This European Standard specifies the product characteristics and test methods for workshop fabricated cylindrical, horizontal steel tanks, single (type S) and double skin (type D) intended to be used for the underground storage of water polluting liquids (both flammable and non-flammable) and installed in industrial processes or in petrol stations at normal ambient temperature conditions ("20 °C to +50 °C) within the following limits: from 800 mm up to 3000 mm nominal diameter and; up to a maximum overall length of 6 times the nominal diameter; with an operating pressure (Po) of maximum 150 kPa (1,5 bar) (abs.) and minimum 5 kPa ( 50 mbar) and; for double skin tanks with a vacuum leak detection system where the kinematic viscosity does not exceed 5 × 10"3 m2/s. Tanks designed to this standard allow for an earth cover of up to 1,5 m. If there are imposed traffic loads or a greater earth cover, calculation is required. This standard is not applicable to tanks used for storage and/or supply of fuel/gas for building heating/cooling systems, and of hot or cold water not intended for human consumption, nor to loads and special measures necessary in areas subject to risk of earthquakes. Guidance on installation of tanks is presented in Annex A, which does not include special measures that might be necessary in areas subject to flooding. This standard is not applicable for the storage of liquids having dangerous goods classes listed in Table 1 because of the special dangers involved.