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14
Competence in Functional Safety
Functional safety of globe valves, rotary plug valves, ball valves and butterfly valves
Responsibility
It is essential to check the actuator forces to ensure that
the valve can overcome
the process pressures to reach its fail-safe position
.
This can be checked by the manufacturer if requested.
The actual actuator forces must not close the valve against a pressure which is 1.5
times above the nominal pressure (PN) of the plant or valve.
If this actuator force restriction cannot be implemented, an excess pressure valve is
necessary for valves connected in series to prevent that the permissible operating
pressure is exceeded.
Manufacturer/
operator
Example: Valves connected in series
It is essential to observe the prescribed direction of flow (arrow on the valve body) of
globe valves.
Operator