[TowerTalk] Mast diameter

[K6OK]

>>WA4PSC wrote:
>>I have a 20' long steel mast (looks like chrome moly) with 0.25" walls

Unfortunately physical dimensions are not a reliable indicator of water
pipe vs. structural-grade tubing because they are both produced in the
1.90-inch O.D. size.  When you say it "looks like" chrome moly, I assume
you mean it is smooth, gray and not galvanized.

The thick wall (0.25") just about rules out ungalvanized black water pipe.
Water pipe in Schedule 80 in 1 1/2 NPS is 1.90" with a 0.20" wall. This is
not good for a mast because the yield strength is low, usually 25 to 30ksi
or sometimes less.

The steel industry also produces structural tubing in 1.90" O.D. in a
variety of thicknesses. Industry calls this HSS (Hollow Structural Steel).
The nomenclature would be HSS1.9x0.250 in your case. Valmont's catalog
shows a 1.90 x 0.25 available in A513 spec., but A513 depending on alloy
and type might range anywhere from 50ksi to 72ksi. HREW is available
elsewhere in 1.90 x 0.20, yield strength around 45 ksi is typical.

So, unfortunately, without the paperwork or markings it's hard to say what
you have in terms of material, except that I'm 99% sure it's structural
grade and not water pipe.

73 Jim K6OK