5806.4 Underground Tanks for Liquid Hydrogen

Underground tanks for the storage of liquid hydrogen shall be in accordance with Sections 5806.4.1 through 5806.4.8.3.

Storage tanks for liquid hydrogen shall be designed and constructed in accordance with ASME Boiler and Pressure Vessel Code (Section VIII, Division 1) and shall be vacuum jacketed in accordance with Section 5806.4.8.

Storage tanks shall be located outside in accordance with the following:

1. Tanks and associated equipment shall be located with respect to foundations and supports of other structures such that the loads carried by the latter cannot be transmitted to the tank.
2. The distance from any part of the tank to the nearest wall of a basement, pit, cellar or lot line shall not be less than 3 feet (914 mm).
3. A minimum distance of 1 foot (305 mm), shell to shell, shall be maintained between underground tanks.

The tank shall be buried such that the top of the vacuum jacket is covered with a minimum of 1 foot (305 mm) of earth and with concrete a minimum of 4 inches (102 mm) thick placed over the earthen cover. The concrete shall extend a minimum of 1 foot (305 mm) horizontally beyond the footprint of the tank in all directions. Underground tanks shall be set on firm foundations constructed in accordance with the International Building Code and surrounded with at least 6 inches (152 mm) of noncorrosive inert material, such as sand.

Tanks and systems shall be secured against accidental dislodgement in accordance with this chapter.

Vent pipes for underground storage tanks shall be in accordance with Section 5503.3.

Underground liquid hydrogen piping shall be vacuum jacketed or protected by approved means and designed in accordance with Chapter 55.

An approved means or method shall be provided to prevent the overfill of all storage tanks.

The vacuum jacket shall be designed and constructed in accordance with Section VIII of ASME Boiler and Pressure Vessel Code and shall be designed to withstand the anticipated loading, including loading from vehicular traffic, where applicable. Portions of the vacuum jacket installed below grade shall be designed to withstand anticipated soil, seismic and hydrostatic loading.

The vacuum jacket shall be constructed of stainless steel or other approved corrosion-resistant material.

The vacuum jacket shall be protected by approved or listed corrosion-resistant materials or an engineered cathodic protection system. Where cathodic protection is utilized, an approved maintenance schedule shall be established. Exposed components shall be inspected at least twice a year. Maintenance and inspection events shall be recorded and those records shall be maintained on the premises for a minimum of three years and made available to the fire code official upon request.

An approved method shall be provided to indicate loss of vacuum within the vacuum jacket(s).