Section 6 Conical ends subject to internal pressure
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Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Ships, July 2022 - Part 5 Main and Auxiliary Machinery - Chapter 11 Other Pressure Vessels - Section 6 Conical ends subject to internal pressure

Section 6 Conical ends subject to internal pressure

Parent topic: Chapter 11 Other Pressure Vessels

6.1 General

6.1.1 Conical ends and conical reducing sections, as shown in Figure 10.5.1 Conical ends and conical reducing sections in Pt 5, Ch 10 Steam Raising Plant and Associated Pressure Vessels, are to be designed in accordance with the equations given in Pt 5, Ch 11, 6.2 Minimum thickness.

6.1.2 Connections between cylindrical shell and conical sections and ends should preferably be by means of a knuckle transition radius. Typical permitted details are shown in Figure 10.5.1 Conical ends and conical reducing sections in Pt 5, Ch 10 Steam Raising Plant and Associated Pressure Vessels. Alternatively, conical sections and ends may be butt welded to cylinders without a knuckle radius when the change in angle of slope, ψ, between the two sections under consideration does not exceed 30°.

6.1.3 Conical ends may be constructed of several ring sections of decreasing thickness as determined by the corresponding decreasing diameter.

6.2 Minimum thickness

6.2.1 The minimum thickness, t, of the cylinder, knuckle and conical section at the junction and within the distance L from the junction is to be determined by the following formula:

where
= t, p, σ, c and J are as defined in Pt 5, Ch 11, 1.2 Definition of symbols
D o = outside diameter, in mm of the conical section or end, see Figure 10.5.1 Conical ends and conical reducing sections
K = a factor, taking into account the stress in the knuckle, see Table 10.5.1 Values of K as a function of ψ and ri/Do.

6.2.2 If the distance of a circumferential seam from the knuckle or junction is not less than L, then J is to be taken as 1,0; otherwise J is to be taken as the weld joint factor appropriate to the circumferential seam,

where
r i = inside radius of transition knuckle, in mm, which is to be taken as 0,01D c in the case of conical sections without knuckle transition
L = distance, in mm, from knuckle or junction within which meridional stresses determine the required thickness, see Figure 10.5.1 Conical ends and conical reducing sections in Pt 5, Ch 10 Steam Raising Plant and Associated Pressure Vessels
=
ψ = difference between angle of slope of two adjoining conical sections, see Figure 10.5.1 Conical ends and conical reducing sections in Pt 5, Ch 10 Steam Raising Plant and Associated Pressure Vessels.

6.2.3 The minimum thickness, t, of those parts of conical sections not less than a distance L from the junction with a cylinder or other conical section, is to be determined by the following formula:

where
Dc = inside diameter, in mm, of conical section or end at the position under consideration, see Figure 10.5.1 Conical ends and conical reducing sections in Pt 5, Ch 10 Steam Raising Plant and Associated Pressure Vessels
α, α1, α2 = angle of slope of conical section (at the point under consideration) to the vessel axis, see Figure 10.5.1 Conical ends and conical reducing sections in Pt 5, Ch 10 Steam Raising Plant and Associated Pressure Vessels.

c is as defined in Pt 5, Ch 11, 1.2 Definition of symbols.

6.2.4 The thickness of conical sections having an angle of inclination to the vessel axis of more than 75° is to be determined as for a flat plate.

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