What do the markings on a container door mean?
Have you ever wondered what all the numbers and codes you can see on a container door stand for?
Each container has a variety of markings, including company names, serial numbers, and codes that indicate what type of cargo it can carry and how heavy it is. The doors of a typical shipping container will have five to seven different markings, each indicating something important about the container's identification, condition, ownership, and contents.
Container number
The container number is the most important marking, typically printed on the door of every shipping container but also seen on the side, top, and inside of the container.
It is a unique alpha-numeric sequence of four letters and seven numbers that serves to identify the container. This coding standard was created by the classification agency ISO (International Standards Organization) under their code ISO6346:1995(E).
The first three letters of the container number are the owner code which must be unique to avoid duplicates and, therefore, should be registered with the BIC (Bureau of International Containers).
The following single letter represents the equipment category identifier and can be either J, U, or Z (J refers to a detachable container, U refers to a freight container, and Z refers to a trailer or chassis).
The remaining six digits are the serial number, which is decided by the owner and used to identify the specific container. The final number is called a check digit and checks whether the entire sequence is valid. It is usually outlined with a box.
ISO code
It is a code sequence of four letters and/or digits located below the container number that identifies the type of container and its dimensions.
The first character specifies the length of the container, the second is width and height, the third provides information about the container type and other characteristics (such as temperature controls), and the fourth indicates a container of reduced strength.
As standard, the ISO code of 22G1 in the above example means it is a 20' container 8'6'' high with a tare weight of 2250kgs.
Operational markings
Help to convey information on the movement of containers and provide visual warnings for the weight and height of containers.
- The maximum gross weight indicates the weight the container can carry (usually around 30 metric tons).
- The container weight (or tare weight) ranges from 4 to 10 metric tons.
- The net weight (or payload) is the maximum weight that can be loaded in the container and is calculated by subtracting the tare weight from the gross weight.
- The
maximum cargo volume in cubic capacity.
CSC Plate
The CSC (Convention for Safe Containers) plate is installed on each shipping container to ensure the container is safe and fit for use. Typically, the CSC plate is attached to the outside of the left container door in a visible location and must be appropriately fastened.
CSC plates contain inspection information about the safety examinations set up for the container. Periodic inspections under the periodic examination scheme (PES) require that the next examination date (NED) is displayed on the plate, while approved continuous examination programs (ACEP) do not have expiration dates.
Containers inspected through ACEP are required to display plates that indicate the ACEP registration number and designation and the country that issued the ACEP.
A container must display a valid ACEP or NED sticker to be loaded onboard a ship. Moreover, a CSC plate is invalid if the container is damaged, which can be taken out of service by any authorized agent. To avoid such situations, it is recommended to have a good inspection process in place.
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