Flat rack vs open top: a flat rack has no side walls, so it takes cargo that is too wide as well as too tall; an open top keeps its walls and doors and takes only cargo that is too tall or must be crane-loaded.
What is a flat rack container?
A flat rack is a strong container base with an end wall at each end and no side walls, roof or doors. Cargo is loaded by crane or forklift from the sides or above, lashed to the floor and end walls, and shipped as part of a container vessel's load. It fills the gap between an enclosed box and breakbulk: machinery, vehicles, steel structures and anything too wide, too tall or too heavy for an enclosed container.
Sizes and figures
| Figure | 20โฒ flat rack (22P3) | 40โฒ high cube flat rack (45P3) |
|---|---|---|
| Length between corner posts | 5,612 mm | 11,652 mm |
| Width between corner posts | 2,227 mm | 2,224 mm |
| Height, floor to top of end walls | 2,219 mm | 2,248 mm |
| Tare | 2,740 kg | 5,950 kg |
| Maximum gross | 34,000 kg | 50,000 kg |
| Payload | 31,260 kg | 44,050 kg |
Figures are from Hapag-Lloyd's Container Specification booklet, first series listed for each size; other series in the same fleet are rated up to 45,000 kg (20โฒ) and 60,000 kg (40โฒ) gross. There is no door and no enclosed volume.
How flat racks are built and used
- Collapsible end walls: Hapag-Lloyd's flat racks have spring-assisted, flush-folding end walls, so empties fold flat and interlock in stacks (seven 20โฒ or four 40โฒ units to an 8โฒ6โณ pile) for repositioning
- Payload depends on the load footprint: the full payload applies only when the weight is spread over the whole floor. A short, heavy piece is rated lower, and on the 40โฒ heavy cargo must rest on the main girders, so send the footprint and weight of each piece
- Lashing: lashing points on the corner posts, rails and base ends are rated up to 5,000 kg each; stanchions are not supplied unless requested at booking
Out-of-gauge cargo
Cargo that overhangs the sides or stands taller than the end walls is out of gauge (OOG). The carrier must accept it in advance and approve the lashing plan before the booking is confirmed. On the road, flat racks and wide or tall loads need a flatbed or specialized trailer and, where they exceed the legal dimensions, state oversize permits; plan the drayage at both ends before booking the ocean leg.
Common mistakes
- Asking for a quote without the details: send the dimensions and weight of each piece, and its footprint on the floor
- Assuming a closed box will do: if a piece fits the width but not the height, an open top is usually simpler and more available
- Leaving insurance to the end: cargo on a flat rack is open to the weather, so check the cover under the Institute Cargo Clauses before shipping
Airlift books flat racks on FCL ocean freight on request, where a carrier offers them on your lane and accepts the cargo. The container dimensions page compares flat racks with open tops and dry boxes.
Related terms
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