IBC Code chapter 21: criteria for assigning carriage requirements
The quantified criteria set that decides every chapter 17 column, rewritten by the 2019 amendments and the reason every product entry was reassessed.
Chapter 21 of the IBC Code carries the criteria for assigning carriage requirements for products subject to the Code. It is the engine behind chapter 17: every column in the product table is the output of a rule in chapter 21, so a change to the criteria propagates to every entry.
That is exactly what happened in the 2019 revision. IMO resolutions MSC.460(101), adopted 13 June 2019, and MEPC.318(74), adopted 17 May 2019, both in force 1 January 2021, replaced chapter 21 in full, and because the criteria changed every product had to be reassessed against them. The results were many ship type upgrades from 3 to 2 and from 2 to 1, a small number of downgrades, the movement of most former chapter 18 products into chapter 17, and the addition of the toxic designation T in column k to a large number of cargoes.
Paragraph 21.4.5.2 sets the ship type criteria in quantified form: inhalation LC50 or acute toxicity estimate read with the ratio of saturated vapour concentration to LC50, dermal LD50 or acute toxicity estimate, the water reactivity index, the auto-ignition temperature, and the explosive range read with the flashpoint, alongside the pollution rules worked from the GESAMP hazard profile. The full article will set out each criterion, its threshold values and the column it determines.