How are shipping containers are constructed? We get this question a lot. Our typical answer is "solid" or "heavy duty". However, if you want more details, here's what we've researched.
Roofs and walls: Generally speaking, there are two kinds of materials used in the construction of roofs and walls for shipping containers.
- The more common containers use 16 gauge corrugated steel sheet Corrugated steel sheet is cost effective and is easy to repair. This is much thicker than the steel they use to make your car.
- Sometimes, we come across aluminum sheet. The aluminum has a lower tare weight but can be easily dented and is harder to repair.
Floor: The floor is generally made of wood, usually planking or plywood. The standard thickness for international shipping containers is 1 1/8" thick. Although wood is relatively expensive, it has substantial advantages over other materials; it is strong and resilient, does not dent, and may be easily replaced during repairs. Underneath the floor, there are steel cross members that increase the strength even more... enough so that you can put up to 28,000 kg in a single 20' container.
Paint: Because of the long-term exposure to the marine elements, containers are manufactured with some amazing paint. The bare steel container surface is primed with a zinc rich primer and once dried a final top coat of marine paint is applied. This marine paint usually contains zinc phosphate and is based on acrylic resin and non-chlorinated plasticizer.
Corner Post: The corner post is the steel corner supports of a container which bears all of the weight when containers are stacked. ISO Standards state that the corner posts of an ISO Series 1 containers should be tested to a load of 86,400 kg. This is the load applied to the posts of the bottom container in an 8-on-1 stack. That's pretty incredible!