Some time before, I attended a short course on handling the small/medium propane tanks. It's like with the nitrogen tank - it's relatively small, some people don't expect it to cause problems really -- but now I flinch every time I see someone kicking/rolling the bottle (way too common thing). In reality it could easily destroy a thick wall and cause a collapse, never mind tearing the people nearby into pieces. Unfortunately many people handling those bottles never learned much about them...