1 General

1.1 Application

1.1.1

The requirements in [1.2] to [1.6] apply to small hatchways at weather deck in positions 1 and 2 as defined in Ch 1, Sec 4, [3.2]. The requirements in [2] apply to small hatchways fitted on the exposed fore deck over the forward 0.25 L. Hatchways of bulk carriers not covered by the definition of small hatchways in [1.4.1] are to comply with applicable requirements in Pt 2, Ch 1.

1.2 Materials

1.2.1

Materials used for the construction of steel hatch covers are to comply with the applicable requirements of the Society.

1.2.2

The use of materials other than steel is considered by the Society on a case-by-case basis.

1.3 Height of hatch coamings

1.3.1

The height above the deck of hatch coamings is not to be less than:

600 mm in position 1.
450 mm in position 2.

1.3.2

The height, given in [1.3.1], of hatch coamings closed by steel covers provided with gaskets and securing devices may be reduced or the coamings may be omitted entirely, on condition that the Flag Administration is satisfied that the safety of the ship is not thereby impaired in any sea conditions.

In such cases the scantlings of the covers, their gasketing, their securing arrangements and the drainage of recesses in the deck are considered by the Society on a case-by-case basis.

1.4 Small hatchways

1.4.1 Small hatches are hatches designed for access to spaces below the deck and are capable to be closed weathertight or watertight, as applicable. Their opening is generally equal to or less than 2.5 m². Hatch covers on exposed decks are to be weathertight. Hatch covers fitted in way of ballast tanks, fuel oil tanks or other tanks are to be watertight.

1.4.2

Securing arrangements and stiffening of hatch cover edges are to be such that weathertightness can be maintained in any sea condition. At least one securing device is to be fitted at each side. Circular hole hinges are considered equivalent to securing devices.

1.4.3

Hatchways of special design are considered by the Society on a case-by-case basis.

1.4.4 The gross thickness of covers is to be not less than 8 mm. This thickness is to be increased or an efficient stiffening is to be fitted where the greatest horizontal dimension of the cover exceeds 0.6 m.

1.4.5 The gross thickness of coaming plate is not to be less than the lesser of the following values:

• The gross thickness for the deck in way of hatch coaming, assuming as spacing of stiffeners the lesser of the values of the height of the coaming and the distance between its stiffeners.
10 mm.

Coamings are to be strengthened where their height exceeds 0.8 m or their greatest horizontal dimension exceeds 1.2 m, unless their shape ensures an adequate rigidity.

1.5 Cargo tank access hatchways

1.5.1

Requirements given in [1.2] to [1.4] have to be considered as minimum requirements for cargo tank hatchways. The requirements of [1.5.4] do not apply to dished covers or covers of other specially approved design.

1.5.2 Covers for access hatches, tank cleaning and other openings for cargo tanks and adjacent spaces are to be manufactured from the following material:

Normal strength steel in accordance with Ch 3, Sec 1.
Non-ferrous material may be considered, such as bronze or brass. Aluminium alloy is not to be used for covers of any opening to cargo tanks and spaces adjacent thereto.
Synthetic materials may be considered, taking into account their fire resistance and their physical and chemical properties in relation to the intended operating conditions. Details of the properties of the material, the design of the cover, and the method of manufacture are to be submitted for approval.

The hatch cover packing material is to be compatible with the cargoes that are intended to be carried and is to be effectively held in place.

1.5.3

The height of the hatch coaming above the upper surface of the freeboard deck is not to be less than 600 mm. Lower heights may be permitted by the Flag Administration. In addition, the top of the hatch coaming is not to be lower than the highest point of the tank over which it is fitted and is to be of sufficient height for the purpose of damage stability.

The gross thickness of the coaming plate is not to be less than 10 mm. Where the coaming height, as fitted, exceeds 600 mm, the thickness may be required to be increased or edge stiffening fitted. The scantlings of coaming plates of tank access coamings that enclose an area of 1.2 m² or more, and/or those that are not configured with a well rounded shape, may be subject to additional requirements.

1.5.4

The gross thickness of unstiffened plate covers with an area less than 1.2 m² is not to be less than 12.5 mm. The gross thickness of covers of a larger area will need to be increased or the cover will require stiffening.

Flat and unstiffened covers on circular hatchways are to be secured by fastenings with a spacing of not more than 600 mm.

On rectangular hatchways, the spacing of fastenings is generally not to be greater than 450 mm and the distance between hatch corners and adjacent fastenings is not to be greater than 230 mm.

Where the cover is hinged, adequate stiffening of the coaming and cover in way of the hinge is to be provided. In general, hinges are not to be considered securing devices for the cover and are to be designed so as to prevent the gasket from being over-tightened.

1.6 Gaskets

1.6.1

The sealing is to be obtained by a continuous gasket of relatively soft elastic material compressed to achieve the necessary weathertightness.

1.6.2

Coamings and steel parts of hatch covers in contact with gaskets are to have no sharp edges.