How to know if steel will rust

Steel, when left exposed to the atmosphere, will slowly rust and lose functionality as the steel weakens. In construction and industrial sectors, a rust-induced failure could be catastrophic. 

The steel can be protected from rusting by preventing contact between the atmosphere and the surface of steel. This can be achieved through various means, such as painting the steel, which can be fragile and require maintenance, using stainless steels, which are comparatively quite expensive, or applying a thin coating layer of another metal over the steel, also known as “galvanising”.

Galvanising is a popular option for protecting large quantities of steel which will be in an exposed environment, e.g.in construction elements, road signs, and light-posts. The galvanisation process uses zinc, forms a robust barrier with a long service life, and can be applied through numerous manners, typically hot-dipping within manufacturing facilities or spray coating on-site. 

A minimum dry film thickness of 75 µm (approx. the width of a human hair) is typically required for steel components which will be in an outdoor environment. The primary drawback of a galvanised is that the protective zinc barrier is slowly eroded over time by this environment.

The service life of a galvanised steel component can be approximated based on the environment in which it will be located and the thickness of the zinc coating. The environment can be established based on guidelines, and the thickness of the zinc coating can be measured using precise equipment.

Here at BBB Technologies, we can both measure the thickness of a zinc coating on any steel surface, whether it’s a sample sent to our laboratory or a construction site we visit in-person, and advise on an expected service life for the component in a given environment.

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