This document specifies requirements for the design and construction of metallic gravity-discharge tanks intended for the carriage of substances having a vapour pressure not exceeding 110 kPa (1,1 bar) (absolute pressure) at 50 °C. NOTE 1 Gravity-discharge tanks have no maximum working pressure. However, during operation, pressure in the shell may occur, for example due to flow restrictions in vapour recovery systems or opening pressures of breather devices. It is important that these operating pressures do not exceed the test pressure of the tank or 0,5 bar, whichever is the highest. This document specifies requirements for openings, closures, pipework, mountings for service equipment and structural equipment. NOTE 2 This document does not specify requirements for items of service equipment other than pipes passing through the shell. This document is applicable to aircraft refuelers that are used on public roads. It is also applicable to inter-modal tanks (e.g. tank containers and tank swap bodies) for the transport of dangerous goods by road and rail. NOTE 3 This document is not applicable to fixed rail tank wagons.