Pressure calculation

I think it is good to have some more explanations since if not the result could be underestimated.

The oval tube is assimilated to a round tube with the radius = to the LOCAL curvature radius and the computation is done as for the cylindrical tube. In the case of an oval (elliptical section ) tube the higher stress will occur at the biggest radius R=a²/b where a>b both being the ellipse semi-axis. The stress being "σ" and the safety coefficient "Cs" the wall thickness will be t= Cs*R*(p/σ). This is valid for relatively THIN walls. If the wall is not to be considered as thin then the tube n be considered as a beam and this leads to bending moments which are neglected in the 1st assumption.

There is a second limitation for the equation validity: the tube length and the presence at the ends of the flange and of the container wall. Both are in radial direction a lot stiffer than the tube which will limit the radial expansion under pressure and generate bending moments in the tube wall with the consequence of a second stress in axial direction. In fact the combination of both stresses should be considered since the axial stress depends on the tube length and can be under circumstances quite important.

It is always dangerous to use formula without a complementary explanation about its background.