Crude oil fouling is typically treated in the literature as a phenomenon involving the deposition of organic material on the thermal surfaces of heat exchangers. Little attention is paid to the effects that inorganic species have on the thermal and hydraulic performance of the heat exchangers affected. When deposition of inorganic species occurs, it is often the cause of an upset in operations (e.g. issues with the desalter) that results in episodes of rapid (acute) fouling. In this paper, a method used to detect acute fouling episodes and identifying their causes is presented.