Corten steel containers
are shipping containers manufactured from a special compound of steel developed to give the best protection around against the elements - short of keeping the container indoors! Trademarked as COR-TEN, but more commonly known as weathering steel because of it's resistance to atmospheric corrosion compared to other steels. Because shipping containers are constantly exposed to the atmospheric weathering, including sea water, without added protection they would very quickly turn into old rust buckets!
From manufacture, Corten steel containers will give at least 20 years of problem free use , because the steel forms a protective layer on the surface under the influence of the weather. It is in fact exposure to the weather that enables the corrosion-retardant surface to develop and regenerate by forming a stable layer of surface rust. This may sound contradictory, but it's actually by allowing the steel to rust on the surface that provides it with a protective coating. It can be described as 'self-healing'. No other form of treatment or coating is required with corten steel.
If you are buying a container for storage and not shipping, bear in mind it is only shipping containers that are made from corten steel. This is why shipping containers make excellent storage containers too, and have an advantage over containers built specifically for storage as they are less susceptible to damage and will last much longer.