The Hazard Characteristic Code (HCC) designation for Flammable Liquid and Corrosive, Alkali. Hazard Group & Comments: UN Class 3 Flammable Liquids (HCCs F1, F2, F3, or F4) that also have the hazards of United Nations Class 8 Corrosive materials and are alkali (caustic/basic) in nature meeting the definition of HCC B1 or B2