A shipping container is a container with strength suitable to withstand shipment, storage, and handling. Shipping containers range from large reusable steel boxes used for intermodal shipments to the ubiquitous corrugated boxes. In the context of international shipping trade, "container" or "shipping container" is virtually synonymous with "(standard) intermodal freight container" (a container designed to be moved from one mode of transport to another without unloading and reloading).
Freight containers are a reusable transport and storage unit for moving products and raw materials between locations or countries. There are about seventeen million intermodal containers in the world, and a large proportion of the world's long-distance freight generated by international trade is transported in shipping containers. In addition, it's estimated that several million of these containers have now been discarded due to the shipping cost of sending them back to their port of origin. Their invention made a major contribution to the globalization of commerce in the second half of the 20th century, dramatically reducing the cost of transporting goods and hence of long-distance trade.
Corrugated boxes are commonly used as shipping containers (more than 90% of all shipping containers are of this type). They are made of corrugated fiberboard which is lightweight, recyclable, and strong enough to ship a variety of products.
The most popular sizes are:
20 foot: 20’ long x 8’ wide x 8 ½’ high external (c. 6.1m x 2.4m x 2.6m) - called twenty-foot equivalent unit (often TEU or teu)
40 foot: 40’ long x 8’ wide x 8 ½’ high external (c. 12.2m x 2.4m x 2.6m) - which equals one forty-foot equivalent unit (often FEU or feu) in cargo transportation (considered to be two TEU
Increasingly used by bulk shippers is the Hi-Cube 40 foot, which has a 9 ½’ height.
There are also refrigerated containers, which can be broader at 2.6m width.
In the USA, longer sizes are common, including 45’, 48’ and 53’, the last of which is used for many rail and truck deliveries.
Other specialist types that you may encounter include Flat Rack, Open Top, Ventilated, Refrigerated, Tank, Platforms and ‘heavy tested’ 20’ containers that are suitable for heavy machinery.
The maximum payload mass for a 20’ container is approx. 22 tonnes: and for 40’, approx. 27 tonnes.
Legislation referring to the identification of containers is laid down in international standard ISO 6346 for coding, identification and marking of intermodal containers (shipping containers) used within intermodal freight transport as part of containerization.
ISO 6346 is an intentional standard managed by the International Container Bureau (BIC)
The containerization system developed from a design of an 8-foot (2.438 m) cube units used by the United States' military and later standardized by extension to 10-foot (3.05 m), 20-foot (6.10 m), and 40-foot (12.19 m) lengths. Longer, higher and wider variants are now in general use in various places.
Container variants are available for many different cargo types. Non-container methods of transport include bulk cargo, break bulk cargo and tankers/oil tankers used for liquids. For air freight the alternative and lighter IATA defined Unit Load Device is used.