[TowerTalk] Need European spec for Chrome moly tube

[TexasRF at aol.com]

John, try a google search for 4130 chromoly specification. Several hits  
will come up.
 
Beware that the material is usually sold without the final heat treatment  
and to reach the yield strength you are looking for, this final step has to 
be  done.
 
Your steel supplier should be able have this done or at least let you know  
where you can have it done.
 
You will have to decide just what yield strength you are looking for. Too  
little and the tubing can bend; too much and the tubing can shatter under  
maximum stress. In our applications, shattering tubing is not good since that 
 would allow the antenna to free fall to the ground.
 
100,000 to 110,000 yield numbers seem to be a good compromise. You may find 
 that using larger diameter tubing with a more commonly available yield 
strength  may be more economical in the long run.
 
73,
Gerald K5GW
 
 
 
In a message dated 7/14/2009 5:05:38 P.M. Central Daylight Time,  
john at airwave.ie writes:



Folks,





Last winter, I had a stack of a  40m full size beam and a tribander wiped 
out
by a storm. The point of  failure was the steel tube that I was using which
bent over and caused a  knock on affect which destroyed the beams. We have
learn the difference  between pipe and tube the hard way.



There are several steel  stockists here in Ireland, but they only carry
standard galvanised piping.  I have checked the towertalk archives and there
is a lot of discussion  there on the merits of Chrome-moly tubing and the
different grades that  would be suitable for this type of installation.

However, these seem to  be US standards and the steel merchants here are not
familiar with  them.





Can anyone point me in the right direction ? If  someone has purchased 
tubing
for a similar project, I would be very  grateful if you could send on 
details
of what tubing you have  used.







Regards



John ei8ir  



For EI7M  Group



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