Series
KNAR/F, KNARP/F, KNAR-D/F, KNARP-D/F,
Page
11
KNAR-S/F, KNARP-S/F
ASME
9520-032-en
Revision 15
TM 9549
Edition 11/2018
7.2 Improper operation and their
consequences
♦
Crystallisation may result in damage to the seat
rings or V-control ball/stem unit. This can be pre-
vented by heating. In extreme cases this may
cause blocking.
♦
If the ball blocks, do not apply force as the
ball/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.
Move V-control ball/stem unit into the "half-open
position".
Prior to starting any repair work, the valve is
to be thoroughly cleaned. 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
exceeded 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 mov-
ing 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. admis-
sible actuating torque as per
section 1.4
, dis-
mantle ball valve and inspect individual compo-
nents.
