Equivalent procedures for conformity assessment and periodic inspection and test
For UN pressure receptacles the requirements of 126.96.36.199 and 188.8.131.52 are considered to have been
complied with when the following procedures are applied:
Type approval (184.108.40.206)
Supervision of manufacture (220.127.116.11)
Xa or IS
Initial inspection and tests (18.104.22.168)
Xa or IS
Periodic inspection (22.214.171.124)
Xa or Xb or IS
Xa means the competent authority, its delegate or inspection body conforming to 126.96.36.199, 188.8.131.52,
184.108.40.206 and 220.127.116.11 and accredited according to EN ISO/IEC 17020:2012 (except clause 8.1.3) type A.
Xb means inspection body conforming to 18.104.22.168, 22.214.171.124, 126.96.36.199 and 188.8.131.52 and accredited according
to EN ISO/IEC 17020:2012 (except clause 8.1.3) type B.
IS means an in-house inspection service of the applicant under the surveillance of an inspection body
conforming to 184.108.40.206, 220.127.116.11, 18.104.22.168 and 22.214.171.124 and accredited according to EN ISO/IEC
17020:2012 (except clause 8.1.3) type A. The in-house inspection service shall be independent from
design process, manufacturing operations, repair and maintenance.
General requirements for non-UN pressure receptacles
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 126.96.36.199.8.1 shall
be tested as laid down in 188.8.131.52.
Acetylene cylinders shall not be fitted with fusible plugs.
Service equipment shall comply with 184.108.40.206.
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 220.127.116.11.
Initial inspection and test
New pressure receptacles shall be subjected to testing and inspection during and after manufacture in
accordance with the requirements of 18.104.22.168.