Okay, I logged into my imprisoned Vivaine Felfiend and the recently deceased Ugly Dirk Rotmouth was in my cell, he asked me if I had a keg of alchemist fire, I replied with a no, and he explained that he had before broke out of prison by threating to blow the entire place up with a keg he had had in his possession.

The question is, Can one, (with DM help of course) blow up a building with alchemist fire? and

How many vials of alchemist fire would add up to a keg? If I had enough vials could a DM take them and give me a keg? And finally, is it possible for a PC to create alchemist fire, and thus a keg?

I'm sure you can tell that I really want a keg.

These are things to explore in game. =)

I'm cool with that, but how can I test it without a DM?

You can't.

If you want to try and make a keg of alchemist's fire with your pouches, contact a DM in-game and it'd go from there.

Its much easier for you and us DMs to just buy one though; where you can purchase them is something you'll need to explore IG.