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Re: [TowerTalk] what not to do in your tower

To: "Tower and HF antenna construction topics." <>
Subject: Re: [TowerTalk] what not to do in your tower
From: Grant Saviers <>
Reply-to: "Tower and HF antenna construction topics." <>
Date: Fri, 23 Apr 2010 15:29:37 -0700
List-post: <">>
Agreed that constructive help is best.  Here is a quick sanity check on 
the danger actually involved with the rigging as photographed.  I've 
taken down worse (after some temporary guying).

EHS and Philystran are rated at breaking strength 2100 to 4000# 
depending on what is up there, not safe working load limits .  What is 
the safe WLL for "man-rated" applications?  I don't know if there is a 
spec but usual engineering practice would be to derate to 1/3 to 1/4 of 
the breaking strength value.  Will the tower fail if a guy breaks while 
on it? Maybe? What if stressed with a gin pole lowering from a 2 way 
guyed section? 

The quick links for 3/8" which kinda look about what is there are rated 
1400# WLL, but certainly aren't man-rated at that WLL.  However, I'm not 
aware of ANY ham tower guy hardware that is man rated such as links, 
chain, hooks, etc are for overhead lifting and made from forged grade 70 
to 100+ steel.  Then there is the matter of how much more to derate the 
Chinese made links sold at the local hardware store even though they 
have WLL 1400# stamped on them.

Round links are available for overhead lifting, forged grade 80 of about 
WLL 2500# for 3/8" but unlikely what I see in the photo.  Plain vanilla 
hardware again is rated 350 to 450# WLL for 1/4" rings.  So these rings 
are the weak points and as suggested earlier both rings and quick links 
ought to be replaced with rated bow shackles with pins secured with 
stainless steel safety wires.

The angle on his guys looks pretty good, better than spec, so maybe on a 
nice calm day it would be reasonable to climb to make some 
improvements.  How did the LP get up there?

Grant KZ1W


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