The brainchild of Malcolm McLean, a trucker who saw the need for consistent shipping sizing and reliability, the shipping container was invented and patented in 1956. The Dictionary of International Trade, by Edward Hinkelman, describes the shipping container as needing to be of permanent character and accordingly strong enough to be suitable for repeated use, and conform to the International Standards Organisation. By ISO definition, a shipping container is a single, rigid, sealed, reusable metal box in which merchandise is shipped by vessel, truck, or rail. Everything about the shipping container is durable – and for many reasons! Their general and conventional uses, like being stacked, being shipped across seas and land require them to be hardy even when they’re older – which also means the materials they’re made of need to be hardy. This hardiness has spawned a large range on unconventional uses, like building houses out of containers.
Shipping containers are specially designed with corner casts that lock into each other, so when they are loaded onto ships they can be stacked on top of each other and kept in place. With the corner casts designed to take most of the weight of the container – most can handle enormous loads, more than 60 tonnes on each corner – they can be loaded or unloaded when stacked. Not only is this perfect for ship loading and time minimisation but also when they are unloaded, they can be stacked at the ports, ready to be on-sold. Containers can be stacked up to 8 high normally, no matter if they are 20ft or 40ft in length. The structural support these corners provide also makes them a choice when deciding on building materials, and explains the recent move towards shipping container housing and offices.
When shipping containers make their first journeys around the world, they are usually brand-spanking-new. As they’re made from heavy duty, hard wearing Cor-ten Steel, and carefully painted with corrosion proof, weatherproof paint, they can take a fair amount of bad weather. One of the reasons for this careful assembly is that first trip on the container tanker, where the containers could be subjected to all kinds of bad weather from general sea spray to hurricanes. Wherever the containers go to make that first trip, because they’re able to be stacked, their durability and their materials, they’re able to be made useful immediately after they’re unloaded.
Shipping container floors needs to match the rest of the container and be particularly tough. To do so, since conception the floor of a container has been generally made out of hardwood plywood. Hardwood Plywood is extremely durable – and can withstand more than 6000 loading and unloading in its lifetime, and take large amounts of weight. However lately the fact that the trees used for hardwood plywood grow so slowly, and to prevent deforestation, there has been a change to using bamboo for flooring. Manufacturers are often using bamboo now, as it grows fast, and thick, and it can handle just as much wear and tear as hardwood plywood.
Load weights are carried through corner posts – and this is because the roof of the container is only designed to take a weight of 200kgs over a 60 x 30cm area, or the amount needed for a man to do maintenance from above. The only real weakness or vulnerability of a shipping container, this is why shipping containers can only be stacked when locked corner to corner, and should not be cut without considering structural damage. Architects for unconventional projects like houses have managed to avoid issues with this structural flaw by using cantilevers, and avoiding the weak roof.
Shipping containers have many benefits, and generally they can last 25 years just on its own. A container will have certification for sea in the first 5 years of its life, and after this it will depend on the condition – so usually they will only be used for 5 to 10 years before they are released to the public to be bought and sold. The containers are graded to show you when you buy it what kind of condition it’s in – and these conditions can vary between companies. To increase the lifespan of your container, there are a few different options you can do – for instance, having the container refurbished (re-primed and painted and dents and rust buffed), or refurbish it yourself. Regular cleaning and checking the container for rust and mould (in the floor) can also help.
Hopefully this article has shown you just how durable a shipping container is! If you need any help with your container, remember to call the Container Traders on 1300 89 89 70!