Pilot
Seating surface
Guiding
surface
Seat rin
g s
eat
Plug
s
eat
Pilot seat
Seating surface Guiding surface
Guiding surface
Seating surface
Valve plug
Seat ring
Guiding
surface
Pilot
Seating surface
Guiding
surface
Seat rin
g s
eat
Plug
s
eat
Pilot seat
Seating surface Guiding surface
Guiding surface
Seating surface
Valve plug
Seat ring
