Metso NELDISC L4 Series, Intallation, Maintenance And Operating Instructions

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2 L6 70 en 11
5.6 Replacing the disc, shafts and bearings
5.6.1 Disassembling the valve
The pin connection of the disc must be opened by drilling for
changing the disc (3), shafts (11, 12) and bearings (15, 16).

Remove the valve from the pipeline and the actuator
from the valve.

Remove the clamp ring (2) and seat ring (4) accord-
ing to section 5.5.

Set the valve horizontally on a sturdy surface so that
the flat side of the disc lays against the surface (see
Fig. 17).

Drill the holes carefully to the centre of the pins (14).
Choose a drill 0.2-0.5 mm smaller than the diameter
of the pin.

Drill the holes deep, but not enough to reach the
disc.

Pull the pins out.

Dismantle the gland packing including anti-extru-
tion ring (22), when applicable, according to
Section 5.3.

Detach the screws (26) and the blind flange (10) and
remove the gasket (18).

Place rubber strips or other protection between the
disc edge and the body and remove the shafts (see
Fig. 18).

Remove the bearings (15, 16).

Clean and check all parts carefully.
5.7 Assembling the valve

Replace damaged parts with new ones.

Set the disc and the shaft together beforehand. In
case the pin holes have been damaged during
removal of the old pins the holes can be drilled to a
larger pin size. File off any burrs from the shafts.
The bearings for the valves (N, U and H constructions) are
cobalt alloy bushings which are mounted into the body
together with the shafts.

Mount the bearing into the shaft. Spray a thin layer
of dry lubricating fluid, e.g. Molykote 321R or equiva-
lent, into the inside surface of the bushing and the
shaft bearing groove. Press the bushing with a tight-
ening ring into the shaft bearing groove and fit the
shaft with the bearings carefully into the body
through the tightening ring.

Place the disc horizontally on a surface so that the
flat side of the disc lays against the surface. Lift the
body around the disc so that the shaft bores are
aligned with the bores in the disc. Protect the disc
(see Fig. 19).

Press the shafts into the disc drillings. Align the pin
holes. The shaft (11) position against the disc must
be according to Fig. 14.

Support the disc well in a horizontal position during
mounting of the pins. Push the new pins into the
holes and press them in a press to final form (see Fig.
19). Use a smaller tool than the pin diameter. See
Table 11 for forces.
Fig. 16. Replacing the seat, L6F
Fig. 17. Drilling the pins
Fig. 18. Protecting the disc during disassembly and assembly
NOTE:
Use only pins supplied by the manufacturer!
NOTE:
The pins must be pressed with enough force to deform them
so that the connection will be free from backlash.
Fig. 19. Pressing the pins