EIA/TIA 222 F requires that all guy anchors and ground rods etc
be galvanized to prevent copper-galvanized corrosion problems which
allegedly led to tower failures. There is disagreement on how far apart
the two must be for no interaction to occur.
The main concern, I suggest, is the pH of the soil.
Acidic soil will destroy copper and
alkaline soil will do the same to galvanized.
The former soil predominates
in the eastern part of this country and
the latter soil ditto the western US.
I think *all* factors need to be taken
into account before deciding on which
to use.
73, Bob AA0CY
----------
From: Pete Smith[SMTP:n4zr@contesting.com]
Sent: Thursday, June 04, 1998 11:33 AM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Galvi steel below ground
At 10:49 AM 6/4/98 -0400, Stan wrote:
>ROHN has a requirement in fine print...
>
>ROHN Drawing B841300R10, Foundation Material Specs., Rev 10 dated
>11/3/94
>
>item 27 ( and I qoute verbatim)....
>
>"For anchor block type foundations, the portion of the steel anchors,
>from top of anchor block to ground level, shall be coated with bitumen.
>Design assumes periodic inspections shall be performed over the life of
>the structure to determine if additional anchor corrosion protection
>measures must be implemented based on observed site -specific
>conditions."
>
>
>
>Bitumen is an asphaultic paint commonly found in the hardware or
>building supply store as
>roofing coating (un-fibered) and is a black and sticky tar coating...
>
>Thus tar coating applied on all exposed galvanized steel below ground
>level (grade) will prevent erosion of the galvi (zinc) coating and
>corrosion of the steel.
>
>2 coats should provide 100% coverage.
>
Good info - thanks!
For whatever it's worth, Anchor-guard acknowledges that bitumen coating
will help to control galvanic corrosion of guy anchors, if it's truly 100
percent coverage. The trouble is that it can be hard to maintain that
integrity over time, and they warn that corrosion may be intensified at the
leak points.
Since someone posted the information about possible galvanic corrosion
between copper guy-wire ground rods and the galvanized guy anchors, I've
replaced all of my copper-plated guy grounds with galvanized rods. In the
process, I discovered that you can buy galvanized clamps to attach wires to
the galvanized ground rods, and since I was already using EHS to get from
the guys to the ground rod, I feel that this combination gives me a much
better galvanic situation.
73, Pete Smith N4ZR
In wild, wonderful, fairly rare WEST Virginia
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