How to prevent aluminium corrosion
Untreated aluminium has very good corrosion resistance in most environments, but in strongly acid or alkaline environments, aluminium normally corrodes relatively rapidly. Here is a checklist on how you can prevent aluminium corrosion problems.
When it is used correctly, aluminium has a longer lifespan than most other construction materials, including carbon steel, galvanized steel and copper. Its durability is excellent. It is also generally superior to the other materials in highly sulphurous and marine enviroments.
The most common types of corrosion are:
- Galvanic corrosion may occur where there is both metallic contact and an electrolytic bridge between different metals.
- Pitting corrosion occurs only in the presence of an electrolyte (either water or moisture) containing dissolved salts, usually chlorides.
- Crevice corrosion can occur in narrow, liquidfilled crevices.
So, what can you do to avoid it?
Here is my checklist on how to prevent corrosion:
- Consider the profile design. The design of the profile should promote drying – good drainage, to avoid corrosion. You should avoid having unprotected aluminium in lengthy contact with stagnant water, and avoid pockets where dirt can collect and then keep the material wet for long periods of time.
- Mind the pH values. pH values lower than 4 and higher than 9 should be avoided to protect from corrosion.
- Pay attention to the environment: In severe environments, especially those with high chloride content, attention must be paid to the risk of galvanic corrosion. In such areas, some form of insulation between aluminium and more noble metals, such as copper or stainless steel, is recommended.
- Corrosion increases with stagnation: In closed, liquid-containing systems, where the water remains stagnant for long periods of time, corrosion increases. Inhibitors can often be used to provide corrosion protection.
- Avoid severe, wet environments. Ideally, keep the aluminium dry. Cathodic protection should be considered in difficult, wet environments to prevent corrosion.