5-8 EB 8026 EN
Installation
To test the valve functioning before start-up
or putting back the valve into operation, per-
form the following tests:
5.5.1 Leakage
The plant operator is responsible for per-
forming the leak test and selecting the test
method. The leak test must comply with the
requirements of the national and internation-
al standards that apply at the site of installa-
tion.
Our after-sales service can support you to
plan and perform a leak test for your plant.
1. Slowly apply the test medium to the valve
until the test pressure is reached. Avoid
sudden surges in pressure since the re-
sulting high velocities may damage the
valve.
2. Check the valve for leakage to the atmo-
sphere.
3. Depressurize the pipeline section and
valve.
4. Rework any parts that leak (see informa-
tion below under “Adjusting the pack-
ing”) and repeat the leak test.
Adjusting the packing
A label on the ange indicates whether an
adjustable packing is installed (see the
'Markings on the device' chapter).
Impaired valve functioning due to increased
friction as a result of the threaded bushing
being tightened too far.
Î Make sure that the plug stem can still
move smoothly after the threaded bush-
ing has been tightened.
1. Tighten the threaded bushing gradually
(by turning it clockwise) until the packing
seals the valve.
2. Open and close the valve several times.
3. Check the valve for leakage to the atmo-
sphere.
4. Repeat steps 1 and 2 until the packing
completely seals the valve.
Î If the adjustable packing does not seal
properly, contact our after-sales service.
5.5.2 Travel motion
The movement of the actuator stem must be
linear and smooth.
Î Apply the maximum and minimum con-
trol signals to check the end positions of
the valve while observing the movement
of the actuator stem.
Î Check the travel reading at the travel in-
dicator scale.
5.5.3 Fail-safe position
Î Shut off the signal pressure line.
Î Check whether the valve moves to the
fail-safe position (see the 'Design and
principle of operation' chapter).
Tip
NOTICE
!
To Next Page
Loading...
