> From: uunet!ritz.mordor.com!wb2k (John A. Ross, IV)
> Subject: Re: masts
> Date: Tue, 25 Jun 1996 02:02:16 -0500
> >I go in and tell them "I want your strongest 3" pipe." I haven't been
> >knowledgeable enough to even know to ask "what schedule is it?" but I do
> >know I have bought 21-24' lengths for about $50. One has been up for
> >eight years holding a 6-element Telrex 20 at 120' on the thrust bearing,
> >with an 8-element Telrex 15 eight feet above it. So, empirically, they
> >seem to be strong enough.
> >Rich Boyd KE3Q
Just to amplify other comments along these lines: up for 8 years doesn't prove
a lot. The general rule of thumb in the building codes is worst case
in 50 years (and not just for wind, but for floods, earthquakes and any other
highly variable phenomena). If it's still up in 42 years, you've proven it
by example, hi hi.
p.s. 3 inch certainly helps - because of the way strength scales with diameter,
3 inch "junk" can be almost as strong as moderately strong and expensive 2 inch
stuff. It would be no match for some of the outrageously expensive heat treated
Very approximate estimates (given I don't know your wind zone or pipe
thickness) suggest you're in the ballpark [i.e. .25 inch wall and 70 MPH zone
gives an OK safety margin, but .12 inch wall in a 100 MPH zone has you living
on borrowed time].