how to make a round pipe oval?

how to make a round pipe oval?

There are usually many manufacturing methods for elliptical tubes, and there are four common manufacturing processes for elliptical tubes. They are respectively casting process, bending process, forging process, and welding process.
Casting Process
Pour the molten metal into the mold, cool and solidify to form an elliptical pipe.
Bending Process
Transform the original circular steel pipe into an elliptical steel pipe through bending processing.
Forging Process
Heat the metal to a high temperature state, and then perform forging plastic deformation through a mold to form the desired elliptical pipe fittings.
Welding Process
Make elliptical pipe fittings by melting and welding metal or steel plates.