Sea cargo reference
20' Tank
A steel cylinder inside a twenty-foot frame. The figures below are the inside of the box, the door, and the weights.
- Internal length
- 6.058 m
- Internal width
- 2.438 m
- Internal height
- 2.438 m
- Door opening, width
- Does not apply
- Door opening, height
- Does not apply
- Cubic capacity
- Does not apply
- Empty weight
- 4190 kg
- Payload
- 26290 kg
Length, width and height below are the ISO frame, not the barrel. A tank's usable capacity is its rated volume in litres, which the operator quotes for each unit.
How a 20' Tank is used
A cylindrical stainless steel vessel inside a twenty-foot frame, for liquids, gases and powders that flow, carried in bulk.
Rated capacity is given in litres, not cubic metres, and there are no door sizes. The rules set both a minimum and a maximum fill. Overfilling leaves no room for the cargo to expand with heat. Underfilling lets the cargo surge inside the barrel as the unit moves.
What a given tank may carry depends on its certificate and on the last product it held. A cleaning certificate for the previous cargo is normally required. Dangerous goods follow that tank's own approval.
Cargo it suits
How the box is made
- A cylindrical stainless steel pressure vessel sits inside a 20' ISO frame, so the whole assembly handles as a standard container.
- Insulation wraps the barrel. Many units also have steam or electric heating so a thick cargo stays pumpable.
- A manlid, valves and a pressure relief sit on top, with a discharge valve and often a bottom outlet at one end.
- Baffles inside some designs limit how far the cargo can surge as the ship moves.
- Fill limits run both ways: at least 80 per cent full so the liquid cannot surge in transit, and as a rule no more than 95 per cent so there is ullage for the cargo to expand with heat.
- Working pressure is generally up to 3 bar above atmospheric, and the tank is tested at 4.5 bar.
- Tanks approved for food are marked 'Potable Liquids only'.
- Some dangerous goods must travel in a tank with no inlet or outlet below the surface of the liquid.
- Insulation, heating and temperature sensors can be fitted when the cargo has to travel warm, or under close temperature control.
Why shippers choose it
- Bulk liquid travels without drums or IBCs, which cuts packaging cost and the work of decanting.
- The tank can be cleaned and reused for different cargoes. A cleaning certificate shows the last product carried.
- Payload per unit is far higher than the same volume packed as drums.
Check these before you book
- The rules set both a minimum and a maximum fill. A tank that is too empty lets the cargo surge.
- Rated capacity is given in litres, not cubic metres, and there are no door sizes.
- Dangerous goods depend on that tank's certificate and on the last cargo it carried.