Section 5 Hatchways for cargo tanks
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 5 Hatchways for cargo tanks

Section 5 Hatchways for cargo tanks

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

5.1 General

5.1.1 Hatchways for cargo tanks are to be made of steel. Their construction is to be such that no leakage of liquid or gas occurs. This is also applicable when the tank is subjected to internal pressure.

5.1.2 Hatch coamings on cargo tanks (may act as expansion trunk) are to be at least 500 mm in height. The thickness of the coaming is to be at least 6 mm.

5.1.3 The plating thickness and the stiffening of flat hatch covers are to comply with the requirements of Table 11.5.1 Steel hatch covers for cargo tanks.

Table 11.5.1 Steel hatch covers for cargo tanks

Item Parameter Requirements
Plating Thickness The greater of:
t = 9s + mm
t = 5 mm
Stiffeners Section modulus
Z = 7,5 × s × le 2 × h 4 cm3
Inertia
I = 2,1 × Z × le cm4
Minimum depth
d w = 50 mm
Symbols
t, Z, I and s are as defined in Pt 3, Ch 11, 1.2 Symbols 1.2.1
h 4 = design pressure to be derived from the appropriate ship type Chapter, but to be taken not less than 1 m above the tank deck or 0,5 m above the top of the hatch cover whichever is the greater, in metres
le = unsupported span of the stiffener, in metres, and is to be taken not less than 1 m

5.1.4 Panel stiffeners are not normally required on hatch covers smaller than 500 x 500 mm, but efficient edge stiffening is to be fitted.

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