I’m not sure if all Bayou Classic brew pots have this but my 15 gallon pot has a lip about 2” below the top of the kettle. If I’m doing a double batch I like to have 11 gallons final volume to split between my two fermenters. With boil off, hops, losses, etc. this means my starting boil volume is 13.75 gallons. With some aluminum flashing and a silicone tube I extended the height of my kettle to keep any expanding foam in the kettle. Worked great today.