Safety aspects in the storage of bitumen
in heated penetration and oxidised grade bitumen storage
tanks in the USA, a number of suggestions were made concerning
the possible presence of components of the fire triangle.
If such conditions exist, then the need for inerting tanks
held above certain storage temperatures can be demonstrated.
Current practice relating to the handling and storage of
bitumens in the UK has been examined, and measurements
made at refineries, Quarries and other installations storing
bitumen under elevated temperatures. This has been supplemented
by the building of small scale replicas in the laboratory
so that conditions in full scale tanks could be simulated.
This enabled generation of flammability and gas concentration
data for a variety of bitumens.
A thorough investigation of bitumens and their associated
coke-like deposits has been made. Flash and autoignition
points have been determined, While a range of thermal analysis
techniques have been employed to determine the pqssible
existence of exothermic decomposition reactions. Inter
alia gas Chromatography/mass spectrometry and infrared
analysis techniques has enabled a detailed study to be
made of the decomposition products evolved from bitumens
and deposits on heating. Scanning electron microscopy
and the use of a micro-combustion technique has provided
information on the elemental composition. The physical
properties of penetration value, -softening point, viscosity
and thermal conductivity have also been determined for
It has been found that current UK practice may, in some
cases, permit two sides of the fire triangle to exist in
non-inerted tanks. The presence of a third component,
an ignition source has not yet been substantiated. Flammable
atmospheres can exist in storage tanks at the currently .
recommended maximum storage temperatures. This is particularly
the case with the oxidised grade bitumens which eXhibit
high values of %LEL at these temperatures.