Technical Specifications

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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”).
Cage
Pilot
Guiding
surface
Guiding
surface
Seating
surface
Figure 5
5.2.2 Sealing surfaces (Figure 6)
Valve Plug
Seat Ring
Plug seating
surface
Pilot seating
surface
(41405 only)
Guiding
surface
Guiding surface
Seating surface
Seating surface
Seat ring seating surface
31°30'
32°30'
62°30'
57°30'
29°30'
30°30'
Figure 6
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.
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.