Butterfly Flange

Dished heads, also known as beveled spherical heads, are composed of a spherical surface, a straight cylindrical section of a certain height, and a transition section connecting the two, with a curvature radius much smaller than the spherical radius. The dished head forms a continuous curved surface, where there is a sudden change in the meridian curvature radius at the junction of the three parts, resulting in bending stress due to the curvature change. The combined effect of bending and tensile stresses makes this section's stress stand out compared to others. Compared to elliptical heads, the stress distribution is not as uniform, but they are easier to process, making them less ideal for engineering applications. However, when it is difficult to machine the molds for elliptical heads, dished heads are used as a substitute.