In September a steel fabricator in Jiangsu loaded six cold-rolled coils, 4.2 tonnes each, into a 20GP for Los Angeles. The booking said 24 tonnes. The gate weighbridge said 25.2 tonnes of cargo, and with the tare the unit was over the carrier's limit for that service. The container was stopped at the terminal, de-stuffed and re-booked as two units. The coils were fine. The paperwork was not.
Weight is the one dimension where a container can look perfectly loaded and still be refused. Three separate limits apply, and they are not the same number.
The three limits nobody adds up
- The container plate. Maximum gross weight is stamped on the door — commonly 30,480 kg for a 20GP. Payload is that figure minus the tare, usually 2,200–2,400 kg. So the plate allows about 28 tonnes of cargo.
- The carrier's limit. Each service publishes its own maximum, and it is lower than the plate — often 21 to 24 tonnes of cargo for a 20GP on a trans-Pacific string, sometimes less in peak weight seasons.
- The road limit at destination. In the United States, gross vehicle weight is capped at 80,000 lb — about 36.3 tonnes — for the tractor, chassis, container and cargo together. A heavy 20GP can exceed that before it leaves the port.
| Check | Typical figure | What it actually limits |
|---|---|---|
| Container plate (MGW) | 30,480 kg for a 20GP | Cargo plus tare, by the box itself |
| Carrier acceptance | 21,000–24,000 kg cargo | What the line will load on that service |
| US road limit | 36,300 kg gross vehicle | Tractor, chassis, box and cargo together |
| VGM declaration | Actual verified mass | Whether the terminal accepts the box at all |
Why coils are their own problem
A coil is a rolling load. Loaded upright it wants to tip; loaded on its side it wants to roll. Either way the weight sits in a small footprint, and a 4.2-tonne coil that shifts can punch through a container wall. The stow is a structure, not a stack.
- Set each coil in a timber cradle or steel frame so the contact is a line, not a point.
- Spread the load over the floor bearers, not on two cross members. Check the floor rating before loading.
- Lash with four straps per coil at roughly 45 degrees, crossed, to the floor rings on both sides.
- Keep the centre of gravity low and on the centreline. More than about 10% lateral offset is a refused stow, and it is also how a chassis tips at a corner.
The loading sequence, eight steps
- Weigh the cargo, not the invoice: per coil on a calibrated scale, and record it.
- Check the carrier's limit for that service in writing, before the booking is confirmed.
- Calculate VGM as cargo plus tare plus any dunnage, using the weighing method you will declare.
- Inspect the container floor and the plate; refuse a box with soft floors or a patch.
- Lay the cradle, then lower each coil into it with the spreader, never rolled in.
- Lash at 45 degrees, four points per coil, and photograph every lashing point.
- Check the offset from the centreline and the weight distribution front to back.
- Apply the seal, record the VGM, and send the lashing plan with the shipping instructions.
The file that has to travel with it
- VGM declaration, with the weighing method and the date.
- Packing list in kilograms per coil, and a weight certificate if the buyer asks for one.
- Lashing plan, signed by whoever supervised the loading.
- Photographs: cradle, lashings, seal, and the plate showing the maximum gross weight.
- For US delivery, confirmation that the trucker holds the permits and the chassis rating for the axle load.
Six places this goes wrong
- Estimating weight from volume, which for steel is wrong by a wide margin.
- Declaring a VGM that matches the booking instead of the weighbridge.
- Loading above the floor rating and finding out at destination.
- Lateral offset that passes the gate and fails at the first corner.
- A trucker at destination without the axle rating for the load.
- Forgetting that the road limit is lower than the ship's limit.
A plain note from the desk: a heavy container is not a loading problem, it is a paperwork problem that becomes a loading problem. Weigh it, get the carrier's number in writing, and let the VGM be the last thing you write.
Before the next heavy booking, send us the coil weights, the container type and the destination address on WhatsApp. We will check the carrier limit and the road limit together, and tell you whether one box will do or the cargo splits.