Just a piece of advice. Keep a small piece of tubing that you use to build the cage with. When you have the inspection done take it with you just in case there are any issues with the sonic test. If so, have them check your small piece to check against the tester. Then use a ball end micrometer to prove the thickness is correct. Then they will have to set up the tester the correct way or get someone who knows how to use it the correct way. Beep