Can Shipping Containers Rust?

A shipping container is a significant investment, so you’ll want yours to last. And you don’t want to face endless maintenance just to keep the container in good working order.

Rust is enemy #1 on both fronts.

Can shipping containers rust? Short answer: yes, shipping containers will rust.

Slightly longer answer: shipping containers have bad rust, which you need to deal with. But they also have good rust, which you don’t need to worry about at all, and which actually helps to protect your container and extend its life.

In this guide we’ll share everything you need to know about shipping container rust: the good vs the bad, how to tell one from the other, and how to find and fix potential rust-related issues early – before they turn into something bigger.

Corten steel and good rust vs bad rust

Rust is usually bad: it weakens structures by eating away at the metal they’re made from.

Shipping containers are made from corten steel, aka weathering steel. Corten steel is different. Rather than weakening and eating away at the metal, the outer layer of rust actually protects the steel beneath. It forms an impermeable barrier that corrosives like moisture and salt struggle to penetrate.

Corten steel is why shipping containers have service lives of 15+ years while stacked high, full of goods, and getting battered by waves, weather and salt spray on the open ocean.

But that’s not to say that all rust is good rust.

A surface-level layer of oxidation on the outside of a shipping container is fine. But if it penetrates deeper, or develops on the inside of the container, rust can turn from friend to foe. It can weaken the container’s structure, risking collapse, and it can eat holes in the container, exposing valuables to water damage or theft.

To recap:

• External surface rust = good.
• Internal/structural rust = bad.

Causes of structural rust

Bad shipping container rust develops in a couple of main ways:

• Dents and scratches: If the exterior is hit or scraped by a forklift, crane or another container, the paint and protective rust can be removed, exposing deeper metal. This can result in ‘pitting’, where rust eats away at a point in the container.
• Standing water: If you place your container on a surface that is prone to puddles or waterlogging, or if there is a slight sag in your roof that leads water to building up in certain spots, the constant exposure to moisture can lead to deep rust.

High-performance coatings and paints

How do you stop rust from developing? While corten steel will organically develop a protective layer of rust, the longer you put that development off, the longer the container will last, so the first line of defence is a high-performance coat of paint.

Before they enter their service life, and face 15 years of marine corrosivity, shipping containers are given multiple protective coats: a zinc-rich epoxy primer, a thick epoxy mid-coat, and a UV-resistant and decorative topcoat, usually branded with the shipping line’s logo and colours.

If you choose to invest in a used container, it’s wise to give it a fresh coat of primer and paint. The specific type will depend on your local climate and what you’re using the container for: check out our complete guide to painting containers for the whats, whys and hows.

Prevention and maintenance tips

The longevity of your container depends on how well you keep on top of potential rust issues. Prevention is better than cure, so your first priority is to avoid structural rust developing in the first place:

• Apply a fresh coat: Give the container a new coat of primer and paint.
• Keep the feet dry: Place it on dry ground, or elevate it above the ground on foundations like concrete piers, strip footings or timber beams.
• Keep the top dry: Ensure rain drains off the roof rather than pooling.
• Clear debris: Remove any leaves, dirt and detritus that could trap moisture against the steel.

But totally preventing the development of rust is essentially impossible, so you’ll need a backup plan:

• Six-month inspections: Conduct a visual check of your container twice a year, looking for new rust, and checking door gaskets and hinges to ensure moisture isn’t getting in.
• Check for spider rust: Keep an eye out for spider rust, aka ‘rust creep’, which forms a web pattern as it spreads beneath paint.
• Spot fix issues early: If you see signs of rust, sand back the affected area then prime and paint it so that the newly exposed metal is completely covered.

Find your perfect container today

While shipping containers will inevitably rust – it’s a design feature of corten steel, after all – keeping on top of rust issues is critical to protecting your investment, as a well-maintained shipping container can last decades.

 

Ready to secure a shipping container with a long life ahead of it? We’re here to help. At shipping-containers.com.au we’re a 100% independent platform that can guide you to a shipping container that will last. We assist you in identifying the ideal container for your situation, then we connect you with local, vetted suppliers and modification partners who can deliver.

Start your shipping container journey today