[TowerTalk] 2" O.D. Pipe???

[Roger (K8RI)]

k2qmf at juno.com wrote:
> Hello All,
>  
> I went in search of 2 Inch O.D. pipe
> on the internet!!
>   

Actually it comes a wide variety of sizes, weights, and s trengths such 
as schedule 40 and 80.  Then there is structural steel tubing.

Then there is Drawn Over Mandrel  or DOM which is seamless and comes in 
a wide variety of wall thicknesses. It is also 3 to 4 times the cost of 
the same size pipe.

I've used structural steel which is a schedule 40 pipe with welded seam, 
but this is not for carrying liquids or gases. Even though it has a 
welded seam it is very strong. 
http://www.rogerhalstead.com/ham_files/Tower29.htm is all on 2" 
structural steel.  It's been through quite a few 70 mph plus winds 
without taking a bend, but those 144 and 440 antennas on the cross boom 
swing around like a bluegill rod that just tied into a BIG Bass. So I am 
going to 2" DOM and probably 1/8" wall. I may have to go to 1/4" wall, 
but I've been using schedule 40 so that shouldn't be a problem.  2" with 
1/4" wall is HEAVY!  Even DOM is still steel. If you are thinking of a 
larger antenna system, then you might want to consider Chrome Moly steel 
tube which adds a new meaning to the word, "pricey". <:-)) BUT if you 
need it, it becomes a good investment and saving money on anything less 
is a false economy.

What you should use and what you can safely get away with are often two 
different things depending on what you are going to put on the mast and 
how high above the top of the tower. Just be sure to err on the strong side.
>  
> Guess what?  I can't find any!!!!
>  
> The outside diameter of pipe is
> either 1.9" O.D. for 1.5 inch pipe or
> 2.375" O.D. for 2 inch pipe!!!
>   
And this is a problem, why?  One tenth of an inch should make little 
difference for thrust bearings, antenna to mast clamps, and rotator 
clamps. The rotator I have would take either of those sizes with no 
modification.
> Nothing in between....
>  
> What am I missing??
Information, but others have already covered that.<:-))
>  
>   
What are you going to put on this thing?

73 and good luck,

Roger (K8RI)

> Thanks for any help for the uninformed...
>  
> 73,
> Ted  K2QMF
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