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. All containers operated within the container fleet, whether owned or leased, are according to the ISO code.
Not all containers which are used by transport companies are ISO containers and under no circumstances should they be accepted for sea passage unless with special agreement obtained from shipping line.
Container Parts :
The main components of a container are described below with accompanying diagram :
Corner Post :
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 provide 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 centers 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 under most structure of the roof and are usually placed at 18 or 24 inch centers. 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. Aluminium containers have aluminium sheathing, bonded with adhesive to the roof bows and riveted to the top rails and headers. GRP containers have fibreglass 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. Aluminium containers have aluminium sheathing on the sides and front of the container which are affixed to aluminium 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 fibreglass 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 aluminium facings), corrugated, or combinations with fibreglass. 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.
Clean: No left overs (sweepings, dust, grease or liquid) of the previous cargo.
Dry: The interior should be dry and free of any sweat or frost.
No infestation: There should be no evidence of pests, insects or rodents which might contaminate cargo and lead to delay by Port Health Authorities.
Taint-free: If delicate goods susceptible to damage by bad odours are to be packed, then the container must be sweet-smelling. This should be checked immediately on opening the doors when any lingering smells will be at their strongest.
Watertight: This is best checked by entering the container and closing both doors. If any spots of light can be seen then water can gain entry. This also applies to the container floor because water can splash upwards during road haulage.
Follow instructions: Any recommendations posted inside the container should be noted.
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 cargos such as ingots, heavy steelwork, drums.
Flatracks: 20/ 40; No sidewalls or roof (and ends may be collapsible); For out of gauge cargos and restricted loading situations.
Platforms: 20/40; Flatbed with corner castings. Limited numbers of high rated equipment; Over-length cargos and special projects.
Fantainers: 20/40; Extractor fan fitted; Agricultural products requiring ventilation e.g. onions, potatoes. Also used as a normal GP container.
Highly Ventilated: 20; Side vents along top and bottom rails; Hygroscopic cargos such as coffee, cocoa, tobacco and seeds.
Top Ventilated: 20; Side vents along top rail; Hygroscopic cargos such as coffee, cocoa, tobacco and seeds.
Open Sides: 20; Side gates and side curtains; Agricultural products requiring ventilation, livestock and side loading.
Bulk: 20; Top loading ports and door discharge shoot; Dry cargos in bulk e.g. malt , sugar also used as a normal GP container.
Tank Containers: 20; Tank within an ISO frame of various types; Liquid cargos in bulks including foodstuffs and hazardous.
Refrigerated Integral: Refrigerated Integral; 20/40; 8' 6" and 9' 6"; electrically powered self contained refrigeration unit; Refrigerated cargos throughout the world with connection to terminals and ships electrical power sockets.
Refrigerated Insulated: 20 (8’ and 8’ 6”); Top & bottom end ports and connects to ships refrigeration system; Reefer cargos on specialized ships operating in ANZ and SAF Trades.
Container Examinations :
Every container must have a Container Safety Certificate (CSC) issued by the manufacturer and this must be renewed every 30 months after inspection by a competent inspector. An approved continuous examination program (ACEP) can be agreed as substitute for this procedure and the ACEP number is stamped on the CSC plate.
Container Damage :
Common types of container damage are listed below...
Racking: Is the twisting of the structural shell of the container due to static or dynamic forces and is commonly associated with movements in a seaway. The standard ISO container racking limit is nominally 15 tonnes. To counter these forces, diagonal lashings may be applied in accordance with the vessel's lashing system. In high stacks, the lower container is subject to the greatest racking forces and the lashing systems must be designed to take this into account.
Toppling: Can occur when containers are subjected to extreme rolling motions aboard ship or standing in a stack, exposed to high winds. Counter measures are twist-locks and lashings.
Container collapse (corner-post compression): Results from exceeding allowable loads on the container corner posts and can be avoided by staying within weights limits of the container. Where lashings are applied aboard ship, avoid over tensioning of lashings.
Local structural failure: Is the separation of structural components of a container such as side-wall separation from top and bottom rails and separation of the corner castings from the side rails.
Holes in containers: These is the most common kind of damage. Roof damage is often caused by lifting spreaders indenting the roof when locating corner castings and twist-locks and lashing gear being thrown down on top. Holes in container walls can be caused by fork-lift trucks, collision with other containers or lifting devices. Holes in containers can be easily detected by interior inspection with the doors closed and noting if any light enters the container. This can also reveal faulty door seal gaskets and is extremely important check to be made.
Interior Contamination: Container floors become seriously contaminated by cargos such as wet hides which can cause tainting to future cargos. Interior paintwork can also be stripped by cargos such as naphthalene and cloves.
Container Repairs : It is important to maintain the containers in a safe and acceptable condition both operationally and visually, whilst avoiding overspending on structural and cosmetic repairs such as small dents and scuffing of paintwork.
Container Cleanliness : There has to be a set cleanliness criteria for cleaning containers. This includes appropriate detergents to be used in order that taint to cargo is not caused by cleaning agents.
Equipment Interchange Receipt (EIR) :
Also referred to as a Trailer Interchange Receipt (TIR) and relates to the land side interchange of containers. Where a contracted trucker, barge or rail operator, exchanges equipment as part of the inland journey, an EIR inspection should record each interchange. This may include receipt or delivery of containers from terminals or depots as appropriate and can serve as a valid contract between shippers the shipping line (or appointed sub-contractor) and the hauler.
Vessel Cell Numbering :
Container slot positions aboard ship are expressed by three co-ordinates indicating:
Bay -- Row -- Tier
Bays: Are numbered lengthwise from bow to stern with odd numbers for 20' containers and even numbers for 40' containers. The even number between two 20' containers is used to define 40' bays.
Rows: Are numbered from centreline to port side with even numbers and from centreline to starboard with odd numbers. The container row stowed on the centreline is marked 00.
Tiers: In under deck stows, containers are numbered vertically downwards with even numbers from top to bottom. The bottom row will be 02, except where as a result of the hull contour, the bottom of an adjacent row is at a higher level. In case of two half heights the bottom ones are to be numbered by an odd number. On deck stowage is indicated by code key 8 followed by an even number sequence.