Conical Heads and Sections. When the cone-to-cylinder
junction is not a line-of-support, the required thickness
of a conical head or section under pressure on the
convex side, either seamless or of built-up construction
with butt joints shall not be less than the minimum required
thickness of the adjacent cylindrical shell and, when a
knuckle is not provided, the reinforcement requirement of
1-8 shall be satisfied (see Fig. UG-28.1). When the cone-tocylinder
junction is a line-of-support, the required thickness
shall be determined in accordance with the following subparagraphs