I dunno, but the stuff I used doesn't wanna burn too well. I tried burning scraps left over thinking it would go up like gangbusters, but it takes a long time to catch & sorta just melts away instead of burning. I'm sure it has to pass some sort of flammability tests. Mine was Accu-Seal roofing membrane IIRC, purchased from Little Rock Builder's Supply. It is meant for transitions between roof height or materials. The only downside i have found is minor edge peeling on uncovered vertical surfaces(behind the tank) in the intense heat of summer, this was remedied by duct tape(the $7-8 a roll pro stuff from said builder's supply)
