ThorPak sea container large load carrier

The ThorPak sea container is the foldable large load carrier from wi-sales that is consistently designed to meet the requirements of international sea transport. With external dimensions of 1130 × 725 mm to 1450 × 1130 mm and payloads of between 250 and 350 kg, the system covers the most common export scenarios – from automotive parts to mechanical engineering components. In contrast to disposable packaging, the sea container returns folded and saves up to 73% volume when transporting empties compared to when full.

Requirements for sea container-compatible packaging

Sea transportation confronts packaging with conditions that are unknown to intra-European truck tours: Salty sea air attacks metal surfaces. Temperature differences from -20 °C in cold zones to over +60 °C in tropical ports stress materials. Stacking pressures act for several weeks without interruption. Moisture condenses when switching between cold cargo holds and warm outside climates.

For use as sea container large load carrier the following minimum requirements apply:

• • Corrosion resistance of the entire container – no bare steel surfaces on the outside
  • Defined load according to ISO 8611 – the stack certification must be valid for the entire storage time, not just for short test intervals
  • High-rack capability – ship storage ports work with racking systems; automated handling is impossible without a pallet system with defined entry dimensions
  • Securing the position of the lid – whipping movements in rough seas must not open the lid closure
  • Foldability – the return transportation of empty containers is a direct cost factor in the sea freight business

Dimensions and stackability for 20ft and 40ft containers

The ThorPak sea container is available in eight variants – two base areas combined with two heights each, as well as two 1150 mm types. Planning with specific quantities is crucial before an exporter books freight capacity.

A standard 20ft sea container has an internal length of 5.89 m. The key figure for the dispatcher: During return transport, a truck can hold 352 folded S 1130×725 H810 containers – compared to 96 full ones. This reduces empty runs by a factor of 3.7.

Corrosion protection and climate resistance

The material concept of the ThorPak sea container is specifically designed for corrosive environments. The pallet and lid are made of pressed TwinSheet HDPE – a high-density polyethylene that does not absorb moisture and is resistant to salt water, mineral oils and most cleaning agents.

The container ring is made of polypropylene (PP), 10 mm thick, with a basis weight of 3,000 g/m². This wall thickness is structurally necessary to permanently meet the load requirements of up to 1,350 kg. Steel reinforcement profiles inside the ring are protected against direct contact with seawater.

The optional Aircell container ring also acts as a climate buffer: the air chamber panels dampen temperature fluctuations and protect temperature-sensitive goods – an aspect that is particularly relevant for electronic components or pharmaceutical pre-products being shipped overseas. Further details can be found in the overview of Aircell air chamber panels.

ThorPak sea container system in detail

The system consists of three main components, which are manufactured separately and can be combined:

• • Sandwich system pallet (HDPE, pressed TwinSheet): Suitable for high racking; defined drive-in dimensions for forklift trucks and reach trucks. Tare weight 27 to 53 kg depending on type.
  • Container ring (PP, M-folded): Folds flat to 210 mm (-25 mm tolerance) packing height. Steel inner structure prevents bulging of the side walls even when permanently loaded.
  • Lid (HDPE, pressed TwinSheet): Waterproof closure; optional flap for side access without fully opening the lid.

All three components remain connected even when folded – pallet remains at the bottom, lid at the top, container rings stacked in between. This prevents component loss in the reusable system.

Accessories for sea transportation

wi-sales supplies the ThorPak sea container as a configurable system. The following accessory options can be integrated at the factory:

• • Flap: Removal flap on the side of the container ring; enables unloading without opening the lid – relevant for hanging or horizontal goods
  • Card pocket: Welded pocket for delivery documents on the outside of the ring – meets customs requirements without additional labeling
  • Imprint: Customer labeling, logistics codes or dangerous goods symbols applied directly using the pressing process; no stickers that peel off in a humid sea climate
  • Aircell container ring: Replaces the standard PP ring; suitable for goods with temperature limits
  • ThorLock: Mechanical stacking lock; prevents stacked containers from shifting sideways on the container floor during ship movements

The combination of card pocket, print and ThorLock fully covers the typical requirements of an automotive Tier 1 supplier in overseas shipping. An overview of other foldable systems can be found on the ThorPak Individual page for customized dimensions outside the standard sea container sizes.

Case study: Automotive exports overseas

An automotive supplier in southern Germany sends car body components by sea container to an assembly plant in Mexico. The previous solution: wooden crates as disposable packaging, no return transport, but disposal costs in the country of destination increase.

Switching to ThorPak sea containers type S 1130×725 H810 results in the following calculation:

• • 96 full containers per 20ft sea container (delivery direction)
  • 352 folded containers per truck in the return transport – i.e. all 96 containers from four transports are returned in a single return transport truck
  • Payload per container: 250 kg → Up to 24,000 kg payload per containership space (96 × 250 kg)
  • Load of up to 1,150 kg in accordance with ISO 8611 enables three-tier stacking in the ship’s hold without additional securing racks

The one-way costs are eliminated. The disposal problem in the destination country is eliminated. The return transport costs – with 4:1 consolidation of empty runs – are significantly lower than the previous freight costs. The ThorPak Medium T offers similarly designed returnable solutions for Europe-wide use.