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Tests and maintenance
8.
Tests and maintenance
Information
8.1.
Safety equipment: check
8.2.
Actuator monitoring for ESD safety function
8.2.1.
Partial Valve Stroke Test (PVST): execute
26
Test and maintenance tasks may only be performed by authorised personnel who
have been trained on functional safety.
Test and maintenance equipment has to be calibrated.
Any test/maintenance must be recorded in a test/maintenance report.
Impact of testing/maintenance on relevant devices, equipment or other work must
be evaluated.
All safety functions within a safety equipment must be checked for perfect functionality
and safety at appropriate intervals. The intervals for safety equipment checks are to
be defined by the plant operator.
The plant operator has to establish a safety schedule for the entire safety lifecycle
of the SIS. It should include the strategy for achieving safety as well as different
activities during the safety lifecycle.
The device, consisting of actuator with actuator controls and integral SIL module has
an internal actuator monitoring. By controlling standard actuator controls/actuator
via standard operation commands, internal actuator monitoring is automatically
performed. Internal actuator monitoring identifies most of the safety-related actuator
components. If a fault occurs, the fault would be signalled via the output contact of
the SIL module (
SIL failure
To ensure the safety figures of the Safe ESD safety function, the device has to be
controlled at least once per month via the standard actuator controls, including output
contact assessment of the SIL module (
page 41, Specific figures for AC 01.2 actuator controls in 22X or 22Y version with
actuators of the SA .1 type
(PVST) may be performed. Refer to
execute.
The control signal and the pertaining operation of the actuator have to be present
for at least 4 seconds. If control signal and pertaining operation of the actuator are
present for at least 4 seconds without signalling a fault via the SIL output contact
(SIL module:
SIL failure
device has to be checked in accordance with a proof test. Perform proof test, refer
to
page 28, Proof test (verification of safe actuator
Other intervals can be selected for automated actuator monitoring. The following
should be observed In this case:
The PFD values and all other safety figures affected by the diagnostic interval
have to be recalculated. The respective values (refer to
for AC 01.2 actuator controls in 22X or 22Y version with actuators of the SA .1
type
range) are not valid.
Automated diagnostics should be performed at least 10 times more often than
the proof test.
Automated diagnostics should be performed at least 10 times more often than
the demand rate of safety function.
— Option —
There are two options for performing the PVST.
SA .1 with AC 01.2-22X/-22Y/ACExC 01.2-22X/-22Y
).
SIL failure
range. As an alternative, a Partial Valve Stroke Test
page 26, Partial Valve Stroke Test (PVST):
), the test was successful. If this is not the case, the
function).
Multi-turn actuators
). For safety figures refer to
page 41, Specific figures
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