5.3 Buildings and Structures.
5.3.1 Buildings or structural enclosures in which LNG, flammable refrigerants, and
flammable gases are handled shall be of lightweight, noncombustible construction with
non–loadbearing
walls.
5.3.2 If rooms containing LNG and flammable fluids are located within or attached to
buildings in which such fluids are not handled (e.g., control centers, shops), the common
walls shall be limited to no more than two, shall be designed to withstand a static pressure of
at least 100 psf (4.8 kPa), shall have no doors or other communicating openings, and shall
have a fire resistance rating of at least 1 hour.
5.3.3 Buildings or structural enclosures in which LNG, flammable refrigerants, and
flammable gases are handled shall be ventilated to minimize the possibility of hazardous
accumulations of flammable gases or vapors, in accordance with 5.3.3.1 through 5.3.3.4.
5.3.3.1 Ventilation shall be permitted to be by means of one of the following:
(1) A continuously operating mechanical ventilation system
(2) A combination gravity ventilation system and normally nonoperating mechanical
ventilation system that is energized by combustible gas detectors in the event
combustible gas is detected
(3) A dual rate mechanical ventilation system with the high rate energized by gas
detectors in the event flammable gas is detected
(4) A gravity ventilation system composed of a combination of wall openings and roof
ventilators
(5) Other approved ventilation systems