What are the IMDG Code cargo classes, and how is the segregation of dangerous goods determined?
Short answer
| Segregation term | Meaning |
|---|---|
| Away from | may share the hold with a minimum horizontal separation of the order of 3 m |
| Separated from | different holds under deck; a defined separation on deck |
| Separated by a complete compartment or hold from | an intervening complete compartment or hold |
| Separated longitudinally by an intervening complete compartment or hold from | a full compartment between them and a longitudinal separation |
- Nine classes (IMDG Part 2): 1 explosives, 2 gases, 3 flammable liquids, 4 flammable solids, 5 oxidizing substances and organic peroxides, 6 toxic and infectious, 7 radioactive, 8 corrosives, 9 miscellaneous.
- Entry details: subsidiary hazards, packing group I, II or III, UN number and proper shipping name from the Dangerous Goods List.
- How segregation is found (§7.2.3.1): the segregation table (7.2.4) by class and the column 16b segregation codes; column 16b takes precedence.
- Four terms: away from; separated from; separated by a complete compartment or hold from; separated longitudinally by an intervening complete compartment or hold from.
- Special cases: class 1 explosives by compatibility group (§7.2.7); empty uncleaned packagings by residue (§7.1.4); SOLAS II-2/19 fire safety overrides.
- Eligibility: only the classes on the ship’s Document of Compliance for dangerous goods (SOLAS II-2/19.4), issued by DGMA or its RO.
- As Chief Engineer: the fire-protection and detection arrangements behind that document are mine; a segregation failure is my fire.
Full answer
The full answer explains each point step by step, with the regulations and figures behind it and the discussion from other candidates. It is in the MEO Class I section of the Marine One forum, open to members enrolled for the MEO Class I exam.