Design and construction
Pressure receptacles and their closures shall be designed, manufactured, tested and equipped in such a
way as to withstand all conditions, including fatigue, to which they will be subjected during normal
conditions of carriage and use.
In no case shall the minimum wall thickness be less than that specified in the design and construction
For welded pressure receptacles, only metals of weldable quality shall be used.
The test pressure of cylinders, tubes, pressure drums and bundles of cylinders shall be in accordance
with packing instruction P200 of 126.96.36.199, or, for a chemical under pressure, with packing instruction
P206 of 188.8.131.52. The test pressure for closed cryogenic receptacles shall be in accordance with packing
instruction P203 of 184.108.40.206. The test pressure of a metal hydride storage system shall be in accordance
with packing instruction P205 of 220.127.116.11. The test pressure of a cylinder for an adsorbed gas shall be in
accordance with packing instruction P208 of 18.104.22.168.
Pressure receptacles assembled in bundles shall be structurally supported and held together as a unit.
Pressure receptacles shall be secured in a manner that prevents movement in relation to the structural
assembly and movement that would result in the concentration of harmful local stresses. Manifold
assemblies (e.g. manifold, valves, and pressure gauges) shall be designed and constructed such that
they are protected from impact damage and forces normally encountered in carriage. Manifolds shall
have at least the same test pressure as the cylinders. For toxic liquefied gases, each pressure receptacle
shall have an isolation valve to ensure that each pressure receptacle can be filled separately and that
no interchange of pressure receptacle contents can occur during carriage.
NOTE: Toxic liquefied gases have the classification codes 2T, 2TF, 2TC, 2TO, 2TFC or 2TOC.
Contact between dissimilar metals which could result in damage by galvanic action shall be avoided.
Additional requirements for the construction of closed cryogenic receptacles for refrigerated liquefied
The mechanical properties of the metal used shall be established for each pressure receptacle,
including the impact strength and the bending coefficient.
NOTE: With regard to the impact strength, sub-section 22.214.171.124 gives details of test requirements
which may be used.
The pressure receptacles shall be thermally insulated. The thermal insulation shall be protected against
impact by means of a jacket. If the space between the pressure receptacle and the jacket is evacuated
of air (vacuum-insulation), the jacket shall be designed to withstand without permanent deformation
an external pressure of at least 100 kPa (1 bar) calculated in accordance with a recognised technical
code or a calculated critical collapsing pressure of not less than 200 kPa (2 bar) gauge pressure. If the
jacket is so closed as to be gas-tight (e.g. in the case of vacuum-insulation), a device shall be provided
to prevent any dangerous pressure from developing in the insulating layer in the event of inadequate
gas-tightness of the pressure receptacle or its fittings. The device shall prevent moisture from
penetrating into the insulation.
Closed cryogenic receptacles intended for the carriage of refrigerated liquefied gases having a boiling
point below –182 °C at atmospheric pressure shall not include materials which may react with oxygen
or oxygen enriched atmospheres in a dangerous manner, when located in parts of the thermal
insulation where there is a risk of contact with oxygen or with oxygen enriched liquid.
Closed cryogenic receptacles shall be designed and constructed with suitable lifting and securing
Additional requirements for the construction of pressure receptacles for acetylene
Pressure receptacles for UN 1001 acetylene, dissolved, and UN 3374 acetylene, solvent free, shall
be filled with a porous material, uniformly distributed, of a type that conforms to the
requirements and testing specified by a standard or technical code recognised by the competent
authority and which:
(a) Is compatible with the pressure receptacle and does not form harmful or dangerous
compounds either with the acetylene or with the solvent in the case of UN 1001; and
(b) Is capable of preventing the spread of decomposition of the acetylene in the porous
In the case of UN 1001, the solvent shall be compatible with the pressure receptacle.