How to rustproof a shipping container (5 steps)

In this blog post we will answer the question, “How to rust proof cast a shipping container”. We are going to cover different ways of rust proofing a shipping container, the process and the benefits of rust proofing.

How to rustproof a shipping container?

You can rustproof a shipping container by the doing the following things:

  • Avoid constant water contact e.g. rain, snow or moist weather
  • Put a layer of material which is non – corrosive over the steel layer of the container
  • Apply corrosion coatings that include zinc, aluminum, or zinc-aluminum blends
  • Inspect the container regularly
  • Improve ventilation in the container
  • Applying zinc paint

I will further elaborate on the above mentioned points for rust proofing a shipping container

Avoiding water contact

Moisture induces the steel metal to oxidise, resulting in the production of rust. As a consequence, ensuring your container is as dry as possible is critical. 

Consider building your container’s foundation on an elevated platform to avoid contact with groundwater, snow, or ice. Because water collects in this location, the bottom surface of container doors is also prone to rusting. Every day, thoroughly clean and dry your container floor.

There should be proper vicinity in which the container is put or the covering of the container with a simple shelter can solve the problem significantly.

Materials neededLarge silica bags

Steps for moisture proofing:

  1. Placing a couple of large silica gel bags inside a shipping container to moisture proof it

Corrosion coatings

They extend the life of containers by preventing sacrificial corrosion on the steel surfaces. The coating has a thickness of around 100 m and gives 15 to 25 years of protection, depending on the environment. 

Following the corrosion coating, you can add a topcoat of paint without altering the corrosion protective qualities.

Inspect the shipping container regularly

Examine the shipping container for any symptoms of rust before buying it. Check the container’s base, the bottom region of the doors, and other spots where water appears to be trapped for signs of rust as soon as possible after it has been delivered to your property. 

Keep an eye out for dents and deformations in the paint because damage to the paint might speed up the rusting process.

Ventilation in the shipping container

Because the container is hermetic and waterproof, condensation can form within, posing a risk of oxidation and condensation. This issue can be solved by enhancing your container’s ventilation.

Material NeededTools needed
12 inch whirlybird turbine ventReciprocating saw with metal cutting blade
Universal shipping container adapterGrinder (8 in maximum thickness)
Eyewear and hearing protectionDrill and Drill bit
RagAcetone
PencilMeasuring Tape
Masking Tape
Caulking Gun

Steps for installing ventilation on a container:

  1. Based on the climates and conditions, decide the location you want the vent. Line it up from the outside walls. If you choose to install the vent on the roof, check that the vent’s bottom end is elevated to the exterior.
  2. Wear your safety gear like gloves and goggles, for this project. Use the angle grinder and cut the opening on the walls to fit your ventilation frame.
  3. Find an area that fits the best. Avoid any that looks uneven due to dents or warping. Make sure the edges are straight and that the opening is a perfect square.
  4. Mark the edges of the vent.
  5. drill one hole in the container in one of the center corrugations and install a screw 
  6. On the drill a hole and install a second screw in the opposite center corrugation
  7. Drill the remaining holes and then remove the two screws
  8. Move the universal adapter aside taking note of which way is facing when installing the unit should face the same way to match the marked holes
  9. Using painters masking tape mask a quarter inch outside of the pencil line
  10. With the supplied abrasive pad thoroughly scuff the roof from the tape line to at least 2 inches inward this will prepare the roof to bond with the adhesive
  11. Measure and pencil to Mark’s approximately 5 inches inside of the line
  12. On each side with your measuring tape then align to your marks and draw a 12 inch by 12 inch square this will be the hole that you will cut using a grinder with a maximum eighth inch thick cutting disc
  13. Start your cuts in two corners you can also use a drill and bit the same size as your reciprocating blade to start your corners
  14. Follow the lines to cut the 12 inch by 12 inch hole with your reciprocating saw
  15.  Using the supplied 3m 5200 adhesive apply two parallel 3/8 inch beads at half-inch and one inch inside the tape line
  16.  Center the universal adapter lining it up with the previously marked holes and ensure that the adapter is facing the same direction with the screws provided in the installation kit
  17. Tighten all the screws alternating from one side to the next so that the universal adapter seats uniformly
  18. Place your 12-inch whirlybird turbine vent onto the mount the screws provided with the installation kit
  19. Seal the frame from the inside of the container.

The process of rusting on a container

Rusting is a reddish brown compound which usually occurs when the exposed surface of the material (in this specific case a container) comes into contact with the oxygen in air or chloride in water. 

A chemical reaction takes place and the external layer of the container gets rusted. Gradually, the rusting takes its toll and it digs deeper until it affects the container’s characteristics to the point where it becomes useless. This is the common phenomenon of rusting.

There are two main types of rust:

  • Structural
  • Non-Structural

Non – Structural rust is when rusting takes place on the external layer of the material and it is common and easily treatable whereas the real damage begins when the rust seeps in and damages the container. This is called structural rust.

Tracing down the rust

To trace down the rust it is important to examine the surface of the container. If the rust is on the surface then the surface will feel quite rough but one can feel the metal intact underneath, this is structural rust.

However, upon examination, if one feels that the layer is forming into a ditch and that there are cracks forming on the surface then this is the rust of non – structural type.

