ISO Codes
The International Standards Organization (ISO) has recommended a series of internal and external dimensions for containers together with gross maximum weights which the container may carry.
Not all containers which are used by transport companies are ISO containers and under no circumstances should they be accepted unless with special agreement.
Container Parts
The main components of a container are described below with accompanying diagram.
- Corner Post: Vertical frame components located at the corners of freight containers and integral with the corner castings and floor structures.
- Corner Castings: Fittings located at the corner of the freight container which provides means for lifting, handling, stacking and securing the container.
- Header and Sill: In way of door entrance with overhead horizontal header frame and similar floor level threshold sill.
- Front-End Frame: The structure at the front end of the container (opposite the door end) consisting of top and bottom rails attached to the front corner posts and the corner castings.
- Top Rail: Longitudinal structural members located at the top edge on either side of the freight container.
- Bottom Rail: Longitudinal structural members located at the bottom edge on either side of the freight container.
- Cross-members: A series of transverse beams at approximately 12 inch centres attached to the bottom side rail and an integral part of the floor frame support.
- Floor: The floor may be hard or soft laminated wood, planks or plywood.
- Roof: Roof bows are the undermost structure of the roof and are usually placed at 18 or 24 inch centre’s. Modern steel GP containers (except open top containers) are not fitted with roof bows but will have corrugated or flat steel sheet roofs welded to the frame members.
Aluminum containers have aluminum sheathing, bonded with adhesive to the roof bows and riveted to the top rails and headers. GRP containers have fiberglass reinforced plywood panels fastened to the rail and headers. The roof is the part of the container most vulnerable to damage. - Sides & Front: Modern steel GP containers will have corrugated steel panels. Aluminum containers have aluminum sheathing on the sides and front of the container which are affixed to aluminum stringers which are in turn bolted to the top and bottom rails and also to the front end frame. The stringers may be on the outside or inside of the sheathing. GRP containers do not use stringers for supporting the fiberglass reinforced plywood panels. The side and the front of steel containers are made of corrugated steel sheets eliminating stringers.
- Doors: Doors may be ply-metal (plywood core with steel or aluminum facings), corrugated, or combinations with fiberglass. The hinged doors have plastic or rubber lined door gaskets as seals against water ingress.
- Security seal: Used in conjunction with locking mechanism in order to seal the containers for security purposes. These seals are numbered and often colour coded.
Container Types
The container fleet can be loosely described in terms of General Purpose (GP) containers or specials.
The GP or general purpose container accounts for the large majority of the fleet and is used for most general cargo commodities. The containers are 20 ft or 40 ft in length with a limited stock of 45 ft.
The standard external height of GP containers is 8 ft 6 inches although high cube containers at 9 ft 6 inches in height are becoming common.
Special containers are provided for specific carriage requirements and examples are listed below.
Type; Sizes (In feet); Characteristics; Typical uses
Open Tops; 20/40; Soft detachable roof tarpaulin or tilt; Machinery requiring top loading and over height cargo.
Half Heights; 20/40; Soft detachable roof tarpaulin or tilt, half height; High density cargoes such as ingots, heavy steelwork, drums.
Flat racks; 20/ 40; No sidewalls or roof (and ends may be collapsible); For out of gauge cargoes and restricted loading situations.
Platforms; 20/40; Flatbed with corner castings. Limited numbers of high rated equipment; Over-length cargoes and special projects.
Refrigerated; 20/40; 8'6" and 9'6"; Electrically powered self contained refrigeration unit; Refrigerated cargoes throughout the World with connection to terminals and ships electrical power sockets.
Half Heights; 20/40; Soft detachable roof tarpaulin or tilt, half height; High density cargoes such as ingots, heavy steelwork, drums.
Flat racks; 20/ 40; No sidewalls or roof (and ends may be collapsible); For out of gauge cargoes and restricted loading situations.
Platforms; 20/40; Flatbed with corner castings. Limited numbers of high rated equipment; Over-length cargoes and special projects.
Refrigerated; 20/40; 8'6" and 9'6"; Electrically powered self contained refrigeration unit; Refrigerated cargoes throughout the World with connection to terminals and ships electrical power sockets.
