Shipping Oversized and Out-of-Gauge Cargo from China — Flat Racks, Open Tops, and Breakbulk

Standard dry containers have internal dimensions of roughly 5.9m long, 2.35m wide, and 2.39m high for a 20-foot box. That's enough for the vast majority of manufactured goods. But when you're moving industrial machinery, construction equipment, wind turbine components, steel structures, or large vehicles, standard containers don't work.

This category of cargo has its own terminology — out-of-gauge (OOG) or oversized cargo — and its own set of logistics requirements. Getting it wrong doesn't just cost money. It can mean your cargo sits at the Chinese port, rejected by the carrier, while you scramble to find an alternative.

What Counts as Out-of-Gauge?

A shipment is considered out-of-gauge when it exceeds the internal or external dimensions of a standard container in any direction — length, width, or height. OOG cargo is also sometimes called project cargo or heavy-lift cargo when it involves exceptional weight.

Common examples:

• Industrial presses, CNC machines, injection molding equipment
• Agricultural machinery (tractors, harvesters)
• Construction equipment (excavators, cranes)
• Pre-fabricated steel structures or beams
• Transformers and large electrical switchgear
• Boats and marine vessels
• Wind energy components (blades, nacelles, towers)
• Vehicles that exceed standard container dimensions

Equipment Options

Flat Rack Containers

A flat rack is essentially a container without walls or roof — just a floor with end walls (collapsible or fixed). Cargo is secured to the flat rack and lashed in place. The flat rack occupies a slot on the vessel like a normal container.

Flat racks allow cargo to overhang the sides and top of the container footprint. When a flat rack shipment is wider than the container it sits in, carriers call this an "over-width" shipment and it requires specific stowage planning — the slots adjacent to the flat rack on the vessel may need to be left empty to accommodate the overhang. You pay for those empty slots. This is called phantom container charges or stowage loss, and it can add significant cost.

Flat racks are available in 20-foot and 40-foot sizes. They can be stacked flat when empty, which is why carriers have them available in most major ports including Shanghai, Ningbo, and Tianjin.

Open Top Containers

An open top container has no roof — just a steel frame with a removable tarpaulin cover. It's used for cargo that can be crane-loaded from above but otherwise fits within standard container dimensions.

Common use cases include:

• Granite slabs and natural stone
• Coils of steel or wire
• Tall machinery that can be top-loaded but doesn't exceed container height excessively
• Cargo that needs to be lifted rather than rolled in through the doors

Open tops are more widely available than flat racks and generally cheaper because they don't involve the stowage loss calculations.

Breakbulk

When cargo is too large for any container option — flat rack included — it ships as breakbulk. Breakbulk cargo is loaded directly onto the vessel without a container. It's lashed and secured to the vessel's deck or in dedicated breakbulk holds.

Breakbulk shipping requires specialized vessels (heavy-lift ships, multipurpose vessels), specialized port handling equipment, and significantly more planning lead time. Not all ports have the cranes or facilities to handle breakbulk, which affects both origin and destination options.

Rates for breakbulk are quoted per freight ton (the higher of actual tons or cubic meters) or per unit, and the pricing is entirely project-specific. There's no published tariff you can look up.

Why It Costs More

Several factors make OOG and breakbulk freight more expensive than standard container shipments:

• Stowage loss — flat rack shipments with overhang require adjacent slots to be left empty; you pay for those
• Special equipment rental — flat racks and open tops cost more per day than dry containers
• Lifting and handling — heavy-lift cranes and specialized stevedores at both origin and destination
• Engineering and planning — carriers require a stowage plan and sometimes structural analysis before confirming a booking
• Vessel restrictions — not all vessels accept OOG cargo; your shipment may have to wait for a vessel with available OOG capacity
• Lashing and securing materials — heavy machinery requires extensive lashing; this is typically quoted separately
• Port surcharges — many ports charge additional handling fees for OOG and breakbulk

For a heavy industrial machine that would normally ship in a 40-foot container if it fit, the OOG version of the same move can cost 2-4x as much when all the additional charges are factored in.

Pre-Planning Is Not Optional

Unlike standard container bookings where you can often book close to cargo-ready date, OOG shipments need to be planned weeks in advance. Here's what your freight forwarder needs from you early:

• Exact dimensions — length, width, height in centimeters or inches, at the widest and tallest points (including lifting lugs, handles, attached components)
• Weight — gross weight, and center of gravity if available
• Special requirements — does the machine need to remain upright? Is it fragile in specific directions? Does it contain residual fluids (some carriers prohibit this)?
• Origin details — factory city, whether the facility has overhead cranes or forklifts capable of loading
• Destination details — port capacity, customs requirements, inland transport options

For large equipment, your forwarder may need to arrange a site survey at the factory to verify dimensions and loading feasibility before confirming the booking.

Customs and Documentation Considerations

OOG cargo typically attracts extra attention at customs. The HS code classification should reflect the actual equipment — not just "machinery" generically — because duty rates vary significantly across equipment categories. For an overview of how HS code classification affects duties on capital equipment, see our guide to HS codes and import duties from China.

Some markets require installation certification, safety approval, or equipment registration for certain classes of industrial machinery. Confirm these requirements before the equipment ships — not after it's sitting at a bonded warehouse waiting for an inspection that takes six weeks.

Cargo Insurance for OOG

Standard marine cargo insurance covers OOG, but the underwriting process is more involved. Insurers want to know the equipment type, value, packing method, and route. For high-value machinery, a surveyor may inspect the packing at origin before the shipment. Read more about the insurance process in our cargo insurance guide.

Where to Start

OOG freight is a specialist area. The team handling your regular LCL or FCL shipments may not have the contacts or experience for a 40-ton industrial press. Start by describing your cargo in as much detail as possible — our freight specialists work with heavy-lift and project cargo regularly and can advise on equipment options, routing, and lead time before you commit to a production schedule.

For a rough cost benchmark to include in your project budget, the freight estimator can give you an OOG estimate based on your dimensions and route.