Specifies vertical, cylindrical, single-wall steel thanks that are used for the above ground storage of flammable and non-flammable water polluting liquids. Such tanks may be provided with a protective lining which has been type approved under Article 12 of the Verordnung uber brennbare Flussigkeiten (German Regulation on Flammable Liquids) or been granted a test mark under the building regulations. They are suitable for storing liquids with a maximum density of 1,9kg/l and may be used at a working pressure of up to 0,5 bar.