GregCortezz's blog

So you bought your own shipping container and are using it for storage. One of your first questions now that you are the proud owner of a Conex container is “What do I need to do to take care of and maintain my shipping container?”

 

The good news is that by their very design, shipping containers are constructed out of heavy gauge steel and built to be durable for many years, with minimal maintenance.

How long do shipping containers last?

You can expect to get a minimum of 15-20 years of use from your shipping container. When a Conex container is retired from international cargo containers for sale service they are resold as wind and water tight units into the storage market or to be repurposed for other uses.

 

With some basic preventative maintenance and planning, your sea container can easily serve you with a further fifteen or more years of use.

 

Annual inspection of your storage container

Mark your calendar to make an annual inspection of your storage container. Check for any indications of structural rust, especially in the frame parts of the box where water may have collected for any period of time. Inspect the rubber door seals to check for deterioration. Old seals eventually become brittle and won’t maintain a water tight seal. As with anything – if you address any problems early on and perform a minimum level of maintenance – you can save time and money on repairs later. Your local climate will be a factor in what kind of maintenance that you have to perform and the rate at which your container will deteriorate. Anyone who has owned a car in a wet, temperate climate will know that the moisture, snow, and freezing temperatures cause a more rapid deterioration of metal compared to a warm, dry environment (like Arizona for instance).

 

Preventative Maintenance is key 

To help maximize the lifetime of your cargo container storage, we will share a few tips to help maintain your container:

 

Protect against the effects of water and excess moisture

Container condensation or “container rain” is a pretty common thing to monitor during your periodic container inspections. While your sea container is designed to be water tight and prevent moisture from entering from the outside, there is moisture in the air and even contained within the items that you may be storing.

 

“Container rain” is the condensation of the moisture in the air that occurs inside the closed metal structures. An excessive accumulation of condensation can cause serious damage to some types of items (example electronics or paper documents) and can also accelerate the oxidation process (appearance of rust we will discuss later).

 

How does condensation occur inside shipping containers?

The metal walls of shipping containers tend to conduct heat very well. As the air temperature drops outside from day to night time, the steel surfaces of the container walls rapidly cool. Once cooled low enough, the metal surfaces will reach what we know as the ‘dew point’ – the temperature where airborne water vapor condenses back into a liquid again.

When warm, humid air comes into contact with the cool metal container walls, the moisture condenses from a vapor to its liquid state, causing water droplets to from on metal surfaces – most of the condensation collects on the ceiling. In regions of the country where there is a great difference between daytime and nighttime temperatures, the risk of container rain damaging your stored items is greater.

 

How can we deal with moisture condensation in shipping containers?

There are three main factors to consider to minimize the problem of moisture condensation in your storage container.

1) Reduce the amount of humidity in the conex container

Inspect the container ceilings and walls for visible moisture condensation. Prior to loading the container, examine the interior surfaces to ensure that there is no pooled water and dry any water that may have collected.

Insulation. Insulating the walls of your container can reduce the temperature of the walls dropping to dew point, and therefore eliminating condensation from occurring.

Check out our Guide How To Insulate A Shipping Container 

Installing a Vapor Barrier

A vapor barrier can help reduce excess moisture condensation on the container walls. A vapor barrier is any material used for damp proofing. Commonly a plastic sheet, that prevents diffusion of moisture through the walls, doors or ceiling.

 

Dehumidifiers and air-con units. If you are intending on storing items that are sensitive to the effects of moisture, you may need to consider using more direct solution to cooling and removing humid air. Air conditioners and / or dehumidifier units are effective at maintaining stable, dry conditions for storage containers in problem climates or seasons of the year.

 

For a less costly and lower maintenance method of managing humidity inside the container, you could employ desiccants inside. Desiccants are “hygroscopic substances” which absorb atmospheric moisture.

 

Think of those “Do Not eat” silica gel packets that are usually found inside bottles of food supplements or product packaging. Desiccants are available in a number of forms – most commonly contained in strips hung on the walls or suspended from the ceiling or bags on the floor of the container. The desiccant bags should be replaced every 10 to 12 weeks – depending on the time of year and your local weather conditions.

 

2) Ventilate to allow warm humid air to escape

Ventilation. Consider your environment. If your container will be stored in a climate where there is a significant day/night temperature fluctuation, you may need to employ greater measures to mitigate “container rain”.

Containers are often renovated and fitted with vents to allow air circulation and avoid the build-up of heated air inside the container. This simple step can go a long way to eliminating the effects of condensation.

 

3) Store dry goods to avoid condensation.

Make sure you only store 100% dry goods in the storage box. Be aware that some materials, such as fresh wood, can have an intrinsically high moisture content. This means that moisture from the items themselves can release moisture into the air and can cause humidity levels to rise inside the container.
Avoid placing moisture sensitive objects (like furniture or cardboard boxes) directly in contact with the walls where water droplets are most likely to condense and collect. Be aware that some items (ex. electronics or dried food stuffs or cardboard boxes of paper documents which are susceptible to mold) may be at risk of the effects of moisture build up and plan accordingly.

 

Rust: How to prevent & avoid shipping container rust

Even though Conex containers are designed to be watertight and be used in all weather conditions, they are ultimately made of steel and thus susceptible to the problem of rust.

 

The good news is that most shipping containers are manufactured out of corrosion resistant Cor-Ten steel and we can take measures to protect against the onset of rust and slow its corrosive effects. If you purchased an “as is” container, it is quite likely that a used shipping container has had a lot of exposure to salt water and salt air which all accelerate corrosion. A 1-trip or new container will not have that degree of corrosion.

 

What causes shipping containers to rust?

Rust occurs when iron reacts with oxygen in the air, or chloride in water. Marine grade steel has anti-corrosive properties, but because of the harsh, maritime environments that containers are exposed to, rust will eventually, occur.

When a shipping container is exposed to both oxygen and water – an oxidation chemical reaction occurs. The reaction between the steel, the water, and oxygen creates hydrated iron (III) oxide, which we can experience as rust. Shipping containers can also start to rust if their metal surface sustains any damage during transit. When the container is impacted during loading, the protective coating on the outside of the container may be damaged and bare metal exposed, which creates a foothold for the oxidation reaction to get started.