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Series GUT/F
8
Malfunctions
♦ Overflow valve is leaking
Is there foreign matter between the seat and plug?
Is there any wear or damage to the seat or plug?
If this does not succeed in stopping the leak, the
sealing surface of the plug must either be re-
worked or the plug or seat must be replaced.
♦ The lift given in the test certificate is not achieved
Are the bellows impeded in their movement by
external influences (e.g. foreign matter, solidified
medium between the folds etc.)?
Has the insert sleeve 308 been screwed out of the
thread of the bellows?
For measuring the valve lift, see Section 9.7.1.
If the required lift is still not attainable after elimina-
tion of the disorders, an examination at the manu-
facturer's is necessary.
9
Maintenance
Overflow valves must be checked for
operability at regular intervals according to
the national regulations (in Germany: UVV -
pressure vessels, VBG 17 § 32 and TRD
601 sheet 2, paragraph 3.4).
♦ The intervals for regular checks are to be laid
down by the customer in line with the operating
conditions.
♦ All repair work is to be performed by qualified
personnel using the appropriate tools.
♦ For the arrangement, designation and item
numbers of all parts of the valve, see Section 10.
♦ Spare parts are to be ordered with all the details in
acc. with the valve identification.
♦ Only original spare parts may be installed.
9.1
Screw connections
♦ To prevent leaks, a regular check of the connec-
tion screws make in line with the operating re-
quirements.
For tightening torques, see Section 1.3.
♦ To prevent screw connections from becoming
loose in the event of pressure fluctuations or plant
vibrations, we recommend the installation of ex-
pansion joints or pulsation dampers.
9530-021-en
Revision 16
TM 10477
Edition
05/2022
♦ Medium is escaping at the bonnet
Have the hex. nuts 920/1 not been tightened?
If, after tightening the screws, tightness still cannot
be restored, either the plastic lining or the bellows
is damaged.
The cause of cracked bellows could have been, for
example, an inadmissibly high back pressure
during operation of the overflow valve. Dismantle
the overflow valve and have it repaired.
♦ Flange connection ball valve/pipe is leaking
Check the torque of the pipe screws with a torque
wrench. (see Section 1.2) If tightness is not
achieved, the recommended torque may be ex-
ceeded by 10%.
If it still proves impossible to stop the leak, then the
lining is damaged. Dismount valve and repair.
9.2
Cleaning
Prior to starting any repair work, the valve is
to be thoroughly cleaned. Even if the valve
has been properly emptied and rinsed,
residual medium may still be found in the
valve, e.g. between the lining and body or in
the bonnet.
Plastic parts may absorb medium which gradually
emerges from the material after cleaning.
Wear the prescribed protective clothing!
Overflow valves which have been cleaned with water
or other media must be dried before re-assembly of
the parts and installation of the valve in the plant.
9.3
Modification of the overflow
valve
If modifications to the valve are required, the
manufacturer must always be consulted.
Examples: Modification with changed test pressure,
replacement of the spring or adaption to the mass flow
by reducing the travel.
After approval by the manufacturer, these modifica-
tions can be performed either by the manufacturer or
by the customer under the guidance of a technical
supervisory agency or any other approval authority.
11
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