geesh opening up a can of worms here lol....other than the massive amount of info you can find on the net, here is my shot at explaining
first off ....pipe is for poop.... maybe a non load bearing (decorative even) bumper lol.... pipe is measured by inside diameter also. ment to carry fluids, gasses, etc, consistent ID..
Tubing is measured by outside diameter and wall thickness consistent OD, say 1-3/4 x .120 wall... which would measure 1-3/4 outside and 1-1/2 inside.(overall diameter - wall thickness{x2}) hope i confused you.. Pretty much everything such as bumpers, sliders, event the roll cage can be made of HREW tubing (hot rolled electric welded). Its cheaper than DOM (drawn over mandrel)...
Now if your looking to make steering, links, or anything that you need to thread the inside of... DOM is usually the way to go ( you could also get threaded plug to put into HREW but the fit usually isnt the best....
Also when it comes to chrome-moly it is not lighter but is stronger comparatively, most sanctioning bodies say that you can use thinner wall thickness which in turn would make it lighter. and because of the nature of the metal if you damage a section it will be easily replaceable compared to regular tubing which would prob require more material be replaced....
Then you get into benders, harbor freight DOES NOT make a tubing bender lol... if you want a good entry level tubing bender get a JD2 model 3 manual bender, or something like the tj diesel performance hydraulic bender......
im sure im forgetting something, but thats what i do... and anyone can feel free to argue any of my points, i may or may not have all my ducks in a row lol.....
here is something i got off my local site, might help more than my babbling
HREW is a 1010 steel, DOM is 1020. The 10 and 20 represent the amount of Carbon in the steel. The higher carbon
content make the steel much stronger. Yield strength on 1010 is around 45,000 psi and DOM is around 70,000 and 4130 is around 90,000. So you can see the strength difference. Also, DOM is "work-hardened" or forged if you will. The Steel itself becomes denser and the surface tougher.
DOM is a process and means "drawn over mandrel". Typically you use DOM when you require precise thicknesses in the ID, OD or wall thickness of a tube. Hydraulic applications come to mind. It is not seamless but is made from sheet steel, rolled and electric resistance welded and finally, DOM'ed. DOM is a cold process. Most typically it is made from low to medium carbon steel. Often a low carbon steel application is preferred because of it's ability to be formed easily. The higher the carbon content, the harder it
becomes to bend. Typical tensile strength of DOM tubing is in the 60-75000 range although some increase can be gained with a 1040 steel base rather than the more common 1020. 4130 Tubing is often referred to as "Chrome Moly" tubing. This jargon term is derived from the chromium and molybdenum concentrations present in the metal itself, which run in the area of .80-1.10 for Chromium and .15-.25 for Molybdenum. typical tensile strength for this material is 95000 - 110000 PSI however it can range as high as 225000 by heat treatment. It is good to
remember that the higher the tensile strength, the more brittle a metal becomes so you need to find a balance. A good balance for 4130 would be somewhere in the 145000-15000 PSI range.
all that being said, if you go to another site (PBB) perhaps, there is a very "spirited" conversation/argument with people that have used heavy duty structural pipe for everything, even rollcages...... so yea Im sticking with HREW thank you very much
