I just did a fast calculation of the pressure pounds of force spread out on the bottom of a canner or any presser vessel at 14 inches in diameter at 15 PSI.
3024 pounds.
Or the area of 14 inch in diameter is 201.6 X 15psi = 3024.
This sounds unreal I must be wrong but I dont think I am.
I have seen huge house sized tanks launch at 10 psi.
Canning is fun.
Worth