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.

WARNING: Magnesium alloy anodes should not be used in salt water without the advice of a corrosion engineer. The use of magnesium alloy anodes in sea water can cause major damage to coating systems on steel and aluminium hulls.

We can produce magnesium anodes according to the following internationally recognised standards:

  • ASTM International ASTM M1C B843
  • ASTM International ASTM AZ31B
  • ASTM International ASTM AZ31D
  • ASTM International ASTM AZ63B
  • ASTM International ASTM AZ63C
  • ASTM International ASTM AZ63D
  • Australian Standard AS2239 – M2
  • Australian Standard AS2239 – M3

Aluminium Alloy Anodes

The use of aluminium anodes is typically limited to sea water applications.

The sea water efficiency and driving potential of modern aluminium anode alloys is slightly better than zinc anodes. This means that in sea water, for an anode of equivalent dimensions, an aluminium anode will offer slightly better performance and slightly longer life. The down side of aluminium anodes is that they are not as efficient as zinc anodes in brackish and fresh water.

Typical uses include applications such as ship hulls, salt water ballast tanks, offshore structures, steel wharf piling and submerged (offshore) pipelines.

We can produce aluminium anodes according to the following internationally recognised standards:

  • Australian Standard AS2239 – A1
  • Australian Standard AS2239 – A2
  • Australian Standard AS2239 – A6
  • Det Norske Veritas DNV RP-B401 – Aluminium
  • National Association of Corrosion Engineers NACE TM0190
  • National Association of Corrosion Engineers NACE SP0607
  • US Military Specification MIL-DTL-24779D(SH)

Zinc Alloy Anodes

Zinc alloy anodes have been used for many years as a reliable and economic means of providing Cathodic protection to the hulls of the world’s steel hulled boats and ships. Aluminium alloys have significantly improved for sea water applications, however because of the universal benefits of being able to operate in sea water, brackish and fresh water, zinc anodes remain very popular in the marine and boating industry.

Large marine structures which require considerable anode mass, will economically justify the use of aluminium alloys over zinc but for most small vessels, the benefits between zinc and aluminium alloys is marginal.

Zinc anodes are widely used in sea water environments. However with the right anode dimensions and in conjunction with a very good hull coating, they can provide sufficient output to protect steel in higher resistivity environments such as tidal areas and brackish to fresh water estuaries.

WARNING: 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 the zinc anode and corrode at a rate more rapidly than existed prior to the installation of the anode.

Seek the advice of a corrosion engineer if you expect to experience these conditions.

We can produce zinc anodes according to the following internationally recognised standards:

  • Australian Standard AS2239 – Z1
  • Australian Standard AS2239 – Z2
  • US Mil Spec MIL-A-18001L
  • Det Norske Veritas DNV RP-B401 – Zinc
  • National Association of Corrosion Engineers NACE SP0607