Steel structures are dense, long and often irregular, which makes container choice a structural decision rather than a freight detail. Member lengths, bundle weights and the unloading sequence at site all narrow the options before price has any weight.
The figures below are typical values for orientation. Internal dimensions and payloads vary between container types and operators, and road weight limits in the destination country often cap the load well below the container's own limit.
The three containers in practice
| Container | Internal length (approx.) | Internal height (approx.) | Typical payload | Suits |
|---|---|---|---|---|
| 20GP | 5.9 m | 2.39 m | Around 28 t | Dense, short members; small orders; heavy sections that keep a short container within weight limits |
| 40HQ | 12.03 m | 2.69 m | Around 26 t | Fabricated beams and columns up to about 11.8 m, packed bundles, most warehouse orders |
| 40OT | 12.03 m | 2.34 m | Around 26 t | Members or assemblies that exceed the standard door height; loaded by crane with the roof open |
Member length drives the container choice
- Members up to about 11.8 m can travel in a 40-foot container with the doors closed.
- Longer members normally need a 40OT, a flat rack, or a designed splice that the engineer approves.
- Members that exceed the door opening in width or diagonal depth will not enter a standard container even when they would fit inside it.
- Trusses and deep fabricated assemblies are often the items that push a shipment from 40HQ to 40OT or flat rack.
If a project has members crossing any of these thresholds, it is worth confirming the transport method before the shop drawings are frozen. Changing a splice later is more expensive than choosing a different container.
Bundling and weight distribution
- Bundle by type and length, and keep each bundle weight inside the capacity of the crane that will handle it at both ends.
- Record bundle weights and lifting points, so the site can plan the lift before the container arrives.
- Distribute weight along the container floor rather than concentrating it at one end.
- Protect connection faces, machined surfaces and coated edges before bundling, not after.
- Pack loose parts separately and itemise them, so a missing item is found at the site rather than after erection starts.
Marking and unloading sequence
The loading sequence is decided by the unloading sequence, not by how neatly things fit. Members needed first should sit where they can come out first.
- Every bundle carries a piece mark, a bundle number and the project reference that matches the packing list and the erection drawings.
- The loading plan states which item comes out first at site, so the carrier and the site team work from the same document.
- Loading photographs are taken before the doors are closed, so the condition and the arrangement are documented.
This guide describes general practice for steel structure projects. It is not a design, and it does not replace the specification or the engineer responsible for your project.