The origin of the sea container dates back to after the Second World War. At that time, a young truck driver from North Carolina, Malcolm McLean, realized the enormous effort and time that went into loading the goods from the trucks onto the ships.
McLean had a great idea that came to be a turning point in transportation. He developed his idea optimizing the processes of directly loading trailers with goods and then removing the chassis and loading only the metal box.
Following the expansion of the use of containers, measures were standardized to simplify loading and unloading. In 1961, standardization led to the development of an international standard called ISO (International Standards Organization) shipping container. These standards are not mandatory, but standardization has been vital to the evolution of container handling.
Over time, responding to the needs of international trade, a wide typology of containers has developed. The 20 ft (5.9m long x 2.3m wide x 2.3m high with a maximum recommended load of 21.8t) and the 40 ft (12m x 2.3m x 2.3m with a maximum recommended load of 26.7t) are the most used dimensions in the maritime transport of goods. In addition to these, the other types of containers and their dimensions are:
- Dry container: 20 ft and 40 ft
- Open top container: 20 ft and 40 ft
- Reefer (or refrigerated) container: 20 ft and 40 ft
- Ventilated container: 20 ft
- Flat rack container: 20 ft and 40 ft
- Tank container: 20 ft
- Dry high cube container: 40 ft and 45 ft
Due to their characteristics and load, the most common containers are the following:
- Dry container. The most used in the world. Made of aluminium or steel, 20 or 40 feet, it is a dry cargo container for all kinds of goods. Closed and with rigid walls, it has a door for loading the goods.If it is made of aluminium, it allows a greater weight capacity; if it is made of steel, its internal capacity is a little higher.
- Reefer container. 20, 40 or 45 feet, it is used for goods that need controlled temperature conditions (between -25º and +25º) such as fruits or meat products. It has a cooling unit that connects to the power supply of the ship, port or truck.
- Flat rack container. 20 or 40 feet, it is made of steel and has no walls. With fixed or folding sides, it is the most suitable for heavy material or for loads with special requirements due to their dimensions, such as pipes.
- Open top container. It has no roof or a removable canvas roof. They usually have side doors for easy loading and unloading, and are used for heavy or large materials.
- Open side container. 20 or 40 feet, it is made of steel and is used for goods with large dimensions (length). It is designed to facilitate loading through the side doors. There are also double doors, with four-leaf doors to access the load from the sides and ends.
In addition to these, the classification includes other types:
- Tank container. Made of steel or aluminium, it has a cylindrical shape and is anchored to steel beams with the shape and dimensions of a standard container, making it easy to handle. It is used for gases or liquids.
- Insulated container. Made of insulating materials, it is used for goods that require a constant temperature.
- Bulk container. For the transport of grain or bulk goods, it has three loading hatches in the roof and two unloading hatches in the door.
- High cube container. 40 or 45 feet, they are very similar to the dry container, but with a greater height. It is used for light and bulky loads.
- Others: hypobaric, cage, for automobiles, etc.