Twenty-foot equivalent unit
The twenty-foot equivalent unit is an inexact unit of cargo capacity used to describe the capacity of container ships and container terminals. It is based on the volume of a 20-foot-long intermodal container, a standard-sized metal box which can be transferred between different modes of transportation, such as ships and trucks; the container is defined by its length though there is a lack of standardisation in regard to height, ranging between 4 feet 3 inches and 9 feet 6 inches, with the most common height being 8 feet 6 inches. It is common to designate 45-foot containers as 2 TEU, rather than 2.25 TEU. The standard intermodal container is designated as 8 feet wide. Additionally there is a standard container with the same width but a doubled length of forty feet called a 40-foot container, which equals one forty-foot equivalent unit in cargo transportation. In order to allow stacking of these types a forty-foot intermodal container has an exact length of 40 feet, while the standard twenty-foot intermodal container is shorter having an exact length of 19 feet 10.5 inches.
The twistlocks on a ship are put at a distance so that two standard twenty-foot containers have a gap of three inches which allows a single forty-foot container to be put on top. The forty-foot containers have found wider acceptance; the length of such a combination is within the limits of national road regulations in many countries, requiring no special permission. As some road regulations allow longer trucks, there are variations of the standard forty-foot container — in Europe and most other places a container of 45 feet may be pulled as a trailer. Containers with a length of 48 feet or 53 feet are restricted to road transport in the United States. Although longer than 40 feet, these variants are put in the same class of forty-foot equivalent units; as the TEU is an inexact unit, it cannot be converted into other units. The related unit forty-foot equivalent unit, however, is defined as two TEU; the most common dimensions for a 20-foot container are 20 feet long, 8 feet wide, 8 feet 6 inches high, for a volume of 1,360 cubic feet.
However, both 9-foot-6-inch-tall High cube and 4-foot-3-inch half height containers are reckoned as 1 TEU. This gives a volume range of 680 to 1,520 cubic feet for one TEU. While the TEU is not itself a measure of mass, some conclusions can be drawn about the maximum mass that a TEU can represent; the maximum gross mass for a 20-foot dry cargo container is 24,000 kilograms. Subtracting the tare mass of the container itself, the maximum amount of cargo per TEU is reduced to 21,600 kilograms; the maximum gross mass for a 40-foot dry cargo container is 30,480 kilograms. After correcting for tare weight, this gives a cargo capacity of 26,500 kilograms. Twenty-foot, "heavy tested" containers are available for heavy goods such as heavy machinery; these containers allow a maximum weight of 67,200 pounds, an empty weight of 5,290 pounds, a net load of 61,910 pounds. Container ship Container terminal Containerization List of unusual units of measurement Panama Canal toll system Shipping ton Maersk Shipping.
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