5 FT 70 en
7
4
Maintenance
4.1
Maintenance general
Although Metso’s Neles valves are designed to work under
severe conditions, proper preventative maintenance can
significantly help to prevent unplanned downtime and in
real terms reduce the total cost of ownership. Metso recom-
mends inspecting the valves at least every five (5) years. The
inspection and maintenance interval depends on the actual
application and process condition. The inspection and
maintenance intervals can be specified together with your
local Metso experts. During this periodic inspection the
parts detailed in the Spare Part Set should be replaced.
Time in storage should be included in the inspection inter-
val.
Maintenance can be performed as presented below. For
maintenance assistance, please contact your local Metso
office. The part numbers in the text refer to the exploded
view and to the parts list in Section 10, unless otherwise
stated.
4.2
Repair of a jammed or stuck valve
Partial jamming may be due to accumulated flow medium
between the plug and seats or in the bearing spaces. The
plug and seats can be cleaned without removing the valve
from the pipeline by turning the plug to the partly open
position and flushing the pipeline. If this does not help, fol-
low the instructions below.
4.3
Changing the packing
4.3.1
FC series
The packings (69) can be replaced without removing the
valve from the pipeline.
The packings must be changed if leakage occurs even after
the nuts of the gland follower have been tightened. The V-
rings must be tightened with care. Excessive force will dam-
age the packings.
Proceed as follows:
Detach the actuator, see Section 4.4. Take care not to
hit the end of the stem.
Unfasten the screws (30) and detach the bracket
(29).
Unfasten the nuts (18), remove the disc springs (150)
and lift the gland follower (9) from the stem. The
studs (14) need not be detached.
Remove the packing rings (69) from around the stem
using a pointed instrument or a detaching tool. Do
not damage the surfaces of the stem and the pack-
ing ring counterbore.
Place the new packing rings (69) over the stem. Do
not damage the sealing lips of the V-rings in the
stem splines. Use the gland follower (9) as a tool for
pushing the packing rings all the way in.
Deform the packing rings first by tightening the
gland nuts (18) without disc springs to the torque Tt,
see the value from Table 2.
Remove the gland nuts and place the disc spring
sets (150) on the gland studs. Tighten the nuts (18)
so that the disc springs are compressed to the height
Hc, see Table 2. Lock the nuts with locking com-
pound e.g. Loctite 221. See Fig. 13
Put the bracket (29) back, lubricate the screws (30)
and tighten them. See Table 1.
Insert the key (10) in the drive shaft (5) keyway.
Re-install the actuator.
Check leakage when the valve is pressurized.
CAUTION:
Observe the safety precautions mentioned in Section
1.8 before maintenance!
CAUTION:
When handling the valve or the valve package as a
whole, bear in mind the weight of the valve or the
entire package.
NOTE:
When sending goods to the manufacturer for repair, do
not disassemble them. Clean the valve carefully and flush
the valve internals. For safety reasons, inform the manu-
facturer of the type of medium used in the valve (include
material safety datasheets (MSDS)).
NOTE:
In order to ensure safe and effective operation, always use
original spare parts to make sure that the valve functions
as intended.
NOTE:
For safety reasons, replace pressure retaining bolting if the
threads are damaged, have been heated, stretched or cor-
roded.
CAUTION:
Do not dismantle the valve or remove it from the pipe-
line while the valve is pressurized!
Table 1
Screw torques (for lubricated screws)
Screw
M6
M8
UNC 5/16
M10
UNC 3/8
M12
UNC 1/2
M16
UNC 5/8
Torque
Nm
ft lb
8
5.9
18
13.3
35
25.8
65/90*
47.9/66
155/210*
114/155
Fig. 13
Spring-loaded packing
9
69
29
18
14
150
30
5
10
