(206b) Diesel Fuel Flashpoint Reduction and Microbial Induced Corrosion in Underground Fuel Tanks Due to Gasoline Contamination

Due to the large number of diesel flash point failures, the Georgia Department of Agriculture has shut down more than 200 retailer diesel service stations every year since 2014. Tremendous efforts have been devoted to find the root causes of the diesel flash point depression.

Automobile industries design their combustion engines based on the properties of the fuels they are intended to consume. Fuels are formulated with additives to meet the requirements of the engines. Flash point has been a key criterion in these properties. If the ignition is too slow, the engine may not combust the fuel appropriately, resulting in difficult startup or incomplete burning. On the other side, using a fuel with an ignition point that is too fast might result in premature ignition. Both conditions could cause severe engine damage. In addition, the flashpoint of a volatile material is the lowest temperature at which it can vaporize to form an ignitable mixture in air. Ignition may continue and lead to explosion. The lower the flashpoint, the more of a fire danger the material is. Flashpoint is one of the number of properties which must be measured in assessing the overall flammability hazard of a material. To ensure that a fuel meeting the performance and safety standards for the intended application, ASTM D975 specification for diesel fuels have been developed and published. Flash point minimum of 125°F is one of the key parameters in this specification.

Based on Georgia Department of Agriculture investigation, gasoline is likely the main source of contamination of diesel fuel to depress the flash point at the local retailers. The contamination is most likely due to the transport of diesel to the retailers through a gasoline contaminated truck compartment, which is known as switch loading (hauling gasoline prior to hauling diesel fuel). Gasoline contaminated diesel not only causes the flash point depression, but also may induce the microbial corrosion of underground fuel storage tanks.

In this presentation, we provide the technical information where the contamination has been introduced and the recommendations to resolve the issue.