³³To illustrate, consider a (vertical) cylindrical storage tank 15 feet tall and 20 feet in diameter, with an internal gas pressure of 8 inches water column. The total force exerted radially on the walls of this tank from this very modest internal pressure would be in excess of 39000 pounds! The force exerted by the same pressure on the tank’s circular lid would exceed 13000 pounds (6.5 tons)!