[TowerTalk] Guy Anchor Safety was:Re: Screw Anchor Experience

Wed Jun 19 09:20:24 EDT 2013

Not always simple, especially when you use a large anchor block and have property with lots of ledge (like mine.)

That said, when your tower is on a steep hill, multiple anchors per direction is the only way to ensure that the guy angles are the same as on flat ground.

73, Dick WC1M

> -----Original Message-----
> From: Pete Smith N4ZR [mailto:n4zr at contesting.com]
> Sent: Wednesday, June 19, 2013 5:30 AM
> To: towertalk at contesting.com
> Subject: [TowerTalk] Guy Anchor Safety was:Re: Screw Anchor Experience
> 
> This discussion prompted me to wonder why every ham installation but one
> that I have ever seen used only one anchor per direction, creating an
> opportunity for a single point failure to bring down the whole
> structure.  It would seem like a simple-enough fix to invest in another
> anchor and some more concrete, and anchor the top guy separately.
> 
> 73, Pete N4ZR
> Check out the Reverse Beacon Network at
> http://reversebeacon.net,
> blog at reversebeacon.blogspot.com.
> For spots, please go to your favorite
> ARC V6 or VE7CC DX cluster node.
> 
> On 6/18/2013 10:45 PM, K0DAN wrote:
> > So the answer, it would seem, is to have any guy anchor (galvanized or
> > not) to not only be embedded in concrete, but in an elevated pier so
> > that the entire guy anchor is 100% above ground soil. If I were to do
> > another guyed tower (which is not my intention) I would do so...the
> > extra labor + materials to "shield" the anchor from soil is worth
> > it...at least based upon my circa 1998 tower disaster. YMMV.
> >
> > There are many very large commercial broadcast and land mobile
> > communications towers (guyed and self supporting) that have been up
> > for 50+ years. Certainly they are inspected and maintained on better
> > budgets than most ham installations, altho they beg the question of
> > what techniques make them successful (even though we know that some of
> > those big boys come down from time to time).
> >
> > 73
> > Dan
> > K0DAN
> >
> > -----Original Message----- From: Dick Green WC1M
> > Sent: June 18, 2013 20:13
> > To: 'K0DAN' ; N3AE
> > Cc: towertalk at contesting.com
> > Subject: RE: [TowerTalk] Screw Anchor Experience
> >
> > Any anchor that's exposed to soil is at risk of corrosion. Anchors
> > sunk in concrete are just as vulnerable because typically a good
> > portion of the anchor rod is not in the concrete -- it's in contract
> > with soil above the concrete footing. For example, Rohn spec calls for
> > my anchor footings to be poured in a 6-foot long by 3-foot wide hole
> > that's 4-feet deep. The concrete footings are only 18" deep, so
> > there's about 2.5 feet of soil that the anchor rod is in contact with.
> > Since the rod is set at an angle, probably 3-4 feet of the rod is in
> > contact with soil above the footing.
> >
> > The Rohn concrete anchor rods are very heavy duty, but just in case I
> > slathered several coats of roofing tar on the portions of the rod that
> > were above the concrete block.
> >
> > Regardless of the type of anchor rod you have, it's a really good idea
> > to inspect them every few years. That means digging down a bit to see
> > if there's corrosion.
> >
> > 73, Dick WC1M
> >
> >> -----Original Message-----
> >> From: K0DAN [mailto:k0dan at comcast.net]
> >> Sent: Tuesday, June 18, 2013 8:20 PM
> >> To: N3AE
> >> Cc: towertalk at contesting.com
> >> Subject: Re: [TowerTalk] Screw Anchor Experience
> >>
> >> Hi Shawn...
> >>
> >> I had screw anchors which I think I purchased from Texas Tower. They
> >> were probably manufactured by Rohn or some other well-known tower
> mfgr.
> >>
> >> IRC they were 4” augers on 4’ 3/4” (or 1”?) rod, all galvanized. They
> >> met the tower mfgr (TriEx) spec. They were installed (with
> >> difficulty) into local soil here near Kansas City. Which is about 2’
> >> of topsoil on top of packed clay. I do not know the pH of the soil.
> >>
> >> The tower was a 72’ crank up (HW series if IIRC) was triple guyed and
> >> was not overloaded. All was fine for 15+ years when one night we had
> >> thunderstorms and 50 MPH wind gusts (the tower was spec’d for 70
> >> MPH), I was on the air at the time, and suddenly all the signals went
> down 50dB.
> >> I turned the rotor and it would only turn about 10 degrees. WTF? I
> >> went outside and to my horror, saw the tower lying over in the trees!
> >> If you ever want a gut-wrenching sight, that is it.
> >>
> >> Later investigation showed that one guy anchor and failed, causing
> >> the equalizer plate and all attached guywires to slingshot in the
> >> direction of the wires; the remaining two anchors kept tension on the
> >> tower, pulling it in the direction bisecting the angle of the two
> >> remaining guys (50’ trees).
> >>
> >> The antennas were destroyed, and the tower sections sufficiently bent
> >> that I did not want to attempt to repair them.
> >>
> >> The cause of the anchor failure was long term corrosion (galvanic
> >> action) from soil working on galvanized anchors. The 3/4” anchor rod
> >> and shrunk down to the diameter of a pencil, and probably pulled
> >> apart like soft taffy when then wind load was high enough.
> >>
> >> Based on my experience I do not think screw anchors are a good
> >> long-term guy wire anchor at all. For short term, probably fine, but
> >> despite what Texas Towers told me, they are NOT permanent.
> >>
> >> However if you drilled and belled footings for the guy anchors,
> >> filled them with concrete, and then inserted the screw anchors, I
> >> think you’d be OK. Ask the tower mfgr or a civil engineer or M.E.,
> >> not me. With galvanized encased in concrete, I think there would not
> >> be the exposure to chemical reaction.
> >>
> >> It is also possible that your local soil is not reactive and what
> >> happened to me is not a risk at your QTH. You will have to ask people
> >> wiser than I.
> >>
> >> I have photos of the crashed tower and failed guy anchor. Someone on
> >> this reflector (maybe the fellow who wrote”Up The Tower”?) was
> >> looking for this stuff a few years ago, and I promised them to him
> >> but I lost my note and never followed through.
> >>
> >> Good luck and 73
> >>
> >> Dan
> >> K0DAN
> >>
> >> From: N3AE
> >> Sent: June 18, 2013 17:16
> >> To: k0dan at comcast.net
> >> Subject: Screw Anchor Experience
> >>
> >>
> >> Dan,
> >>
> >>
> >>
> >> I was reading your recent post in TowerTalk regarding thoughts on a
> new
> >> tower for KR5DX.   You mentioned a failure you experienced with a
> screw-
> >> in guy anchor.  Wondering if you could share some info on that, like
> >> the type on anchor, auger diameter, depth and a description of your
> >> soil type.
> >>
> >>
> >>
> >> Obviously I'm considering a screw-in anchor here for a tower (EZ-
> Way).
> >> This tower came from a local who had it guyed using screw anchors and
> >> it held up fine for 15+ years, including hurricanes and tropical
> storms.
> >> I've been basing my plans on published info from companies like A.B.
> >> Chance and Hubble Power Systems.   See
> >> http://www.hubbellpowersystems.com/anchoring/no-wrench/
> >>
> >>
> >>
> >> tnx
> >>
> >>
> >>
> >> Shawn - N3AE
> >>
> >> Southern Maryland
> >
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