When arranging manhole covers on the deck, they should generally be located close to the lower bulkhead, with the long axis of the manhole cover parallel to the compartment, facilitating the installation of a straight ladder below the manhole. For ease of personnel access and ventilation, larger liquid tanks and empty tanks should have at least two manhole covers spaced far apart. Larger compartments within a double bottom should have manhole covers at both ends, and if necessary, an additional manhole cover should be installed midway along its length. Manhole covers located on the inner floor should be at least 800–1000 mm away from the main bulkhead to avoid weakening the strength of the inner floor near the main bulkhead.
Whether manhole covers are installed on the deck, parallel, inner floor, or bulkhead, the hull structure should be kept as intact as possible. If arrangement is difficult and it is unavoidable to cut through the hull structure, appropriate reinforcement should be implemented. Manhole covers should not be installed in critical areas ensuring the structural strength of the hull, such as deck edges, hatch corners, and stress concentration areas.
When manhole covers are installed on two lower decks or platforms, their positions should be staggered. If a hatch cover is on the upper deck or platform, the manhole cover on the lower deck or parallel platform should not be located outside the projection range of the hatch cover.
