If I have a cylinder 4 in. in Dia. Hallow and encircle it with another cylinder that has walls 1/8 in. thicker, pack sand around the smaller cylinder between the 2 cylinders, and I pack the sand evenly, how much pressure will it take to break the smaller cylinder, the smaller cylinder is plastic and the outer is metal, the smallers wall thickness is 3/16 in and the metal is 1/4 in thick?