Design and construction
Pressure receptacles and their closures not designed, constructed, inspected, tested and approved
according to the requirements of 6.2.2 shall be designed, constructed, inspected, tested and approved
in accordance with the general requirements of 6.2.1 as supplemented or modified by the requirements
of this section and those of 6.2.4 or 6.2.5.
Whenever possible the wall thickness shall be determined by calculation, accompanied, if needed, by
experimental stress analysis. Otherwise the wall thickness may be determined by experimental means.
Appropriate design calculations for the pressure envelope and supporting components shall be used to
ensure the safety of the pressure receptacles concerned.
The minimum wall thickness to withstand pressure shall be calculated in particular with regard to:
- The calculation pressures, which shall not be less than the test pressure;
- The calculation temperatures allowing for appropriate safety margins;
- The maximum stresses and peak stress concentrations where necessary;
- Factors inherent to the properties of the material.
For welded pressure receptacles, only metals of weldable quality whose adequate impact strength at
an ambient temperature of –20 °C can be guaranteed shall be used.
For closed cryogenic receptacles, the impact strength to be established as required by 22.214.171.124.8.1 shall
be tested as laid down in 126.96.36.199.
Acetylene cylinders shall not be fitted with fusible plugs.
Service equipment shall comply with 188.8.131.52.
Pressure drums may be provided with openings for filling and discharge and with other openings
intended for level gauges, pressure gauges or relief devices. The number of openings shall be kept to a
minimum consistent with safe operations. Pressure drums may also be provided with an inspection
opening, which shall be closed by an effective closure.
(a) If cylinders are fitted with a device to prevent rolling, this device shall not be integral with the
(b) Pressure drums which are capable of being rolled shall be equipped with rolling hoops or be
otherwise protected against damage due to rolling (e.g. by corrosion resistant metal sprayed on to
the pressure receptacle surface);
(c) Bundles of cylinders shall be fitted with appropriate devices ensuring that they can be handled
and carried safely;
(d) If level gauges, pressure gauges or relief devices are installed, they shall be protected in the same
way as is required for valves in 184.108.40.206.
Initial inspection and test
New pressure receptacles shall be subjected to testing and inspection during and after manufacture in
accordance with the requirements of 220.127.116.11.
Specific provisions applying to aluminium alloy pressure receptacles
(a) In addition to the initial inspection required by 18.104.22.168.1, it is necessary to test for possible
intercrystalline corrosion of the inside wall of the pressure receptacles where use is made of
an aluminium alloy containing copper, or where use is made of an aluminium alloy
containing magnesium and manganese and the magnesium content is greater than 3.5% or the
manganese content lower than 0.5%;
(b) In the case of an aluminium/copper alloy the test shall be carried out by the manufacturer at
the time of approval of a new alloy by the competent authority; it shall thereafter be repeated
in the course of production, for each pour of the alloy;
(c) In the case of an aluminium/magnesium alloy the test shall be carried out by the manufacturer
at the time of approval of a new alloy and of the manufacturing process by the competent
authority. The test shall be repeated whenever a change is made in the composition of the
alloy or in the manufacturing process.
Periodic inspection and test