Quote Originally Posted by roadster32 View Post
I think you will find only Moly cages have to be TIG welded, Mild steel can be either MIG or TIG.
Exactly...
From the NHRA rule book

Section 20 - General Regulations 20.19
4:11 ROLL CAGE
All cage structures must be designed in an attempt to protect the
driver from any angle, 360 degrees. "All 4130 chromoly tube welding
must be done by approved TIG heliarc process; mild steel tube
welding must be approved MIG wire feed or TIG heliarc process.
Welding must be free of slag and porosity. Any grinding of welds
prohibited." Plating of chassis prohibited for all cars manufactured
after Jan. 1, 2003, unless otherwise noted in Class Requirements;
painting permitted. Additionally, roll cage must be padded anywhere
the driver’s helmet may contact it while in the driving position.