What are Corner Castings and Why are They Important?

Shipping containers are a vital component of global trade. Whether purchasing leather goods from Australia or tennis shoes from china, they help ship goods securely across rail, road, or sea.

In fact, over 20 million shipping containers travel across the ocean daily. Furthermore, an astounding average of 1,390 shipping containers are lost at sea every year. In 2019, 16,000 cargo containers were lost.

Often, an overlooked aspect of the shipping process is finding the right container corner castings that meet ISO standards. They help to secure multiple containers together to prevent them from being damaged or lost during transport.

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What is a corner casting?

new bottom corner casting made from quality steel
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Source: Special container

Shipping container corner castings are the structural pieces attached to the corner of the shipping container. These corner castings are used as connection points for stacking, joining, lifting, and connecting shipping containers as they make their journeys across the world.

They are used primarily to lock the container horizontally and vertically while also connecting them to another ISO 6346 shipping container through the use of bridge clamps and twist locks.

The primary benefit of using corner castings is allowing the containers to be easily picked up and moved around as needed.

Since they allow containers to be stacked, it’s convenient to haul more containers without damage. Corner castings are typically made from steel, which is the strongest and most durable material that can be molded.

Manufacturers can mold the casting to the right shape and weight for optimal use. The downside of the corner castings is that there are different types of castings; therefore, you’ll need to ensure the sizing fits the container.

Related: Complete Guide to Shipping Container Foundational Footings

Types of corner castings

types of steel connected shipping container corner casting
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Source : Special container

An ISO shipping container typically uses eight corner castings: the top right, top left, bottom right, and bottom left. Each corner needs two corner castings to outfit the container.

Are all the corner castings the same?

It’s important to note that not all shipping container corner castings are the same. The top corner fitting features an acorn shape side hole. Comparatively, the bottom corner fitting features a semi-circle side hole.

For the right and left corner castings, both the top and bottom are mirror images of each other. However, in all other respects, they are the same.

If you’re confused as to which corner casting you’re looking at, you can look inside the stacking hole. The top left will be labeled as TL, the top right as TR, the bottom left as BL, and the bottom right as BR.

Dimensions

The width of the corner fitting top aperture must not exceed 66 millimeters. In addition, the length of the corner fitting top aperture can’t exceed 127 millimeters. Furthermore, the top plate thickness can’t fall below 23 millimeters.

Exceeding these dimensions for any corner casting requires that the container be taken out of service immediately. It’s vital to inspect all three dimensions: length, width, and thickness.

Materials

A corner casting is created by forming a substance into a particular shape using a mold. There are many types of effective metal materials that can be used for shipping container corner castings.

Gray Iron

gray iron related products
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Source: indiamart.com

Gray Iron is one of the more common casting materials used. That’s because it can be machined easily, formulated to meet specific requirements like ISO 1161 standards, cost-effective to produce at scale, and tested for quality control.

Ductile Iron

Ductile Iron
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Source : m.made in china

Ductile iron is similar to gray iron, but it has greater strength, improved resistance, superior ductility, reduced weight, and shrinkage.

Aluminum

aluminum related products for bottom door
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Source: conexwest.com

Aluminum is popular due to its versatility of the metal. It has many advantages, such as good strength at high temperatures, high electrical and thermal conductivity, and corrosion resistance.

Steel

steel iso 1161 related product set for container corner castings
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Source : truckbodyfitting.com

Steel is another tough casting material because it can withstand the wear, shock, and weight of heavy loads. Its corrosion resistance properties make it useful for aqueous environments like shipping containers that will travel by sea. Steel materials are designed to work for extremely low temperatures at -40°C.

Although steel is the strongest and safest material, you may want to consider the cost involved in purchasing these shipping container corner castings in bulk.

Cost

Shipping container corner castings vary significantly in price depending on their dimensions, materials, and shape. On the lower end, you may find castings between $40 to $60.

However, they might use less durable materials like aluminum. Higher quality materials and ISO 1161 standard castings might run between $160 to $200 per corner casting.

How do I know if my shipping container is ISO standard?

iso 1161 connected casting
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Source : pacificmarine.com

Shipping containers and corner castings should be ISO standard, meaning they are safe for freight use. The ISO rating dictates the dimensions and ratings of the container and the container corner castings. The easiest way to identify whether the shipping container is constructed for ISO standards is to look for certain markings.

All ISO standard shipping containers will have a four-digit code printed on the top right-hand corner of the door. Check under the container number on the top right-hand corner, where the four-digit code should be printed as well.

If the container has been painted over and the marketing isn’t visible, you can look at the corner castings to determine whether the shipping container is ISO standard or not.

All ISO standard corner castings should have the following shapes. Top corner castings contain a stadium hole on the long side of the container and a shield hole located on the rear or front of the container. Conversely, the bottom corner castings have two stadium-shaped holes located on two sides.

Also, evaluate the thickness of the steel corner casting. Anything below 18 millimeters in thickness means that the corner casting and shipping container isn’t ISO standard.

Conclusion

Doing a proper inspection of each container corner casting and choosing the right ones can ensure safe transportation of the cargo. Shipping container corner castings play a critical role in handling and lifting containers. Follow the guidelines mentioned to minimize the risk of damage or loss of cargo and ensure the safety of the products.

Ryan Stetson

Ryan Stetson

Currently own two 20' and 40' containers converted into an office/workshop. Having worked in the shipping industry for 6 years, my goal is to share my personal experiences as well as connect potential container buyers with suppliers around the US.

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