Travel Motion; Fail-Safe Position; Pressure Test - Samson 3349 Mounting And Operating Instructions

5. Check the valve for leakage to the atmo-
sphere.
6. Depressurize the pipeline section and
valve.
7. Rework any parts that leak and repeat
the leak test.
Adjusting the packing
A label on the yoke indicates whether an ad-
justable packing is installed (see the 'Mark-
ings on the device' section).
NOTICE
!
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.
5.4.2

Travel motion

The movement of the actuator stem must be
linear and smooth.
EB 8048-2 EN
Î With Type 3271 or Type 3277 Actuator:
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.
5.4.3

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' section).
5.4.4

Pressure test

The plant operator is responsible for per-
forming the pressure test.
Tip
Our after-sales service can support you to
plan and perform a pressure test for your
plant.
During the pressure test, make sure the fol-
lowing conditions are met:
− Retract the plug stem to open the valve.
− Observe the maximum permissible pres-
sure for both the valve and plant.
Installation
5-9