strength of mig vs tig on tubing

I want to know if the strength of a properly tig welded weld is as strong as a properly mig weld on tubing. I was told that the metallurgy is different and that tig is superior for welding tubing because it is stronger. Is this true and why? Please explain what the metallurgy test results explain and why.

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In my opinion, if both welds are done properly, the main issue will be grain size.

Tig welds can have large grains because of slow travel speed.

large grain size can cause failure of weld in service with cyclic loading, vibration, etc.

That is not to say all tig welds have large grains, its just hard to inspect because visually, the weld can look great.

best regards,

Jody