Samson 3244 - Page 48

9-4 EB 8026 EN
Servicing
Inspection and testing Recommended action to be taken in the event of a
negative result
Check to ensure that the actuator and
plug stem move smoothly.
Version with adjustable packing
2)
: tighten the packing
correctly (see section 'Adjusting the packing' in the
'Installation' chapter > 'Testing the installed valve').
If the actuator and plug stem is blocked, put the control
valve out of operation (see the 'Decommissioning' chapter)
and remove the blockage.
WARNING! A blocked actuator or plug stem (e.g. due to
seizing up after remaining in the same position for a long
time) can suddenly start to move uncontrollably. Injury to
hands or ngers is possible if they are inserted into the
actuator or valve.
Before trying to unblock the actuator or plug stem,
disconnect and lock the pneumatic air supply as well as the
control signal. Before unblocking the actuator, release any
stored energy in the actuator (e.g. spring compression). See
associated actuator documentation.
SAMSON recommends the use of positioners with
integrated diagnostic rmware for valves used for on/off
service. The partial stroke test included in this software helps
prevent a shut-off valve normally in its end position from
seizing up or getting jammed.
Seat leakage
1)
(see Fig.9-1)
(without testing to check that the
leakage class requirements are met)
Shut off the section of the pipeline and ush the valve to
remove any dirt and/or deposited foreign particles between
the seat and plug.
Check the valve for external damage
that could impair the proper functioning
of the control valve or even its safe
operation.
Repair any damage immediately. If necessary, put the
control valve out of operation (see the 'Decommissioning'
chapter).
Check the valve accessories to ensure
they are mounted properly.
Tighten the connections of the valve accessories.
If possible, check the valve's fail-safe
position by briey interrupting the air
supply.
Put the control valve out of operation (see the
'Decommissioning' chapter). Identify the cause for the
malfunction and rectify it (see the 'Troubleshooting' chapter).
1)
EXPERTplus valve diagnostics can help identify external leakage at dynamic sealing systems as well
as seat leakage in valve versions without balanced plugs while the valve is in use. EXPERTplus comes
as standard in the digital positioners (Type3730, TROVIS3730, Type3731, TROVIS3793, TRO-
VIS3797).
2)
See the 'Markings on the device' chapter