HOW SHIPPING CONTAINERS ARE MADE_10
Monday, July 03, 2017

HOW SHIPPING CONTAINERS ARE MADE

We spend a lot of time on social media showing all the possible applications and unique features of our shipping containers. Thanks to their modular design and solid construction, they are suitable for various uses including durable means of transportation, secure storage spaces and even safe enclosures to work in. But we never spent time discussing how shipping containers are built. Their fabrication process is important to our understanding of their safe and effective means of modification, but we also find the process fascinating and worth sharing with you.

Although construction takes place in specialized factories equipped with advanced pieces of technology, the process itself begins with a simple roll of steel. The steel is unrolled and cut into separate sheets that are later welded together to create the walls, roof and doors of the container. Each sheet of metal is degreased, shot blasted and treated with zinc rich primer. The copper reacts with the metal to form CORTEN steel, the material that gives containers their well-known anti-rust properties.

The sheets that become wall panels are pressed and corrugated to give the container more strength and structural integrity. Depending on the type of container, holes are drilled to create ventilation points which are later covered with weather-proof ventilation covers. The sheets that become part of the roof undergo the same pressing and corrugation process but the corrugation pattern is different and requires a bit of an angle to allow water to escape the roof.

After this treatment, all side wall panels are welded into one solid sheet of metal and each side wall is welded to the bottom and top rails. The top rail profile is steel tubing, also known as a rolled hollow section rail.

At the same time, the assembly of the floor frame takes place. The floor setup is pretty straightforward where side rails are welded together to cross members at predetermined measuring intervals. The cross members give the container more structural support and allow for standard sized forklift pockets to be built in. The cross members also give the container floor more support to support the weight of the cargo that goes in.  

The step that follows is the assembly of the container doors and essentially the entire rear of the container. Each door is built out of a sheet of corrugated CORTEN steel and has 2 pieces of steel tubing and 2 pieces of C-Chanel welded all around it to form one solid door. This process is repeated twice, so 2 doors can be built. The 2 doors are installed within the rear frame of the container which is constructed simultaneously. The frame’s construction includes corner castings and all the hardware necessary to install the 2 doors within the rear frame, and later, the entire rear frame to the rest of the container.

It is at this point that everything starts to come together. The rear frame is attached to the sub assembly of the container, the side walls are welded to the bottom frame, the front is installed and then its roof is welded on top.

To remove imperfections caused by welding, the container is shot blasted once again, primed and then painted. To ensure the paint adheres to the surface of the container, the entire assembly is introduced to a temperature controlled drying room for a certain period of time. Once the paint has fully cured, bamboo flooring is installed inside it. Sheets of bamboo are pre-cut and screwed directly into the bottom frame with self-tapping screws. Several flooring options are available, but we choose bamboo because of its environmentally beneficial qualities. Bamboo is durable and more widely available, unlike rarer woods that are more scarce.

The last step of the installation process involves a series of small steps that end up making a huge difference. All the door hardware is installed including locking bar handles and lockboxes. Then rubber weather stripping is installed all around the container doors to make it watertight. Weather-sealed ventilation covers are installed on top of the ventilation holes that were previously drilled in and all the container identification markers are added on – this includes container identification numbers, CSC plates and ISO size and weight measurements.

The container then continues down the assembly line where its underside is waterproofed with a tar undercoating. The last stop on the assembly line is a testing facility where the container undergoes several tests to ensure it is safe to handle cargo, it is watertight and it can sustain a certain cargo weight and volume. As the final inspection is completed, the container is now finished and ready to make its way to our yard.

From there, we make our own modifications to create more usable enclosures, like mobile offices.