How shipping containers are made

August 14, 2022

A shipping container is a durable and weathertight storage or transport solution made of high-quality, robust materials. They are built to withstand extreme conditions and hard knocks.

Whether they are being transported on a truck, shipped at sea on a container ship, or used as a home office, we see shipping containers around us almost every day. There are many uses for containers, and they can be adapted to meet almost any transportation or storage need.

You may have wondered how a shipping container is made. They look like rectangles made of metal, but there is some clever science and design behind their construction. We’ve put together a step-by-step guide to explain how shipping containers are made and answer some commonly asked questions.

How are shipping containers made?

The process of manufacturing a shipping container follows four key steps:

  1. Create the wall panels

Large sheets of corrugated steel are cut down to the required size to make the wall panels of a container. There are many shipping container sizes, so the exact dimensions of the wall panels depend on the specific requirements for the container that’s being manufactured.

  • Install the floor panels

A container’s floor is constructed using two long l-beams placed parallel to each another. A slab-like base is then created by welding smaller l-beams between the long beams. Flooring – usually a high-grade plywood – is then placed on top of the steel frame to form the floor.

  • Construct the doors and corner posts

Like the walls, container doors are also cut down from large steel sheets to the correct size, then protected with steel tubing. The corner posts are first welded to the l-beams, then the doors are welded inside the l-beams.

  • Assemble the container

The final step is to assemble the container. A crane is used to lift the door frames and position them on top of the floor frame, before they’re welded into place. The wall panels are then lifted and welded into position. Finally, the roof panel is welded in place to complete the structure.

After the container structure is complete, it can then be primed and painted. This is essential for ensuring the container remains weathertight and can withstand extreme weather conditions. Containers are primed with an undercoat, then spray painted multiple times. In the case of NZBOX containers, the exterior is painted three times and the interior twice.

Inside the container, the floor panels are finished with polyurethane for protection, then installed. As a final step, rubber seals are fitted to the doors to ensure they remain water- and vermin-proof.

What are shipping containers made of?

Most shipping container components are made from extremely tough COR-TEN (Corten) steel. This is a special type of steel, also known as weathering steel, that is thick and robust to ensure the container is secure and remains weatherproof.

These steel alloys were developed to remove the need for painting. They form a stable, rust-like appearance after several years’ exposure to weather. This means that, if a piece of paint chips off the steel, a thin layer of rust will form at the surface but not go deeper.

Corten steel is used to make the doors, corrugated walls, frames, and beams of a container. This type of steel requires little maintenance and can endure extreme weather conditions.

Marine-grade plywood is commonly used for the container floor. The plywood is treated to ensure that the cargo remains free of insects and bugs, and it is sealed with polyurethane, which helps keep the floor watertight.

Are shipping containers waterproof?

Shipping containers must be suitable for transporting goods safely and securely by sea and on land. This means they must be waterproof. The container shell is watertight, and the quality rubber seals used during manufacturing ensure that the doors remain waterproof too, even in extreme weather conditions. This keeps the transported or stored goods safe and dry inside.

As well as being waterproof, NZBOX shipping containers are built to handle extreme temperatures, ranging from -40C up to +70C.

How thick are the walls and bottom of a shipping container?

The exact thickness of the walls and bottom of a shipping container depends on its size. The floor on standard containers is about 27mm and the walls 25mm thick. Specially designed containers, such as insulated containers, feature thicker walls due to their heavy-duty insulation.

What is the life expectancy of a shipping container?

Quality shipping containers that are well looked after have a life expectancy of around 20-25 years. Depending on what the container is used for and provided its well maintained, a shipping container could well last longer.

To increase a container’s life expectancy, it’s important to regularly check for pests, inspect the door seals, and keep the container clean. If you make any modifications to a container, such as install windows, it’s important to inspect these for any damage or deterioration that could cause issues in the future.

NZBOX containers are the perfect option if you want to transport goods by sea or on land, or if you want to store surplus items. We are also a good option for a unique office or sleepout. You can even buy container homes these days.

If you’re looking for a shipping container to hire, or a shipping container for sale, the team at NZBOX can help you choose the perfect option. Get in touch with us today.

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