DIN 6625

Standard for square steel containers intended for above-ground storage of liquids with a flash point of more than 55 °C.

Steel tanks according to DIN 6625 are also referred to as "rectangular tanks" due to their construction. The rectangular shape allows for particularly economical and space-saving use indoors.

These tanks are primarily used for storage in basement rooms. Hence, they are commonly known as "basement tanks" or "basement-welded" storage tanks.

Rectangular tanks are typically assembled on-site (in basements or other indoor spaces) by the manufacturer or installation companies from individual components, as they cannot be introduced into the space as complete units.

These containers are available as single-walled or double-walled steel tanks, with or without coatings. In addition to standard sizes, custom dimensions and configurations are possible.

In practice, these containers are used as heating oil tanks in businesses and private households, as well as storage for chemicals and other liquids.