| Résumé : |
With the entering into force of the new regulations on the moveÂment of dangerous goods (ADR, RID, IMDG), a new type of dangeÂrous substances has been included in class 4.1, ie polymerising substances.
With this new type of dangerous goods, the concept of self-accelerating polymerisation temperature (SAPT) has been introduced, meaning the lowest temperature at which the polymerisation of a substance may occur in the packaging, IBC or tank as delivered for transport. The SAPT shall be determined in accordance with the test procedures established for the self-accelerating decomposition temperature (SADT) for self-reactive substances in accordance with Part II, section 28 of the Manual of Tests and Criteria.
Without stabilisation, polymerising substances are liable to undergo an intense exothermic reaction resulting in the formation of larger molecules or polymers under normal conditions of transportation.
Such substances belong to the category of easily polymerising substances of class 4.1 when:
a) Their self-accelerating polymerisation temperature (SAPT) is 75°C or less under standard conditions (with or without chemical stabilisation as delivered for transport) or in the packaging, IBC or tank in which the substance or mixture is to be carried;
b) They have a heat reaction of more than 300 J/g; and
c) They do not meet any other criteria for inclusion in classes from 1 to 8.
A mixture that meets the criteria of a polymerising substance must be classified as a polymerising substance of class 4.1.
Polymerising substances are subject to temperature control during transportation if their self-accelerating polymerisation temperature (SAPT) is:
a) When delivered for transport in a packaging or IBC, 50°C or less in the packaging or IBC in which the substance is to be carried; or
b) When delivered for transport in a tank, 45°C or less in the tank in which the substance is to be carried.
These substances are classified according to the following categorisation codes - PM (polymerising substances), PM1 (not requiring temperature control) and PM2 (requiring temperature control). These codes belong to packaging group III. List of entries:
1. UN 3531 Polymerising Substance, Solid, Stabilized, N.O.S.
2. UN 3532 Polymerising Substance, Liquid, Stabilized, N.O.S.
3. UN 3533 Polymerising Substance, Solid, Temperature Controlled, N.O.S.
4. UN 3534 Polymerising Substance, Liquid, Temperature Controlled, N.O.S.
Further details on the goods’ properties are included in the new IMDG Regulations, amendment 38-16. UN 3531 and UN 3532 report that these substances polymerise at high temperatures or in a fire, burning vigorously.
They are insoluble in water and, on contact with alkalis or acids, they may cause dangerous polymerisation. The products of combustion or self-accelerating polymerisation may be toxic if inhaled. In the case of UN 3533 and UN 3534, the goods polymerise at higher temperatures than the SAPT or in a fire. These goods are insoluble in water and, on contact with alkalis or acids, may cause dangerous polymerisation. The products of combustion or self-accelerating polymerisation may be toxic if inhaled. Control and emergency temperatures can be found in the bill of lading, as required by IMDG regulation 5.4.1.5.2. Temperatures must be checked regularly.
The new special provision number 386 applies to the newly introduced four sections. The conditions for the stabilisation of substances and for the regulation of temperature are defined in this provision. |
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Transportation of polymerising substances in POLYMERS PAINT COLOUR JOURNAL - PPCJ, Vol. 207, N° 4630 (04/2017)
