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Re: retrofitting of towers

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Arman:

Bolts:  It depends on what kind of bolts you are using.  If the bolts are
high strength and designed as slip-critical, then the standard high
strength tensioning is required.  If they are in shear, then we use a
"snug-tight" method.  If you are worried that the "snug-tight" method might
loosen, then use Anco nuts.  Some tower fabricators perform the high
strength torquing as well as using the Anco nuts.

Welds:   If you are bolting in new members and you are using pipe with end
tabs, the fillet welds require no special inspection.  If there are other
types of welds, then the shop should be certified with welding procedures
already established.  

Any inspection should be performed by a certified welding inspector.  If
you want more information on welding inspection, review Section 6 of the
Structural Welding Code (ANSI/AWS D1.1)


>we are currently undergoing retrofitting of our telecom towers.  we will
be additiong additional atennae and our consultants have checked the towers
and they require strengthening.  my questions are:
>
>1.  additional horizontal and diagonal members will have to be added.  is
there a code requirement regarding the tightness of the bolts?  i.e. up to
what torque should they be tightened to?
>
>2.  how do you inspect the effectiveness of the welds of the additional
members?  what do you look for in inspecting the welds?
>
>thank you very much
>
>arman rivera
>
>
>__________________________________
>www.edsamail.com
>
>