Abstract: When the vacuum tank is working, the external pressure will act on the shell of the vacuum tank. If the shell is square, the pressure resistance is high at the corners of the square.

When the vacuum tank is working, external pressure will act on the shell of the vacuum tank. If the shell is square, because the corners of the square have high pressure resistance, it will shrink and deform at the neutral position of the plane. The circular shell has uniform force in all directions and has no weak points, so it can ensure better pressure resistance from the process.