|Element||GS EP COR 201|
|Al – Zn – In|
|Zinc (Zn)||4.75 – 5.75%|
|Indium (In)||0.015 – 0.02%|
|Cadmium (Cd)||0.002% Max.|
|Silicon (Si)||0.06 – 0.12%|
|Iron (Fe)||0.12% Max.|
|Copper (Cu)||0.003% Max.|
|Others Total||0.10% Max.|
Why is aluminium best for tanks?
The steel tank base or bottom plate is the area that is most prone to severe corrosion in storage tanks. Corrosion in this area is exacerbated by the sediment contents of the contained liquid which will settle here.
Accelerated corrosion can also occur on the external surface of the base, especially for heated tanks due to the temperature differential between one side of the tank and the other.
Aluminium is considered a safe and popular choice for cathodic protection systems installed on tank surfaces.
Other sacrificial anodes (e.g. magnesium) are considered too active, resulting in over protection which can prove detrimental to long-term performance, whereas zinc anodes can be vulnerable at high temperatures.