UL Standard for Safety Steel Underground Tanks for Flammable and Combustible Liquids Ninth Edition; Reprint with Revisions Through and Including 07/27/1998
These requirements cover horizontal atmosheric-type steel tanks intended for the storage underground of flammable and combustible liquids. These tanks are intended for installation and use in accordance with the Standard for the Installation of Oil-Burning Equipment, NFPA 31, and the Flammable and Combustible Liquids Code, NFPA 30, of the National Fire Protection Association. Tanks covered by these requirements are cylindrical tanks which are fabricated, inspected, and tested for leakage before shipment from the factory as completely assembled vessels.