How to Prevent Shipping Container Rust

Don’t Trust The Rust ​

Whether you are buying or renting, your shipping container is a valuable investment. To get the most out of your investment, it’s worth taking some time to perform regular maintenance to prevent deterioration over time and rust is the biggest threat to the lifespan of your container.  Although containers are made with steel that slows down rust they are not impervious to it and it is important to treat rust spots before they create holes and become a problem. Rust on containers is caused by oxidation through contact with moisture and also untreated dings and dents that have lost their protective layer of paint. It is important to protect your container from moisture and treat dents promptly so that your container not only looks better but lasts longer. So what’s the cause behind your shipping container rust?

The causes of rust to your container have to do with moisture. If you purchase a used container it will indeed have some surface rust due to the over 12 years of overseas voyages. It will also have dings and dents caused by years of being handled with heavy equipment. Although your used container is guaranteed to be wind and watertight with no holes or leaks these small rust spots and dents can become a problem over time if not attended to. Your best protection is to purchase a one-trip container with minimal damage, however, if that is not in your budget there are some things you can do to prevent further rust damage. This is especially important if you live in a wet climate or if you place your container on soft or unpaved ground. These are some tips that you can use to prevent or repair rust spots

1. Keep Your Container Dry To Keep It From Rusting​

If you want to keep your container from rusting the best thing to do is to keep it dry and away from water or any moisture. These are some simple tips you can use to limit your container from moisture. It’s important to protect your container from wet and harsh weather as well as long term water exposure from trees or wet ground.

2. Tarp Protection​

The best offense is a good defense. Protecting your container from surface rust is as easy as placing a thick plastic tarp over your container when it’s not in use. This is perfect for rainy climates or snowy conditions. The tarp will protect the container from direct exposure to rain, hail, snow, and even heavy winds that may blow rocks or branches that can damage your container.  Although rust will not develop overnight, this is an important precaution to ensure that your container is protected even when it’s not in use. If your tarp is large enough, you can also use stakes to pitch a “tent” over your container for regular and easy access. Tarps do not need to be cleaned at all, and only replaced if they have major holes in them. Pitching a tarp will also protect your shipping container and it’s goods from public view.

3. Keep Your Container Off Soft Or Wet Ground

Placing your container on a concrete slab will protect the bottom of your container from being in contact with moisture over time. However, if your container is placed on soft or wet ground such as dirt, grass, gravel, or sand you can lift it off the ground to prevent direct moisture to the bottom of your container that may cause erosion and rust. We recommend placing your container on top of two railroad ties, one at each end. Railroad ties are treated and can withstand the elements such as water and bugs. Raising your container off of the soft ground will allow air to flow underneath your container so that it dries out if it gets wet.

4. Keep Your Container Away From Potentially Wet Areas​

If you are placing your container in an area with no overhead protection it is important to keep it away from areas where there can potentially be extreme moisture such as underneath a large tree or adjacent to a roof that can drain water onto the roof of the container. If you must place your container under a tree then we recommend trimming the branches to make sure your container can dry off quickly after rain or snow. 

5. Gabling The Roof ​

Some used shipping containers contain small dents on the roof due to being stacked during overseas shipping or being handled with heavy equipment. The dents are mostly concave and can cause water to pool on the roof of the container. Since these dents are on the roof of the container they often go unseen and overtime can create rust that can potentially become holes that lead to a leaky container.

One way to prevent water from pooling on the roof is to gable the roof. Gabling the roof is a relatively simple process.  To gable the roof you’ll need a 4×4 wood plank and a simple jack. From within the container you find the  low spot on the roof, place the plank at the low point of the roof and slowly push the plank into the ceiling with the jack. This should allow for the water to roll off the roof of the container and prevent it from pooling. It’s also important to inspect the roof periodically especially after rain or snowfall.

6. Power Wash Caked On Mud

Containers may sometimes have caked on mud that builds up while in storage at the depot or after rainy or wet weather. It’s important to remove this dirt before it causes rust to the container. Power washing the container with a hose nozzle that produces a strong stream of water is the most effective way to do this. Power washing also helps to prep your container before you paint or perform any other maintenance to the container.

7. Remove Surface Rust Immediately

It is highly likely that a used container will contain some surface rust. The good news is that most of the surface rust has not yet reached the internal layer of the container, and is still treatable. The bad news is, if it remains untreated it will inevitably create a hole overtime. If the rust is minimal you can use a wire brush to scrape away any visible surface rust. Follow up with  a damp cloth to wipe away any of the scrubbed particles. If the rust goes a bit deeper than the surface layer then you can use a wire wheel to remove the rust. Wire wheels are also what you would use to prep the container before painting it.

8. Repair The Roof Dents to Prevent Water Pooling

Dents in the roof are more susceptible to rust and potential holes for two reasons. One, most people don’t regularly inspect the roof of the container so damage can often be overlooked and two, water can pool on the container roof and can take a long time to dry on it’s own. The longer the water sits on the roof the more likely it is to cause rust and holes in the container. It’s important to fill in the roof dents to prevent water from pooling. The best way to do this is to fill the dents with Bondo. Filling the dents will make the surface flat and minimize water from pooling and allow the roof to drain properly. Be sure to scrape off the existing rust with a wire brush or wheel before applying  the Bondo. 

9. Spot Treat The Rust With Spray On Primer ​

If you’re not quite ready to repaint your container you can spot treat the rust spots to prevent the rust from spreading. A great way to do this is with a spray on primer made especially to protect metal surfaces such as Rustoleum. These primers can be used on metals that are rusty, provided you prepare the surface by removing existing rust so that the primer adheres to it properly. The primer will aid in protecting against further rust.

10. Paint Your Container Regularly

The best offense against container rust is to regularly paint your container. Prior to painting the container it’s important to properly prepare it by power washing it, scraping surface rust with a wire or wheel brush, filling in the roof dents with Bondo, and painting the rust spots with Direct to Metal (DTM) Primer. Although the original manufacturer paint used is made especially for  metal, regular house paint will work. See “How to Paint Your Shipping Container” for a detailed step by step guide to painting your container.

11. Paint the Roof And Gaskets Regularly

The areas most susceptible to rust on your container will be the roof and doors. As discussed previously, if the roof does not drain properly water sits and creates rust. The same is true for the doors around the gaskets. Water gets trapped underneath the door gaskets and stays wet for long periods of time which creates rust. It is important to paint the roof and anything in contact with the door gaskets regularly even more often than you paint the entire container.    

12. Regular Maintenance

The lifespan of your container is directly related to how well you maintain it. If you treat small scratches, dents and rust spots before they become a problem then you will have a sturdy and watertight container for years to come. The overall key to preventing rust from overtaking your container is to keep it dry. Here are some helpful and simple maintenance tips to follow.

  • Treat tiny scratches immediately with sandpaper or even a hard toothbrush if you don’t have a wire brush available.

  • Use trailer tape to cover even the tiniest holes in your container. Trailer tape has aluminum backing that is made especially for  metal buildings, trailers, pipes etc. and can work to seal seams and small holes in your container.

  • Using caulking for cuts and small holes in your container can also aid in sealing your container and stopping tiny holes from becoming a problem. 

  • Repairing large holes can be expensive and may require a professional welder and patch work  that can ruin the integrity and look of your container. This can be avoided with some proper TLC. Although all of our containers are guaranteed to be wind-and-watertight, we recommend checking your container upon delivery to ensure that the container is in proper wind and watertight condition.

Here’s a video to learn more information about treating rust spots on your shipping container:

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