Why are most gas containers cylindrical in shape?

Answer 1

In brief The most efficient shape for withstanding high pressure is a sphere but that would be costly to manufacture. A cylinder with a domed top and a domed bottom (look underneath, the flat base is actually welded around the outside, the bottom of the gas container is actually domed) is a much cheaper shape to manufacture whilst still having good stength to resist the internal gas pressure.

Some other ideas

The idea that "cylindrical vessels have minimum surface area to volume ratio and thus reduces heat transfer" is incorrect. The surface area to volume ratio for a cylinder depends on the ratio of its length to its diameter and most cycinders are manufactured with a much greater length than is ideal for minimising surface area. In fact a cube would be a better shape than most gas cylinders if this was the primary design consideration. Also heat transfer is actually often a good thing for gas containers, liquids require heat to convert to gases. Try using a butane cylinder on a near freezing day......

The idea that "they are cylindrical because there are no weak points such as joins and corners that the gas molecules could force apart" is partially correct, a cylinder with hemisperical ends has no corners which would certainly act as stress concentrators and therefore be much weaker for the same material thickness but many low to mid pressure gas containers are welded from sheet material so there are joins.

Answer 2

Allows for a seamless construction making for a stronger container.

A gas container could really be in any shape (a sealed zip-lock plastic bag is a container for air). However, if you want to pressurize the gas you would need a container that could handle the pressure. cylinders tend to be the best shape for containing compressed gases.

Answer 3

Curved containers provide the maximum volume for minimum surface area. Since the forces on the container are usually the result of the pressure of the gas within the container - and pressure is Force/Area, this minimizes the total force exerted on the container. Also, in containers with sides meeting at edges, the forces will be concentrated at those edges making them areas with greater potential risk of failure. In addition, since curved containers minimize the total surface area of the container for a given volume, they also minimize the total amount of material required to construct the container - and hence the container is less expensive to make.

Answer 4

Strength. Ounce for ounce, a round container is stronger than a box. Easier to make, as well.

Answer 5

Relatively, no. Gas is lighter than its liquid form, and most times the solid form is heavier than its liquid form.

Answer 6

Because a spherical tank distributes the pressure of the liquid evenly

Answer 7

Because round shapes are stronger and contain pressure better. Pressure vessels that don't have to be handled/moved are often spherical for the same reason.

Answer 8

They are made from steel and the walls are thick.