Types of Shipping Container
Shipping container types can be classified according to the intended purpose of the container.
Whether new or second-hand (see used shipping containers), they fall into one of two convenient categories:
- General cargo container
- Specific purpose container
ISO shipping container standards (see ISO 6346), set down in 1970, provides for standard shipping container dimensions. Homes made from containers are generally constructed using standard ISO containers of 20, 40 and 45 feet lengths.
High cube containers are slightly larger than those described below in that they provide an additional foot of height for bulkier cargo.
Types of General Purpose Container
1. Dry Cargo Shipping Containers
They are fully enclosed with strong, rigid walls, a roof and floor and resistant to the elements as well as animals, birds and vermin.
One of the walls is usually adapted to create an aperture for a door opening.
End loaders have a door at one of the ends on the shortest side, while some containers are fitted with side wall doors for convenient “side loading”. 20′ shipping containers and their 40 foot equivalents are the most common lengths while the standard width is 8 feet.
2. Special Dry Cargo Containers
Sometimes, loading (also known as packing) and unloading (also known as unpacking) cannot be easily accomplished through the end or side doors and therefore, special containers are used to do so.
Open top shipping containers have similar characteristics to dry cargo containers but do not have a hard top steel roof.
Instead, a canvas or reinforced cover is used to protect the cargo. The cover is supported on special “roof bows”.
Such containers are used for heavy, bulky or fragile items such as sheet glass or machinery. Open top containers are sometimes in short supply and are not always available in some markets.
Flat rack containers lack the superstructure of enclosed, dry cargo boxes. They do not have, therefore, fixed walls or any load-carrying structures.
They do have special corner fittings at the top and bottom of the container to ensure safe stacking and handling at the container ports.
These containers might be used in the transport and distribution of wood or other heavy and difficult to manage objects. They are not always available in some countries as supply is scarce.
c. Closed Ventilated Containers
Where goods need to be protected against excess moisture or humidity, special ventilation-adapted containers are used.
Types of Specific Purpose Container
For the transportation of food, frozen, perishable or cold goods, shipping containers are adapted to maintain their internal temperatures.
Worldwide demand for these products have created a market and a requirement for different types of specific purpose container.
Thermal containers are known in the industry as reefers. They are characterized by interior insulation on the doors, roof, floor and walls.
Used for prolonging the shelf-life of food items and perishables, thermal reefers help to restrict the temperature range inside the containers.
Reefers are commonly found in 20 foot and 40 foot shipping container sizes and are further classified as follows:
a. Insulated Shipping Containers
b. Refrigerated Shipping Containers
Refrigerated shipping containers have no external power or energy supply, so cold temperatures are maintained using dry ice or liquified gas.
c. Mechanically Refrigerated Containers
In these cases, a power supply is required to a refrigeration appliance. This is provide on land at sea ports, on road distribution trucks, or even on some container ships.
d. Heated Containers
Similarly, a power supply is needed to run a heat-producing device.
2. Named Cargo Containers
These containers transport items such as cars, other vehicles, livestock and poultry.
Dry bulk containers are used where no external packaging is required. Grains and dry foodstuffs fall into this category.
4. Tank Containers
Tank containers incorporate a tank for the transport and distribution of chemicals, gases and hazardous liquids.
Shipping Container Types – Summary
There are then, 2 general shipping container types:
- dry cargo
- specific-purpose containers.
In the dry cargo category there are 3 further sub-types:
- open top
- platform or “flat rack”
- closed ventilator containers.
In the specific purpose category there are 4 sub-types:
- thermal shipping containers or “reefers“
- named cargo
- dry bulk
- tank containers.
Reefers can be further sub-categorized into 4 sub-types:
- mechanically refrigerated
Standard Intermodal Container Sizes
In the early 1970s, the intermodal container industry was standardized to improve efficiencies and relieve congestion at international sea ports.
As such, shipping containers are governed by ISO mark 6346 where the following standard lengths are recognized:
- 20′ shipping containers
- 40′ shipping containers
- 45′ shipping containers
- 48′ shipping containers (generally only in USA)
- 53′ shipping containers (generally only in USA)
Which Types of Container Are Suited To Container Homes?
In general, architects working on container house plans tend towards used dry cargo containers in their specifications.
By relying on ISO standard containers, architects and construction companies know that each container will easily stack and align perfectly with the next, in turn permitting easier conversion as well as structures with more than one storey. See Container City phases I and II in London for a good example.