TIG stands for tungsten inert gas. The arc is struck from a non-consumable tungsten electrode, and the filler material is fed into the weld separately, by hand, rather than being carried by the arc itself. That single difference - separating the heat source from the filler - is the whole point of the process.
When the heat source and the filler are independent, the welder controls two things instead of one: how much heat the joint is receiving, and how much material is going into it. That means you can bring a joint to fusion temperature and then add exactly the filler it needs, rather than flooding it with wire along with the heat. On thin-wall tubing that control is not a nicety. It is the difference between a sound joint and a hole.
Thin-wall tube and perforated cores are the hardest geometry in exhaust work, because there is very little material to absorb excess heat. Processes with less precise heat control tend to burn through thin material, or to throw spatter into the inside of the pipe. Both problems are partly hidden - you cannot see the inside of a finished system - which is exactly why they matter.
The goal of a performance exhaust weld is full penetration: the weld fuses through the wall thickness rather than sitting on the surface. A full-penetration weld has no crevice on the inside where a crack can start, and it produces a clean internal flow path. On a pipe carrying high-velocity exhaust gas, an internal ridge or a blob of spatter is not just untidy - it disturbs flow and can break loose later and travel down the system.
You do not need to be a welder to judge a weld. Look for a consistent bead width along the joint, a regular ripple pattern rather than a lumpy one, and a surface with no visible pits or pin holes. Look at the inside of a joint if you can see it through a bend - it should be smooth, not spattered. Consistency along the whole joint is the strongest signal, because it means the welder held control for the full length rather than starting well and fading.
We use TIG across our welded work, including titanium welding and stainless steel welding. If a particular joint matters to your build, ask and we will send a close-up photograph of that joint before the order is made.
