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[TowerTalk] Re: short story

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Subject: [TowerTalk] Re: short story
From: (Joseph L. Rossmiller)
Date: Thu, 24 Apr 1997 04:20:49 -0500
David O. Hachadorian wrote:
> It was not a typical balmy afternoon in Yuma, Arizona on Friday.
> There was a cold front approaching from the north, which was
> kicking the wind up to about 30 mph. I happened to glance out
> the back window and noticed that one of the guy wires on the
> 48' Rohn 25 foldover seemed to be vibrating more than usual,
> so I went out to investigate. The tower is four-way guyed, using
> the recommended Rohn GAS604 earth augers to secure the guy wires.
> The vibrating guy wire seemed a little loose, so I began to tighten
> the turnbuckle. The guys tightened up momentarily, but then went slack
> again! The wind was blowing pretty good at this point, and I was
> horrified to realize that the earth auger was pulling out of the
> ground! There is no way to get a vehicle into the back yard to serve
> as a temporary guy support. I immediately released tension on the
> opposing guy wire, trusting in Jesus and Rohn's conservative
> engineering to keep the tower standing. There is about 17 square feet
> of antennas on top of the tower. Naturally, the wind was blowing
> in the worst possible direction.
> I got on the phone, and found the one and only source of earth
> augers in town, a farm supply store a few miles away. I got their
> largest one, about 4' long, painted, not galvanized, with a 5" diameter
> auger on the bottom. I screwed it in next to the defective one,
> transferred the guy wires, and tightened them all up.
> The defective earth auger could then be twisted by hand, but
> I had to tap it with a hammer to get it out of the ground. What
> came up was a scaly, crusty, two foot long rod, rather than Rohn's
> four foot long rod with a 6" auger plate at the end! The end of the
> rod had a pointy piece of metal that looked as if it had been
> stretched too far. I guess that corrosion had eaten through the
> 5/8 rod, to the point where the remaining metal couldn't support
> the tension, and then it just stretched like taffy and pulled
> apart.
> The augers have been in place since 1978. They looked perfect
> above ground. Even below ground, it was hard to tell whether
> the crusty stuff was dirt or corrosion. Looking at it more
> closely, the galvanizing had eroded off, and rust had penetrated
> to a depth of about 1/8 inch all around.
> The moral of the story of course is to routinely inspect all guy
> anchors. I remember reading that advice before, but of course
> problems always happen to the other guy, and we don't need to
> worry about corrosion here in the desert! There's nothing like a little 
> personal experience with a Significant Emotional Event to drive a point
> home! Needless to say, I will order four new anchors from Texas Towers on
> Monday. It _can_ happen to you!
> Dave, K6LL
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I've heard of a similiar failure to this before.  I work for the
Illinois State Police as a radio technician.  In the mid 1980s, we had
the failure of a 400 foot tower at one of the district headquarters in
the state.  Upon investigation, they found the anchor rod for one of the
guy points on this tower had been eaten away until it was no wider than
a pencil lead.  It was determined that this rapid corrosion was due to
the tower anchor being located near a buried gas line.  The utility
company had place a small voltage on the buried pipe to keep it from
corroding.  This voltage protected the gas pipe, but caused any other
buried metal in the area to corrode at a faster rate. This caused the
anchor rod to grow thinner and thinner until it finally gave way.  We
now have anodes of magnesium buried at the anchor points of any tower
located close to a gas line.  The magnesium is attached to the anchor
rod.  The idea is that the magnesium will corrode before the anchor rod
does, thus saving the anchor rod, and the tower, from failing.

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