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[TowerTalk] Bolt torques

To: <>
Subject: [TowerTalk] Bolt torques
Date: Wed, 9 Apr 1997 07:38:37 -0500
We have had some difficulty with the systems here at work and 
they say that some mail might not be getting through, so my
apologies if someone else has already provided this info:

The Rohn catalog I just received from Steve has a page titled
"ROHN Information", dated Nov.1, 1994.  Under a heading of
"Bolts:" are the following lines:  "Be sure to tighten all leg bolts
until they partially flatten the sleeves, causing the sleeves to
actually grip the legs inside. Always replace stripped bolts.
Upon completing an installation, there should be no vertical 
movement between tower sections at the joints when the tower
is deliberately swayed from side to side."

KJ7CH wrote:

(some stuff deleted)

>A question that has been bugging me, and perhaps isn't readily answered, is
>about a torque recommendation for the 45G leg bolts to join sections
>together. None appears in the Rohn drawings, and calling Rohn didn't turn
>up an answer. In fact the Rohn representative seemed rather surprised and
>condescending, "We don't specify a torque value, these things are put up by
>amateurs like yourself. Just tighten 'em up real snug -- not TOO tight, you
>don't want to bend the legs, you know what I mean. . . " etc, etc. I tried
>to explain to him that in the engineering world, WE DO specify torque
>values, for just the reasons he so eloquently demonstrated trying to
>verbally describe how to tighten the bolts -- it ensures consistant,
>repeatable results without the danger of failure through undertightening,
>or material damage through overtightening, regardless of who does the
>tightening, or what "real tight" and "not TOO tight" means. I also
>emphasized that I wasn't looking for one specific value, but a nominal
>range for each size leg bolt. No joy. Surely there must be a torque spec
>out there in the commercial world -- I can't believe that you just tell a
>110 pound tower-monkey and his 230 pound tower-gorilla partner to each
>"just tighten 'em tight, not TOO tight now, you know." This spec would not
>be just a bolt spec, but would take into account the guage of the tower leg
>and the stress required to elastically deform the leg enough for a strong
>union without permanent deformation or weakening the union because of
>"egg-shaping" the tower legs.
><more stuff deleted>

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