Originally Posted by TaterTott
build it strong by design, not by material..
the actual strength differences are insignificant if the welds are crap or if the design of the cage is poor, those are the places it will fail first.
Dom is cleaner over-all so you pay up front to not have to remove scale, get material that bends cleaner, and is easier to give a top notch paint job too. When the steel is drawn over the mandrel (DOM) there is a certain amount of internal stress that is released from the steel and this in turn strengthens the steel and makes it ideal to bend and form...especially near the weld seam.
Pipe is generally dirtier, has some lower grades that you want to avoid, may have some ugliness on seams, and might not fit in your bender.. but is very inexpensive and plenty strong enough when built correctly.
Here is a link with some info..http://www.greatlakes4x4.com/showthread.php?t=1919
about what kind of pipe you want to look for.
If you are building a full blown buggy comp chassis that will see many multiple roll-overs then you should be worried about strength differences...but since your probably building a cage that should only be used once then getting a good solid design (triangulate) and good solid welds (penetrate) are what makes the biggest difference.
Splitting hairs over a couple thousand lbs of tensile strength and saving a few bucks is all the builders choice.