Why is LPG stored in spherical tanks?

“LPG,” or liquefied petroleum gas, is a type of hydrocarbon gas that is considered highly flammable.  Many people are familiar with LPG in the form of tanks that are cylindrical or spherical in shape.  These tanks are commonly used for cooking or heating purposes.  The shape of LPG tanks are always spherical, and this has led many people to wonder why this is so.  One reason for this is that the spherical shape of the tank adds to its strength. This is especially important for LPG because it is a pressurized type of gas.  Apart from being flammable, LPG must be stored in a secure environment, and the spherical tank is the best shape that can contain it.  Spherical tanks literally have no corners, and this translates into zero weak points in any part of the tank.

Another reason for the use of spherical tanks in LPG is their ability to neutralize internal pressure while holding the hydrocarbon gas inside.  The spherical shape helps in neutralizing pressure coming from all directions making it more stable.  And because of the neutralized internal pressure, spherical tanks are also able to hold much more gas volume when compared to other tanks in different shapes.  This property translates into more gas volume that can be contained within the tank maximizing its capacity.  A typical LPG tank is filled up to about 80 or 85 percent of its original capacity to give an allowance for possible thermal expansion of the hydrocarbon gas inside.

For most people, LPG tanks serve as heating appliances for cooking food.  In some countries, LPG tanks also serve to fuel car engines.  Cars running on LPG are especially popular among public utility vehicles because this fuel is cheaper when compared to engines running on gasoline or diesel. LPG is also used for refrigeration and air-conditioning machines and appliances.