Dangerous Goods by Road
Shells of vacuum-insulated tanks of not more than 1.80 m in diameter shall be not less than 3 mm
thick in the reference steel or of equivalent thickness in the metal to be used. Such shells of more
than 1.80 m in diameter shall be not less than 4 mm thick in the reference steel or of equivalent
thickness in the metal to be used.
For vacuum-insulated tanks, the aggregate thickness of the jacket and the shell shall correspond to the
minimum thickness prescribed in 6.7.4.4.2, the thickness of the shell itself being not less than the
minimum thickness prescribed in 6.7.4.4.3.
Shells shall be not less than 3 mm thick regardless of the material of construction.
where:
e1 = required equivalent thickness (in mm) of the metal to be used;
e0 = minimum thickness (in mm) of the reference steel specified in 6.7.4.4.2 and 6.7.4.4.3;
Rm1 = guaranteed minimum tensile strength (in N/mm2) of the metal to be used (see 6.7.4.3.3);
A1 = guaranteed minimum elongation at fracture (in %) of the metal to be used according to
national or international standards.
In no case shall the wall thickness be less than that prescribed in 6.7.4.4.1 to 6.7.4.4.5. All parts of the
shell shall have a minimum thickness as determined by 6.7.4.4.1 to 6.7.4.4.6. This thickness shall be
exclusive of any corrosion allowance.
There shall be no sudden change of plate thickness at the attachment of the ends (heads) to the
cylindrical portion of the shell.
Service equipment
Service equipment shall be so arranged as to be protected against the risk of being wrenched off or
damaged during handling and carriage. When the connection between the frame and the tank or the
jacket and the shell allows relative movement, the equipment shall be so fastened as to permit such
movement without risk of damage to working parts. The external discharge fittings (pipe sockets,
shut-off devices), the stop-valve and its seating shall be protected against the danger of being
wrenched off by external forces (for example using shear sections). The filling and discharge devices
(including flanges or threaded plugs) and any protective caps shall be capable of being secured against
unintended opening.
Each filling and discharge opening in portable tanks used for the carriage of flammable refrigerated
liquefied gases shall be fitted with at least three mutually independent shut-off devices in series, the
first being a stop-valve situated as close as reasonably practicable to the jacket, the second being a
stop-valve and the third being a blank flange or equivalent device. The shut-off device closest to the
jacket shall be a quick closing device, which closes automatically in the event of unintended
movement of the portable tank during filling or discharge or fire engulfment. This device shall also be
possible to operate by remote control.
Each filling and discharge opening in portable tanks used for the carriage of non-flammable
refrigerated liquefied gases shall be fitted with at least two mutually independent shut-off devices in
series, the first being a stop-valve situated as close as reasonably practicable to the jacket, the second a
blank flange or equivalent device.
For sections of piping which can be closed at both ends and where liquid product can be trapped, a
method of automatic pressure relief shall be provided to prevent excess pressure build-up within the
piping.
Vacuum insulated tanks need not have an opening for inspection.
External fittings shall be grouped together so far as reasonably practicable.
Each connection on a portable tank shall be clearly marked to indicate its function.
Each stop-valve or other means of closure shall be designed and constructed to a rated pressure not
less than the MAWP of the shell taking into account the temperature expected during carriage. All
stop-valves with a screwed spindle shall be closed by a clockwise motion of the handwheel. In the
case of other stop-valves the position (open and closed) and direction of closure shall be clearly
indicated. All stop-valves shall be designed to prevent unintentional opening.