Metso L12 Series, Installation Maintenance And Operating Instructions

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8 2 L12 71 en
The gland packing (20) must be changed if leakage occurs
even after the hex nuts (25) have been tightened.
The actuator needs not be removed if the gland packing is
made of PTFE. Remove the actuator if the gland packing is
made of graphite.
5.3.1 Standard packing

Make sure the valve is not pressurized.

Unfasten the nuts (25) and remove the retaining
plates (42) and the gland (9) (see Fig. 11).

Remove the old packing V-rings (20). Do not damage
the surfaces of the packing ring counter-bore and
shaft.

Clean the gland packing and packing ring counter-
bore. Install new V-ring set by pushing it into place
with the gland.
Slip the graphite rings onto the shaft. Ensure that
there are no burrs in the keyway groove which could
damage the packing.

Install the gland.

Mount the retaining plates with the text UPSIDE on
top (see Fig. 10).

Place the nuts on the studs and tighten the gland
packings while the valve is not pressurized (see Table
4).

Retighten if necessary.
5.3.2 Live-loaded packing

Make sure the valve is not pressurized.

Unfasten the nuts (25) and remove the disc spring
(TA-Luft) sets (44), the retaining plates (42) and the
gland (9) (see Fig. 11).

Remove old packing rings (20). Do not damage the
surfaces of the packing ring counterbore and shaft.

Clean the gland packing and packing ring counter-
bore. Install new set of packings (V-ring or graphite).
Slip the rings onto the shaft. Ensure that there are no
burrs in the keyway groove which could damage the
packing.

Install the gland.

Mount the retaining plates with the text UPSIDE on
top (see Fig. 10).

Mount the disc spring sets.

Place the nuts on the studs.

Pre-compress the gland packing by tightening the
nuts with a tool until the disc springs have value of
compression (h1–h2) as in Table 5.

Carry out 3…5 operation cycles with the valve. Suita-
ble range of movement is about 80 %.
It is not necessary to fully close or open the valve
during the operation.

Unfasten the nuts and disc springs.

Measure the height h1 of the disc springs and use
these values as a basis when defining the final
height of the springs (as compressed condition).

Re-install the disc springs and tighten the nuts with
the tool. Tighten the nuts until the set value of com-
pression (h1–h2) of disc springs is achieved, see
Table 5.

If the leakage still occurs when the valve is pressur-
ized, re-tighten the nuts but don't exceed the values
in the Table 5 by 50 % or do not fully compress the
disc springs.
Fig. 10 Mounting the retaining plates
Table 4 Tightening of gland packing (no springs)
Size Thread
Torque Nm
Packing ring material
DN / NPS M, UNC Gr PTFE PTFE
80 / 3 M8, 5/16 10 5
100 / 4 M8, 5/16 12 7
125 / 5 M8, 5/16 12 7
150 / 6 M8, 5/16 12 7
200 / 8 M10, 3/8 24 15
250 / 10 M10, 3/8 24 15
300 / 12 M10, 3/8 29 14
350 / 14 M10, 3/8 29 20
400 / 16 M10, 3/8 29 19
500 / 20 M14, 1/2 65 39
600 / 24 M18, 5/8 100 67
700 / 28 M18, 5/8 100 67
800 / 32 M18, 5/8 110 79
900 / 36 M20, 3/4 220 150
1000 / 40 M20, 3/4 220 150
1200 / 48 M20, 3/4 240 150
1400 / 56 M20, 3/4 240 190
springs when
live-loaded
packing
Fig. 11. Gland packing
retainer plate (42)
stud (24)
hexagon nut (25)
disc spring set (44)
packing (20)
V-ring set or
graphite packing
gland (9)
bearing (15)
dia
h
1
h
2
springs when
live-loaded
packing