IMO circular on provisional categorization of liquid substances

Eda Zenic -

The International Maritime Organization has issued a document that provides a provisional categorization of liquid substances in line with MARPOL Annex II and the IBC (International Bulk Chemical) Code. This circular is intended to update and replace previously issued circulars on the same subject.

Overview and Structure

The circular includes several annexes, each providing detailed information on different categories of substances:

  1. Annexes 1 to 5: These annexes list various noxious liquid substances (NLS), categorized by their pollution potential, safety hazards, and assessment status:
    • Annex 1: Pure or technically pure products.
    • Annex 2: Pollutant-only mixtures that contain at least 99% of substances already assessed by the IMO.
    • Annex 3: Trade-named mixtures (at least 99% by weight of assessed substances) that present safety hazards.
    • Annex 4: Pollutant-only mixtures containing components that have not yet been assessed by the IMO.
    • Annex 5: Substances used only as components in trade-named mixtures.
  2. Annexes 6 to 12: These contain supplementary information, such as lists of country abbreviations, cleaning additives for cargo tanks, approved biofuels, and energy-rich fuels subject to MARPOL Annex I. Annexes 11 and 12 provide specific guidance for the carriage of biofuels and energy-rich fuels in accordance with the 2019 Guidelines.

Product Lists and Amendments

The circular highlights important updates and amendments made to the previous version (MEPC.2/Circ.29). This includes new products, changes to existing product entries, and products covered by new tripartite agreements. It also notes that amendments to the product lists are highlighted by shading in the relevant fields.

The circular also explains how certain products may have been removed from the lists, with reasons such as changes in product names, withdrawal from the market, or reassessment leading to new categorization.

Additionally, for substances listed in Annexes 2 and 3, which were assessed before 2019, the validity of their assessment expires in 2025 unless reassessed. This document ensures that proper handling and shipping of these substances continue until their reassessment.

Shipping Names and Categories

The circular provides detailed instructions on how products should be listed and named when shipped. For example, when shipping mixtures, especially those with safety hazards or pollution potential, the correct shipping name should include both the trade name and a description of the most dangerous component. For substances from List 2 (pollutant-only mixtures) or List 4 (unassessed mixtures), the shipping name must include the most harmful component by name. This helps ensure the appropriate handling and response in the event of an incident.

If a product undergoes reassessment with new carriage requirements, it may be given a provisional name with an "amended" qualifier. This temporary name ensures that the product can still be shipped with the updated safety measures, even if the formal changes to the IBC Code haven't been finalized.

Tripartite Agreements

The IMO also emphasizes the importance of tripartite agreements in the provisional assessment of substances for shipping. These agreements allow for the provisional assignment of categories to substances that haven’t been fully assessed. Administrations that sign these agreements must submit detailed information to the IMO, specifying the appropriate list and providing all necessary data. This helps ensure that substances are properly categorized for safe shipping.

The document also outlines procedures for submitting this data, the importance of using the correct format, and the potential consequences of incomplete or incorrect information. For substances to be listed in Annexes 2 or 4, the data should include information such as the pollutant category, flashpoint, and viscosity.