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Re: [TowerTalk] How much does EHS stretch?

To: "Keith Dutson" <>,"'Tower'" <>
Subject: Re: [TowerTalk] How much does EHS stretch?
From: "jeremy-ca" <>
Date: Fri, 4 May 2007 17:05:34 -0400
List-post: <>
I moonlighted for about 25 years for a commercial tower installer and had 
plenty of opportunity to see failures due to overloading and trees falling 
on guy wires. Some commercial installations were as poorly engineered as Ive 
ever seen with hams/CBers! We often got the call to do emergency repairs 
since the original installer magically disappeared.

Luckily the tower in this thread had the full girdle torque assembly as well 
as the arms. This saved the tower from failure at the guy attachment point.

Definitely replace the guy that was hit. Instead of an eyeball use a transit 
to shoot the legs and check for any deviation from pure vertical from top to 
bottom. 100' of 45G should be trued within the width of the transit 
graticule from top to bottom. If the tower is currently straight within the 
width of a tower leg then Id say the other guys are fine and everything just 
needs retorquing and plumbing.

Id pay particular attention to the lower guy stations as well as the base 
plate area. A down force of several tons may have fractured the legs at 
those points. Check VERY carefully for any cracked or flaking galvanizing at 
those points. Any failures there will require replacing that section or 
securly clamping a split section of tubing over the wound. 45G legs are mild 
steel so use equal or better quality for the splice. I hit a leg of my 180' 
45G with a truck bumper and put a big dent in the leg. After heating and 
working the metal as best I could I put a splice over it; no problems in the 
past 18 years.

If the bottom section needs to be replaced there are installers that can do 
it in place. I worked on one job that the bottom 2 sections of a 300' 65G 
had to be replaced and without disturbing the operating FM BC array at the 
top. After that was done then we thinned out the 20 or so  2 way antennas 
that caused the problem.

Should you decide to take the tower down I'd suggest 1/4" EHS as a 
replacement. I havent used 3/16" on anything except short 25G in over 30 
years; the price difference is minimal when starting fresh and the extra 
stability, especially with a pier pin, is well prounounced.

Good luck

----- Original Message ----- 
From: "Keith Dutson" <>
To: "'Tower'" <>
Sent: Friday, May 04, 2007 1:24 PM
Subject: Re: [TowerTalk] How much does EHS stretch?

> If it were my tower, I would replace all of the guys and be done with the
> problem.  If the tree did not bring down the tower, climbing it will not
> either.  I would prepare the replacement guys and haul them up the tower 
> on
> a non-windy day.  I would start with the lower guys, replacing one at a 
> time
> with proper tensioning when all 3 are in place, then proceed to the upper
> guys.
> 73, Keith NM5G
> -----Original Message-----
> From:
> [] On Behalf Of Dick Green
> Sent: Thursday, May 03, 2007 8:09 PM
> To: Tower
> Subject: [TowerTalk] How much does EHS stretch?
> TowerTalkians,
> I need your expert advice. I climb for a friend who has a 100' Rohn 45
> tower. When the big Nor'easter tore through New England recently, a large
> tree fell on one of his top guys. Luckily, the tower did not collapse.
> Off the top of my head, I think the tree was at least  40 feet tall and 
> the
> trunk was 8-12 inches in diameter. Maybe bigger. Way too heavy to move by
> hand. It was a deciduous hardwood, perhaps beech or birch, I can't 
> remember.
> The main trunk didn't hit the guy wire, but at least one of the large 
> upper
> branches did. When I got there, the branch in question (at least 5-6 
> inches
> in diameter), was resting on the lowest part of the guy wire, just a few
> feet above the big grip connecting to the equalizer plate. Further up the
> guy, about 15 feet off the ground, there was a noticeable dip in the wire.
> Not exactly a kink, but a deformity that strongly suggests the tree
> initially hit the guy there and either bounced or rolled down to the 
> bottom.
> Even so, the weight of the tree had caused the wire to sink at least 1/4"
> into the branch that was resting on the lower portion of the guy.
> Using my chainsaw, I separated the upper portion of the tree from the 
> trunk,
> and cut apart the mass of branches until the weight was reduced enough for
> the two of us to wrestle the big branch off the guy wire. We had to yank
> back and forth on the branch pretty hard to disengage it from the guy.
> We noticed right away that the top guy was much looser than it should be. 
> In
> fact, all nine guys have considerably more slack than they did when 
> tension
> was last set with a Loos gauge last fall. My friend doesn't tension his 
> guys
> particularly tight, probably somewhat less than the recommended 10%, but I
> climbed the tower last fall and felt the tension was at an acceptable 
> level.
> The catenary was pretty shallow. After the tree hit, the catenary was much
> deeper and you could grasp one of the top guys and kind of whip it up and
> down. I'm not real experienced at this, but would guess anywhere from 
> 6"-12"
> of slack will have to be taken out to retension the guys, with the top 
> guys
> needing the most.
> We inspected the guys and anchors for damage. Aside from the mild dip in 
> the
> top guy at the point of impact, there does not appear to be any damage to
> the wire, even where it cut into the branch. The anchors appear solid and
> there is no sign they have deformed or the anchor blocks have moved (this
> tower uses 3'x3'x1.5' concrete footings four feet down, per Rohn spec.)
> However, I was able to grasp an anchor rod and move it up and down a few
> inches. This was partly due to the guys being slack, but I think the soil 
> is
> relatively loose near the surface, too.  It's an area of forest that was
> cleared about 20 years ago and has that soft forest floor consistency. 
> BTW,
> this is why the tree (and many others) fell -- the root balls disengaged
> from the loose, super-saturated soil and the heavy winds blew them over.
> Anyway, if I had to bet on  it, I'd say the anchor blocks didn't move. My
> friend doesn't think so, either, and he's intimately familiar with them,
> having done the digging and pouring himself.
> The guys are broken up with insulators. I visually inspected the grips and
> could see the little stub of EHS sticking into the thimble area, as it
> should be. I don't think any of the grips slipped. I was not able to 
> closely
> inspect the grips right at the guy brackets, but will do that through
> binoculars before climbing the tower. I think it's unlikely the grips
> slipped at the tower end.
> The tower appears to be perfectly plumb and there's no obvious damage to 
> the
> legs or lattice. I plan to inspect the legs and welds through binoculars
> before climbing.
> It was a very windy day, and we were impressed with the fact that the 
> tower
> wasn't swaying at all, despite the loose guys. It was rock solid (though 
> I'm
> sure I would have felt some sway if I was riding the top.) This tower has 
> a
> 40-2CD, 6m beam and TH-7 on a 12'+ mast and a TH-7 on a TIC ring at 60'.
> That's 25-30 sq feet of wind load. The 3/16" guys are at about 
> 95'/60'/30'.
> Torque arms are used on the brackets. The tower sits on a pier pin. The
> tower and guys were installed about 20 years ago.
> Questions: What caused the slack in the guys? Is it possible for EHS to
> stretch that much? If so, is it OK to simply retension the guys, or is 
> there
> a compelling reason to replace them? Is it likely that the impact point is
> weakened enough to require that section of the guy to be replaced? Should 
> I
> look elsewhere for the source of the slack?
> Before I climb the tower, I want to be confident that it's in good order.
> Please, no speculation. This is a serious safety issue and I would
> appreciate answers from people with lots of experience, preferably with
> similar damage.
> Thanks & 73,
> Dick WC1M
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