Section 3 Ship structure

3.1.1 The position of bulkheads is to comply with the requirements of Pt 3, Ch 3, 4 Bulkhead requirements.

3.1.2 Any tanks not utilised during oil recovery operations are to be arranged so that recovered oil cannot be transferred to them inadvertently.

3.1.3 In tanks intended for recovered oil, internal obstructions are to be avoided as far as practicable to prevent the entrapment of foreign objects usually present in recovered oil. Adequate drainage openings are to be provided to ensure free flow of residues to assist in cleaning and gas freeing on completion of recovery operations.

3.1.4 Tanks used for the storage of recovered oil are to be located outside the accommodation and machinery spaces.

3.1.5 Except where permitted by Pt 7, Ch 5, 3.1 Structural arrangement 3.1.6 and Pt 7, Ch 5, 3.1 Structural arrangement 3.1.7, tanks intended for the storage of recovered oil are to be separated from accommodation and machinery spaces by cofferdams. Cofferdams are to be at least one frame spacing in length (600 mm minimum) and are to cover the whole area of the boundary under consideration.

3.1.6 A pump room, fuel oil bunker, water ballast tank or other closed space where oil recovery handling equipment is stored will be accepted in lieu of a cofferdam.

3.1.7 In the case of a ship not primarily intended for oil recovery operations, where cofferdams are impractical to arrange, tanks arranged adjacent to machinery spaces may be accepted for storage of recovered oil. Acceptance will be conditional upon the tank boundary bulkheads being readily accessible for inspection. The bulkheads are to be carried continuously through joining structure to the top of the tank, where full penetration welding is to be carried out. Such tanks will require to be pressure tested at every Periodical Survey, see Table 1.9.1 Testing requirements in Pt 3, Ch 1, as applicable to oil tankers. Special consideration will be given to arrangements incorporating double bottom tanks in these locations.

3.1.8 All openings to tanks for recovered oil are to be located on the open deck. This includes sounding pipes, vent pipes, and hatches for the deployment of portable pumps and hoses. Suitable access hatches, not less than 600 mm x 600 mm, are to be arranged to facilitate tank cleaning and gas freeing. Dual access hatches, as widely separated as practicable, are to be provided for tanks of a cellular internal structure.

3.1.9 Where there is a risk of significant sloshing induced loads, additional strength calculations may be required, see Pt 3, Ch 3, 5.4 Design pressure for partially filled tanks.

3.1.10 Where recovered oil temperatures are to be increased significantly above 65°C during transit voyages, attention is drawn to Pt 4, Ch 9, 12 Cargo temperatures regarding thermal stress considerations.

3.2.1 The scantlings and arrangements are, in general, to be as required by Pt 4, Ch 1 General Cargo Ships. If the ship is to perform the duties of a supply ship the requirements of Pt 4, Ch 4 Offshore Support Vessels are also to be complied with, as applicable.