Magnesium Alloy Anodes
Magnesium Anodes have a high negative driving potential which makes them suitable for the protection of steel structures where the environment has a high resistivity, such as in soil and fresh water.
Magnesium Anodes are used extensively for the protection of buried pipelines and also in hot and cold potable water applications. Their corrosion by-products are generally considered non-toxic. Magnesium anodes are generally never used in a salt water environment as they can cause disbanding or removal of paint on wetted surface areas. Magnesium die casting
Zinc Alloy Anodes
Zinc alloy anodes have been used for many years as a most reliable and economic means of providing cathodic protection to the hulls of the world’s steel hulled boats and ships. With the changes in technology in recent years, Aluminium alloys have shown distinct improvements in anode applications for marine use in sea water. However because of the universal benefits of being able to operate in sea water and fresh waters, Zinc anodes remain very popular in the marine and boating industry.
Large marine structures which require considerable anode mass for cathodic protection, will economically justify the use of Aluminium alloys over Zinc alloy anodes. For most small vessels, the benefits between Zinc and Aluminium alloys may be marginal.
Zinc anodes are widely used in marine environments. However in the right geometry, Zinc anodes, in conjunction with a very good hull coating system, can provide sufficient output to protect steel in higher resistivity environments such as some tidal fresh water estuaries.
It is important to note that at temperatures in excess of 50ºC, hard non-saline waters (such as some fresh water cooling systems) may cause the polarity of a Zinc anode/steel couple to reverse. That is, the steel may become anodic to Zinc and corrode at a rate more rapidly than existed prior to the installation of the anode. zinc die casting
Seek the advice of a corrosion engineer if you expect to experience these conditions.
Aluminium alloy anodes
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The use of Aluminium anodes is generally limited to marine applications.
The driving potential of Aluminium anodes is slightly higher than zinc anodes. Aluminium alloy anodes are more efficient than the zinc anode alloy, which can provide performance and lifetime benefits of the anode protection system. This results in more protection in the same anode sizes due to the corrosion efficiency of the Aluminium alloys.
Typical uses include applications such as ship hulls, salt water ballast tanks, offshore structures, steel wharf piling and submerged (offshore) pipelines.