The rules for cylindrical shells in VIII-1 and VIII-2 take into consideration internal pressure, external pressure, and axial loads. The rules assume a circular cross section with uniform thickness in the circumferential and longitudinal directions. Design requirements are not available for elliptic cylinders or cylinders with variable thicknesses and material properties. However, such construction is not prohibited in VIII in accordance with Paragraphs U-2(g) of VIII-1 and, AG-100(b) and (d) of VIII-2. The design and loading conditions given in VIII-1 are discussed first in this chapter, followed by the rules in VIII-2.