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Servicing
Legend for Fig. 9-1
1
Body
2
Bonnet
3
Yoke
4
Seat
5
Plug (with plug stem)
7
Guide bushing
8
Threaded bushing (packing nut)
9
Stem connector nut
10
Lock nut
9.2 Preparing the valve for
service work
WARNING
!
Risk of personal injury due to incorrect
removal of the anti-rotation fixture under
tension.
Once the actuator has been mounted on the
valve and the assembly is ready for use, the
clamps (301) of the anti-rotation fixture on
the plug stem are under tension.
Î Follow the instructions in this document
during mounting or removal.
Î Do not loosen the screws (303) of the an-
ti-rotation fixture while the force generat-
ed by the supply air and/or the actuator
springs is transmitted to the actuator stem
and the stem (9).
Î First remove the actuator from the valve
or ensure it cannot transmit any forces to
the actuator stem before removing the
anti-rotation fixture on the plug stem.
1. Lay out the necessary material and tools
to have them ready for the service work.
9-6
13
Stud bolt
14
Nut
15
Packing
17
Body gasket
21
Insulating section
92
Castellated nut
93
Expansion sleeve (for Class 150 to 2500)
100
Flange
2. Put the control valve out of operation (see
the 'Decommissioning' section).
3. Remove the actuator from the valve. See
associated actuator documentation.
Note
To remove an actuator with "stem extends"
fail-safe action and/or with preloaded
springs, a certain signal pressure must be
applied to the actuator (see associated actu-
ator documentation). Afterwards, the signal
pressure must be removed and the air supply
disconnected again and locked.
Tip
We recommend removing the valve from the
pipeline before performing any service work
(see the 'Removing the valve from the pipe-
line' section).
The following service work can be per-
formed after preparation is completed:
− Replace the top gasket as described in
section 9.4.1.
EB 8061 EN
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