Requirements for the design, construction, inspection and testing of UN multiple-element gas containers (MEGCs) intended for the carriage of non-refrigerated gases
For the purposes of this section:
Alternative arrangement means an approval granted by the competent authority for a portable tank or
MEGC that has been designed, constructed or tested to technical requirements or testing methods
other than those specified in this Chapter;
Elements are cylinders, tubes or bundles of cylinders;
Leakproofness test means a test using gas subjecting the elements and the service equipment of the
MEGC to an effective internal pressure of not less than 20% of the test pressure;
Manifold means an assembly of piping and valves connecting the filling and/or discharge openings of
Maximum permissible gross mass (MPGM) means the sum of the tare mass of the MEGC and the
heaviest load authorized for carriage;
UN Multiple-element gas containers (MEGCs) are multimodal assemblies of cylinders, tubes and
bundles of cylinders which are interconnected by a manifold and which are assembled within a
framework. The MEGC includes service equipment and structural equipment necessary for the
carriage of gases;
Service equipment means measuring instruments and filling, discharge, venting and safety devices;
Structural equipment means the reinforcing, fastening, protective and stabilizing members external to
General design and construction requirements
The MEGC shall be capable of being filled and discharged without the removal of its structural
equipment. It shall possess stabilizing members external to the elements to provide structural integrity
for handling and carriage. MEGCs shall be designed and constructed with supports to provide a secure
base during carriage and with lifting and tie-down attachments which are adequate for lifting the
MEGC including when filled to its maximum permissible gross mass. The MEGC shall be designed to
be loaded onto a vehicle, wagon or sea-going or inland navigation vessel and shall be equipped with
skids, mountings or accessories to facilitate mechanical handling.
MEGCs shall be designed, manufactured and equipped in such a way as to withstand all conditions to
which they will be subjected during normal conditions of handling and carriage. The design shall take
into account the effects of dynamic loading and fatigue.
Elements of an MEGC shall be made of seamless steel and be constructed and tested according to
6.2.1 and 6.2.2. All of the elements in an MEGC shall be of the same design type.
Elements of MEGCs, fittings and pipework shall be:
(a) Compatible with the substances intended to be carried (see ISO 11114-1:2012 and ISO 11114-
(b) Properly passivated or neutralized by chemical reaction.
Contact between dissimilar metals which could result in damage by galvanic action shall be avoided.
The materials of the MEGC, including any devices, gaskets, and accessories, shall not adversely affect
the gas(es) intended for carriage in the MEGC.
MEGCs shall be designed to withstand, without loss of contents, at least the internal pressure due to
the contents, and the static, dynamic and thermal loads during normal conditions of handling and
carriage. The design shall demonstrate that the effects of fatigue, caused by repeated application of
these loads through the expected life of the multiple-element gas container, have been taken into
MEGCs and their fastenings shall, under the maximum permissible load, be capable of withstanding
the following separately applied static forces:
(a) In the direction of travel: twice the MPGM multiplied by the acceleration due to gravity (g) 1;
(b) Horizontally at right angles to the direction of travel: the MPGM (when the direction of travel
is not clearly determined, the forces shall be equal to twice the MPGM) multiplied by the
acceleration due to gravity (g)1;
(c) Vertically upwards: the MPGM multiplied by the acceleration due to gravity (g) 1; and
(d) Vertically downwards: twice the MPGM (total loading including the effect of gravity)
multiplied by the acceleration due to gravity (g)1.
Under the forces defined in 18.104.22.168.8, the stress at the most severely stressed point of the elements
shall not exceed the values given in either the relevant standards of 22.214.171.124 or, if the elements are not
designed, constructed and tested according to those standards, in the technical code or standard
recognised or approved by the competent authority of the country of use (see 6.2.5).
Under each of the forces in 126.96.36.199.8, the safety factor for the framework and fastenings to be
observed shall be as follows:
(a) for steels having a clearly defined yield point, a safety factor of 1.5 in relation to the
guaranteed yield strength; or
(b) for steels with no clearly defined yield point, a safety factor of 1.5 in relation to the guaranteed
0.2% proof strength and, for austenitic steels, the 1% proof strength.
MEGCs intended for the carriage of flammable gases shall be capable of being electrically earthed.
The elements shall be secured in a manner that prevents undesired movement in relation to the
structure and the concentration of harmful localized stresses.