Galvanized pipe is made from steel of unknown parentage. But presume it
is real junk. These days, the 'iron' part of it refers to the sizes base
on the old pipe system where it is the ID that is important. The only
real specs it needs to meet is to be round and hold 300 PSI. The
galvanized coating on it needs to be cleaned off to avoid getting the
zinc into the weld and into your lungs. This is NOT the sort of thing
you want to use for any kind of mobile chassis.

The tubing you want comes in 3 general classifications:
-cold or hot rolled welded tube. Typically around 1008 to 1018 mild
steel, available in many wall thicknesses, outside diameter in
reasonable fractions of an inch ie 1-1/8" or 1-1/2" Yield strengths vary
but 50,000 psi is a reasonable number to start with.

-DOM (Drawn Over Mandrel)steel tubing is the same basic tube as above
except that it has been drawn over a mandrel to make it more uniform and
work harden it. Typically made from 1018 or 1026 steel. The work
hardening moves the yield up to perhaps 80kpsi

-4130 alloy (and some similar grades) This can be either welded or
seamless, runs around 90Kpsi yield if it is annealed, can be pushed to
over 200kpsi with heat treating.

Prices on the last 2 will be enough to take your breath away. But for
that price you will get uniform product, known specs, and mill
certification sheets to prove it.

I couldn't tell you which one you need to use without a lot more detail.
If this is for any kind of sanctioned racing, the tech inspectors will
have a lot to say about what you use. For our rules, we have to use 1026
DOM in certain specified diameters and wall thicknesses, with a mill
cert sheet handy to show the inspector. Then they use an ultrasonic
thickness gage to prove we are not lying.


wrote:
I need steel tubing to build a tubular chassis.

The problem is, I'm not sure what kind of metal my supplier is
selling.

they sell G.I. or galvanized iron which is what i'm interested in
getting......
problem is, I'm not sure if it's steel or iron.

of course I so prefer steel.

how do i know if it's steel or iron?