[tpm]

Well my wife had one and it exploded (and it was Italian, Bialetti I think), we have several friends with explosions etc. It's of course possible that Italians use it properly and we don't, but I'm not an expert in this topic, so I just stay away from them.

[GTP]

This is unexpected to me: I would have assumed that, even if you did something wrong, the valve would have prevented an explosion. I can understand a single valve going bad, but if this happened to many of your friends there might be something going on there.