Richter GU/F Series Overflow Valves - Manual (Page 13)

Series GU/F
Page 13
9530-070-en Revision 00
TM 6908 Edition 10/2007
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?
Have the nuts at the inlet nozzle been unevenly
tightened?
Actuation of the lifting lever can help to regain the
required sealing effect. If this does not succeed in
stopping the leak, the sealing surface of the plug
must either be reworked 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
elimination of the disorders, an examination at the
manufacturer's is necessary.
Medium is escaping at the bonnet
Have the hex. socket screws 914/1 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 leaking
Check the torque of the pipe screws with a torque
wrench (see Section 1.3). If tightness is not achieved,
the recommended torque may be exceeded by 10%.
If it still proves impossible to stop the leak, then the
lining is damaged. Dismantle the overflow valve and
check.
The overflow valve chatters during discharge
Do the inlet and outlet lines conform to the relevant
regulations?
See also Section 6.1 and 6.2.
Is the valve oversized ?
Valves which are too large can subsequently be
adapted to the mass flow reducing the lift. To this end,
the required lift is determined and a travel stop ring is
mounted inside the valve.
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.
The lifting lever 238 allows the valves to be
actuated from outside, they then open at the
operating pressure available. For lifting, the
pressure is to be at least 85% of the test pressure.
All repair work is to be performed by qualified
personnel using the appropriate tools. Generally
recognised practice in mechanical engineering is
to be observed.
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
connection screws should be made in line with the
operating requirements.
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
expansion joints or pulsation dampers.
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.