[TowerTalk] How to deal with bad fitting Rohn 45 sections?

[Kimo Chun]

We shipped out about 4 pallets of 45G sections. Almost a third had ends bent
slightly, presumably, during shipment. If you have reasonably good judgment
you can just LOOK at a few section ends and see that a leg may be bent. Find
one section that looks good and use that as a reference. Mate up the "bent"
section and confirm degree and direction of the bend. Lay the tower section
horizontally on the ground with the bent end up. Use a 2" pipe, say, four
feet or so long. Have someone (or two) sit or hold the section down. Place
the pipe over the bent end and bend it the opposite direction to fix the
error. Of course you will have to go slightly past to allow for it springing
back. Once you have the three legs lined up with the reference (or actual
one it will mate with) apply some conductive anti-seize compound in the
female end. This is necessary here in Hawaii if we want them to come apart
more easily later and will help you mate the sections together on the tower.
As Bud advised, marking one leg on both sections to ensure correct mating
with the next section is necessary. Mark the (hopefully only) one that was
bent so you know that up on the tower it is the most likely one you need to
readjust. To mate with existing sections on an erected tower you just have
to assume theirs are true and you got it close with your assumed good
reference section end.

 

There is always the chance you may need to do slight corrections on the
tower with a hammer and we usually don't have many problems. Since the
corrections up there are slight you probably don't need to protect the
galvanizing as you won't be hammering hard or much but you can opt to use a
strike buffer (or whatever it is called)to reduce the odds of cracking the
zinc.

 

If you are talking about vertical legs being creased or bent in between
welded webbing within the section you should not use it. In theory and based
on severity the whole section is out of true and should not be used.

 

We replaced half the sections on 3 towers using this method without TOO many
problems. Of course, I was lucky and was not the man on the tower having to
do final fit. this time.

 

Good luck.

 

Kimo Chum, KH7U

At contest station KH7X

 

Message: 11

Date: Mon, 21 Apr 2008 09:02:34 -0400

From: "W2RU - Bud Hippisley" <W2RU at frontiernet.net>

Subject: Re: [TowerTalk] How to deal with bad fitting Rohn 45

      sections?

To: "'Rob Frohne'" <rob.frohne at wallawalla.edu>,

      <TowerTalk at contesting.com>

Message-ID: <01a801c8a3af$f90b49d0$eb21dd70$@net>

Content-Type: text/plain;     charset="us-ascii"

 

I've used automobile scissors jacks (old GM and Datsun/Nissan ones, for

example) to realign the ends of Rohn 25 and 45 sections.  "Buffer" the

jack-leg interface with short pieces of 2 x 4.  I've done many realignments

with the sections lying on the ground and also with them up in the air.

Getting them to nest properly while they're still on the ground is probably

a little easier and has the advantage of not requiring you to hoist the jack

up the tower, but either way works.  If you do it on the ground, however,

make sure you actually nest the two sections that you're planning on

connecting, and *mark* one of the three mating legs of each section so you

know what goes with what once you get them up the tower.   (When you spread

the ends of tower sections, you have no reason to believe the result is

going to be perfect equilateral triangles, so later rotation of one section

with respect to the other is to be avoided.)

 

I've never had to have a section re-welded; never even considered it, to

tell you the truth.  BTW, I think TowerJack makes an alignment tool that

replaces the scissors jack.

 

If you do the work on the ground, make sure the insides of the upper section

legs and the outside of the lower section legs are absolutely clean and

devoid of dirt, gravel, etc., before you nest them.

 

There was a period some years ago when it seemed as though Rohn was totally

incapable of delivering new sections with unbent leg ends.  But, then,

that's the stuff that leg ends are made of.....(Awwwww....)

 

Bud, W2RU   

 

-----Original Message-----

From: towertalk-bounces at contesting.com

[mailto:towertalk-bounces at contesting.com] On Behalf Of Rob Frohne

Sent: Sunday, April 20, 2008 10:12 PM

To: towertalk at contesting.com

Subject: [TowerTalk] How to deal with bad fitting Rohn 45 sections?

 

Hi Gentlemen:

 

Thanks to Steve's good advice, I checked the alignment of the Rohn 45

sections I have and found that some sections are out of alignment by

almost 1/4".  Some of this tower was left over from a project up in

Seattle, and I suspect that it may have been put aside as not well

fitting, but I'm not sure.  I think N2EA mentioned a while back on this

list that he had to have a section cut apart and re-welded.  I hope I

don't have to do that.  I am tempted to try and bend the ends a little

with a jack or something to make things align, especially on one section

that looks a little bent already (in the wrong direction).  What advice

do you have for me?

 

73,

 

Rob, KL7NA  

 

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