Section 6 Conical ends subject to internal pressure
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Naval Ships, January 2023 - Volume 2 Machinery and Engineering Systems - Part 8 Pressure Plant - Chapter 2 Other Pressure Vessels - Section 6 Conical ends subject to internal pressure

Section 6 Conical ends subject to internal pressure

Parent topic: Chapter 2 Other Pressure Vessels

6.1 General

6.1.1 Conical ends and conical reducing sections, as shown in Figure 1.5.1 Conical ends and conical reducing sections, are to be designed in accordance with the equations given in Vol 2, Pt 8, Ch 2, 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 1.5.1 Conical ends and conical reducing sections. 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, c σ and J are as defined in Vol 2, Pt 8, Ch 2, 1.2 Definition of symbols

D o = outside diameter, in mm of the conical section or end, see Figure 1.5.1 Conical ends and conical reducing sections.
K = a factor, taking into account the stress in the knuckle, see Table 1.5.1 Values of K as a function of ψ and r i / D o .

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

ri = 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 1.5.1 Conical ends and conical reducing sections.
=
ψ = difference between angle of slope of two adjoining conical sections, see Figure 1.5.1 Conical ends and conical reducing sections.

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 1.5.1 Conical ends and conical reducing sections.
α, α1, α2 = angle of slope of conical section (at the point under consideration) to the vessel axis, see Figure 1.5.1 Conical ends and conical reducing sections in Vol 2, Pt 8, Ch 1 Steam Raising Plant and Associated Pressure Vessels.

c is as defined in Vol 2, Pt 8, Ch 1, 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.

Copyright 2022 Clasifications Register Group Limited, International Maritime Organization, International Labour Organization or Maritime and Coastguard Agency. All rights reserved. Clasifications Register Group Limited, its affiliates and subsidiaries and their respective officers, employees or agents are, individually and collectively, referred to in this clause as 'Clasifications Register'. Clasifications Register assumes no responsibility and shall not be liable to any person for any loss, damage or expense caused by reliance on the information or advice in this document or howsoever provided, unless that person has signed a contract with the relevant Clasifications Register entity for the provision of this information or advice and in that case any responsibility or liability is exclusively on the terms and conditions set out in that contract.