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 bitumens. 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.