[TowerTalk] What is this mast??

[Kurt Andress]

WA5JWU@aol.com wrote:

> I was recently given (yep, free) a mast by one of my customers to use with an
> upgrade of the top antennas on my tower.  Can anyone assist me in identifying
> what the mast actually is?  Here are the details stamped on the side of it:
>
> AL TCH SMLS 304-L ASME 312 1-1/2 SCH 40 HEAT A5557H
>
> I was told it is stainless steel and is 22'  9 1/4'' long, 1 7/8'' OD and
> 1/8'' wall thickness.  I would like to know the truth about this
> mast...whether this "freebie" IS or IS NOT a bargain to be used with a KLM
> KT34XA with a shorty forty on top up at 100 feet or should be used on another
> tower with much smaller VHF, UHF, TV and other miscellaneous beams/antennas.
>

Mike,
This material is 304L Stainless pipe. I.D. is nominal 3 1/2", wall thickness is
.226
The 304L alloy has less carbon content to prevent intergranular corrosion when
welded, and therefore has a lower yield strength than the 304. The 304L per ASME
SA-312/ASTM A 312/Mil-P-1144 is listed at  25,000 psi yield strength. The 304
alloy is listed at 30,000 psi. Not as strong as 6063-T832 aluminum tubing, but it
is almost 3 times stiffer than the aluminum. Good thing its free!
You'll need to get something like K7LXC's MARC program to see if it will hold
your antennas at your expected wind speeds.
73, Kurt

YagiStress - The Ultimate Software for Yagi Mechanical Design
Visit http://www.freeyellow.com/members3/yagistress



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