Your sales representative is misleading you. Schedule 40 and 80 "pipe" is
designed for carying liquids and gasses and there is no particular attempt to
make it structural in nature. "Tubing," on the other hand, can be purchased
in various alloys and yield strengths that lend itself to our application as
mast material.
If you intend to mount your antenna just above the tower and up to a foot or
two, you can use .250 wall aluminum or schedule 40 for most commerical
antennas. As you move up from the top of the tower, there is an exponetial
increase in bending moment on the mast. At ten feet above the tower, 120,000
PSI chrome moly about the only common material that could safely hold up a
TH6 in 80 MPH winds.
W7NI has written a number of articles on this subject. K7LXC has a program
that will calculate the required mast strength for your installation. I have
a spreadsheet that does the same thing. Do it safely, please!
We have all "gotten away" with less than optimal installations. In most
locations, however, mother nature eventually wins!
73 and DX,
Tom, K5RC/7
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