What is Tare Weight of a Container?
23/09/2021Other than the container number and the Container Safety Convention (CSC) plate fixed on intermodal containers, various other acronyms and short forms can be found displayed on them.
Typically, all this information is found printed on the doors of the container. The most prominent among this data being the Max Gross or MGW, Tare or Unladen, Net or Payload, and Cu. Cap. Details.
The MGW is also required to be shown on the CSC Plate.
Just like the container number and the CSC plate that must be displayed on a container, the details regarding the different weights are also a requirement for any intermodal container that is used in shipping and freight.
Here, we will take a look at the term tare weight of an intermodal container, and understand its significance.
Simply stated, tare weight is the weight of an empty container. The term unladen weight is sometimes used in place of tare weight. Tare and unladen weight means the same and it is the weight of the container when it is not loaded with cargo.
The tare weight of a container is shown on the container along with the other essential details of the container. Typically, the container tare weight when added with the weight of the cargo gives the gross chargeable weight.
To understand tare weight better, we may quickly go through some of the other terms mentioned above. To begin with, a simple example would help us to understand these terms better.
Consider a bottle of tomato sauce purchased from the supermarket. The label on this bottle would show the net weight, while some other products might include the gross weight also on their labels.
Net weight is just the weight of the tomato sauce inside the bottle. It does not include the weight of the packaging or the bottle. The weight of the packaging or the bottle is the tare weight. If you add the weight of the tomato sauce and the weight of the bottle, then you have the gross weight. Gross weight is the weight of the product and the weight of its packaging.
Max Gross (MGW)
In shipping, maximum gross weight (MGW) is the total allowable weight of the container as well as the cargo that is packed inside it. Now, this may also include any extra packaging that goes into the container for the protection of cargo during handling and transport.
Maximum gross weight and gross weight are not to be confused with each other. While MGW is the maximum weight allowed for the container and cargo, that cannot be exceeded, the gross weight is the actual weight of the container and the cargo inside it. The gross weight should naturally be less than the maximum gross weight displayed on the container.
Net or Payload
The net weight, shortened to Net, is the weight of the goods inside the shipping container. It includes the weight of pallets or any other packaging materials that are used to pack the goods inside the container.
Cu. Cap. or Cubic Capacity
The cubic capacity shown on a container is its cargo-carrying capacity in volume. Cubic capacity is usually measured and shown in m3 (Cubic Meter) or f3 (Cubic Feet). Sometimes it is shown as CBM (Cubic Meter) or CBF (Cubic Feet). One CBM is the volume of a cargo that is 1 meter in width, 1 meter in height, and 1 meter in length.
The CBM or m3 of cargo is used in the calculation of its chargeable weight. Converted to kilograms, 1 CBM equals 1000 kilograms or in other words, 1 KG equals 0.001 CBM.
A 20’ GP container has a cubic capacity of 33 m3 (CBM) while that of a 40’ GP container is 67 m3 (CBM).
One thing to note here is that the cubic capacity shown on a container is the total that can be accommodated within and is inclusive of any packaging or palletization of the goods.
Tare Weight and Freight Calculation
How is the freight rate of cargo calculated? Factors such as the method of transport – whether by land, sea, or air, type of goods to be shipped, the distance from the port of origin to the port of destination, goods pick up and drop-off points, and the weight or volume of the cargo are used to arrive at freight rates.
While several factors are considered in the calculation of freight rates, the tare weight and the net weight of the cargo being shipped are among the main factors when it comes to the freight of cargo by an intermodal container. Shipping documents such as bills of lading, etc. show these two figures on them.
The correct gross weight, tare weight, and net weight are used to calculate the chargeable weight of a cargo being shipped. All the parties involved in doing business – the buyer, the seller, and the transporter should understand the importance of each of these terms. They should know how they are connected so that they are used correctly in documentation to avoid any misunderstanding or miscalculation.
The tare weight of a 20’ GP container (2.35 M width x 2.39 M height x 5.9 M length in meters) is 2230 kilograms. A container of this size can take a maximum load of about 26500 kilograms weight.
A 40’ GP container (2.35 M width x 2.39 M height x 12.03 M length in meters) has a tare weight of 3780 kilograms and it can take a maximum load of about 26700 kilograms weight.
How are Containers and Cargo Weighed?
Shipping lines normally accept the weights that are provided by the shipper. However, intermodal containers are sometimes weighed using weighbridges. A weighbridge is a heavy-duty platform scale that is mounted on a strong concrete foundation that can withstand the enormous loads and their weights.
Weighbridges are large enough to accommodate a trailer truck with a loaded container on it. The difference between the weight of the vehicle with the loaded container on it, and the weight of the vehicle without any load confirms the declared weights as per the shipping documents.
What are the Weights Shown on a Bill of Lading?
Being a legal shipping document, a bill of lading must show the correct weights, quantities, descriptions of the products, and all other required details of the consignor and consignee on it. With regard to weights, a typical bill of lading shows the tare weight of the container and the gross weight of what is being shipped.
Misdeclaration of Weights on a Bill of Lading
Misdeclaration of the weight of cargo on a bill of lading can have drastic consequences. It can result in accidents such as container stack collapse, failure of equipment, etc. There have been instances of ships running aground because of incorrect stacking based on the declared weights. Misdeclaration of weights on shipping documents is a serious offence for which the shipper can be held accountable.
Source: Marine Insight
