Section 12 Closing arrangements for deck and shell

12.1.1 The requirements are given for single panel, steel plated or equivalent, cargo hatch covers, stiffened longitudinally and secured around the perimeter by manual ‘kestner’ type, clamping devices. The hatch covers are, in general, lifted by a travelling gantry deck crane.

12.1.2 For hatch covers of other types and designs, the scantlings will be specially considered.

12.1.3 The definition of the Positions 1 and 2 of hatches on the strength deck is stated in Ch 4, 1.4 Definitions 1.4.6.

12.1.4 Where hatch covers are manufactured from material other than steel, then direct equivalency to these requirements is to be complied with.

12.2.1 The typical weathertight sealing arrangement, in general, is achieved by a rubber gasket on the hatch cover, compressed onto the top rail of the hatch coaming, see Figure 4.12.1 Typical hatch cover sealing arrangement.

Figure 4.12.1 Typical hatch cover sealing arrangement

12.2.2 For testing of hatch covers after installation, the requirements of Pt 3, Ch 11, 4.2 Steel covers − Clamped and gasketed 4.2.23 and Pt 3, Ch 11, 4.2 Steel covers − Clamped and gasketed 4.2.24 of the Rules and Regulations for the Classification of Ships, July 2022 will apply.

12.2.3 The spacing of the perimeter clamping devices shall satisfy the requirements of Pt 3, Ch 11, 4.2 Steel covers − Clamped and gasketed 4.2.19 and Pt 3, Ch 11, 4.2 Steel covers − Clamped and gasketed 4.2.22 of the Rules and Regulations for the Classification of Ships, July 2022.

12.2.4 The clamping devices may be cast or fabricated.

12.3.1 The thickness of the plating of the hatch cover is to be not less than 6,0 mm or , whichever is greater, where s is the spacing of longitudinals or stiffeners (shorter panel dimension), in mm.

12.4.1 The scantlings and strength criteria of the hatch cover stiffeners are to be as follows:

1. For ships 110 m in length and greater, calculated with design loading for Position 1, not less than 11,97 kN/m²and for Position 2, not less than 9,52 kN/m², with an equivalent design head of 1,70 m and 1,35 m respectively. The product of the maximum stress thus calculated and the factor of 4,25 shall not exceed the minimum tensile strength of the material, with the maximum permissible deflection limited to not more than 0,0028 times the span.

2. For ships 24,1 m in length, the design loading on the hatch cover for Position 1, may be 9,52 kN/m² and for Position 2, may be 7,16 kN/m² with an equivalent design head of 1,35 m and 1,01 m respectively.

3. For intermediate lengths the values shall be obtained by linear interpolation.

   The maximum permissible shear stress is not to exceed 108/k Nmm².

12.4.2 Additional stiffening members are generally also arranged, so as to provide suitable rigidity to the hatch cover during the lifting operation.

12.5.1 Hatch coamings, either vertical at sides or ends or sloped at sides, are to have a minimum thickness of 11 mm. The top edge is to be stiffened by a horizontal flat bar with a minimum width of 75 mm.

12.5.2 Additional support is to be given to the hatch coamings by the fitting of stays not more than 3 m apart. Each stay is to have a minimum thickness of 9,5 mm and is to be suitably supported under the deck.

12.5.3 Where hatch side coamings are sloped, the support arrangements of the coaming will be specially considered.

12.5.4 The deck plating is generally to extend inside the coamings.

12.5.5 A hatch end beam is to be arranged under the hatch end coaming. Transverse continuation brackets are to be arranged outboard of the hatches in line with the hatch end beam.

12.5.6 The height of the coamings above the upper surface of the deck, for hatchways, closed by covers secured weathertight by clamping devices shall be:

Position 1 (as defined in Ch 4, 1.4 Definitions 1.4.6) – 460 mm

Position 2 (as defined in Ch 4, 1.4 Definitions 1.4.6) – 300 mm

12.5.7 Where coamings of less height than required by 12.5.6 are fitted, the agreement of the Canadian Authority shall be obtained and the requirements of Pt 3, Ch 11, 5.1 General 5.1.3 of the Rules for Ships shall apply.

12.6.1 For the definition of the engine room gangway door, see Ch 4, 1.4 Definitions 1.4.5.

12.6.2 These requirements cover cargo and service doors in the side shell plating in way of the engine room.

12.6.3 Engine room gangway doors shall be so fitted as to ensure tightness and structural integrity commensurate with their location and the surrounding structure.

12.6.4 Without the special agreement of the Canadian Authority, the lower edge of the door openings shall not be below a line drawn parallel to the freeboard deck at side, that has its lowest point at the upper edge of the uppermost load line.

12.6.5 When the doors open inward, the structure and closing arrangements will be specially considered.

12.6.6 Where an additional opening is arranged in the gangway door, then suitable closing arrangements are to be fitted.

12.6.7 The strength of the gangway doors is to comply with the requirements of Pt 3, Ch 11, 8.3 Scantlings of the Rules for Ships.

12.6.8 Doors are to be fitted with an adequate means of closing, securing and support so as to be commensurate with the strength and stiffness of the surrounding structure. The hull supporting structure in way of the doors is to be suitable for the same design loads and design stresses as the securing and supporting devices. Where packing is required the packing material is to be of a comparatively soft type and the supporting forces are to be carried by the steel structure only. The maximum design clearance between securing and supporting devices is generally not to exceed 3 mm.