(a) Unenclosed tanks shall not be located within 5 feet, horizontally, of any fire or flame.
(b) Tanks larger than 60 gallons capacity shall not be located in buildings above the lowest story, cellar or basement, except in commercial, industrial or processing plants where storage on a higher floor is required by the process.
(c) Tanks exceeding 275 gallons individual capacity or 1,100 gallons aggregate capacity in an individual building or in a section of a building separated by firewall shall be installed in an enclosure constructed as follows: The walls of the enclosure shall be constructed of solid masonry units or poured concrete construction having a fire-resistance rating of not less than three hours. Such enclosures shall be installed only on concrete or other fire-resistive floors and shall be bonded to the floors. Enclosures shall have tops of reinforced concrete at least 5 inches thick or equivalent fire-resistive construction, except that where floor or roof construction above the enclosure is concrete or other fire-resistive construction, the walls may be extended to and bonded to the underside of the construction above in lieu of the provision of a separate top. Any openings to such enclosures shall be provided with fire doors or other approved closures and six-inch noncombustible liquid-tight sills or ramps. Provision shall be made for adequate ventilation of such enclosures prior to entering for inspection or repairs on tanks.
(d) Inside storage tanks shall be securely supported to prevent settling, sliding or lifting.