Cylinders, tubes, pressure drums, bundles of cylinders constructed as specified in 6.2 and MEGCs constructed as specified in 6.7.5 are authorized for the transport of a specific substance when specified in the following tables. For some substances, the special packing provisions may prohibit a particular type of cylinder, tube, pressure drum or bundle of cylinders.

1. Pressure receptacles containing toxic substances with an LC₅₀ less than or equal to 200 mL/m³ (ppm) as specified in the table shall not be equipped with any pressure relief device. Pressure relief devices shall be fitted on pressure receptacles used for the transport of UN 1013 carbon dioxide and UN 1070 nitrous oxide. Other pressure receptacles shall be fitted with a pressure relief device if specified by the competent authority of the country of use. The type of pressure relief device, the set-to-discharge pressure and relief capacity of pressure relief devices, if required, shall be specified by the competent authority of the country of use.

2. The following three tables cover compressed gases (Table 1), liquefied and dissolved gases (Table 2) and substances not in Class 2 (Table 3). They provide:

   1. The UN Number, proper shipping name, and classification of the substance;

   2. The LC₅₀ for toxic substances;

   3. The types of pressure receptacles authorized for the substance, shown by the letter "X";

   4. The maximum test period for periodic inspection of the pressure receptacles;

      Note: For pressure receptacles which make use of composite materials, the maximum test period shall be 5 years. The test period may be extended to that specified in Tables 1 and 2 (i.e. up to 10 years), if approved by the competent authority of the country of use.

   5. The minimum test pressure of the pressure receptacles;

   6. The maximum working pressure of the pressure receptacles for compressed gases (where no value is given, the working pressure shall not exceed two thirds of the test pressure) or the maximum filling ratio(s) dependent on the test pressure(s) for liquefied and dissolved gases;

   7. Special packing provisions that are specific to a substance.

3. In no case shall pressure receptacles be filled in excess of the limit permitted in the following requirements.

   1. For compressed gases, the working pressure shall be not more than two thirds of the test pressure of the pressure receptacles. Restrictions to this upper limit on working pressure are imposed by special packing provision "o" in (5) below. In no case shall the internal pressure at 65 °C exceed the test pressure.

   2. For high pressure liquefied gases, the filling ratio shall be such that the settled pressure at 65°C does not exceed the test pressure of the pressure receptacles.

      The use of test pressures and filling ratios other than those in the table is permitted, except where (5), special packing provision "o" applies, provided that:

      1. the criterion of (5), special packing provision "r" is met when applicable; or

      2. the above criterion is met in all other cases.

      For high pressure liquefied gases and gas mixtures for which relevant data are not available, the maximum filling ratio (FR) shall be determined as follows:

      \( FR = 8.5 \times 10^{-4} \times d_g \times P_h \)

      where

      FR

      = maximum filling ratio

      d_g

      = gas density (at 15 °C, 1 bar)(in g/L)

      P_h

      = minimum test pressure (in bar)

      If the density of the gas is unknown, the maximum filling ratio shall be determined as follows

      \( FR = \frac{ P_h \times MM \times 10^{-3} }{ (R \times 338) } \)

      where

      FR

      = maximum filling ratio

      P_h

      = minimum test pressure (in bar)

      MM

      = molecular mass (in g/mol)

      R

      = 8.31451 x 10^-2 bar·L/mol·K (gas constant)

      For gas mixtures, the average molecular mass is to be taken, taking into account the volumetric concentrations of the various components.

   3. For low pressure liquefied gases, the maximum mass of contents per litre of water capacity shall equal 0.95 times the density of the liquid phase at 50°C; in addition, the liquid phase shall not fill the pressure receptacle at any temperature up to 60°C. The test pressure of the pressure receptacle shall be at least equal to the vapour pressure (absolute) of the liquid at 65°C, minus 100 kPa (1 bar).

      For low pressure liquefied gases and gas mixtures for which relevant data are not available, the maximum filling ratio shall be determined as follows:

      \( FR = (0.0032 \times BP - 0.24) \times d_1 \)

      where

      FR

      = maximum filling ratio

      BP

      = boiling point (in kelvin)

      d₁

      = density of the liquid at boiling point (in kg/L)

   4. For UN 1001, acetylene, dissolved, and UN 3374 acetylene, solvent free, see (5), special packing provision "p".

   5. For liquefied gases charged with compressed gases, both components – the liquefied gas and the compressed gas – have to be taken into consideration in the calculation of the internal pressure in the pressure receptacle.

      The maximum mass of contents per litre of water capacity shall not exceed 0.95 times the density of the liquid phase at 50°C; in addition, the liquid phase shall not completely fill the pressure receptacle at any temperature up to 60°C.

      When filled, the internal pressure at 65°C shall not exceed the test pressure of the pressure receptacles.

