Cathodic Corrosion Protection

GA Peter. In the Navy, we used sacrificial zinc anodes on small craft to help minimize corrosion of steel hulls. On larger vessels, we used active systems, impressing a DC current upon the anodes, which was somewhat more effective. The only real problem I see here is that sacrificial anodes have a limited lifespan, and it may be difficult to pull his grounds out of the ground to replace them.

Would it be possible to place the sacrificial blocks in a shaft attached to a retrieval rod and connected to the grid,

then every so often the rods and blocks could be removed and replaced if required.?

Tinned copper is considered to be corrosion resistant. Such as if it is a harsh environment with acidic pH level in the local soil. The wording quoted seems to imply that there should be a cathodic corrosion protection specification section (or subsection) for which to comply with.

In this context it refers to dissimilar metals. For example, a power station with a steel earth mat with corrode if connected to a copper earth mat via a Transmission Line.

The soultion can be simple or a detailed study of the half cell reactions. It depends on details of the earth mat, nearby infra structure, grid infrastructure, soil structure and the "requirements for the specified cathodic corrosion protection" etc.

Thank you very much for your contribution.

The power station in question is a mat grid and am using copper conductor of 150mm2 ."The request for proposal stated that all conductors embedded in concrete shall be copper and adequate protection should be provided when the copper conductors leave the concrete",so am thinking concrete mix has a way of affecting copper conductors and probably they should be something i should apply to reduce the effect.Presently the few conductors that i have passed through concrete are some how changing color to black.I was thinking of using short piece of RGS conduit at the point where the conductors leave the concrete.What do u think?

Thanks to everybody that have contributed thus far.

This is a common request. You should consider using a PVC sleeve at the boundary. The PVC sleeve should be filled with concrete. We have implemented this on our 765kV tower foundations, where the guys corroded. This should ensure that the conductor is encased in concrete below the soil surface. Time will tell if this is good solution.

I would however highlight to your customer that the entire system must be studied from a corrosion point of view. By making this requirement without first understanding all the mechanisims in play can have undesirded effects. I am an electrical engineer, but I have been around long enough to appreciate the value of a competent corrosion engineer.

Good luck.

Anode (sacrificial) & cathode (protected pipe) connection:

Thanks Abdel for your contribution on this subject.