NHRA Welding rules??
No offense but learn to weld or take it to someone. Your wasting your time right now. If you cant weld and you can tell its not right, its not going to hold. As stated get scrap, clean it to bare steel, then weld. set the pressure to 30psi flowing (left gauge) and start practicing.
Tony when we had our chassis certed for 8.50 on the landy dart they didn't X ray it but they did due a ton of tube thickness measurements. I thought X ray was only on Chrome moly tube.