Comprehensive Guide to Understanding Containers in Maritime Shipping

Containers are the main transportation tool for maritime shipping, and those involved in import and export trade are certainly familiar with them. Freight forwarders, in particular, deal with containers almost daily. Today, we’ve compiled essential basic knowledge about containers, which you’ll find very useful. If you need this information and prefer not to search elsewhere, we strongly recommend bookmarking this article for its direct and practical content.

Introduction to Containers
A container, also known as a "cargo container" and technically referred to as a "container," is a large cargo container used for turnover with specific strength, stiffness, and dimensions. Freight forwarders facilitate import and export by sea by transporting customers' goods from one port to another using containers or other means and ultimately delivering them to the consignee.

Common Types of Containers

• Dry Container (DRY CONTAINER, abbreviated as DC or GP): This is the most common type of container, used for all types of goods except for frozen items, live animals, and plants, given its suitability in size and weight for container transport.
• Reefer Container (REEFER CONTAINER, abbreviated as RF, high cube abbreviated as HR): These are used for goods that require temperature control, such as perishables, and other goods that need a constant temperature.
• Open Top Container (OPEN TOP, abbreviated as OT): These containers allow loading from the top and are particularly suitable for oversized machinery. They are equipped with PVC waterproof tarpaulins and removable frames with wire rope sealing devices. The doors of these containers can also be detached, facilitating easier loading.
• Flat Rack (FLAT RACK, abbreviated as FR): Designed for heavy loads that need to be loaded from the top or sides, such as pipes and machinery.
• Hanger Container (HANGER CONTAINER, abbreviated as HT): Clients can choose to use rope or pole or both to hang garments. This type of container is flexible, has a large internal capacity, and can save on transport and handling costs.
• Tank Container (TANKER CONTAINER): Comprising a liquid tank and frame, these are used for transporting alcoholic beverages, oils, liquid foods, chemicals, and other liquid goods.

Common Container Specifications
The nominal gross weight is 17.5 tons, with a volume of 28-31 cubic meters.

• 20GP: Internal dimensions 5.898x2.352x2.385 meters.
• 40GP: Internal dimensions 12.032x2.352x2.385 meters, nominal gross weight 22 tons, volume 54-64 cubic meters.
• 40HQ: Internal dimensions 12.032x2.352x2.69 meters, nominal gross weight 22 tons, volume 68-74 cubic meters.
• 45HQ: Internal dimensions 13.556x2.352x2.698 meters, nominal gross weight 26 tons, volume 78-86 cubic meters. Note: The dimensions and weight limits of each shipping company may vary slightly; it is always best to confirm with the shipping company or check the specific container retrieval conditions individually.

Tips:

1. The content volume of a container refers to the cargo volume calculated based on the internal dimensions of the container. Due to differences in structure and manufacturing materials, the content volume of the same type of container may vary slightly.
2. Due to differences in loading experience among loading personnel and factors such as the load factor of goods, containers often cannot achieve 100% utilization. On average, the utilization rate can reach about 85%. Thus, when freight forwarders discuss business with clients, if clients inquire about the content volume of containers, it is crucial not to promise how much cargo can be loaded based on theoretical volume calculations. From experience, a 20-foot container can generally hold about 24-26 cubic meters of cargo, and if space is utilized well, up to about 28 cubic meters. A 40-foot container can generally hold about 54 cubic meters, and a 40-foot high container can hold about 68 cubic meters.
3. Regarding weight limits, every container door displays information about the container's tare weight and maximum load capacity. However, when doing business, one should not load goods based on the maximum load capacity indicated on the container door alone. Shipping companies and terminals have specific requirements for the gross weight of containers. If the client's goods are heavy, it is essential to confirm the maximum weight limit with the shipping company before booking the space. If overweight, additional overweight fees may apply. Additionally, different shipping companies have different weight requirements, and freight forwarders can choose ship owners based on the actual conditions of the client's goods.
4. Flat racks are generally used for transporting oversized and heavy items; therefore, they do not have a fixed volume or weight limit. In practice, it is vital for clients to provide accurate dimensions and weights of the goods to confirm with the ship owner whether a flat rack can be used for shipment.
5. The top of open-top containers is open, suitable for loading extra tall cargo with the assistance of a crane. For goods that are not excessively tall, open-top containers can also be used for convenience in loading.

Container Identification Codes and Nameplates
Container doors carry many identification labels that are frequently used in business processes by freight forwarders, including container numbers, dimensions, type codes, maximum total weight, tare weight, net load, content volume, and safety convention nameplates.

Still confused between COC and SOC containers?

COC Box (Carrier's Own Container): This refers to containers owned by the carrier. A COC slot means that, in addition to providing a slot to the shipper, the shipping company also provides a container. The shipper, with a Shipping Order, can pick up an empty container from the designated terminal yard, and then arrange for the goods to be containerized.

SOC Box (Shipper's Own Container): This refers to using the shipper's own container for cargo loading for export. Generally, customers use their own containers to avoid fees associated with using shipping company containers or to obtain discounts from the shipping company to reduce costs. If a client requests the use of an SOC container for export, the freight forwarder should ask the client to provide photos of the container door, nameplate, half-closed interior, overall exterior, and container certification to avoid issues during booking.