Series
KNA/F, KNAP/F, KNA-D/F, KNAP-D/F,
Page
11
KNA-S/F, KNAP-S/F
to ASME
9520-030-en
Revision 19
TM 10477
Edition 05/2022
7
Operation
7.1 Initial commissioning
Normally, the valves have been tested for leaks with
air or water. Prior to initial operation check cover
screws. For tightening torques, see
section 1.3
.
Unless otherwise agreed there could be
residual amounts of water in the flow
section of the valve. This could result in a
possible reaction with the medium.
To prevent leaks, retighten all connection screws after
the initial loading of the valve with operating pressure
and operating temperature.
For tightening torques, see
section 1.3
.
7.2 Improper operation and their
consequences
♦
The ball valve is an on/off valve and shall not be
operated in an intermediate position.
♦
Damage to the seat rings or the ball/stem unit or
Al
2
O
3
-ball and stem could occur.
♦
Crystallisation may result in damage to the seat
rings or the ball/stem unit or Al
2
O
3
-ball/stem. This
can be prevented by heating. In extreme cases this
may cause blocking.
♦
If the ball blocks, do not apply force as the
ball/stem unit/stem may break if the max. adm.
torque is exceeded.
♦
Increased wear occurs in operation with solids
contents.
♦
Operation during cavitation leads to increased
wear.
♦
Non-observance of the pressure-temperature
diagram can lead to damage.
♦
Do not subject the lever to heavy loads; the lever
or ball valve may be damaged.
♦
Do not use a lever extension as otherwise there is
a risk of damage.
7.3 Shutdown
The local regulations are to be observed when
dismantling the valve.
Prior to undoing the flange connection ensure,
that the plant is depressurised and emptied.
Prior to the start of maintenance work, clean
the valve thoroughly. Medium residue may
be in the valve even if it has been properly
drained and flushed.
After dismantling, immediately protect the valve
flanges against mechanical damage by using flange
caps. See also
section 6.1
.
Make sure that a remote-controlled actuator
cannot be switched on by accident.
8
Malfunctions
♦
Flange connection ball valve/pipe is leaking
Retighten the flange screws to a tightening torque
according to
section 1.3
. If this does not remedy
the leak, the recommended torques may be ex-
ceeded by 10%.
If this also fails to stop the leak, dismantle and
inspect the valve.
♦
Flange connection main body/body end piece is
leaking
Retighten body screws. See paragraph "Flange
connection ball valve/pipe is leaking".
♦
Packing is leaking
Retighten packing nuts according to the details in
section 1.3
.
♦
Ball valve does not operate
Is the actuator supplied with power?
Is any directional control valve correctly connect-
ed?
Is there foreign matter in the valve?
♦
The ball no longer closes completely
Is the stem deformed?
Is the coupling worn?
With a worm gear or actuator, check whether the
end stops can be re-adjusted. The operating
manuals of the gear and actuator manufacturers
contain accurate instructions.
Never apply force to the lever or use an
extension.
1. Try to get the ball valve working again by moving
the lever to and from.
2. Remove the lever stop and try to switch against
the normal direction of rotation.
3. If actuation is not possible with the max. admissi-
ble actuating torque as per
section 1.4
, dismantle
ball valve and inspect individual components.
