Intent 1:
To exempt certain valves and materials from the
application of Sentence 4.5.7.2.(3) if special conditions warrant
their use.
This is to limit the probability that:
- internal stress or mechanical damage will lead to failure
of the valves, which could lead to the escape of liquid, which could
lead to the ignition of vapour from a nearby ignition source, which
could lead to damage to the building or facility, and
- exposure of the valves to fire will lead to failure
of the valves, which could lead to the escape of liquid, which could
lead to the ignition of vapour from a nearby ignition source, which
could lead to damage to the building or facility.