Connections to pressure-relief devices

Connections to pressure-relief devices shall be of sufficient size to enable the required discharge to
pass unrestricted to the pressure relief device. No stop-valve shall be installed between the element
and the pressure-relief devices, except when duplicate devices are provided for maintenance or other
reasons, and the stop-valves serving the devices actually in use are locked open, or the stop-valves are
interlocked so that at least one of the duplicate devices is always operable and capable of meeting the
requirements of There shall be no obstruction in an opening leading to or leaving from a vent
or pressure-relief device which might restrict or cut-off the flow from the element to that device. The
opening through all piping and fittings shall have at least the same flow area as the inlet of the
pressure relief device to which it is connected. The nominal size of the discharge piping shall be at
least as large as that of the pressure relief device outlet. Vents from the pressure-relief devices, when
used, shall deliver the relieved vapour or liquid to the atmosphere in conditions of minimum backpressure
on the relieving device.

Siting of pressure-relief devices

Each pressure relief device shall, under maximum filling conditions, be in communication with the
vapour space of the elements for the carriage of liquefied gases. The devices, when fitted, shall be so
arranged as to ensure that the escaping vapour is discharged upwards and unrestrictedly as to prevent
any impingement of escaping gas or liquid upon the MEGC, its elements or personnel. For flammable,
pyrophoric and oxidizing gases, the escaping gas shall be directed away from the element in such a
manner that it cannot impinge upon the other elements. Heat resistant protective devices which deflect
the flow of gas are permissible provided the required pressure relief device capacity is not reduced.

Arrangements shall be made to prevent access to the pressure-relief devices by unauthorized persons
and to protect the devices from damage caused by the MEGC overturning.

Gauging devices

When an MEGC is intended to be filled by mass, it shall be equipped with one or more gauging
devices. Level-gauges made of glass or other fragile material shall not be used.

MEGC supports, frameworks, lifting and tie-down attachments

MEGCs 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 element mountings (e.g. cradles, frameworks, etc.) and MEGC
lifting and tie-down attachments shall not cause excessive stress in any element. Permanent lifting and
tie-down attachments shall be fitted to all MEGCs. In no case shall mountings or attachments be
welded onto the elements.

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

When MEGCs are not protected during carriage, according to, the elements and service
equipment shall be protected against damage resulting from lateral or longitudinal impact or
overturning. External fittings shall be protected so as to preclude the release of the elements' contents
upon impact or overturning of the MEGC on its fittings. Particular attention shall be paid to the
protection of the manifold. Examples of protection include:
(a) Protection against lateral impact which may consist of longitudinal bars;
(b) Protection 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 elements and service equipment against damage from impact or overturning
by use of an ISO frame in accordance with the relevant provisions of ISO 1496-3:1995.

Design approval

The competent authority or its authorized body shall issue a design approval certificate for any new
design of an MEGC. This certificate shall attest that the MEGC has been surveyed by that authority, is
suitable for its intended purpose and meets the requirements of this Chapter, the applicable provisions
for gases of Chapter 4.1 and of packing instruction P200. When a series of MEGCs 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 materials of construction of the manifold, the standards to which
the elements are made and an approval number. The approval number shall consist of the
distinguishing sign or mark of the country granting the approval, indicated by the distinguishing sign
used on vehicles 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 MEGCs made of materials of the same type 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 framework test specified in ISO1496-3:1995;
(b) The results of the initial inspection and test specified in;
(c) The results of the impact test specified in; and
(d) Certification documents verifying that the cylinders and tubes comply with the applicable
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