      The vapour pressures and volumetric expansions of all substances in the pressure receptacles shall be considered. When experimental data is not available, the following steps shall be carried out:

      1. calculation of the vapour pressure of the liquefied gas and of the partial pressure of the compressed gas at 15°C (filling temperature);

      2. calculation of the volumetric expansion of the liquid phase resulting from the heating from 15°C to 65°C and calculation of the remaining volume for the gaseous phase;

      3. calculation of the partial pressure of the compressed gas at 65°C considering the volumetric expansion of the liquid phase;

         Note: The compressibility factor of the compressed gas at 15°C and 65°C shall be considered.

      4. calculation of the vapour pressure of the liquefied gas at 65°C;

      5. the total pressure is the sum of the vapour pressure of the liquefied gas and the partial pressure of the compressed gas at 65°C;

      6. consideration of the solubility of the compressed gas at 65°C in the liquid phase.

      The test pressure of the pressure receptacle shall not be less than the calculated total pressure minus 100 kPa (1bar).

      If the solubility of the compressed gas in the liquid phase is not known for the calculation, the test pressure can be calculated without taking the gas solubility (subparagraph (vi)) into account.

4. The filling of pressure receptacles shall be carried out by qualified staff using appropriate equipment and procedures.

   The procedures should include checks of:

   • the conformity of receptacles and accessories with the provisions of this Code;

   • their compatibility with the product to be transported;

   • the absence of damage which might affect safety;

   • compliance with the degree or pressure of filling, as appropriate;

   • marks and identification.

   These requirements are deemed to be met if the following standards are applied:

   ISO 10691:2004	Gas cylinders – Refillable welded steel cylinders for liquefied petroleum gas (LPG) – Procedures for checking before, during and after filling.
   ISO 11372:2011	Gas cylinders – Acetylene cylinders – Filling conditions and filling inspection
   ISO 11755:2005	Gas cylinders – Cylinder bundles for compressed and liquefied gases (excluding acetylene) – Inspection at time of filling
   ISO 13088:2011	Gas cylinders – Acetylene cylinder bundles – Filling conditions and filling inspection
   ISO 24431:2016	Gas cylinders – Seamless, welded and composite cylinders for compressed and liquefied gases (excluding acetylene) – Inspection at time of filling

5. Special packing provisions: Material compatibility

   a:

   Aluminium alloy pressure receptacles shall not be used

   b:

   Copper valves shall not be used.

   c:

   Metal parts in contact with the contents shall not contain more than 65% copper.

   d:

   When steel pressure receptacles or composite pressure receptacles with steel liners are used, only those bearing the "H" mark in accordance with 6.2.2.7.4 (p) are permitted.

   Requirements for toxic substances with an LC₅₀ less than or equal to 200 mL/m³ (ppm)

   k:

   Valve outlets shall be fitted with pressure-retaining gas-tight plugs or caps having threads that match those of the valve outlets.

   Each cylinder within a bundle shall be fitted with an individual valve that shall be closed during transport. After filling, the manifold shall be evacuated, purged and plugged.

   Bundles containing UN 1045 fluorine, compressed, may be constructed with isolation valves on groups of cylinders not exceeding 150 litres total water capacity instead of isolation valves on every cylinder.

   Cylinders and individual cylinders in a bundle shall have a test pressure greater than or equal to 200 bar and a minimum wall thickness of 3.5 mm for aluminium alloy or 2 mm for steel. Individual cylinders not complying with this requirement shall be transported in a rigid outer packaging that will adequately protect the cylinder and its fittings and meeting the packing group I performance level. Pressure drums shall have a minimum wall thickness as specified by the competent authority.

   Pressure receptacles shall not be fitted with a pressure relief device.

   Cylinders and individual cylinders in a bundle shall be limited to a maximum water capacity of 85 L.

   Each valve shall be capable of withstanding the test pressure of the pressure receptacle and be connected directly to the pressure receptacle by either a taper thread or other means which meets the requirements of ISO 10692-2:2001.

   Each valve shall either be of the packless type with non-perforated diaphragm, or be of a type which prevents leakage through or past the packing.

   Each pressure receptacle shall be tested for leakage after filling.

   Gas specific provisions

   l:

   UN 1040 ethylene oxide may also be packed in hermetically sealed glass or metal inner packagings suitably cushioned in fibreboard, wooden or metal boxes meeting the packing group I performance level. The maximum quantity permitted in any glass inner packaging is 30 g, and the maximum quantity permitted in any metal inner packaging is 200 g. After filling, each inner packaging shall be determined to be leaktight by placing the inner packaging in a hot water bath at a temperature, and for a period of time, sufficient to ensure that an internal pressure equal to the vapour pressure of ethylene oxide at 55°C is achieved. The maximum net mass in any outer packaging shall not exceed 2.5 kg.

   m:

   Pressure receptacles shall be filled to a working pressure not exceeding 5 bar.

   n:

   Cylinders and individual cylinders in a bundle shall contain not more than 5 kg of the gas. When bundles containing UN 1045 fluorine, compressed are divided into groups of cylinders in accordance with special packing provision "k" each group shall contain not more than 5 kg of the gas.

   o:

   In no case shall the working pressure or filling ratio shown in the table be exceeded.

   p:

   For UN 1001 acetylene, dissolved and UN 3374 acetylene, solvent free: cylinders shall be filled with a homogeneous monolithic porous material; the working pressure and the quantity of acetylene shall not exceed the values prescribed in the approval or in ISO 3807-1:2000, ISO 3807-2:2000 or ISO 3807:2013, as applicable.

