[MW:25580] Re: Functional Test of Cathodic Protection by filling the tank partially with water

Hi Chandulal

This test is related to anodic and cathodic protection of metal structures. Two different metals can stand near each other in air without having any effect on each other, as air space is an insulator). When the metals are in water (an electrolyte) it's a different story as they are able to form an electrical bond through the water (water is generally regarded as a conductor). Differing metals occupy a different position on the Anodic Index, with some being described as more noble than others. The more noble metal is less susceptible to galvanic corrosion than the less noble. To protect the less noble steel from attack, a sacrificial anode is attached to it, which will be eaten away instead of metal. This whole process only takes place in an electrolyte, in this case, water. It's a problem in the marine world, but without this process we generally wouldn't have batteries in the form we know them, and the very protective coating known as galvanising originates here too.

Cheers

John

On Monday, November 8, 2010 at 5:46:56 AM UTC, Chandulal Vithlani wrote:

Can any throw light why water filling is needed for such a functional test?

Chandulal S Vithlani

050 614 2950

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