I failed my 6-g, I had a small incusion on the cover pass.
Oh-well, time ta jump back on the horse…
I took a tour of a non-destructive testing facility where they evaluated welders using X-rays and Ultrasounds on their test welds.
It’s amazing what you have to go through to get that certification.
Good luck, Tony on your next test! 
And thank goodness, too. Speaking for those of us who live, work, ride and fly in the things you folks magically fuse together with heat and extreme skill, your work is more appreciated than you may ever know.