Section 3 Self-supporting aluminium hatch covers
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Inland Waterways Ships, July 2022 - Part 3 Ship Structures (General) - Chapter 11 Closing Arrangements to Openings in Shell and Deck, Ventilators, Air Pipes, Sounding Pipes and Discharges - Section 3 Self-supporting aluminium hatch covers

Section 3 Self-supporting aluminium hatch covers

Parent topic: Chapter 11 Closing Arrangements to Openings in Shell and Deck, Ventilators, Air Pipes, Sounding Pipes and Discharges

3.1 General

3.1.1 This Section applies to hatch covers fabricated from aluminium alloys as defined in Ch 8 Aluminium Alloysof Lloyd’s Register’s (hereinafter referred to as ‘LR’) Rules for the Manufacture, Testing and Certification of Materials (hereinafter referred to as the Rules for Materials).

3.1.2 When aluminium alloys other than those defined in Ch 8 Aluminium Alloys of LR’s Rules for Materials are used, details of this composition and minimum mechanical properties of the material of the finished cover are to be submitted for approval. The approval will be based on the properties of the material, durability, etc.

3.2 Plating

3.2.1 The thickness of the plating of aluminium hatch covers is to be not less than required by Table 11.3.1 Aluminium hatch cover scantlings.

Table 11.3.1 Aluminium hatch cover scantlings

Item Parameter Requirements
Top plating for h H ≤ 0,75 m Thickness The greater of:

t = 8,4s mm

t = 2 mm, see Note

Top plating for h H > 0,75 m Thickness The greater of:

t = 9,25s mm

t = 2 mm, see Note

Webs and stiffeners Section modulus

Z = 12,75 × b × h H × lo 2 cm3

Inertia I = 3,7 × Z × lo cm4
Minimum thickness The greater of:

t = 0,025d w mm

t = 4 mm

Effective plating to be included in the section modulus Width The lesser of:

w = 0,08t m

w = s m

The symbols are defined in Pt 3, Ch 11, 1.2 Symbols 1.2.1

Note The top plating thickness may be reduced, when the plating is stiffened by swedges or equivalent, provided the maximum permissible stresses and deflections of Table 11.2.2 Parameters for direct calculation are not exceeded. Proposals are to be submitted for approval.

3.3 Stiffeners

3.3.1 The scantlings of stiffeners and swedges of aluminium hatch covers are to comply with the requirements of Table 11.3.1 Aluminium hatch cover scantlings.

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