Intent 1:
To exempt timber supports from the application of Sentence 4.3.3.1.(1), which would otherwise require the supports to
be made of concrete, masonry or steel, on the basis that such supports
provide an equivalent level of safety.
This is
to limit the probability that:
- the supports will contribute to a fire under the tank,
which could lead to failure of the tank from exposure to the fire,
which could lead to fire growth and spread of fire, which could lead
to harm to persons, and
- a fire will lead to the premature failure [collapse]
of the supports, which could lead to the collapse of the tank, 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 harm
to persons.