wrote in message
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On Monday, July 20, 2020 at 3:04:56 PM UTC-5, Steve W. wrote:

That is a lot thicker than needed. The 20' one I have is 3" with 1/8"
thick aluminum.

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Steve W.

Good to know. I priced 1-3/4" .120 wall 4130 and it came to about $325!
I think i'm going to go back to 1-1/4" sch 40 inside the aluminum. I think
I only had 1" previously after seeing how Sch40 is measured from ID, not OD.
I would like 1-1/2", but it's just a tad too big to fit inside the 2"
aluminum at the joint. So I think stepping up 1 size, and making it 1 full
20' piece instead of 2 with a joint,,,,,, hopefully it will be enough.

==============================

Pipe standards originated back when pipe was made from wrought iron which is
weaker than steel. The ID of modern steel pipe is approximately the same as
the old Extra-Strong standard.

http://machineryequipmentonline.com/...ght-iron-pipe/

http://www.iceweb.com.au/Tubings/Gla...ad_History.pdf

Chain link fence posts have the same OD as pipe, though thinner walls and
different size designations in fractions close to the actual OD. Electrical
conduit has the same ID as pipe and a smooth interior without the weld seam,
thus EMT and fence posts of the same nominal pipe size telescope in some
combinations.