TIG isn’t used for structural. But it can be in some cases. It’s mainly Flux cored, Metal cored, and Arc welding that are used for structural as they have the best penetration. MIG is more for production.
On a cage however, the metal is far from structural grade metal. If refering to structural as items such as bridges and buildings.
In the case of a roll cage. TIG can be as strong as anything else. Also creates a much more appealing weld.
To me, it makes perfect sense that the welder welding the in the cage be qualified. If the welds are at all to be inspected for their quality, it makes perfect sense.
I just wanna know if I’ll have to re-test myself every two years for TIG or not…