Pictures of this pipe failure in China where shown at work yesterday. We build gas compressors and some times with pretty high pressure ratings. All our components are hydrotested and then a final air/nitrogen test is done on the unit. I'm not sure what pressure this was at when it failed but the damage is incredible:
http://weldingweb.com/showthread.php?p=518971
No mention of the size or flange rating but judging from the pictures I'm thinking 20-24" 600# rating and 1" wall thickness at least. Pretty amazing how the pipe has been folded near the floor.