Hogg,
The first number in the Packing Instruction refers to it's Class. Anything starting with 4 is flammable solid/dangerous when wet/& what the other one (4.1, 4.2, 4.3). Nothing wrong with a "4G fibreboard box" - I just called our office to check on PI 412! A 4G box is ok for the outer packaging.
Are you refering to CeRium? if so PI 415/417 depending on pax/cao. Couldn't find CeSium.
Flammable liquid will have a PI starting with 3. Explosive is Class 1.
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rgds Rat
[This message has been edited by CargoRat2 (edited 06 May 2001).]