Stainless Steel is known for its corrosion properties and suitability in coastal applications close to the sea – but not all grades will perform the same. Proximity to the ocean, other pollutants, weather and cleaning also need to be taken into consideration.
Understanding Stainless Steel Coastal Applications
In this blog we discuss the best grades to go for the closer you get to the sea.
1. Austenitic Stainless Steel
Austenitic grades are steels that are included in both the AISI 300 and AISI 200 series and contain nickel along with the chromium with low to very low carbon contents. These materials have excellent corrosion and high temperature oxidation resistance. The strength and hardness can be increased by cold work. They have excellent cryogenic properties and are non-magnetic. The most well-known of Austenitic stainless steels are grades 304 and 316 and the low carbon variations of these. They are readily available in most forms off the shelf.
Grade 316 should definitely be your first choice when choosing a grade for gates or balustrades close to the ocean as their resistance to chlorides such as salt, is high due to the chromium content as well as the molybdenum content. Grade 304 would be a close second, but would need to be cleaned more regularly to stop pitting corrosion as 304 does not contain molybdenum. One must note both would need to be cleaned – but 316 could be done less times per year.
2. Ferritic Stainless Steels
If Austenitic grades are out of the budget another option could be painted or epoxy powder coated ferritic grades such as 3cr12. However on a general basis this is not recommended. Ferritic Grades are plain chromium alloys with low carbon levels and are included in the AISI series. These steels have moderate to excellent corrosion resistance depending on the chromium content. They cannot be strengthened or hardened and with the exception of 3CR12 have poor weldability. They are magnetic which is useful tool (although not 100% reliable) to differentiate between grades. The most well-known of Ferritic stainless steels are grades 430, 409 and 3CR12.
They are readily available in coil and sheet form as well as plate form – 3CR12 only. One must consider that due to this one would need to get it rolled and manufactured which would add to the costs.
Maintenance costs would also need to be taken into consideration as powder coating or repainting may need to be redone after a certain period. Grade 444 is an option for ornamental tubing but is not as readily available as are the austenitic grades. Also Grade 444 although technically suitable does not perform optimally in coastal applications if there has been any mechanical polishing done to it in final preparation of the finished product – such as balustrades.
These grades of stainless steel are vastly superior to galvanised steel in terms of degradation and life span, but will tarnish and lose aesthetic appeal without a coating in coastal applications.
Get in Touch with Euro Steel Today
There are many grades of stainless steel used for various different applications. Always do your homework when selecting a fabricator and note cheaper is not always better! If you are ever in doubt about the fabricator you are using or the grade choice, please contact the Southern Africa Stainless Steel Development Association – SASSDA for assistance www.sassda.co.za Euro Steel is a member of SASSDA. We at Euro Steel stock and supply stainless steel and aluminium and supply to many reputable fabricators across South Africa.