I am a TIG welder and have been since the 80's (god I am getting old). I remember welding alot of small plane tanks back then that would fracture, I think the mechanics said they were stored with not enough fuel...??? I can't remember the exact reason. Anyway I was wondering if you guys have ever had this problem with cracks in fuel tanks? And if you have is it even legal or ethical to weld a tank? The reason I am asking is I am renewing my certifications, and shopping for a portable tig rig. I am not a pilot or an airplane mechanic, so I thought you guys would be able to give me advise. I work in the Fairbanks area.