Out-of-Gauge and Breakbulk Shipping for Oversize Frames
Ocean freight for a containerised frame is a commodity with a published rate. Ocean freight for a frame 20 cm too tall is a negotiation. The step between them is the single most underestimated cost in heavy fabrication sourcing.
The envelopes
Know these numbers before you freeze a design.
| Equipment | Internal L × W × H | Max payload |
|---|---|---|
| 20 ft standard | 5.90 × 2.35 × 2.39 m | ~28 t |
| 40 ft standard | 12.03 × 2.35 × 2.39 m | ~26 t |
| 40 ft high cube | 12.03 × 2.35 × 2.69 m | ~26 t |
| 40 ft flat rack (collapsible) | 12.10 × 2.40 m, open top | ~40 t |
| 40 ft platform | 12.19 × 2.44 m, no walls | ~40 t |
Figures vary by operator and by individual unit, treat them as planning values and confirm with your forwarder before committing.
Notice that flat racks carry more weight than boxes. On heavy frames, the constraint is almost always dimension, not mass.
The four cost tiers
1. In-gauge containerised
Fits inside a standard or high-cube box. Rate is per container, published, competitive, and the cargo is handled like everything else.
2. In-gauge on a flat rack
Fits within the flat rack’s deck footprint and roughly its height. A modest premium over a standard box, still a per-unit rate, still routine.
3. Out-of-gauge (OOG)
Exceeds the flat rack in width, height or length. The cargo must be stowed where its overhang does not foul other cargo, which means the carrier loses the slots around it.
You pay for the slots you block. A frame 30 cm over height on a flat rack can block the slots above it across the bay. The charge is calculated in “slot equivalents” and can be several times the base rate.
The step from tier 2 to tier 3 is the cliff. It is where a small dimensional change on the drawing saves a large amount of money.
4. Breakbulk / project cargo
Cargo too large or heavy for any container equipment, loaded directly into the hold or onto the deck of a multipurpose or heavy-lift vessel.
- Quoted per shipment, not per unit
- Depends on vessel availability, routing and the sailing schedule of ships that call at both ports
- Sailings are less frequent, so schedule risk is real
- Requires a lift study, lashing plan and often a marine warranty surveyor
Breakbulk is not exotic, it is how most large industrial equipment has always moved. But it needs planning months ahead, not weeks.
The inland leg is often the harder problem
Ocean carriers handle oversize cargo routinely. Roads do not.
Moving an oversize piece from an inland shop to the port typically requires:
- An oversize permit, with lead time measured in days to weeks
- A defined route survey, bridge heights, power lines, roundabouts, turning radii
- Escort vehicles, sometimes police escort
- Night movement restrictions
- Occasionally, temporary removal of street furniture
Every one of these costs money and, more importantly, adds schedule risk that is outside anyone’s control.
This is why the fabricator’s distance from a deep-water port is a selection criterion, not a detail. A well-equipped shop 300 km inland can be the more expensive option for an oversize piece than a merely adequate shop 40 km from the terminal. It belongs in the vetting conversation, see how to choose a heavy fabrication supplier.
Design decisions that keep you in tier 1 or 2
Put the container envelope in your CAD model
As a reference body, from the first sketch. It is the cheapest design constraint available, and it makes the trade-off visible while it is still free to change.
Split the frame
The dominant answer when a piece breaks the envelope. Two shippable sections with machined, dowelled mating faces will almost always land cheaper than one out-of-gauge piece, even after the extra machining and site assembly. The method is in split-and-bolt frame design.
Ship it on its side
Sometimes trivially effective. A frame 2.9 m tall and 2.1 m wide is out-of-gauge upright and in-gauge on its side, provided it is designed to be lifted and supported that way, which means transport lugs and bracing on the correct faces. Decide this at design stage, not on the loading dock.
Remove and ship separately
Tall vessels, stacks, handrails, walkways and cable trays often carry the height. Bolting them on at site rather than welding them in the shop can drop a package a whole tier. Cost it both ways.
Design collapsible or removable bracing
Transport bracing that stiffens the package for the journey and comes off at site adds little cost and lets you ship a lighter, more open structure safely.
Packing for the ocean
Oversize cargo on deck or in an open hold gets weather. Specify:
- A designed cradle or skid that supports the piece where it can carry load, not where it is convenient
- Lashing points: rated, marked and clear of pipework and instruments
- Machined faces protected: greased, wrapped, and boxed where practical
- Desiccant and VCI for anything with bright surfaces on a long tropical voyage
- ISPM 15 compliant timber: with the mark visible and the fumigation certificate in the document pack
- Centre of gravity marked on the piece, and lifting points marked and rated
Ask for photographs of the packed piece before it ships. It costs nothing and it catches problems while they can still be fixed.
Insurance
For project cargo, minimum-cover marine insurance is not adequate. Specify Institute Cargo Clauses A at 110% of invoice value, and check whether loading and discharge operations are covered, for heavy lifts that is where damage happens. If you are buying CIF, this needs to be written into the contract, because the default is much narrower. See Incoterms for heavy fabrication.
For the duty, insurance and document lines that follow the ocean leg, see our guide to importing heavy steel fabrications.
A planning sequence
- At concept: put the container envelope in the model
- At design review: decide split, orientation or one-piece, with a freight number for each
- At RFQ: ask for package dimensions and gross weights per package, so your forwarder can quote
- At order: book the freight, for breakbulk, months ahead
- Before shipment: lashing plan, photographs, document pack
Have a frame that is close to the envelope and you are not sure which side of it falls? That is the most valuable question to ask early. Send the dimensions and the destination port, we will tell you what tier it lands in, within 24 business hours.
See also: securing heavy frames for transport: CTU Code, EN 12195-1 and lashing points.