Piper Alpha is an odd-ball, because there were so many points in time that it could have been stopped, or the damage reduced, yet it seemed that everything that could go wrong did. From my knowledge (backed up be wiki), if one person had just told the person in charge about the gas pipe being out of action nothing would have happened. First time I watched the docco on it, it blew my mind. Interesting read on wiki, if you're interested. (also, from memory, it was initially designed as gas, and was converted to both gas and oil... or vice-virsa.)