As of today, more than 17 million containers of different dimensions and types are used globally to make container shipping the most efficient method of transportation. These shipping containers are ISO certified, which means that they are brought into business only when they are manufactured and tested as per the specifications provided by the International Organization for Standardization (ISO) to ensure that the goods carried are suitable for multiple transportation modes, i.e. via ship, truck or rail. The materials used for manufacturing a shipping container is either aluminium or steel, making them excellent to use for dry and packaged cargo. The advantage of aluminium dry containers over a steel container is that the former has a slightly larger payload, whereas the dry steel containers have a slightly larger internal cube.

For professionals working with containers – whether in maritime shipping, on port facilities or elsewhere -, it is important to understand the different container dimensions, nomenclature, signals, symbols and signs displayed on the cargo containers.

There are several kinds of containers:

• 20 ft. container: lxwxh=6.06×2.44×2.59m; maximum gross weight=30,480 kg (67,200 lbs) for general purpose containers, up to 45,000 kg (99,207 lbs) for flatracks, 27,400 kg for reefer containers
• 40 ft. container: lxwxh=12.19×2.44×2.59m; maximum gross weight=30,480 kg (67,200 lbs) for general purpose containers, up to 60,000 kg (123,276 lbs) for flatracks and 35,000 kg (77,161 lbs) for reefer containers
• 40 ft. container High Cube Heigth: lxwxh=12.19×2.44×2.89m.
• 45 ft. container: lxwxh=13,71×2.44×2.59m; The payload capacity of 45 ft container is almost similar to a 40 ft container.
• 40 ft. container High Cube Heigth: lxwxh=13,71×2.44×2.89m.

The above specifications are a representation of the most commonly used shipping containers. Specific container dimensions and capacity may vary depending on the manufacturer, the age of the container, and the container owner. There are also other dimension containers available in the market which are mostly used for road and rail transportation – 8 ft, 10 ft, 53 ft, 60 ft.

Markings on a container
Shipping containers have standard markings on them to make them recognizable. These markings are standardized according to the DIN EN ISO 6346 standard for the coding, identification, and marking of containers, dated January 1996.

The different markings provided on an ISO container can be explained as follows:

• Approved Classification society label
  Before the container is used by a shipping company for cargo transfer; it is tested for seaworthiness and compliance to the ISO standards by an approved classification society. The label of the class is provided on the end door of the container.
   
• Owner details
  The shipping line or container vendor’s logo/name is provided on the end door.
   
• Certifications
  The container can have different certificates which are displayed using plates, such as:

   

  • CSC: the IMO has developed an International Convention for Safe Containers. The 1972 Convention has two goals. One is to maintain a high level of safety of human life in the transport and handling of containers by providing generally acceptable test procedures and related strength requirements. The other is to facilitate the international transport of containers by providing uniform international safety regulations, equally applicable to all modes of surface transport. In this way, proliferation of divergent national safety regulations can be avoided. The requirements of the Convention apply to the great majority of freight containers used internationally, except those designed specially for carriage by air. As it was not intended that all containers or reusable packing boxes should be affected, the scope of the Convention is limited to containers of a prescribed minimum size having corner fittings ‑ devices which permit handling, securing or stacking. The Container Safety Convention plate shows the container has been inspected and tested by approved authorities. It also contains details of the owners and other technical specifications.
  • ACEP: ACEP stands for Approved Continuous Examination Programme and is provided on the container. This is a safety program for shipping containers, wherein the container has to undergo an extensive inspection in a container depot every 30 months of its service. The container owner will renew the ACEP every 10 years.

   

• Manufacturer details
  The logo/name of the container manufacturer can also be provided.
   
• Container Number/BIC-code
  The container number is the primary identification marking on the door end of an ISO container. It consists of four letters and seven digits, which are allotted to identify every container to its owner. The number is unique and is registered with the Bureau International des Containers (BIC), Paris, France.

   

  The number is constructed as follows: ABCY 123456 7

  • The first 3 letters, i.e. ‘ABC’ identify the owner of the container
  • The 4th letter (Y) provides the container category, where the category identifier can be:
    • J: detachable freight container related equipment
    • R: reefer (refridgerated) containers
    • U: freight containers
    • Z: trailers and chassis
  • The first six numbers, i.e. ‘123456’ is the serial number of the container
  • The last number, i.e. ‘7’ is a check digit which is used to validate if the owner or product group code and the registration number have been accurately transmitted.

   

• ISO container size and type code
  The ISO container size and type code is stencilled below the container identification number and provides details of the type of container. The code denotes:

   

  • the size of the container, e.g. 20 ft. container codes start with "2", 40 ft. with "4".
  • the purpose of the container, i.e. if it is a general purpose container (GP), insulated (HR) or reefer (RC, RS, RT) container, a tank container (TD, TG or TN) or a bulk container (BU) with hard top (UP) or open top (UT). Flat containers can be fixed (PF), collapsible (PC) or space saving (PS).

  Certain subtypes have different codes. More information on the ISO container size and type codes can be found on containercontainer.com.

• Weights & payload
  All the details of container weight and cargo weight can also be found on the door.

   

  • The max. gross weight of the shipping container: the maximum total weight of the container including cargo within the safe limit
  • The Tare weight: the true weight of an empty container provided by the manufacturer post the manufacturing process.
  • The net weight or payload: This is the maximum net cargo weight an approved ISO container can carry

   

• Cubic capacity/volume
  The cubic capacity or the volume of the container is marked in the end door in m. and/or ft..
   
• Warning and Operational Signs
  The container may carry various warning labels and signs, depending upon its type and the cargo it is carrying. E.g. a heightened container will contain the height or warning stripes on the top part of the container. Similarly, a container carrying hazardous cargo will carry one or more warning signs about the type of hazard or cargo associated with it.

The information contained here is for guidance only and based on "A Guide to Shipping Container Dimensions” by Anish | In: Maritime Insight Law and information from containercontainer.com.