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there is only slight damage, a light abrasive can be used.
Otherwise the part must be replaced as soon as possible
(see paragraph "Spare parts").
Guiding
surface
Cage
5.2.2 Sealing surfaces (Figure 6)
Seating surface
31°30'
32°30'
Plug seating
surface
Seat ring seating surface
If the surface of the auxiliary pilot plug (20) is damaged,
the auxiliary pilot plug must be replaced (see paragraph
"Spare parts").
The seat ring (13), plug and auxiliary pilot plug (20)
seating surfaces must be completely free of dents,
wear and scratches.
If the auxiliary pilot plug seat in the valve plug (15) and/or
other valve plug or seat ring seating surfaces show signs
of slight deterioration, they can be touched up on a lathe.
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Guiding
surface
Seating
Pilot
surface
Figure 5
Guiding surface
Guiding
surface
Valve Plug
Seating surface
Seat Ring
62°30'
57°30'
Pilot seating
29°30'
30°30'
surface
(41405 only)
Figure 6
However, not more than 0.25 mm (0.010") of metal must
be removed in the case of a 50, 80 or 100 mm (2", 3" or 4")
valve or more than 0.4 mm (0.015") in the case of a 150 to
400 mm (6" to 16") valve. Make sure that the seating angle
indicated in Figure 6 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:
• Spread a fine layer of high quality sealing compound
on the seating surface.
• Put the seat ring (13) in the body, noting the angle.
• In the case of 41305, 41505, 41605 and 41905 valves,
put the cage (16) on the seat ring.
• In case of 41375 valves, put the stack (48) on the seat
ring and the cage (16) on the stack.
• In the case of 41405 valves, assemble the valve plug,
cage and stem (15)-(16)-(1).
• In case of 41305, 41505, 41605, 41375 and 41905,
assemble the valve plug (15) and stem (1).
• Assemble the bonnet (7) and its guide bushing (22).
• Place an appropriate tool on the valve plug stem (1) to
turn it.
• Lap by slightly rotating the valve plug or the auxiliary
pilot plug in alternative directions. After several
rotations, lift the valve plug, turn it 90°, and start again.
• Lapping can be repeated, but must be limited as much
as possible so that the seat remains sufficiently narrow
to guarantee tightness.
• Disassemble the parts, clean them and put them back,
respecting the initial angle.
5.2.3 Gasket seating surfaces
Gasket seating surface must be free of dents, scratches
and corrosion; otherwise, they will need to be repaired.
5.2.4 Seal rings and gaskets
Spiral-wound gaskets (10), (14) and (36) must always be
changed after disassembly. Seal rings (11A), (11C) or (11E)
can be reused if they are free of scratches, erosion and
corrosion.
5.2.5 Valve plug, valve plug stem
If the valve plug has to be changed, then the stem must
also be completely changed to guarantee correct pinning
of the assembly. If only the valve plug stem has to be
changed, then the valve plug can be reused.
Masoneilan 41005 Series Globe Valve Instruction Manual | 11
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