domeTypeType

Both domes of a vessel have this shape, so the vessel is symmetric about the middle of its cylinder. The shape also sets the dome height h, and with it the length of the vessel, which is the cylinder length plus twice h (see vesselType).

Each panel shows the meridian section of a forward dome above the axis of revolution, all three at the same cylinder radius R and the same scale. In figure (a) the height of an ellipsoidal dome is R times its half axis fraction, drawn for the fractions 0.5, 1 and 1.5. Figure (b) names the two radii of a torispherical dome, the point at which they meet and the angle under which they meet; R₁ is the dish radius and R₂ the knuckle radius. Figure (c) shows an isotensoid dome, which does not reach the axis but ends at a flat polar opening.

The three shapes serve different purposes. An ellipsoidal dome is the general case and the one to use where no particular head is meant. A torispherical dome is the head that pressure vessels are usually built from, because dish and knuckle can be pressed from sheet. An isotensoid dome is the shape a filament-wound vessel takes when every filament carries the same tension.