Why can circular tubes withstand large pressure differences compared to noncircular pipes?
Pipes with circular cross sections can withstand large pressure differences (in the range of Mega Pascals, MPa) between the inside and outside without undergoing much distortion.
The gases are usually transported through non-circular pipes where small pressure (in the range of hundreds of Pascals) differences are present for example in HVAC applications square/rectangular ducting is used. This ducting solves the problem of space constraints as well as they are easy to manufacture.
Note: There are some other benefits of circular pipes, for instance, liquid flows faster through round pipes compared to other types of pipes, liquid flows evenly through circular pipes hence rusting is prevented, and the circular shapes are cheaper to produce (less material is required for the same flow rate).