Siting of pressure-relief devices

Each pressure-relief device inlet shall be situated on top of the shell in a position as near the
longitudinal and transverse centre of the shell as reasonably practicable. All pressure-relief device
inlets shall under maximum filling conditions be situated in the vapour space of the shell and the
devices shall be so arranged as to ensure that the escaping vapour is discharged unrestrictedly. For
refrigerated liquefied gases, the escaping vapour shall be directed away from the tank and in such a
manner that it cannot impinge upon the tank. Protective devices which deflect the flow of vapour are
permissible provided the required relief-device capacity is not reduced.

Arrangements shall be made to prevent access to the devices by unauthorized persons and to protect
the devices from damage caused by the portable tank overturning.

Gauging devices

Unless a portable tank is intended to be filled by weight, it shall be equipped with one or more
gauging devices. Glass level-gauges and gauges made of other fragile material, which are in direct
communication with the contents of the shell shall not be used.

A connection for a vacuum gauge shall be provided in the jacket of a vacuum-insulated portable tank.

Portable tank supports, frameworks, lifting and tie-down attachments

Portable tanks shall be designed and constructed with a support structure to provide a secure base
during carriage. The forces specified in and the safety factor specified in shall be
considered in this aspect of the design. Skids, frameworks, cradles or other similar structures are

The combined stresses caused by portable tank mountings (e.g. cradles, frameworks, etc.) and portable
tank lifting and tie-down attachments shall not cause excessive stress in any portion of the tank.
Permanent lifting and tie-down attachments shall be fitted to all portable tanks. Preferably they shall
be fitted to the portable tank supports but may be secured to reinforcing plates located on the tank at
the points of support.

In the design of supports and frameworks the effects of environmental corrosion shall be taken into

Forklift pockets shall be capable of being closed off. The means of closing forklift pockets shall be a
permanent part of the framework or permanently attached to the framework. Single compartment
portable tanks with a length less than 3.65 m need not have closed off forklift pockets provided that:
(a) The tank and all the fittings are well protected from being hit by the forklift blades; and
(b) The distance between the centres of the forklift pockets is at least half of the maximum length
of the portable tank.

When portable tanks are not protected during carriage, according to, the shells and service
equipment shall be protected against damage to the shell and service equipment resulting from lateral
or longitudinal impact or overturning. External fittings shall be protected so as to preclude the release
of the shell contents upon impact or overturning of the portable tank on its fittings. Examples of
protection include:
(a) Protection against lateral impact which may consist of longitudinal bars protecting the shell on
both sides at the level of the median line;
(b) Protection of the portable tank against overturning which may consist of reinforcement rings or
bars fixed across the frame;
(c) Protection against rear impact which may consist of a bumper or frame;
(d) Protection of the shell against damage from impact or overturning by use of an ISO frame in
accordance with ISO 1496-3:1995;
(e) Protection of the portable tank from impact or overturning by a vacuum insulation jacket.

Design approval

The competent authority or its authorized body shall issue a design approval certificate for any new
design of a portable tank. This certificate shall attest that a portable tank has been surveyed by that
authority, is suitable for its intended purpose and meets the requirements of this Chapter. When a
series of portable tanks are manufactured without change in the design, the certificate shall be valid
for the entire series. The certificate shall refer to the prototype test report, the refrigerated liquefied
gases allowed to be carried, the materials of construction of the shell and jacket and an approval
number. The approval number shall consist of the distinguishing sign or mark of the State in whose
territory the approval was granted, indicated by the distinguishing sign for use in international road
traffic2, and a registration number. Any alternative arrangements according to shall be
indicated on the certificate. A design approval may serve for the approval of smaller portable tanks
made of materials of the same kind and thickness, by the same fabrication techniques and with
identical supports, equivalent closures and other appurtenances.

The prototype test report for the design approval shall include at least the following:
(a) The results of the applicable frame-work test specified in ISO 1496-3:1995;
(b) The results of the initial inspection and test in; and
(c) The results of the impact test in, when applicable.
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