Allen:
MY WIFE reminded me that Rohn stores the leg bolts inside the bottom of one
of the section legs in each 25G section. They are inside of a plastic tube
with a tight fitting plug. If your installer was not aware of that, he may
have left one or more bolt kits inside of a leg, effectively preventing
water from draining from that leg. This could trap water in MANY places all
up and down the tower inside the legs. You could get splits whereever there
is trapped water. As you know, water freezes with the ice forming on the
surface first so the surface is where you would expect the split to first
occur. Drilling a small hole at the bottom near the concrete base does not
prove there is no water trapped higher in the tower rather than near the
base. So, if no water runs out the bottom, you still have not proved the
splits are not due to trapped water freezing in the legs well above the
base.
One simple test you might run is to take a close look at the leg bolts you
can see from the ground. Are they REAL Rohn bolts or did the installer
leave the real ones in the tower legs? Real Rohn bolts are Grade 5 (three
hash marks on the bolt head), plated, and fine threaded. If that is not
what the visible bolts look like, I would bet they are still in the tower
leg and trapping water there. Maybe I have wrongly suspected your
installer, but my personal opinion is that you should look carefully at the
job he did for you . . .
By the way, I understand that Rohn clearly points out in their catalog that
you have to take extra precautions to be sure the tower legs will drain.
This info is published in their catalog and every installer should know it.
They should also know the leg bolts are in the leg. This could be an
expensive lesson for your installer . . .
Stan w7ni@teleport.com
Allan W. Schlaugat wrote:
> Early this year I put up a 180ft tower of Rohn 25G to be used only for
> a 440 Mhz repeater vertical at the top and one run of 1 5/8" heliax.
> Everything went up without any problems and it was erected by a
> professional tower installer and everything followed the specs in the
> Rohn 'bible' with the help of many local hams on the ground.
> Today while a friend was on this tower to install a termporary side
> arm at the first guy point he noticed something that caused him to get
> off the tower and literally run away.
> On the south tower leg below the first guy point (33') the leg has
> split like a frozen water pipe 18" below the guy bracket for about 3
> inches between one of the Z braces. 5' above the guy bracket there is
> another split but that one is only 2 inches long between a Z brace.
> The 3 inch split looks like it is still 'running' with the metal not
> rusted.
> About 3 weeks ago we had a good 50+ MPH wind here that took down one
> commercial tower so that is probably when the damage occurred.
> My question to the masses of Towertalk is if anyone has any
> *temporary* solution. I am thinking of a sleeve and clamp arrangement.
> NO, this tower *will* be coming down but any temporary arrangement
> would be something to allow for the unstacking of the tower and
> removal of the antenna and feedline in the spring at the latest.
> What can be done now to minimize any continuing splitting of that
> tower leg? What might of caused it.. guy tension problem?
>
> The tower is located away from everything in the middle of a pasture
> field and there is a 8x8' shed underneath the tower by the south tower
> leg. Guy points are NW, NE and S.
>
> Excuse me while I have another anxiety attack... ARGHH!
>
> 73 Al N9ISN
>
> --
> Allan W. Schlaugat * APS #186089 * Albertville, WI USA
> Amateur Radio: N9ISN * Member of the Lumber Cartel (tinlc) Member #1390
>
> #33#33#33 WISCONSIN BADGERS 1999 Big Ten Football Champions #33#33#33
>
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