Valves, piping and other fittings subjected to pressure, excluding pressure relief devices, shall be
designed and constructed so that the burst pressure is at least 1.5 times the test pressure of the pressure
Service equipment shall be configured or designed to prevent damage that could result in the release
of the pressure receptacle contents during normal conditions of handling and carriage. Manifold
piping leading to shut-off valves shall be sufficiently flexible to protect the valves and the piping from
shearing or releasing the pressure receptacle contents. The filling and discharge valves and any
protective caps shall be capable of being secured against unintended opening. Valves shall be
protected as specified in 22.214.171.124.
Pressure receptacles which are not capable of being handled manually or rolled, shall be fitted with
devices (skids, rings, straps) ensuring that they can be safely handled by mechanical means and so
arranged as not to impair the strength of, nor cause undue stresses in, the pressure receptacle.
Individual pressure receptacles shall be equipped with pressure relief devices as specified in packing
provision P200 (2) or P205 of 126.96.36.199 or in 188.8.131.52.6.4 and 184.108.40.206.6.5. Pressure-relief devices shall be
designed to prevent the entry of foreign matter, the leakage of gas and the development of any
dangerous excess pressure. When fitted, pressure relief devices on manifolded horizontal pressure
receptacles filled with flammable gas shall be arranged to discharge freely to the open air in such a
manner as to prevent any impingement of escaping gas upon the pressure receptacle itself under
normal conditions of carriage.
Pressure receptacles whose filling is measured by volume shall be provided with a level indicator.
Additional requirements for closed cryogenic receptacles
Each filling and discharge opening in a closed cryogenic receptacle used for the carriage of flammable
refrigerated liquefied gases shall be fitted with at least two mutually independent shut-off devices in
series, the first being a stop-valve, the second being a cap or equivalent device.
For sections of piping which can be closed at both ends and where liquid product can be trapped, a
method of automatic pressure-relief shall be provided to prevent excess pressure build-up within the
Each connection on a closed cryogenic receptacle shall be clearly marked to indicate its function (e.g.
vapour or liquid phase).
Every closed cryogenic receptacle shall be provided with at least one pressure-relief device. The
pressure-relief device shall be of the type that will resist dynamic forces including surge.
Closed cryogenic receptacles may, in addition, have a frangible disc in parallel with the spring loaded
device(s) in order to meet the requirements of 220.127.116.11.6.5.
Connections to pressure-relief devices shall be of sufficient size to enable the required discharge to
pass unrestricted to the pressure-relief device.
All pressure-relief device inlets shall under maximum filling conditions be situated in the vapour
space of the closed cryogenic receptacle and the devices shall be so arranged as to ensure that the
escaping vapour is discharged unrestrictedly.
Capacity and setting of pressure-relief devices
NOTE: In relation to pressure-relief devices of closed cryogenic receptacles, maximum allowable
working pressure (MAWP) means the maximum effective gauge pressure permissible at the top of a
loaded closed cryogenic receptacle in its operating position including the highest effective pressure
during filling and discharge.