[TowerTalk] TIA-222-G standard and chrome moly masts

[Michael J. Carter]

I've been working with a P.E. on design of a rooftop, 70 foot guyed Rohn 
45G tower for an academic building.  I specified use of 4130 chrome moly 
tubing mast material, but he informed me that TIA-222-G doesn't list 
this particular steel as an allowable material, and heavy wall aluminum 
tube is prohibited.  He specified instead ASTM A53 Gr. B steel pipe for 
the mast material, which has a much lower yield stress (35 ksi 
minimum).  After searching the TowerTalk archives for discussions on 
mast materials, I'm wondering why 4130 chrome moly steel tubing with its 
much higher yield stress doesn't make the list of allowed materials 
under TIA-222-G?

Any insights?

Thanks!

Mike, K8CN