tig is versatile as processes go, but impractical in many applications due to it's sensitivity to moving air and the loss of shielding gas...
any outdoor work generally has to be tented up to achieve good heliarc welds... fans are a detriment...
i was on a small outage (outside boiler) a few weeks back where engineering finally approved a 5p root for the wall tubes... this results in a lot of effort to flush tubes after welding, and/or shortened turbine life...
tig is great where it works, but not a true do-all process....
