title_body: Carbonation in pressure barrel
upvoted_answer: Actually, this does happen - but, perhaps 'explode' is a bit of a dramatic term to use... 'Spring a leak' is more like it; because the building pressure would pop the seal of the barrel in order to off-gas.
  
  Check out this thread from the Homebrewing beta:
  Flat beer after priming in a pressure barrel
  
  
    That's probably the main culprit (CO2 leak).
  
  
  Also, this brewer describes the exact same scenario occurring during a couple of his brews due to a specific yeast:
  
  Pressure Barrel Blues