The Type of Metal Used For Shipping Containers

Sheet Metal Used For Shipping Containers

When you think about the weather and elements that a shipping container is subjected to, it's a wonder that they are still standing. From local weather based on location to being stacked on boats and shipped across the salt water seas, what makes these shipping containers so durable? Well it comes down to the type of steel that's used to build them. Here Porta-Stor will take a closer look at all of the factors that make shipping container steel the best option and how it came to be.


COR-TEN is United States Steel's trademark for their created brand of weathering steel. The COR stands for 'corrosion resistant' and the TEN stands for the 'tensile strength.' The metals that are contained within this type of steel are usually iron, copper, manganese, nickel, and chromium. There are also other elements in this steel that are not metals, such as carbon, sulfur, and silicon.

COR-TEN is also the steel that is used on bridge towers as well as rail care and even outdoor sculptures.

So why is this material important, and why is it a better option than the steel shipping containers that are meant for a one-trip-lifespan across the sea? It's created out of a chemical makeup that, when exposed to the elements, allows for a slower process of rusting, and the rust that does form will adhere to the surface of the steel instead of eat into it.

COR-TEN Steel on Shipping Containers

When a new shipping container is built, the first line of defense applied to this steel is a solid coat of marine-grade paint. This gives the container an extra line of protection from being banged around on a cargo ship or truck. As this paint starts to wear thin over time, the properties of the steel itself will then form a second layer of defense.

This is where that thin layer of rust comes into play. It can actually help give a new layer of protection to the container and will help slow the process of completely rusting out. This layer that comes out after the paint wears thin now acts as an anti-rusting patina for the container.

How To Protect Your Shipping/Storage Container

If you're using a shipping container for a storage unit or some other purpose, you are sure to want an extended life for it. To accomplish that, there are a few simple steps you can follow to ensure that you can use your shipping container for years to come. You need to first remember that COR-TEN steel is not rust-proof.  It will slowly corrode. Pay attention to any pockets or dents in the container. You do not want water to speed up the oxidation process of the steel. Also, you should make sure to pay attention to the welding seams of the container and keep an extra coat of outdoor paint applied to them. This paint will act as a sealer over any small cracks or chips that you may not be able to see.

Your container needs to undergo a regular process of getting wet and then drying for its rust layer to do its job and prolong the life of your container. That's why it's important to check crevices and welded spots to make sure they are always dry, free of dirt, and sealed with a rustolium/outdoor paint, so more damaging rust spots don't form.

If you want more information on shipping containers, check out Porta-Stor's other blogs, such as this one that goes over how to expand your business using containers!