Alexander is a professional engineer who specializes in the construction of affordable houses and structures using recycled materials.
Shipping containers are manufactured using COR-TEN steel. A very strong and sturdy type of steel, which allows it to remain stronger than any other fabricated system. Also known as the Weathering Steel, the alloy it was made from is designed to cater to weather conditions without the need to keep painting.
The secret of the pioneering engineers was to allow the container to rust just enough to avoid corrosion. Unfortunately, after a long time using the shipping container, the damage is prone to occur. So when you purchase your container, especially second hand, you will find dents, scratches, and numerous rust patches.
So what do you do after that? Read further and find out more.
Protective Clothing That you will Need
● Nose cover-up
What Causes Shipping Containers to Rust?
Rust on metal is a very normal occurrence, in fact, many will prefer rust on the container because it will provide an additional layer of protection for the box. What's disheartening is that it looks very ugly, and continuous exposure to water will further damage the container.
So what happens to the corten steel that makes it rust?
The underlying reason is that extended periods of exposure with saltwater as the containers are being transported over the sea will cause the steel to react to the salts giving it a brown-orange rustic yet antique look.
Chemically speaking, however, the weathering steel will try as much as possible to avoid reactions between its chemical compounds and water, but with continuous use, the steel will give in. On a positive note, corten steel does have the strongest alloy compared to other mild steel that requires a protective barrier.
Another factor that causes shipping containers to rust besides exposed to a moist environment is its use. During transportation, the containers are stacked on top of each other all the time hence they tend to scratch and push against each other. This movement back and forth strips the container its material integrity.
This greatly affects the corners and welded areas as they are the stress points in a shipping container. The weaker the areas are, the more likely they are to rust.
Why is Shipping Container Steel Stronger Than Other Types of Steel?
Shipping containers are manufactured using COR-TEN steel. A very strong and sturdy type of steel, which allows it to remain stronger than other types of steel.
How to Treat Rust on Your Shipping Container
We have already established that rust is more probable to occur than not. So what do you do when you see those patches? How do you remove and treat them?
Removing Rust on the Shipping Container
You need to clear up that area of the rust first. Many will encourage you to use sandblasting where you scrape off the entire paint along with the rust patches as a way of clearing out the impurities and best-looking areas on the steel. Before you decide if you want to take on this sandblasting technique, here's something to consider;
- The Price of Sandblasting - It's rather expensive to take up sandblasting the entire shipping container especially if you have a tight budget.
- The age or Outlook of the container - There are different types of second-hand containers available for sale. If it is over 15 years, the process may not be worth it as you will greatly compromise the quality of the box.
- Painting Systems - Different types of paint have different features. For water-soluble, once you add a double layer of paint, the creases of paint below may not be seen because it forms a solid rock finish once it dries.
If you place all these into consideration, you can choose to lease one and blast the container. If not, there's is always the easier method, something similar to a DIY process.
Easy DIY Cleaning
Take your supplies such as the wire brush and sandpaper and clean off the rust patches along with areas where the paint looks old and ugly. Ensure you do that on all the four sides placing keep attention to the corners and vertices.
After that's done, take some vinegar and wipe off the area you have scrubbed. The purpose is to see whether the area is smooth enough to apply your layer of paint. If there are stick pocket-like objects or shavings and scrapes; keep brushing with the sandpaper.
One factor you should keep in mind is that you need to be gentle while scrubbing to avoid making holes, especially where the rust patch seems almost completely overhauled in that area. Another thing is that you have to keep safety first.
Rust and other oxides you will be removing tend to releases poisonous and hazardous gases and chemicals. So you should invest in protective clothing such as;
- Nose cover-up
These items should prevent any allergies you can get once on contact, or protect you from inhaling the gases.
Treating the Rust Patches on a Shipping Container
Once you have thoroughly cleaned the rusty areas, it's time to fill up any gaps, spaces, or holes that may be left after the cleaning process. You can use foam to coat those areas or apply Corroseal.
This is just a smoother used to show any parts that may need further cleaning or something else. After that, apply a rust primer and you can spray paint the shipping container with a color of your choice. Coat it twice to fully cover and layer the shipping container.
If you had difficulties using the sandpaper and wire brush, plus you didn't want to incur the extra expenses of sandblasting, you can get a pneumatic orbital sander with a coarse grade disc. It will also effectively remove the dust granules, paint, and rust on the container.
It will leave a clean surface for the paint to adhere properly. You can use a primer, insulating paint, or a flex seal to fix the holes first, then adding the paint on top.
