I'd imagine that grounding effectiveness may also be decreased with the
encasement approach. This might be concern in a lightning prone region.
On Thu, May 30, 2019, 22:01 Tony Brock-Fisher via TowerTalk <
towertalk@contesting.com> wrote:
> By coating a guy anchor rod with an protective material such as tar, one
> is attempting to prevent galvanic corrosion by removing one of the
> necessary components, the electrolyte (water) in contact with the metal
> of the guy rod. In theory, this sounds like a reasonable approach. as
> long as the coating is complete and intact, this will work to prevent
> galvanic corrosion. However, if there is any small void in the coating,
> water can again contact the guy rod. In this case, there is an area
> concentration effect at the void, which actually increases the rate of
> corrosion at the void. All the current is concentrated in this small
> area. In the case of a zinc coated (galvanized) guy rod, the zinc
> coating will be corroded more rapidly because of the concentration of
> current at this location. Once the zinc is gone, the steel will also be
> corroded.
>
> A tar or other waterproof insulated coating may increase the life of guy
> rods, but must be complete in it's covering of the guy rod. If not, it
> could be worse than nothing at all. The best way to prevent galvanic
> corrosion is by preventing the flow of current in the first place, by
> providing a sacrificial anode that changes the potential of the guy rod
> and diverts the current to the sacrificial anode.
>
> -Tony, K1KP
>
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