What does ‘Selecting the Correct Grade of Stainless Steel’ actually mean?

Stainless steel is often used in jobs because of its strength and corrosion resistance. Whilst it is very resistant to corrosion, it can be susceptible in certain situations. Corrosion usually manifests itself initially as an ugly brown stain on the surface of the steel. This is known as ‘tea-staining’. Choosing the correct grade of stainless steel for the application goes a long way in ensuring that stainless steel will resist corrosion.

There are two generally accepted grades of stainless steel, 304 grade, and 316 grade. Which grade is necessary depends on the proposed application. As a rule of thumb, 304 grade stainless steel is used for internal jobs, e.g. a stair balustrade indoors, and 316 grade stainless is used for external applications, e.g. an outside balcony balustrade.

Why is selecting the right grade important?

Stainless steel can provide an outstanding combination of aesthetic appeal, corrosion resistance and strength. However, stainless steel depends on its passive layer for corrosion resistance. This is a very thin chromium oxide layer formed on its surface when chromium is present at 10.5% or above. The environment in which the stainless steel is installed plays a large part in the long term appearance of the product. But by selecting the correct grade, it will help ensure that the stainless steel stays at its best for the longest.

How to select the correct grade of stainless steel

This table is intended as a guideline only and the specifier should take care and time to ensure the correct grade is selected for the actual application.

There are 3 main things to take into consideration when selecting the correct grade of stainless for your project.

  • Will your balustrade be inside or outside?
  • Are you in a coastal area?
  • Will your balustrade need to withstand exposure to a lot of chemicals? (e.g. in a swimming pool)

Different finishes of stainless steel

Satin finish stainless steel - selecting the correct grade

Satin finish is the standard finish of stainless steel we would supply for all applications that aren’t in marine areas. Brushed satin is a more modern finish, but does have crevices where corrosive substances can manifest. However, this is a minor concern in most non-marine areas.

Mirror polished stainless steel - selecting the correct grade

Mirror polished finish is a highly reflective and smooth finish to the steel. More important than its visual appeal is the increased resistance to corrosion. This is due to the small grooves in the steel being polished out, leaving a totally smooth finish.

If you have any more questions about choosing the correct grade of stainless steel, or the differences between them, get in touch with our friendly customer support team today!