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INNOVATIVE TECHNOLOGY

appropriateness of additional protective equipment. The result
of the HAZOP analysis is a technological hazard table with
ranking by consequences. Next, the distribution of security
functions by layers of protection. First of all, the possibility
of using mechanical protections is considered such as safety
valves, explosive diaphragms. Where this is not possible, you
need implement instrument protection circuits.
The determination of SIL safety integrity levels for Safety
Instrumented Function (SIF) instrument protection circuits
can be performed using one of the methods, for example, a
risk matrix or analysis of LOPA (Layers of protection analysis)
protection layers, a risk graph, etc. It should be noted that the
level SIL is defined for the protection circuit from the sensor to
the actuator. After determining the SIL levels, it is possible to distribute the protection functions
according to their execution: implement the SIL0 level with a risk reduction coefficient of less
than 10 using DCS; implement SIL1 levels and higher using EAP system. At the output of the
stage, the Safety Requirment Specification (SRS) should appear. This is the technical task for
the creation of a EAP system. The specification defines blocking circuits: sensor-controller-
executive device; requirements for them according to the SIL level, requirements for testing
intervals, requirements for architecture, requirements of orders of Rostekhnadzor, etc.

Fig. 3. An example of a protection circuit, where XooN is the voting scheme X of N inputs, blocking (implemented in the
controller); YooZ - voting scheme Y from Z outputs, ensuring blocking (determined by the installation of the executive
devices in the "field"); ED - executive device (shut-off valve, pump, etc.).

Implementation phase Operation phase
Based on the SRS specification, instrumentation, Since any system degrades over time
controller, actuators are selected. By calculation both in terms of reliability and in terms
it is confirmed that the designed protection of security, the enterprise should have
circuits according to the SIL level correspond plans for testing circuit elements. They are
to the required values from the specification. tested at the frequency specified in the
The development of documentation includes: a SRS specification. Test results should be
"field" project, a top-level project, development documented. Periodically, it is necessary to
of working documentation, system assembly, conduct an assessment of functional safety
acceptance tests, commissioning, complex tests. with the participation of technologists,
Validation is carried out this is the confirmation electricians, specialists of the instrumentation
that the embedded algorithms and implementation and control systems. The person responsible
fully comply with the original requirements of the for maintaining the functional safety life
SRS specification. cycle must be identified. All people involved
in the life cycle stages of a EAP system must
be trained.

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