Section 7 Tanker access arrangements and closing appliances

7.1.1 Covers for access hatches, tank cleaning and other openings to cargo tanks and adjacent spaces are to be manufactured from steel complying with the Rules for the Manufacture, Testing and Certification of Materials, July 2022.

7.1.2 Consideration will be given to the use of bronze, brass or other materials; however, aluminium alloy is not to be used for the covers of any openings to tanks.

7.1.3 Synthetic materials will be considered, taking into account their fire resistance and 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.

7.1.4 The hatch cover packing material is to be compatible with the cargoes to be carried and is to be efficiently held in place.

7.2.1 Attention is drawn to IMO Resolutions concerning safe access to, and working in, large tanks.

7.2.2 Oiltight hatchways are to be kept to the minimum size required to provide reasonable access and ventilation. Where tanks are large or subdivided by wash bulkheads, additional hatchways may be required. In determining the size and location of hatchways, consideration should be given to the handling of materials and staging for maintenance in the tank.

7.2.3 The size and location of hatchways should also take into account access for personnel wearing breathing apparatus, and removal of injured personnel (possibly on a stretcher) from the bottom of the tank.

7.2.4 The height of hatch coaming is to be not less than 600 mm, measured above the upper surface of the freeboard deck, unless a lower height is permitted by the Administration of the country in which the ship is to be registered.

7.2.5 Taking account of sheer and camber, the height of any cargo tank hatch coaming is to be such as to ensure that the top of the hatch coaming is above the highest point of the tank over which it is fitted.

7.2.6 The height of the coaming may be required to be increased if this is shown to be necessary by the floatability calculations required by the Load Lines, 1966/1988 - International Convention on Load Lines, 1966, as Amended by the Protocol of 1988.

7.2.7 The thickness of the coaming plate is to be not less than 10 mm, but may be required to be increased, and edge stiffening fitted, where the coaming height exceeds 600 mm.

7.2.8 Unstiffened plate covers are to be not less than 12,5 mm in thickness, but if the area of the cover exceeds 1,2 m² this thickness may be required to be increased or stiffening fitted.

7.2.9 Unstiffened covers are to be secured by fastenings spaced not more than 600 mm apart on circular hatchways. On rectangular hatchways the spacing of fastenings is generally not to exceed 450 mm, and the distance between hatch corners and adjacent fastenings is to be not more than 230 mm.

7.2.10 The arrangement of fastenings on stiffened hatchway covers and covers of special design will be specially considered.

7.2.11 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 used as securing devices for the cover.

7.3.1 Proposals to fit enlarged cargo tank accesses closed by bolted plate covers will be considered. Such openings may be of extended dimensions for ease of access and evacuation of personnel, see Pt 3, Ch 11, 7.2 Cargo tank access hatchways 7.2.3, and may incorporate a smaller access hatch for normal use constructed as required by Pt 3, Ch 11, 7.2 Cargo tank access hatchways.

7.3.2 The plate cover is to be not less than 15 mm in thickness and is to be secured by closely spaced studs to a ring of suitable dimensions, welded to the deck. The studs are not to penetrate the deck plating.

7.4.1 Small openings for tank cleaning, ullage and similar purposes may be closed by flush covers which are to be not less than 12,5 mm in thickness and secured by studs not more than 100 mm apart. Studs are to be arranged in a ring of suitable width and thickness attached to the deck, and are not to penetrate the deck plating.

7.4.2 Small diameter holes provided for staging wires are to be closed by plugs of an approved pattern. The plugs are to be provided with a thick washer of suitable material which is also compatible with the intended cargoes. Spare plugs equal to at least 10 per cent of the number of holes are to be provided and maintained on board, see also Pt 4, Ch 9, 4 Hull envelope plating. If these openings are threaded they are to be protected while in use with a protective sleeve of suitable material.

7.5.1 Access to clean ballast or dry tanks and to cofferdams may be either by access hatch or by manhole generally complying with the preceding requirements.

7.6.1 Alternative access cover designs and securing arrangements will be considered on the basis of equivalence to the above requirements and taking into account any relevant National Requirements.

7.7.1 For access to structure within cargo tanks, see Pt 4, Ch 9, 13 Access arrangements and closing appliances.