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Steel loses its structural
integrity between 550ºC and 620ºC when fully loaded. ‘Standard’ testing
methods are based upon exposing protected steel sections to furnace
temperatures that reach 837ºC in 30 minutes,
940ºC in 60 minutes, 1001ºC in
90 minutes and 1044ºC in 120 minutes.
If a fully loaded beam or
column is exposed to these temperatures, failure is deemed to occur when
the steel had deflected to its maximum before collapse, or when all, or
part of the coating falls off. |
Obviously, if the coating
comes away, the protected steel section is exposed to the furnace
temperature and rapidly reaches the failure range of 550ºC to 620ºC. For
this reason, the
loaded beam or column tests are also known as the ‘stickability’ tests.
In addition to its ability
to prevent the structural steel from reaching the temperature at which
it will collapse, a passive fire protection product itself must not
signifi-cantly contribute to the quantity of combustible material in a
building. |
This is a Building
Regulation requirement and is tested by the fire testing laboratories.
Passive fire protection
products are therefore tested for the extent of their inherent fire
resisting properties, that
includes:
a) combustibility
b) rate of surface
spread
of flame.
c) contribution to
fire
propagation. |
