Yes. Caustic soda is dangerous goods for sea, air and road transport in every form. It is a Class 8 corrosive substance, listed as UN 1823 when solid and UN 1824 when in solution.
That means it must travel in UN-approved packaging, carry hazard labels and marks, and be declared to the shipping line on a dangerous goods declaration.
The classification
- Solid caustic soda, as flakes, prills or pearls, is UN 1823, sodium hydroxide, solid, Class 8, packing group II.
- Caustic soda lye is UN 1824, sodium hydroxide solution, Class 8, in packing group II or III depending on its corrosive effect.
- Packing group shows the degree of danger, with group I the highest and group III the lowest.
Where the classification comes from
The correct entry for your product must come from the supplier's safety data sheet, section 14, and be confirmed by the shipper. If you need background on the class system, read the IMDG classes for hazardous chemicals.
What it means in practice
Every package must be UN-approved for the packing group. Bags for flakes need the right UN mark and an inner liner. Drums and IBCs for lye must be compatible with strong alkali. Plain steel drums are often used for solid caustic, but aluminium and zinc must never touch the product, because sodium hydroxide attacks them and releases hydrogen.
Each package and container must show the Class 8 label, the UN number and the proper shipping name. The container needs placards on all four sides. The shipper signs a dangerous goods declaration, and the shipping line must accept the booking before the cargo is loaded.
Not every line or route accepts every DG cargo, and DG bookings often need more time. Freight also costs more than for general cargo. Our article on why DG freight costs more explains the drivers.
Can it go in a flexitank?
No. Flexitanks are for non-hazardous liquids only. Caustic soda lye in bulk travels in a stainless steel ISO tank container, cleaned and certified for the product. Smaller lots go in UN-approved drums or IBCs.
Who is responsible
Under the IMDG Code, the shipper is responsible for classifying, packing, marking, labelling and declaring dangerous goods. In an FOB sale, that is usually the Indian seller or its forwarder. Your own regulator may also require an SDS in your language and local hazard labels when the goods arrive.
Rules are updated regularly, so confirm the current requirements with your freight forwarder and customs broker for each shipment. A wrongly declared DG cargo can be refused, delayed or fined, and an undeclared one is a serious safety risk at sea.
Next step
We check the safety data sheet, packaging marks and DG documents before loading, and supervise the stuffing of the container. To plan a compliant caustic soda shipment, book a free sourcing review.