Why TANKER TRUCKS are made cylindrical and not cubical?

 Many kinds of liquids are transported by road and railway. The tanks carrying these liquids are made cylindrical in shape and not cubical. Why is this so?  If tanks are made in cube or cuboid, the capacity of the tanks will increase and they can hold more cargo. Even the large tanks used in refineries for holding the petroleum products are cylindrical in shape.

          This is because cylinders don’t have corners. Cubes and cuboid have more space, but their corners make them unsuitable for carrying fluid. When carrying liquids under pressure, the stress acting at a corner is more than the stress acting on the sides. Because of this, the stress concentrates more at the corners. And because of this there are more chances of a tank to buckle or break if they are made cubical. There are less chances for cracks in a cylindrical tank than in a cubical tank. Even the ends are made semi-spherical in modern tanker trucks.

The LPG cylinders used for cooking are also made cylindrical. This is not to make them roll easily. If you observe closely, you will find that the LPG cylinder is not flat bottomed. It has a false bottom welded to the bottom of the cylinder.

         This is why all the tanks transporting liquids are made cylindrical in shape. One more advantage is that, the liquids can be easily drained in these tanks.

🎥For better understanding :