How to Prevent Rusting
1. Regulate the wet and dry cycles.
2. Purchase a container that it's far off rusted.
3. Invest in good quality paint.
4. Zinc paint.
How to Prevent Further or Future Rusting
Weathering steel is best known for its corrosion resistance. It provides a protective layer of oxide that prevents further rusting that could adversely affect the structural abilities of the shipping container. But even though it can resist the corrosion, it can't withstand forever.
You'll need to find a way to maintain the appearance of a rust-free shipping container home. Here's how you can do that;
- Regulate the wet and dry cycles. The steel will form a firm oxide layer when first introduced to the moisture. But it'll keep on deteriorating and diminishing in strength the more it keeps getting rusty.
- Purchase a container that isn't far off rusted. For a five-year-old container, the exposure to seawater and oxygen will be so severe that the hydra III oxide will have chewed up the container.
- Invest in good quality paint. The type if the paint you use could determine if you'll need to repaint it again or if it can be affected by rust again. Water-soluble paint will dry completely leaving it safe to use, but for the enamel coating, it may only be good for the shiny finish.
- Zinc paint - Applying a zinc paint coat can slow down the process of shipping container rust significantly. By the process of 'cathodic protection,' the zinc slows the process of the rusting of the underlying steel. Quality zinc paint should contain at least 90% dry zinc powder.
Those few tips should help you prevent your shipping container home from being affected by rust.
Maintaining a Rust Free Shipping Container Home
Sometimes, you need to be cautious and protective of your assets even before you acquire them. You have read that rust can occur from various causes; moist environment from the location you have placed the container, exposure to saltwater and oxygen, and structural rusting by moving and scraping.
As so, it's important to learn how you can maintain your shipping container home right from when you decide to purchase your shipping container. Let's take a look at these major factors to look for during the process of maintenance.
Your architectural plan should highlight the location of your home. If you could set base in an area with less exposure to weather conditions such and floods, you can help shelter the shipping container home from getting into contact with a lot of water that can damage it.
You can also invest in the shade to protect the container from excess heat from the sun. The ultraviolet rays can be strong affecting the integrity of the paint or could cause condensation that can form rust patches or mold. If you want to stay close to waters like the beach, maybe stay over 3 miles away to avoid the salty air that could cause oxidation and finally rust.
You should also check to see that the foundation can't affect the weathering steel on the shipping container.
2. Inspections of the Container Condition
Next up, it is essential that you thoroughly inspect your shipping container. Look at the top, bottom, as well as the sides. Pay close attention to the area under the floor. This space may have been exposed to excess water and the elements.
Make sure the container is well washed off the impurities and extra dirt around. Check the flooring to see if it is affected by water, harsh pesticides used in the hardwood or other elements. You can then look into painting the container.
One of the best ways to prevent excess rusting is by using an insulating paint. They are usually hard to crack and offer numerous advantages. In this section, there are various types of insulation you can choose from;
- Spray Foam - This insulation forms a vapor barrier with the container, thus reducing condensation and mold. It can be applied to the exterior and interior. It will keep the appearance of the container and the convenience of the insulation.
- Insulation panels - These panels provide excellent insulation for their thickness. They include different types of foam insulation thick enough to cover the walls.
- Blanket insulation- yet another thick type of insulation that needs to require stud walls for placement, which will decrease floor space. It is the least expensive form of insulation, however.
- Eco-friendly - you need to have something hospitable to stay in. Ans since one reason for living in shipping container homes is eco-friendliness, using eco-friendly insulation is consistent with your philosophy; wool or cotton insulation is effective but expensive.
Choosing either of these options will allow you to protect the outer coating of the weathered steel.
4. Knowing the Signs of Possible Corrosion
Always keep an eye out for any signs that the rusting has become worse or the corrosion has spread. You can easily do this by undertaking regular inspections.
Check on the dented area, where the welding has been previously done, look the roof or walls after extreme weather conditions. If there's a small dent or mere damage, repair it as soon as possible.
After a rainy season, check to see the roof isn't holding on to much water as this also poses the risk of faster corrosion. Always look at the small details to ensure that they are been handled as soon as they occur.
As mentioned above, you can follow either of these methods to treat the rust once it occurs. Don't wait out until the holes have already formed. You can conduct sandblasting to even out the painting surface if it fits within your budget seeing that it's rather expensive.
You could simply use the sandpaper and brush to quickly get the rust off the container gently. you wouldn't want to strip off its protective layer that features a very high-quality marine-grade paint and a zinc coating that protects from further rusting.
From this article, you have learned the major elements of how you can remove and treat rust on your shipping container. Upon modification, you want your home to look beautiful and rust-free. If you heed all the guidelines above, you can enjoy long-lasting painting on your shipping container.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2019 Alexander Okelo