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[TowerTalk] AB-105 Safety Question

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Subject: [TowerTalk] AB-105 Safety Question
From: (Bill Hider)
Date: Tue, 11 Mar 1997 04:48:38 -0800
I believe the product is called: Rustoleum Rust Reformer.  I've used it
successfully on several tower-related and non-tower related projects.

Bill, N3RR wrote:
> In a message dated 97-03-09 20:07:37 EST, (Dave Hawes)
> writes:
> >  Unfortunately, the holes in the plates are
> >  not large enough to pass the bolt from the clevis, so merely
> >  repainting the existing plates is not an option.
> Hi, Dave --
>       Why not wire brush them and then use one of the rust converter
> products? It'll react with the rust and neutralize it while putting a tough
> coating on the steel.   Before you do that, drill out the holes so that it
> will take an appropriate clevis then you don't have to replace ANYTHING.
>  Personally, I'd rather not make any more work for myself than I have to.
>  BTW, TOWER TECH has the Rustoleum Rust Converter ($8.00 for 8 ozs.).
> >
> >  The issue of safety in this project is two-fold:
> >
> >  1.  Detaching the existing guy wires, one a at a time, to do the
> >  work on the attachment plates, and
> >  2.  Unbolting the plates and replacing them.
> >
> >  As to Issue #1, I believe that the AB-105 tower is robust enough to
> >  withstand this kind of maneuver.  In fact, I have detached one top
> >  guy wire many times to allow my large yagis to pivot down to the
> >  tower using a "PVRC (tm) Yagi Mount."  I see no reason why removal
> >  of intermediate guy wires, one at a time, should present any
> >  significant danger, but am interested in opinions.  Of course, the
> >  work would be done in calm wind conditions to minimize the potential
> >  for buckling forces.
>       You'll want to slack off the remaining guys on the same level while
> leaving them attached because you don't want to put unnecessary forces on the
> other tower legs.
> >
> >  Regarding Issue #2, it is important to note that guy attachment
> >  plates mount on top of the splice plates at each tower juntion.
> >  Replacement of the plate requires unbolting half of the bolts at the
> >  splice!
> >
> >  Concern:  Structural stability of the tower.  Probably not a worry,
> >  since the splice plate has six more bolts holding the joint stable.
> >
> >  Concern:  Settling of the tower section.  This is my real fear.  I'm
> >  not so sure that the tower sections are actually butting.  I think
> >  that the bolts at the splice plate are in shear and taking most or
> >  all of the dead weight load of the tower.  If I take the bolts out,
> >  even of just half of the splice plate, especially at the 47 foot
> >  level, and the tower settles, I might not be able to get the holes
> >  lined up again.  In that event, I can visualize (in my nightmares)
> >  having to jury rig some kind of jack to separate the tower sections
> >  far enough to get the bolt holes lined up.  (I'm pretty sure a drift
> >  pin would not have the mechanical advantage needed for the job, but
> >  then again it might.) This would not be able to be done right away,
> >  and the tower could be left in a dangerous condition for some period
> >  of time while a workaround is developed.  Not a happy thought.
> >
> >  I would appreciate any insights other owners of or maintainers of
> >  AB-105 tower might be able to provide on this subject.  I'm hoping
> >  my fears as described above are merely overreaction, but better safe
> >  than sorry.  I fully realize that this is a very, very narrowly
> >  focused question, and apologize for the bandwidth.  However, this
> >  reflector is a great resource, and I figured it was worth a shot,
> >  especially since this is essentially a safety related issue.
> >
>      The leg joint brackets are very substantial and will keep things intact
> enough that you should be able to remove half of the bolts to replace the
> brackets.  Loosening all of the guys will minimize the downward compression
> forces on the legs while still providing  enough tethering to hold the tower
> up.   Refinishing the existing brackets will avoid this problem completely.
>      Your drift pin is all you need to get the holes lined up again.  Pound
> it in with a hammer and then you'll be able to put most of the bolts back in.
>  Don't forget that the bolts go OUT through the legs so you can secure the
> nuts on them.  It looks like there's less than 1/8 inch gap between the
> sections of my AB105 so you're not talking about a lot of movement.
> 73 and GL,  Steve   K7LXC
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