Isomerisation is a ”bottom of the barrel” process of molecular conversion of a hydrocarbon into its more useful Isomer (equal molecular weight, quantitative and qualitative composition, but with different physical and chemical characteristics). It is usually intended to convert low Octane oil fractions containing straight-chain alkanes into high Octane gasoline components comprising branched-chain alkanes, through structural change of the Carbon skeleton or spatial and configurational change. This change takes place in the presence of a catalyst which depending on the change required could be finely dispersed platinum on an aluminium oxide catalyst, chlorinated Alumina or sulphated metal oxide. These isomeric compounds can be blended into gasoline to improve its octane rating and increase its value. BIH supply fired heaters to pre-heat the feed going into the isomerisation unit.