--- title: "corten steel: Definition and Meaning | NPSA" description: "Corten steel is a weathering steel alloy used for the walls and roof of most standard shipping containers. It contains copper and chromium." url: https://npsa.preview.multisites.ai/glossary/corten-steel publisher: National Portable Storage Association (NPSA) phone: "(816) 960-6552" email: info@npsa.org --- Materials and construction # corten steel Corten steel is a weathering steel alloy used for the walls and roof of most standard shipping containers. It contains copper and chromium. When it is exposed to weather, it forms a stable, rust-like surface layer that protects the metal below. COR-TEN began as a trademarked name. ## Why it matters Corten is why a container can sit outdoors for years with little care. The surface layer slows further rust, so the steel does not flake away like ordinary rust. Operators still need to watch the weak spots. Water pools along the bottom rail, and if the protective layer is damaged by scrapes, cuts or repairs, rust can develop. A common mistake is to think corten means rust-proof. It resists corrosion but is not rustproof. Another is to expect every storage unit to be corten. Some mobile storage units use other materials. After welding or patching, clean, prime and paint the repair so the protective layer is not left open. [Read: Container modifications for rental: Doors, windows, lock boxes and HVAC](https://npsa.preview.multisites.ai/guides/container-modifications) Definition source: [hz-containers.com](https://hz-containers.com/en/news/shipping-container-parts/) ## Related terms [### weathering steel Weathering steel is a group of steel alloys that form a stable outer layer of rust, which removes the need for painting. U.S. Steel introduced it in 1933 under the COR-TEN name. It is widely used in intermodal containers, bridges and outdoor structures.](https://npsa.preview.multisites.ai/glossary/weathering-steel)[### corrugated steel Corrugated steel is sheet steel pressed into a pattern of ridges and valleys. Shipping containers use it for the walls and roof. The ridges add stiffness, so a thin panel resists bending and racking forces during ocean transport, lifting and everyday handling.](https://npsa.preview.multisites.ai/glossary/corrugated-steel)[### 14 gauge steel 14 gauge steel is steel sheet about 0.0747 inch (1.9 mm) thick on the standard steel gauge scale. Many sources name 14 gauge corrugated corten steel for the walls and roof of a standard shipping container. Actual builds can vary by maker.](https://npsa.preview.multisites.ai/glossary/14-gauge-steel)[### container repair Container repair is work that fixes damage to a container, such as holes, dents, floors and doors. The IICL repair manual says the purpose of any repair is to restore structural integrity so the container can work safely in intermodal transport. Methods include straightening, welding, patching, inserting and replacing parts.](https://npsa.preview.multisites.ai/glossary/container-repair)[### patch repair A patch repair fixes a damaged container panel by welding a steel plate over the damage. The IICL manual treats it as one option when straightening or welding will not work. In the same section, an insert replaces a cut-out damaged section instead of overlaying it.](https://npsa.preview.multisites.ai/glossary/patch-repair)[### shipping container A shipping container is a standardized steel box used to move freight by ship, rail and truck without unloading the goods. Most are rectangular, closed boxes with doors at one end. Many are reused for storage after their sea service ends.](https://npsa.preview.multisites.ai/glossary/shipping-container) [All 220 terms](https://npsa.preview.multisites.ai/glossary) For the industry ## Grow your portable storage business with NPSA Members get event rates, the Community Forum, the directory listing and leads from this website. [Join NPSA](https://npsa.preview.multisites.ai/join-us)[See member benefits](https://npsa.preview.multisites.ai/member-benefits) Need storage? ## Get quotes from NPSA member companies Tell us what you need and where. A member company that serves your area will contact you. [Request a quote](https://npsa.preview.multisites.ai/request-a-quote)[Which unit do I need?](https://npsa.preview.multisites.ai/find-storage)