Section 3 Hatch Covers

301. Hatch covers

1. The thickness of steel hatch covers is not to be less than 0.01 times of the spacing of stiffeners or 6 ᾩᾩ , whichever is the greater.

2. Stiffeners in steel hatch covers are to be provided at an interval of not more than 750 mm and to be of section modulus not less than obtained from the following formula;

Ě Ņ ǼĊᾨ Ī (cm3)

where :

Ċ = Spacing of stiffeners (m)

l = Length of stiffeners (m)

Ǽ = Coefficient obtained from the following formula

Ǽ Ņ LǾÌJ Ã Ñ ÌĪ

3. Stiffeners are to be provided around the edges of steel hatch cover, so as to ensure sufficient ri- gidity to withstand deformation while handling.

4. The scantlings of portable beams are to comply with the requirements in Par 2. However,

Ċ is to

be taken as the spacing of portable beams, l

as the length of portable beams. The thickness of

wooden hatch covers is not to be less than

case is it to be less than 60 mm.

obtained from the following formula, however, in no

ᾼ Ņ ĨL Ċ (mm)

where:

Ċ = Spacing of portable beam (m)

302. Miscellaneous

1. The depth of portable beams and the width consideration their tripping and deflection.

of face bars are to be suitably designed, taking into

2. The parts supporting hatch covers and portable beams are to be effectively strengthened.

3. The carriers for portable beams are to be of steel, with the bearing surface of not less than 75 mm wide and not less than 12.5 mm thick.

4. The carriers on the side coamings are to be provided with appropriate devices to prevent the port- able beams from falling off.