Non – Structural Rust 

Structural Rust

Treatment of rust on shipping containers

In case, you have not been able to prevent rusting due to whatsoever reason you should try to treat the surface as soon as possible. The rust may be only non – structural by then and the damage further can be eliminated.

  • Local Treatment

You might begin by wire brushing the corroded portions and then sanding them down. Rubbing vinegar on the damaged regions and allowing it to dry is a good idea. 

To cover the cleaned portions, you can use DTM (direct to metal) paint. Clean the spots with diluted Ospho and then prime and topcoat the surface.

  • Sandblasting

The most common method is to sandblasting the rust away, covering the material from further exposure and then painting the surface.

Sandblasting requires sandpaper and the process can be manual by hand or utilizing a proper sandblasting tool as per the area of the rust. Sandblasting takes the rust away and brings the undamaged layer on top once again. 

You should sandblast until the rust completely wears off and the surface turns smooth. It is yet also recommended to use a wire brush first before sandblasting for better results.

Materials NeededTools needed
Mineral sand to remove rust and paint.Portable blaster
Plastic or a soda abrasive around sensitive areas.Compressor with a minimum of 80 PSI at 5 cubic feet per minute (CFM)
Glass beads for a smooth finishNozzle about 9.5 mm
Walnut for blastingShort hose

Steps for sandblasting:

  1. Lay down a tarp in an open space to collect your blasting media. (Do not sandblast in non ventilated areas)
  2. Add the blasting medium into the hopper. Tear off a corner from the bag of your abrasive. Either use a hand scoop or pour the medium directly from the bag into the hopper. Fill the hopper to the top with the abrasive.
  3. Attach a hose from the compressor to the hopper. There will be a port on the back or side of the hopper to attach a hose.
  4. Turn on the compressor and test the blaster on a scrap piece of material.
  5. Hold the nozzle at a 45-degree angle 6 in (15 cm) from the material. If the nozzle is too close, the material will be damaged or warped.
  6. Blast the material in smooth, back and forth strokes until it is clean. Overlap your strokes in the area you’re blasting so you remove all of the residue.

Once you are done with the sandblasting, you should cover the surface with an agent that has anti – oxidizing properties. Mostly, vinegar has been used for this purpose since it is quite available and not much expensive in comparison to other agents. Put the vinegar on the sandblasted surface and let it dry.

In the end after the vinegar has dried out, paint the surface to finish the process. The paint should be marine grade DTM (direct to metal). 

  • Zinc painting

Because zinc paint has the ability to inhibit the growth of rust, you can go ahead and try this cathodic technique. Zinc ensures electrical conductivity with the underlying steel when coated on rusted areas. 

At least 90% dry zinc powder should be included in good zinc paint. To avoid corrosion, you might also bolt or weld zinc anodes into the hulls.

Materials neededTools needed
Thicker brighter 69% zinc paintGrinder with sanding pad
Greco magnum sprayer and extension
Complete Suit Trudsafe Full Face Respirator

Steps for zinc painting:

  1. Grind and sand all rough and corrosion affected areas.
  2. Pressure wash the container to remove any saltwater and allow to completely dry.
  3. Paint the surface with primer and let dry.
  4. Spray paint the container and let dry.
  5. Second coat the container with the paint again and let dry.

Benefits of rustproofing a shipping container

  • Rust has a terrible visual appearance.
  • It can have a detrimental impact on resale value, especially if the rust is only on the surface.
  • When rust begins to form, the resulting corrosion can be exceedingly costly to fix.
  • Once the rust reaches its worst stage, it could be a dangerous concern for neighbouring residents or anyone who comes into contact with it.

Conclusion

Rusting of shipping containers have become a major problem in the commercial and trading industry. Most businesses do not know how to track down and eliminate the root cause of rusting due to lack of knowledge. This causes monetary losses but after the thorough examination of the material and the proper understanding of the process, businesses will likely come to the understanding that the problem can be easily resolved.

Frequently Asked Questions (FAQ)

How do you keep rust off a shipping container?

It can be done through eliminating the contact with the oxygen and chloride in the environment i.e. contact with moist air and water. Sheltering, covering and isolating the container from air and water are two main solutions.

What kind of coating do shipping containers need in order to avoid rust?

The coating must have a compound of non – corrosive nature. The most commonly used compound is Zinc Aluminum. However, depending on the budget, polymer and other coatings can also be used.

How long will a shipping container last?

A common shipping container takes about 20 – 25 years. However, the period can vary depending upon the care and treatment of the container.

Are shipping containers waterproof?

In most cases, yes. Shipping containers are waterproof and they can withhold their strength against strong weathers as well.

What type of steel is used in shipping containers?

The common type of steel used in shipping containers is corten steel. It is highly durable and non – corrosive in nature.

References     https://www.discovercontainers.com/shipping-container-home-rust-and-corrosion-treatment/

https://caddetailsblog.com/post/how-should-i-protect-my-shipping-container-home-from-rust
https://equipmentmanagementservices.com/how-to-identify-prevent-and-treat-rust-in-your-shipping-container-office-or-home/

 https://usacontainers.co/keeping-rust-and-corrosion-away-from-your-conex-box/  https://www.containerhome.info/shipping-container-homes-and-corrosion-rust-issues.html

https://www.containeraddict.com/how-to-paint-a-shipping-container-best-paint/
https://blog.mobilemodularcontainers.com/prevent-your-shipping-containers-rusting
https://www.wikihow.com/Sand-Blast

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