Steel contained tanks assemblies are used for aboveground storage of flammable liquids and combustible liquids such as gasoline, fuel oil, or similar products with a relative density not greater than 1.0. Contained tank assemblies consist of primary tanks contained in steel containments having capacities of not less than 110% of the capacities of the primary tanks.

The primary tank has to be constructed and tested for full compliance with one of the following standards: