Chapter 4.2

Use of portable tanks and multiple-element gas containers (MEGCS)

 
The provisions of this chapter also apply to road tank vehicles to the extent indicated in chapter 6.8.
4.2.0
Transitional provisions
4.2.0.1

The provisions for the use and construction of portable tanks in this chapter and chapter 6.7 are based on the United Nations Recommendations on the Transport of Dangerous Goods. IMO type portable tanks and road tank vehicles certified and approved prior to 1 January 2003 in accordance with the provisions of the IMDG Code in force on 1 July 1999 (amendment 29) may continue to be used provided that they are found to meet the applicable periodic inspections and test provisions. They shall meet the provisions set out in columns (13) and (14) of chapter 3.2. Detailed explanation and construction provisions may be found in CCC.1/Circ.3 Revised guidance on the continued use of existing IMO type portable tanks and road tank vehicles for the transport of dangerous goods.

Note: For ease of reference, the following descriptions of existing IMO type tanks are included:
IMO type 1 tank means a portable tank for the transport of substances of classes 3 to 9 fitted with pressure-relief devices, having a maximum allowable working pressure of 1.75 bar and above.
IMO type 2 tank means a portable tank fitted with pressure-relief devices, having a maximum allowable working pressure equal to or above 1.0 bar but below 1.75 bar, intended for the transport of certain dangerous liquids of low hazard and certain solids.
IMO type 4 tank means a road tank vehicle for the transport of dangerous goods of classes 3 to 9 and includes a semi-trailer with a permanently attached tank or a tank attached to a chassis, with at least four twist locks which comply with ISO standards, (e.g. ISO 1161:1984).
IMO type 5 tank means a portable tank fitted with pressure-relief devices which is used for non-refrigerated liquefied gases of class 2.
IMO type 6 tank means a road tank vehicle for the transport of non-refrigerated liquefied gases of class 2 and includes a semi-trailer with a permanently attached tank or a tank attached to a chassis which is fitted with items of service equipment and structural equipment necessary for the transport of gases.
IMO type 7 tank means a thermally insulated portable tank fitted with items of service and structural equipment necessary for the transport of refrigerated liquefied gases. The portable tank shall be capable of being transported, loaded and discharged without the need of removal of its structural equipment, and shall be capable of being lifted when full. It shall not be permanently secured on board the ship.
IMO type 8 tank means a road tank vehicle for the transport of refrigerated liquefied gases of class 2 and includes a semi-trailer with a permanently attached thermally insulated tank fitted with items of service equipment and structural equipment necessary for the transport of refrigerated liquefied gases.
IMO type 9 tank tank means a road gas elements vehicle for the transport of compressed gases of class 2 with elements linked to each other by a manifold, permanently attached to a chassis, which is fitted with items of service equipment and structural equipment necessary for the transport of gases. Elements are cylinders, tubes and bundles of cylinders, intended for the transport of gases as defined in 2.2.1.1.

Note: IMO type 4, 6 and 8 road tank vehicles may be constructed after 1 January 2003 in accordance with the provisions of chapter 6.8.

4.2.0.2
UN portable tanks and MEGCs constructed according to a design approval certificate which has been issued before 1 January 2008 may continue to be used provided that they are found to meet the applicable periodic inspection and test provisions.
4.2.0.3

Portable tanks and MEGCs manufactured before 1 January 2012, that conform to the marking provisions of 6.7.2.20.1, 6.7.3.16.1, 6.7.4.15.1 or 6.7.5.13.1 of the IMDG Code in force on 1 January 2010 (amendment 34-08), as relevant, may continue to be used if they comply with all other relevant provisions of the current edition of the Code including, when applicable, the requirement of 6.7.2.20.1 (g) for marking the symbol "S" on the plate when the shell or the compartment is divided by surge plates into sections of not more than 7,500 litres capacity. When the shell, or the compartment, was already divided by surge plates into sections of not more than 7,500 litres capacity before 1 January 2012, the capacity of the shell, or respectively of the compartment, need not be supplemented with the symbol "S" until the next periodic inspection or test according to 6.7.2.19.5 is performed.

Portable tanks manufactured before 1 January 2014 need not be marked with the portable tank instruction as required in 6.7.2.20.2, 6.7.3.16.2 and 6.7.4.15.2 until the next periodic inspection and test.

Portable tanks and MECGs manufactured before 1 January 2014 need not comply with the requirements of 6.7.2.13.1.6, 6.7.3.9.1.5, 6.7.4.8.1.5 and 6.7.5.6.1(d) concerning the marking of the pressure relief devices.

IMO portable tanks manufactured before 1 January 2003 shall be marked with an indication of the portable tank instruction for which it meets the minimum test pressure, minimum shell thickness, pressure relief requirements and bottom opening requirements as shown in 4.2.5.2.6 as required in 6.7.2.20.2, 6.7.3.16.2 and 6.7.4.15.2. These portable tanks need not be marked with the portable tank instruction until the next periodic inspection and test.

4.2.1
General provisions for the use of portable tanks for the transport of substances of class 1 and classes 3 to 9
4.2.1.1
This section provides general provisions applicable to the use of portable tanks for the transport of substances of classes 1, 3, 4, 5, 6, 7, 8 and 9. In addition to these general provisions, portable tanks shall conform to the design, construction, inspection and testing provisions detailed in 6.7.2. Substances shall be transported in portable tanks conforming to the applicable portable tank instruction and the portable tank special provisions assigned to each substance in the Dangerous Goods List.
4.2.1.2
During transport, portable tanks shall be adequately protected against damage to the shell and service equipment resulting from lateral and longitudinal impact and overturning. If the shell and service equipment are so constructed as to withstand impact or overturning, it need not be protected in this way. Examples of such protection are given in 6.7.2.17.5.
4.2.1.3
Certain substances are chemically unstable. They are accepted for transport only when the necessary steps have been taken to prevent their dangerous decomposition, transformation or polymerization during transport. To this end, care shall in particular be taken to ensure that shells do not contain any substances liable to promote these reactions.
4.2.1.4
The temperature of the outer surface of the shell, excluding openings and their closures, or of the thermal insulation shall not exceed 70°C during transport. When necessary, the shell shall be thermally insulated.
4.2.1.5
Empty portable tanks not cleaned and not gas-free shall comply with the same provisions as portable tanks filled with the previous substance.
4.2.1.6

Substances shall not be transported in adjoining compartments of shells when they may react dangerously with each other and cause:

  1. combustion and/or evolution of considerable heat;

  2. evolution of flammable, toxic or asphyxiant gases;

  3. the formation of corrosive substances;

  4. the formation of unstable substances;

  5. dangerous rise in pressure.

4.2.1.7
The design approval certificate, the test report and the certificate showing the results of the initial inspection and test for each portable tank issued by the competent authority or its authorized body shall be retained by the authority or body and the owner. Owners shall be able to provide this documentation upon the request of any competent authority.
4.2.1.8
Unless the name of the substance(s) being transported appears on the metal plate described in 6.7.2.20.2, a copy of the certificate specified in 6.7.2.18.1 shall be made available upon the request of a competent authority or its authorized body and readily provided by the consignor, consignee or agent, as appropriate.
4.2.1.9
Degree of filling
4.2.1.9.1
Prior to filling, the shipper shall ensure that the appropriate portable tank is used and that the portable tank is not loaded with substances which, in contact with the materials of the shell, gaskets, service equipment and any protective linings, are likely to react dangerously with them to form dangerous products or appreciably weaken these materials. The shipper may need to consult the manufacturer of the substance in conjunction with the competent authority for guidance on the compatibility of the substance with the portable tank materials.
4.2.1.9.1.1
Portable tanks shall not be filled in excess of the maximum degree of filling specified in 4.2.1.9.2 to 4.2.1.9.6. The applicability of 4.2.1.9.2, 4.2.1.9.3 or 4.2.1.9.5.1 to individual substances is specified in the applicable portable tank instructions or special provisions in 4.2.5.2.6 or 4.2.5.3 and columns 13 and 14 of the Dangerous Goods List.
4.2.1.9.2

The maximum degree of filling (in %) for general use is determined by the formula:

\( \text{Degree of filling} = \frac{ 97 }{ 1 + \alpha \left( t_r - t_f \right) } \)

4.2.1.9.3

The maximum degree of filling (in %) for liquids of class 6.1 and class 8, in packing groups I and II, and liquids with an absolute vapour pressure of more than 175 kPa (1.75 bar) at 65°C, or for liquids identified as marine pollutants is determined by the formula:

\( \text{Degree of filling} = \frac{ 95 }{ 1 + \alpha \left( t_r - t_f \right) } \)

4.2.1.9.4

In these formulae, α is the mean coefficient of cubical expansion of the liquid between the mean temperature of the liquid during filling (tf) and the maximum mean bulk temperature during transport (tr) (both in °C). For liquids transported under ambient conditions, α could be calculated by the formula:

\( \alpha = \frac{ d_{15} - d_{50} }{ 35 d_{50} } \)

in which d15 and d50 are the densities of the liquid at 15°C and 50°C, respectively.

4.2.1.9.4.1
The maximum mean bulk temperature (tr) shall be taken as 50°C except that, for journeys under temperate or extreme climatic conditions, the competent authorities concerned may agree to a lower or require a higher temperature, as appropriate.
4.2.1.9.5
The provisions of 4.2.1.9.2 to 4.2.1.9.4.1 do not apply to portable tanks which contain substances maintained at a temperature above 50°C during transport (such as by means of a heating device). For portable tanks equipped with a heating device, a temperature regulator shall be used to ensure the maximum degree of filling is not more than 95% full at any time during transport.
4.2.1.9.5.1

The maximum degree of filling (in %) for solids transported above their melting points and for elevated temperature liquids shall be determined by the following formula:

\( \text{Degree of filling} = 95\frac{ d_r }{ d_f } \)

in which df and dr are the densities of the liquid at the mean temperature of the liquid during filling and the maximum mean bulk temperature during transport respectively.

4.2.1.9.6

Portable tanks shall not be offered for transport:

  1. with a degree of filling, for liquids having a viscosity less than 2680 mm²/s at 20°C or at the maximum temperature of the substance during transport in the case of a heated substance, of more than 20% but less than 80% unless the shells of portable tanks are divided, by partitions or surge plates, into sections of not more than 7500 L capacity;

  2. with residue of substances previously transported adhering to the outside of the shell or service equipment;

  3. when leaking or damaged to such an extent that the integrity of the portable tank or its lifting or securing arrangements may be affected; and

  4. unless the service equipment has been examined and found to be in good working order.

For certain dangerous substances, a lower degree of filling may be required.

4.2.1.9.7
Forklift pockets of portable tanks shall be closed off where the tank is filled. This provision does not apply to portable tanks which, according to 6.7.2.17.4, need not be provided with a means of closing off the forklift pockets.
4.2.1.9.8
Portable tanks shall not be filled or discharged while they remain on board.
4.2.1.10

Additional provisions applicable to the transport of class 3 substances in portable tanks

All portable tanks intended for the transport of flammable liquids shall be closed and be fitted with relief devices in accordance with 6.7.2.8 to 6.7.2.15.

4.2.1.11

Additional provisions applicable to the transport of class 4 substances (other than class 4.1 self-reactive substances) in portable tanks

[Reserved]

Note: For class 4.1 self-reactive substances, see 4.2.1.13.

4.2.1.12

Additional provisions applicable to the transport of class 5.1 substances in portable tanks

[Reserved]

4.2.1.13
Additional provisions applicable to the transport of class 5.2 substances and class 4.1 self-reactive substances in portable tanks
4.2.1.13.1

Each substance shall have been tested and a report submitted to the competent authority of the country of origin for approval. Notification thereof shall be sent to the competent authority of the country of destination. The notification shall contain relevant transport information and the report with test results. The tests undertaken shall include those necessary:

  1. to prove the compatibility of all materials normally in contact with the substance during transport;

  2. to provide data for the design of the pressure and emergency relief devices, taking into account the design characteristics of the portable tank.

Any additional provisions necessary for safe transport of the substance shall be clearly described in the report.

4.2.1.13.2
The following provisions apply to portable tanks intended for the transport of type F organic peroxides or type F self-reactive substances with a self-accelerating decomposition temperature (SADT) of 55°C or more. In case of conflict, these provisions prevail over those specified in 6.7.2. Emergencies to be taken into account are self-accelerating decomposition of the substance and fire-engulfment as described in 4.2.1.13.8.
4.2.1.13.3
The additional provisions for transport of organic peroxides or self-reactive substances with an SADT less than 55°C in portable tanks shall be specified by the competent authority of the country of origin. Notification thereof shall be sent to the competent authority of the country of destination.
4.2.1.13.4
The portable tank shall be designed for a test pressure of at least 0.4 MPa (4 bar).
4.2.1.13.5
Portable tanks shall be fitted with temperature-sensing devices.
4.2.1.13.6
Portable tanks shall be fitted with pressure-relief devices and emergency relief devices. Vacuum-relief devices may also be used. Pressure-relief devices shall operate at pressures determined according to both the properties of the substance and the construction characteristics of the portable tank. Fusible elements are not allowed in the shell.
4.2.1.13.7
The pressure-relief devices shall consist of spring-loaded valves fitted to prevent significant build-up within the portable tank of the decomposition products and vapours released at a temperature of 50°C. The capacity and start-to-discharge pressure of the relief valves shall be based on the results of the tests specified in 4.2.1.13.1. The start-to-discharge pressure shall, however, in no case be such that liquid would escape from the valve(s) if the portable tank were overturned.
4.2.1.13.8

The emergency relief devices may be of the spring-loaded or frangible types, or a combination of the two, designed to vent all the decomposition products and vapours evolved during a period of not less than one hour of complete fire-engulfment as calculated by the following formula:

\( q = 70961 FA^{0.82} \)

where:

q
= heat absorption (W)
A
= wetted area (m2)
F

= insulation factor;

F
= 1 for non-insulated vessels, or
F
= \( \frac{ U(923 -T) }{ 47032 } \) for insulated shells

where:

K
= heat conductivity of insulation layer (W·m-1·K-1)
L
= thickness of insulation layer (m)
U
= K/L = heat transfer coefficient of the insulation (W·m-2·K-1)
T
= temperature of substance at relieving conditions (K)

The start-to-discharge pressure of the emergency relief device(s) shall be higher than that specified in 4.2.1.13.7 and based on the results of the tests referred to in 4.2.1.13.1. The emergency relief devices shall be dimensioned in such a way that the maximum pressure in the tank never exceeds the test pressure of the portable tank.

Note: An example of a method to determine the size of emergency relief devices is given in appendix 5 of the Manual of Tests and Criteria.

4.2.1.13.9
For insulated portable tanks, the capacity and setting of emergency relief device(s) shall be determined assuming a loss of insulation from 1% of the surface area.
4.2.1.13.10
Vacuum-relief devices and spring-loaded valves shall be provided with flame arresters. Due attention shall be paid to the reduction of the relief capacity caused by the flame arrester.
4.2.1.13.11
Service equipment such as valves and external piping shall be so arranged that no substance remains in them after filling the portable tank.
4.2.1.13.12
Portable tanks may be either insulated or protected by a sun-shield. If the SADT of the substance in the portable tank is 55°C or less, or the portable tank is constructed of aluminium, the portable tank shall be completely insulated. The outer surface shall be finished in white or bright metal.
4.2.1.13.13
The degree of filling shall not exceed 90% at 15°C.
4.2.1.13.14
The mark as required in 6.7.2.20.2 shall include the UN Number and the technical name with the approved concentration of the substance concerned.
4.2.1.13.15
Organic peroxides and self-reactive substances specifically listed in portable tank instruction T23 in 4.2.5.2.6 may be transported in portable tanks.
4.2.1.14

Additional provisions applicable to the transport of class 6.1 substances in portable tanks

[Reserved]

4.2.1.15

Additional provisions applicable to the transport of class 6.2 substances in portable tanks

[Reserved]

4.2.1.16
Additional provisions applicable to the transport of class 7 substances in portable tanks
4.2.1.16.1
Portable tanks used for the transport of radioactive material shall not be used for the transport of other goods.
4.2.1.16.2
The degree of filling for portable tanks shall not exceed 90% or, alternatively, any other value approved by the competent authority.
4.2.1.17
Additional provisions applicable to the transport of class 8 substances in portable tanks
4.2.1.17.1
Pressure-relief devices of portable tanks used for the transport of class 8 substances shall be inspected at intervals not exceeding one year.
4.2.1.18

Additional provisions applicable to the transport of class 9 substances in portable tanks

[Reserved]

4.2.1.19
Additional provisions applicable to the transport of solid substances transported above their melting point
4.2.1.19.1
Solid substances transported or offered for transport above their melting point which are not assigned a portable tank instruction in column 13 of the Dangerous Goods List of chapter 3.2 or when the assigned portable tank instruction does not apply to transport at temperatures above their melting point may be transported in portable tanks provided that the solid substances are classified in classes 4.1, 4.2, 4.3, 5.1, 6.1, 8 or 9 and have no subsidiary hazard other than that of class 6.1 or class 8 and are in packing group II or III.
4.2.1.19.2
Unless otherwise indicated in the Dangerous Goods List, portable tanks used for the transport of these solid substances above their melting point shall conform to the provisions of portable tank instruction T4 for solid substances of packing group III or T7 for solid substances of packing group II. A portable tank that affords an equivalent or greater level of safety may be selected in accordance with 4.2.5.2.5. The maximum degree of filling (in %) shall be determined according to 4.2.1.9.5 (TP3).
4.2.2
General provisions for the use of portable tanks for the transport of non-refrigerated liquefied gases and chemicals under pressure
4.2.2.1
This section provides general provisions applicable to the use of portable tanks for the transport of non-refrigerated liquefied gases of class 2 and chemicals under pressure.
4.2.2.2
Portable tanks shall conform to the design, construction, inspection and testing provisions detailed in 6.7.3. Non-refrigerated liquefied gases and chemicals under pressure shall be transported in portable tanks conforming to portable tank instruction T50 as described in 4.2.5.2.6 and any portable tank special provisions assigned to specific non-refrigerated liquefied gases in the Dangerous Goods List and described in 4.2.5.3.
4.2.2.3
During transport, portable tanks shall be adequately protected against damage to the shell and service equipment resulting from lateral and longitudinal impact and overturning. If the shell and service equipment are so constructed as to withstand impact or overturning, it need not be protected in this way. Examples of such protection are given in 6.7.3.13.5.
4.2.2.4
Certain non-refrigerated liquefied gases are chemically unstable. They are accepted for transport only when the necessary steps have been taken to prevent their dangerous decomposition, transformation or polymerization during transport. To this end, care shall be taken to ensure that portable tanks do not contain any non-refrigerated liquefied gases liable to promote these reactions.
4.2.2.5
Unless the name of the gas(es) being transported appears on the metal plate described in 6.7.3.16.2, a copy of the certificate specified in 6.7.3.14.1 shall be made available upon a competent authority request and readily provided by the consignor, consignee or agent, as appropriate.
4.2.2.6
Empty portable tanks not cleaned and not gas-free shall comply with the same provisions as portable tanks filled with the previous non-refrigerated liquefied gas.
4.2.2.7
Filling
4.2.2.7.1
Prior to filling, the shipper shall ensure that the portable tank is approved for the non-refrigerated liquefied gas or the propellant of the chemical under pressure to be transported and that the portable tank is not loaded with non-refrigerated liquefied gases, or with chemicals under pressure which, in contact with the materials of the shell, gaskets and service equipment, are likely to react dangerously with them to form dangerous products or appreciably weaken these materials. During filling, the temperature of the non-refrigerated liquefied gas or propellant of chemicals under pressure shall fall within the limits of the design temperature range.
4.2.2.7.2
The maximum mass of non-refrigerated liquefied gas per litre of shell capacity (kg/L) shall not exceed the density of the non-refrigerated liquefied gas at 50°C multiplied by 0.95. Furthermore, the shell shall not be liquid-full at 60°C.
4.2.2.7.3
Portable tanks shall not be filled above their maximum permissible gross mass and the maximum permissible load mass specified for each gas to be transported.
4.2.2.7.4
Portable tanks shall not be filled or discharged while they remain on board.
4.2.2.8

Portable tanks shall not be offered for transport:

  1. in an ullage condition liable to produce an unacceptable hydraulic force due to surge within the portable tank;

  2. when leaking;

  3. when damaged to such an extent that the integrity of the tank or its lifting or securing arrangements may be affected; and

  4. unless the service equipment has been examined and found to be in good working order.

4.2.2.9
Forklift pockets of portable tanks shall be closed off when the tank is filled. This provision does not apply to portable tanks which, according to 6.7.3.13.4, need not be provided with a means of closing off the forklift pockets.
4.2.3
General provisions for the use of portable tanks for the transport of refrigerated liquefied gases of class 2
4.2.3.1
This section provides general provisions applicable to the use of portable tanks for the transport of refrigerated liquefied gases.
4.2.3.2
Portable tanks shall conform to the design, construction, inspection and testing provisions detailed in 6.7.4. Refrigerated liquefied gases shall be transported in portable tanks conforming to portable tank instruction T75 as described in 4.2.5.2.6 and the portable tank special provisions assigned to each substance in column 14 of the Dangerous Goods List and described in 4.2.5.3.
4.2.3.3
During transport, portable tanks shall be adequately protected against damage to the shell and service equipment resulting from lateral and longitudinal impact and overturning. If the shell and service equipment are so constructed as to withstand impact or overturning, it need not be protected in this way. Examples of such protection are provided in 6.7.4.12.5.
4.2.3.4
Unless the name of the gas(es) being transported appears on the metal plate described in 6.7.4.15.2, a copy of the certificate specified in 6.7.4.13.1 shall be made available upon a competent authority request and readily provided by the consignor, consignee or agent, as appropriate.
4.2.3.5
Empty portable tanks not cleaned and not gas-free shall comply with the same provisions as portable tanks filled with the previous substance.
4.2.3.6
Filling
4.2.3.6.1
Prior to filling, the shipper shall ensure that the portable tank is approved for the refrigerated liquefied gas to be transported and that the portable tank is not loaded with refrigerated liquefied gases which, in contact with the materials of the shell, gaskets and service equipment, are likely to react dangerously with them to form dangerous products or appreciably weaken these materials. During filling, the temperature of the refrigerated liquefied gas shall be within the limits of the design temperature range.
4.2.3.6.2
In estimating the initial degree of filling, the necessary holding time for the intended journey, including any delays which might be encountered, shall be taken into consideration. The initial degree of filling of the shell, except as provided for in 4.2.3.6.3 and 4.2.3.6.4, shall be such that if the contents, except helium, were to be raised to a temperature at which the vapour pressure is equal to the maximum allowable working pressure (MAWP) the volume occupied by liquid would not exceed 98%.
4.2.3.6.3
Shells intended for the transport of helium can be filled up to but not above the inlet of the pressure-relief device.
4.2.3.6.4
A higher initial degree of filling may be allowed, subject to approval by the competent authority, when the intended duration of transport is considerably shorter than the holding time.
4.2.3.6.5
Portable tanks shall not be filled or discharged while they remain on board.
4.2.3.7
Actual holding time
4.2.3.7.1

The actual holding time shall be calculated for each journey in accordance with a procedure recognized by the competent authority, on the basis of the following:

  1. the reference holding time for the refrigerated liquefied gas to be transported (see 6.7.4.2.8.1) (as indicated on the plate referred to in 6.7.4.15.1);

  2. the actual filling density;

  3. the actual filling pressure;

  4. the lowest set pressure of the pressure-limiting device(s).

4.2.3.7.2
The actual holding time shall be marked either on the portable tank itself or on a metal plate firmly secured to the portable tank, in accordance with 6.7.4.15.2.
4.2.3.7.3
The date at which the actual holding time ends shall be entered in the transport document (see 5.4.1.5.18)
4.2.3.8

Portable tanks shall not be offered for transport:

  1. in an ullage condition liable to produce an unacceptable hydraulic force due to surge within the shell;

  2. when leaking;

  3. when damaged to such an extent that the integrity of the portable tank or its lifting or securing arrangements may be affected;

  4. unless the service equipment has been examined and found to be in good working order;

  5. unless the actual holding time for the refrigerated liquefied gas being transported has been determined in accordance with 4.2.3.7 and the portable tank is marked in accordance with 6.7.4.15.2; and

  6. unless the duration of transport, after taking into consideration any delays which might be encountered, does not exceed the actual holding time.

4.2.3.9
Forklift pockets of portable tanks shall be closed off when the tank is filled. This provision does not apply to portable tanks which, according to 6.7.4.12.4, need not be provided with a means of closing off the forklift pockets.
4.2.4
General provisions for the use of multiple-element gas containers (MEGCs)
4.2.4.1
This section provides general requirements applicable to the use of multiple-element gas containers (MEGCs) for the transport of non-refrigerated gases.
4.2.4.2
MEGCs shall conform to the design, construction, inspection and testing requirements detailed in 6.7.5. The elements of MEGCs shall be periodically inspected according to the provisions set out in packing instruction P200 and in 6.2.1.6.
4.2.4.3
During transport, MEGCs shall be protected against damage to the elements and service equipment resulting from lateral and longitudinal impact and overturning. If the elements and service equipment are so constructed as to withstand impact or overturning, they need not be protected in this way. Examples of such protection are given in 6.7.5.10.4.
4.2.4.4
The periodic testing and inspection requirements for MEGCs are specified in 6.7.5.12. MEGCs or their elements shall not be charged or filled after they become due for periodic inspection but may be transported after the expiry of the time limit.
4.2.4.5
Filling
4.2.4.5.1
Prior to filling, the MEGC shall be inspected to ensure that it is authorized for the gas to be transported and that the applicable provisions of this Code have been met.
4.2.4.5.2
Elements of MEGCs shall be filled according to the working pressures, filling ratios and filling provisions specified in packing instruction P200 for the specific gas being filled into each element. In no case shall an MEGC or group of elements be filled as a unit in excess of the lowest working pressure of any given element.
4.2.4.5.3
MEGCs shall not be filled above their maximum permissible gross mass.
4.2.4.5.4
Isolation valves shall be closed after filling and remain closed during transport. Toxic gases of class 2.3 shall only be transported in MEGCs where each element is equipped with an isolation valve.
4.2.4.5.5
The opening(s) for filling shall be closed by caps or plugs. The leakproofness of the closures and equipment shall be verified by the shipper after filling.
4.2.4.5.6

MEGCs shall not be offered for filling:

  1. when damaged to such an extent that the integrity of the pressure receptacles or their structural or service equipment may be affected;

  2. unless the pressure receptacles and their structural and service equipment have been examined and found to be in good working order; and

  3. unless the required certification, retest, and filling marks are legible.

4.2.4.5.7
Multiple-element gas containers (MEGCs) shall not be filled or discharged while they remain on board.
4.2.4.6

Filled MEGCs shall not be offered for transport;

  1. when leaking;

  2. when damaged to such an extent that the integrity of the pressure receptacles or their structural or service equipment may be affected;

  3. unless the pressure receptacles and their structural and service equipment have been examined and found to be in good working order; and

  4. unless the required certification, retest, and filling marks are legible.

4.2.4.7
Empty MEGCs that have not been cleaned and purged shall comply with the same requirements as MEGCs filled with the previous substance.
4.2.5
Portable tank instructions and special provisions
4.2.5.1
General
4.2.5.1.1

This section includes the portable tank instructions and special provisions applicable to dangerous goods authorized to be transported in portable tanks. Each portable tank instruction is identified by an alpha-numeric designation (T1 to T75). The Dangerous Goods List in chapter 3.2 indicates the portable tank instruction that shall be used for each substance permitted for transport in a portable tank. When no portable tank instruction appears in the Dangerous Goods List, transport of the substance in portable tanks is not permitted unless a competent authority approval is granted as set out in 6.7.1.3. Portable tank special provisions are assigned to specific dangerous goods in the Dangerous Goods List in chapter 3.2. Each portable tank special provision is identified by an alpha-numeric designation (such as TP1). A listing of the portable tank special provisions is provided in 4.2.5.3.

Note: The gases authorized for transport in MEGCs are indicated in the column "MEGC" in Tables 1 and 2 of packing instruction P200 in 4.1.4.1.

4.2.5.2
Portable tank instructions
4.2.5.2.1
Portable tank instructions apply to dangerous goods of classes 1 to 9. Portable tank instructions provide specific information relevant to portable tank provisions applicable to specific substances. These provisions shall be met in addition to the general provisions in this chapter and chapter 6.7 6.10 or chapter 6.10.
4.2.5.2.2
For substances of class 1 and classes 3 to 9, the portable tank instructions indicate the applicable minimum test pressure, the minimum shell thickness (in reference steel or the minimum shell thickness of fibre-reinforced plastics), bottom opening provisions and pressure-relief provisions. In T23, self-reactive substances of class 4.1 and class 5.2 organic peroxides permitted to be transported in portable tanks are listed along with applicable control and emergency temperatures.
4.2.5.2.3
Non-refrigerated liquefied gases are assigned to portable tank instruction T50. T50 provides the maximum allowable working pressures, bottom opening provisions, pressure-relief provisions and degree of filling provisions for non-refrigerated liquefied gases permitted for transport in portable tanks.
4.2.5.2.4
Refrigerated liquefied gases are assigned to portable tank instruction T75.
4.2.5.2.5

Determination of the appropriate portable tank instructions

When a specific portable tank instruction is specified in the Dangerous Goods List, additional portable tanks which possess higher test pressures, greater shell thicknesses, more stringent bottom opening and pressure-relief device arrangements may be used. The following guidelines apply to determining the appropriate portable tanks which may be used for transport of particular substances:

Portable tank instructions specified Portable tank instructions also permitted
T1 T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22
T2 T4, T5, T7, T8, T9, T10, T11, T12, T13, T14,T15, T16, T17, T18, T19, T20, T21, T22
T3 T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22
T4 T5, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22
T5 T10, T14, T19, T20, T22
T6 T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22
T7 T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22
T8 T9, T10, T13, T14, T19, T20, T21, T22
T9 T10, T13, T14, T19, T20, T21, T22
T10 T14, T19, T20, T22
T11 T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22
T12 T14, T16, T18, T19, T20, T22
T13 T14, T19, T20, T21, T22
T14 T19, T20, T22
T15 T16, T17, T18, T19, T20, T21, T22
T16 T18, T19, T20, T22
T17 T18, T19, T20, T21, T22
T18 T19, T20, T22
T19 T20, T22
T20 T22
T21 T22
T22 None
T23 None
T50 None
4.2.5.2.6

Portable tank instructions

Portable tank instructions specify the provisions applicable to a portable tank when used for the transport of specific substances. Portable tank instructions T1 to T22 specify the applicable minimum test pressure, the minimum shell thickness (in mm of reference steel or the minimum shell thickness for fibre-reinforced plastics (FRP) portable tanks), and the pressure relief and bottom-opening provisions.

T1 - T22 PORTABLE TANK INSTRUCTIONS T1 - T22
These portable tank instructions apply to liquid and solid substances of Class 1 and Classes 3 to 9. The general provisions of section 4.2.1 and the requirements of section 6.7.2 shall be met. The instructions for portable tanks with FRP shells apply to substances of classes or divisions 1, 3, 5.1, 6.1, 6.2, 8 and 9. Additionally, the provisions of chapter 6.10 apply to the portable tanks with FRP shells.
Portable tank instruction Minimum test pressure (bar) Minimum shell thickness (in mm - reference steel)
(see 6.7.2.4)		 Pressure-relief provisionsa
(see 6.7.2.8)		 Bottom opening provisionsb
(see 6.7.2.6)
T1 1.5 See 6.7.2.4.2 Normal See 6.7.2.6.2
T2 1.5 See 6.7.2.4.2 Normal See 6.7.2.6.3
T3 2.65 See 6.7.2.4.2 Normal See 6.7.2.6.2
T4 2.65 See 6.7.2.4.2 Normal See 6.7.2.6.3
T5 2.65 See 6.7.2.4.2 See 6.7.2.8.3 Not allowed
T6 4 See 6.7.2.4.2 Normal See 6.7.2.6.2
T7 4 See 6.7.2.4.2 Normal See 6.7.2.6.3
T8 4 See 6.7.2.4.2 Normal Not allowed
T9 4 6 mm Normal Not allowed
T10 4 6 mm See 6.7.2.8.3 Not allowed
T11 6 See 6.7.2.4.2 Normal See 6.7.2.6.3
T12 6 See 6.7.2.4.2 See 6.7.2.8.3 See 6.7.2.6.3
T13 6 6 mm Normal Not allowed
T14 6 6 mm See 6.7.2.8.3 Not allowed
T15 10 See 6.7.2.4.2 Normal See 6.7.2.6.3
T16 10 See 6.7.2.4.2 See 6.7.2.8.3 See 6.7.2.6.3
T17 10 6 mm Normal See 6.7.2.6.3
T18 10 6 mm See 6.7.2.8.3 See 6.7.2.6.3
T19 10 6 mm See 6.7.2.8.3 Not allowed
T20 10 8 mm See 6.7.2.8.3 Not allowed
T21 10 10 mm Normal Not allowed
T22 10 10 mm See 6.7.2.8.3 Not allowed

a When the word "Normal" is indicated, all the provisions of 6.7.2.8 apply except for 6.7.2.8.3.

b When this column indicates “not allowed”, bottom openings are not permitted when the substance to be transported is a liquid (see 6.7.2.6.1). When the substance to be transported is a solid at all temperatures encountered under normal conditions of transport, bottom openings conforming to the provisions of 6.7.2.6.2 are authorized.

T23, T50, T75

4.2.5.3

Portable tank special provisions

Portable tank special provisions are assigned to certain substances to indicate provisions which are in addition to or in lieu of those provided by the portable tank instructions or the provisions in chapter 6.7. Portable tank special provisions are identified by an alpha-numeric designation beginning with the letters "TP" (tank provision) and are assigned to specific substances in column 14 of the Dangerous Goods List in chapter 3.2. The following is a list of the portable tank special provisions:

TP1
The degree of filling prescribed in 4.2.1.9.2 shall not be exceeded.
TP2
The degree of filling prescribed in 4.2.1.9.3 shall not be exceeded.
TP3
The maximum degree of filling (in %) for solids transported above their melting points and for elevated temperature liquids shall be determined in accordance with 4.2.1.9.5.
TP4
The degree of filling shall not exceed 90% or, alternatively, any other value approved by the competent authority (see 4.2.1.16.2).
TP5
The degree of filling prescribed in 4.2.3.6 shall be met.
TP6
To prevent the tank bursting in any event, including fire engulfment, it shall be provided with pressure-relief devices which are adequate in relation to the capacity of the tank and to the nature of the substance transported. The device shall also be compatible with the substance.
TP7
Air shall be eliminated from the vapour space by nitrogen or other means.
TP8
The test pressure for the portable tank may be reduced to 1.5 bar when the flashpoint of the substances transported is greater than 0°C.
TP9
A substance under this description shall only be transported in a portable tank under an approval granted by the competent authority.
TP10
A lead lining, not less than 5 mm thick, which shall be tested annually, or another suitable lining material approved by the competent authority is required. A portable tank may be offered for transport after the date of expiry of the last lining inspection for a period not to exceed three months beyond that date, after emptying but before cleaning, for purposes of performing the next required test or inspection prior to refilling.
TP11
[Reserved]
TP12
[Reserved]
TP13
Self-contained breathing apparatus shall be provided when this substance is transported, unless no self-contained breathing apparatus, as required by SOLAS regulation II-2/19 (II-2/54), is on board.
TP14
[Reserved]
TP15
[Reserved]
TP16
The tank shall be fitted with a special device to prevent under-pressure and excess pressure during normal transport conditions. This device shall be approved by the competent authority. Pressure-relief provisions are as indicated in 6.7.2.8.3 to prevent crystallization of the product in the pressure-relief valve.
TP17
Only inorganic non-combustible materials shall be used for thermal insulation of the tank.
TP18
Temperature shall be maintained between 18°C and 40°C. Portable tanks containing solidified methacrylic acid shall not be reheated during transport.
TP19
At the time of construction, the minimum shell thickness determined according to 6.7.3.4 shall be increased by 3 mm as a corrosion allowance. Shell thickness shall be verified ultrasonically at intervals midway between periodic hydraulic tests and shall never be lower than the minimum shell thickness determined according to 6.7.3.4.
TP20
This substance shall only be transported in insulated tanks under a nitrogen blanket.
TP21
The shell thickness shall be not less than 8mm. Tanks shall be hydraulically tested and internally inspected at intervals not exceeding 2.5 years.
TP22
Lubricant for joints or other devices shall be oxygen-compatible.
TP23
[Reserved]
TP24
The portable tank may be fitted with a device located, under maximum filling conditions, in the vapour space of the shell to prevent the build-up of excess pressure due to the slow decomposition of the substance transported. This device shall also prevent an unacceptable amount of leakage of liquid in the case of overturning or entry of foreign matter into the tank. This device shall be approved by the competent authority or its authorized body.
TP25
Sulphur trioxide 99.95% pure and above may be transported in tanks without an inhibitor provided that it is maintained at a temperature equal to or above 32.5°C.
TP26
When transported under heated conditions, the heating device shall be fitted outside the shell. For UN 3176, this provision only applies when the substance reacts dangerously with water.
TP27
A portable tank having a minimum test pressure of 4 bar may be used if it is shown that a test pressure of 4 bar or less is acceptable according to the test pressure definition in 6.7.2.1.
TP28
A portable tank having a minimum test pressure of 2.65 bar may be used if it is shown that a test pressure of 2.65 bar or less is acceptable according to the test pressure definition in 6.7.2.1.
TP29
A portable tank having a minimum test pressure of 1.5 bar may be used if it is shown that a test pressure of 1.5 bar or less is acceptable according to the test pressure definition in 6.7.2.1.
TP30
This substance shall be transported in insulated tanks.
TP31
This substance shall be transported in tanks in solid state.
TP32

For UN Nos. 0331, 0332 and 3375, portable tanks may be used subject to the following conditions:

  1. To avoid unnecessary confinement, each portable tank constructed of metal or fibre-reinforced plastics shall be fitted with a pressure relief device that may be of the re-closing spring-loaded type, a frangible disc or a fusible element. The set-to-discharge or burst pressure, as applicable, shall not be greater than 2.65 bar for portable tanks with minimum test pressures greater than 4 bar.

  2. For UN 3375 only, suitability for transport in tanks shall be demonstrated. One method to evaluate this suitability is test 8 (d) in Test Series 8 (see Manual of Tests and Criteria, part 1, subsection 18.7).

  3. Substances shall not be allowed to remain in the portable tank for any period that could result in caking. Appropriate measures shall be taken to avoid accumulation and packing of substances in the tank (e.g. cleaning, etc).

TP33
The portable tank instruction assigned for this substance applies for granular and powdered solids and for solids which are filled and discharged at temperatures above their melting point and which are cooled and transported as a solid mass. For solids which are transported above their melting point, see 4.2.1.19.
TP34
Portable tanks need not be subjected to the impact test in 6.7.4.14.1 if the portable tank is marked "NOT FOR RAIL TRANSPORT" on the plate specified in 6.7.4.15.1 and also in letters at least 10 cm high on both sides of the outer jacket.
TP35
[Deleted]
TP36
Fusible elements in the vapour space may be used on portable tanks.
TP37
[Deleted]
TP38
[Deleted]
TP39
[Deleted]
TP40
Portable tanks shall not be transported when connected with spray application equipment.
TP41
The 2.5 year internal examination may be waived or substituted by other test methods or inspection procedures specified by the competent authority or its authorized body, provided that the portable tank is dedicated to the transport of the organometallic substances to which this tank special provision is assigned. However this examination is required when the conditions of 6.7.2.19.7 are met.
TP90
Tanks with bottom openings may be used on short international voyages.
TP91
Portable tanks with bottom openings may also be used on long international voyages.
4.2.6
Additional provisions for the use of road tank vehicles and road gas elements vehicles
4.2.6.1
The tank of a road tank vehicle or the elements of a road gas elements vehicle shall be attached to the vehicle during normal operations of filling, discharge and transport. IMO type 4 tanks shall be attached to the chassis when transported on board ships. Road tank vehicles and road gas elements vehicles shall not be filled or discharged while they remain on board. A road tank vehicle or road gas elements vehicle shall be driven on board on its own wheels and be fitted with permanent tie-down attachments for securing on board the ship.
4.2.6.2
Road tank vehicles and road gas elements vehicles shall comply with the provisions of chapter 6.8. IMO type 4, 6, 8 and 9 tanks may be used according to the provisions of chapter 6.8 for short international voyages only.
4.2.6.3
Substances permitted to be transported in IMO type 9 tanks are assigned special provision 974.

Chapter 4.1

Chapter 4.3