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9.1 Periodic testing
Depending on the operating conditions,
check the valve at certain intervals to prevent
possible failure before it can occur. Plant op-
erators are responsible for drawing up an
inspection and test plan.
Tip
Our after-sales service can support you in
drawing up an inspection and test plan for
your plant.
9.2 Preparing the valve for
service work
1. Lay out the necessary material and tools
to have them ready for the service work.
2. Put the control valve out of operation (see
the 'Decommissioning' section).
3. Remove the valve from the pipeline (see
the 'Removal' section).
4. Make sure that the valve is completely
open (the plug stem is completely retract-
ed).
Version with "actuator stem extends"
fail-safe action: apply a signal pressure
that corresponds to the upper bench
range value to the connection on the bot-
tom diaphragm chamber.
Version with "actuator stem retracts"
fail-safe action: make sure that no signal
pressure is applied to the actuator.
The following service work can be per-
formed after preparation is completed:
EB 8115 EN
− Replace the gaskets as described in sec-
tion 9.4.1.
− Replace the packing (see section 9.4.2)
− Replace the seat and plug (see sec-
tion 9.4.3)
9.3 Installing the valve after
service work
1. Reinstall the valve into the pipeline (see
the 'Installation' section).
2. Put the control valve back into operation
(see the 'Start-up' section). Observe the
requirements and conditions for start-up
or putting the valve back into operation.
9.4 Service work
Î Before performing any service work,
preparations must be made to the control
valve (see section 9.2).
Î After all service work is completed, check
the control valve before putting it back
into operation (see 'Testing the installed
valve' in the 'Installation' section).
Servicing
9-3
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