SECU, Stora Enso Cargo Unit, is a type of intermodal container (shipping container) built to transport bulk cargo like paper on railway and ship.
A SECU looks like a standard 40-foot ISO Container but is bigger, measuring 13.8×3.6×3.6 m (45×12×12 ft) and which can carry 80 tonnes (79 long tons; 88 short tons) of cargo. This is compared to the normal 12.2×2.7×2.4 m (40.0×8.9×7.9 ft) size and 26.5-tonne (26.1-long-ton; 29.2-short-ton) capacity of an ISO Container.
A SECU is too big and heavy to be transported on road (ISO-Containers are designed to fit roads), and instead they are transported only by railway and ship. A special vehicle or crane is used to load and unload them. Special railcars are also needed. They can be transported on truck ferries, but they don't fit normal container ships.
The benefit is that their much higher weight reduces the number of containers and therefore reduces handling cost. The drawback is that special solutions are needed.
They are invented and used by Stora Enso (forest and paper company). The ports used are mainly in production countries like Finland (Kotka, Oulu) and Sweden(Göteborg) and in consumer countries Belgium (Zeebrugge), UK (Tilbury, Immingham) and Germany (Lübeck).
Dimensions
The Stora Enso Cargo Unit has fixed legs so that the inner floor has a height of 874 millimetres (34.4 in) for an unloaded container - the basic container (without legs) has outer dimensions of 3600 by 3600 millimeters.