An adhesive manufacturer in Bao'an booked 18.4 tonnes of solvent-based cleaner to Los Angeles last spring. The quote read "1×20GP, drums, general cargo", because that is how the cargo had always moved, by air and by LCL. Two things were missing: the flash point of the product, 23 °C, which puts it in Class 3; and the fact that a dry container full of drums stops being general cargo the moment it carries a dangerous goods declaration.
The booking was refused at documentation, five days before the cut-off. Two options were left: rebook as DG in drums, or move the same 18.4 tonnes in an ISO tank. This note covers one cargo type only, liquids, and the arithmetic that decides between the two.
Step 0: read section 14 before you read the price
- UN number, proper shipping name, class, packing group and flash point all sit in MSDS section 14
- Water-based and solvent-based products of the same family often land on different sides of the line
- To move a product as non-dangerous you need a transport condition report issued for that product, not last year's certificate for a similar one
- A flash point at or below 60 °C is normally Class 3, and the packing group follows the flash point and the boiling point
Three ways a liquid actually ships
| Packaging | Usual volume | What it needs | Where it stops working |
|---|---|---|---|
| 200 L drum in a 20GP | 0.5–15 t | UN packaging, DG approval, upright loading, bungs up | Above roughly 15 t, drums and handling labour outrun the freight saving |
| 1,000 L IBC in a 20GP | 5–20 t | Palletised, blocked and braced, spill containment | No stacking two high without a frame; the weight sits on a small footprint |
| ISO tank, 20 ft | 15–26 t | Tank operator, cleaning certificate, DG approval, receiver with pump and hose | Below about 12 t the tank premium does not pay; tanks run one-way and repositioning is charged |
None of the three is cheaper in the abstract. What decides it is tonnage per booking, the receiver's unloading equipment, and how many days you have before the cut-off.
Step 1: book earlier than the drums route
- Carrier DG approval: 3–7 days before the documentation cut-off, and 10 working days with some carriers on the US trade
- ISO tank availability, cleaning and certification: 7–10 days; a food-grade or heated tank, about two weeks
- A receiving appointment at a dangerous goods warehouse at origin: 1–3 days, and not every yard takes Class 3
- Tank imbalance: a tank is not always sitting at the load port, so budget for repositioning and book the return leg at the same time
If the vessel sails on the 12th, the tank request goes out around the 1st, not on the 9th.
Step 2: the securing plan belongs in the booking file
- Drums: upright, bungs up, one tier where possible; timber dunnage between rows and no gap at the door; lashing runs from the top tier to the floor rings, never drum to drum
- IBCs: strapped to their pallets, blocked against the side walls with timber, one tier unless the carrier approves a frame
- Absorbent sheeting on the floor, plus absorbent material equal to roughly 10% of the volume; keep the spill kit on the loading bay, since nothing can be reached once the doors close
- No mixed loading with oxidisers (Class 5.1) or acids; check the segregation table rather than habit
- Tank: the tank is the container, so nothing is lashed inside. What gets checked is the frame, the valve cabinet and the manhole cover, the test dates on the plate, and the seal number written on the bill
Step 3: the document set
- MSDS in the current format, section 14 consistent with the declaration
- Dangerous goods declaration signed by a trained person: UN number, proper shipping name, class, packing group, net and gross quantity
- UN packaging certificate for drums and IBCs; the tank certificate for a tank
- Tank papers: UN portable tank or IMO type approval, the last hydraulic and visual test dates, cleaning certificate, tare weight and capacity, plus a food-grade certificate where the cargo is food
- Transport condition report if the cargo is declared non-dangerous
- Packing list with net and gross weight per package; for a tank, tare, payload and density on the same sheet
- Bill of lading description matching the declaration, with the tank or container number in the container field
- Photos of markings, placards, valves and seal, taken before the doors close
Step 4: loading checklist, eight steps
- Confirm the class, and confirm the booking says DG rather than general cargo
- Check the UN mark on every drum or IBC, bungs tight, no weeping, fill level leaving ullage for expansion
- Line the floor with absorbent sheet, and lay timber to spread the load
- Load upright and tight, heaviest toward the door end, but never against the doors
- Brace the last row with timber, and lash the top tier to the floor rings
- Fit Class 3 placards and the UN number on both sides and one end, then check they survive the wash
- For a tank: confirm tare, capacity and the fill limit for the density and route temperature, caps on, seal recorded
- Photograph everything, sign the container packing certificate, and send the file to the broker before the vessel sails
Where this usually goes wrong
- The quote says general cargo, and the DG surcharge arrives after the booking is refused
- Drums filled to the neck: expansion inside a hot container pushes product past the bung
- The fill limit ignored on a tank, which is the same mistake with 24,000 litres behind it
- No cleaning certificate, so the tank is rejected at the load port and the vessel leaves without it
- The receiver has no pump or hose, the tank sits at destination, and demurrage starts
- Weight declared per drum but pallet and dunnage left out, so the VGM does not match the terminal scale
Send us MSDS section 14 and the monthly tonnage on WhatsApp before the next booking. Whether the answer is drums or a tank depends on volume, route and the receiver's unloading equipment, and it takes ten minutes to work out.