From what I have seen the areas failing are not thin (not what I would consider thin anyway). Seems to just be an area that after prolonged use (too much to test in a lab) can get weaked and split open. Problem could be from many variables also. Could be getting burned hotter than they expected, the baffle could be dislodged slightly allowing and irregular burn in one spot. Could be some units don't get welded as good as planned and its not noticeable in the QC checks. Lots of things could factor in...
