Clasification Society Provisional Rules - Provisional Rules for Existing Ships, July 2015 - Chapter 1 Existing Ships - Section 3 Strength requirements for foredeck fittings and equipment
Section 3 Strength requirements for foredeck fittings and equipment
3.1 Application
3.1.1 This section applies to air pipes, ventilator pipes and their closing devices on the exposed deck serving spaces forward of the collision bulkhead, and to spaces which extend aft over this line.
3.2 Applied loading for air pipes, ventilator pipes and their closing devices
3.2.1 The pressures, p, in kN/m2 acting on air pipes, ventilator pipes and their closing devices may be calculated from:
3.2.2 Forces acting in the horizontal direction on the pipe and its closing device may be calculated from Ch 1, 3.2 Applied loading for air pipes, ventilator pipes and their closing devices 3.2.1 using the largest projected area of each component.
3.3 Strength requirements for air pipes, ventilator pipes and their closing devices
3.3.1 Bending moments and stresses in air and ventilator pipes are to be calculated at critical positions:
- at penetration pieces;
- at weld or flange connections; and
- at toes of supporting brackets.
3.3.2 Bending stresses in the net section are not to exceed 0,8σy, where σy is the specified minimum yield stress or 0,2 per cent proof stress of the steel at room temperature. Irrespective of corrosion protection, a corrosion addition to the net section of 2,0 mm is then to be applied.
3.3.3 For standard air pipes of 760 mm coaming height closed by heads of not more than the tabulated projected area, pipe thicknesses and bracket heights are specified in Table 1.3.1 760 mm air pipe thickness and bracket standards. Where brackets are required, three or more radial brackets are to be fitted. Brackets are to be of gross thickness 8 mm or more, of minimum length 100 mm, and height according to Table 1.3.1 760 mm air pipe thickness and bracket standards but need not extend over the joint flange for the head. Bracket toes at the deck are to be suitably supported.
Table 1.3.1 760 mm air pipe thickness and bracket standards
| Nominal
pipe diameter, in mm |
Minimum
fitted gross; thickness, in mm |
Maximum projected area of head, in cm2 |
Height(1)
of brackets, in mm |
| 40A | 6,0 | - | 520 |
| 50A | 6,0 | - | 520 |
| 65A | 6,0 | - | 480 |
| 80A | 6,3 | - | 460 |
| 100A | 7,0 | - | 380 |
| 125A | 7,8 | - | 300 |
| 150A | 8,5 | - | 300 |
| 175A | 8,5 | - | 300 |
| 200A | 8,5(2) | 1900 | 300(2) |
| 250A | 8,5(2) | 2500 | 300(2) |
| 300A | 8,5(2) | 3200 | 300(2) |
| 350A | 8,5(2) | 3800 | 300(2) |
| 400A | 8,5(2) | 4500 | 300(2) |
| (1) Brackets (see Ch 1, 3.3 Strength requirements for air pipes, ventilator pipes and their closing devices 3.3.3) need not extend over the joint flange for the head. | |||
| (2) Brackets are required where the as fitted (gross) thickness is less than 10,5 mm, or where the tabulated projected head area is exceeded. | |||
|
Note For pipe heights other than 760 mm (see Ch 1, 3.3 Strength requirements for air pipes, ventilator pipes and their closing devices 3.3.3). |
|||
3.3.4 For other configurations, loads according to Ch 1, 3.2 Applied loading for air pipes, ventilator pipes and their closing devices are to be applied, and means of support determined in order to comply with the requirements of Ch 1, 3.3 Strength requirements for air pipes, ventilator pipes and their closing devices 3.3.1. Brackets, where fitted, are to be of suitable thickness and length according to their height. Pipe thickness is not to be taken less than as indicated in Pt 5, Ch 12 Piping Design Requirements of the Rules for Ships.
3.3.5 For standard ventilators of 900 mm coaming height closed by heads of not more than the tabulated projected area, pipe thicknesses and bracket heights are specified in Table 1.3.2 900 mm ventilator pipe thickness and bracket standards. Brackets, where required, are to be as specified in Ch 1, 3.3 Strength requirements for air pipes, ventilator pipes and their closing devices 3.3.3.
Table 1.3.2 900 mm ventilator pipe thickness and bracket standards
| Nominal
pipe diameter in mm |
Minimum
fitted gross; thickness, in mm |
Maximum projected area of head, in cm2 |
Height
of brackets, in mm |
| 80A | 6,3 | - | 460 |
| 100A | 7,0 | - | 380 |
| 150A | 8,5 | - | 300 |
| 200A | 8,5 | 550 | - |
| 250A | 8,5 | 880 | - |
| 300A | 8,5 | 1200 | - |
| 350A | 8,5 | 2000 | - |
| 400A | 8,5 | 2700 | - |
| 450A | 8,5 | 3300 | - |
| 500A | 8,5 | 4000 | - |
|
Note For ventilator heights other than 900 mm, the relevant requirements of Ch 1, 3.3 Strength requirements for air pipes, ventilator pipes and their closing devices are to be applied. |
|||
3.3.6 For ventilators of coaming height greater than 900 mm, the coaming support will be specially considered. Pipe thickness is not to be taken less than as indicated in Pt 5, Ch 12 Piping Design Requirements of the Rules for Ships.
3.3.7 All component parts and connections of the air pipe or ventilator are to be capable of withstanding the loads defined in Ch 1, 3.2 Applied loading for air pipes, ventilator pipes and their closing devices.
3.3.8 Rotating type mushroom ventilator heads are unsuitable for application within this region.
| Copyright 2016 Clasification Society, International Maritime Organization, International Labour Organization or Maritime and Coastguard Agency. All rights reserved. Clasification Society, its affiliates and subsidiaries and their respective officers, employees or agents are, individually and collectively, referred to in this clause as 'Clasification Society'. Clasification Society 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 Clasification Society 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. |  |