   For UN 1001 acetylene, dissolved: cylinders shall contain a quantity of acetone or suitable solvent as specified in the approval (see ISO 3807-1:2000, ISO 3807-2:2000 or ISO 3807:2013, as applicable); cylinders fitted with pressure relief devices or manifolded together shall be transported vertically.

   The test pressure of 52 bar applies only to cylinders fitted with a fusible plug.

   q:

   Valve outlets of pressure receptacles for pyrophoric gases or flammable mixtures of gases containing more than 1% of pyrophoric compounds shall be fitted with gas-tight plugs or caps. When these pressure receptacles are manifolded in a bundle, each of the pressure receptacles shall be fitted with an individual valve that shall be closed during transport, and the outlet of the manifold valve shall be fitted with a pressure-retaining gas-tight plug or cap. Gas-tight plugs or caps shall have threads that match those of the valve outlets.

   r:

   The filling ratio of this gas shall be limited such that, if complete decomposition occurs, the pressure does not exceed two thirds of the test pressure of the pressure receptacle.

   ra:

   This gas may also be packed in capsules under the following conditions:

   1. The mass of gas shall not exceed 150 g per capsule;

   2. The capsules shall be free from faults liable to impair the strength;

   3. The leakproofness of the closure shall be ensured by an additional device (cap, crown, seal, binding, etc.) capable of preventing any leakage of the closure during transport;

   4. The capsules shall be placed in an outer packaging of sufficient strength. A package shall not weigh more than 75 kg

   s:

   Aluminium alloy pressure receptacles shall be:

   • equipped only with brass or stainless steel valves; and
   • cleaned in accordance with ISO 11621:1997 and not contaminated with oil

   t:

   1. The wall thickness of pressure receptacles shall be not less than 3 mm.

   2. Prior to transport, it shall be ensured that the pressure has not risen due to potential hydrogen generation.

   Periodic inspection

   u:

   The interval between periodic tests may be extended to 10 years for aluminium alloy pressure receptacles when the alloy of the pressure receptacle has been subjected to stress corrosion testing as specified in ISO 7866:2012 + Cor 1:2014.

   v:

   The interval between periodic inspections for steel cylinders may be extended to 15 years if approved by the competent authority of the country of use.

   Requirements for N.O.S. descriptions and for mixtures

   z:

   The construction materials of the pressure receptacles and their accessories shall be compatible with the contents and shall not react to form harmful or dangerous compounds therewith.

   The test pressure and filling ratio shall be calculated in accordance with the relevant requirements of (3).

   Toxic substances with an LC₅₀ less than or equal to 200 mL/m³ shall not be transported in tubes, pressure drums or MEGCs and shall meet the requirements of special packing provision "k". However, UN 1975 nitric oxide and dinitrogen tetroxide mixtures may be transported in pressure drums.

   For pressure receptacles containing pyrophoric gases or flammable mixtures of gases containing more than 1% pyrophoric compounds, the requirements of special packing provision "q" shall be met.

   The necessary steps shall be taken to prevent dangerous reactions (i.e. polymerization or decomposition) during transport. If necessary, stabilization or addition of an inhibitor shall be required.

   Mixtures containing UN 1911 diborane shall be filled to a pressure such that, if complete decomposition of the diborane occurs, two thirds of the test pressure of the pressure receptacle shall not be exceeded.

   Mixtures containing UN 2192 germane, other than mixtures of up to 35% germane in hydrogen or nitrogen or up to 28% germane in helium or argon, shall be filled to a pressure such that, if complete decomposition of the germane occurs, two thirds of the test pressure of the pressure receptacle shall not be exceeded.

   Mixtures of fluorine and nitrogen with a fluorine concentration below 35% by volume may be filled in pressure receptacles up to a maximum allowable working pressure for which the partial pressure of fluorine does not exceed 31 bar (abs.).

   working pressure (bar) < (31/x_f) -1

   in which x_f = fluorine concentration in % by volume/100.

   Mixtures of fluorine and inert gases with a fluorine concentration below 35% by volume may be filled in pressure receptacles up to a maximum allowable working pressure for which the partial pressure of fluorine does not exceed 31 bar (abs.), additionally taking the coefficient of nitrogen equivalency in accordance with ISO 10156:2017 into account when calculating the partial pressure.

   working pressure (bar) < (31/x_f)(x_f + _Kk x _xk) -1

   in which x_f = fluorine concentration in % by volume/100;

   _Kk = coefficient of equivalency of an inert gas relative to nitrogen (coefficient of nitrogen equivalency); and

   _xk = inert gas concentration in % by volume/100.

   However, the working pressure for mixtures of fluorine and inert gases shall not exceed 200 bar. The minimum test pressure of pressure receptacles for mixtures of fluorine and inert gases equals 1.5 times the working pressure or 200 bar, with the greater value to be applied.