4.1.1 Deck structure
is subjected to longitudinal hull girder bending caused by load distribution
and wave actions. Moreover, deck structures may be subjected to severe
loads due to green seas on deck. Certain areas of the deck may also
be subjected to additional compressive stresses by slamming or bow
flare effect at the foreship in heavy weather.
4.1.2 The cross-deck
structure is subjected to transverse compression from sea pressure
on the ship’s sides and inplane bending due to distortion of
the hull girder under wave action. In association with this, the area
around the corners of openings and deck-houses is subjected to high
cyclical stress due to the combined effect of longitudinal and transverse
hull girder bending and torsional loading.
4.1.3 The marine
environment, the humid atmosphere in some spaces and high temperature
on deck from the sun may result in corrosion of structure making the
structure more vulnerable.
4.1.4 Particular
attention should be paid to the following areas in machinery spaces:
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Bilges.
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Inside seatings.
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Lower areas of bulkheads.
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Stabilizer wells.
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Beneath evaporators,
boilers and condensers.
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Ship’s sides and
deckheads.
4.1.5 Bulwarks are
provided for the protection of the crew and equipment on deck. Although
bulwarks are not taken into account in the strength of hull girders,
they are subjected to considerable longitudinal bending stresses.
Therefore, bulwarks may suffer fractures and corrosion, especially
at the termination of bulwarks, such as at ladder access or expansion
joints. The fractures may propagate to deck plating and cause serious
damage.
4.1.6 The deterioration
of various fittings on deck, such as ventilators, air pipes and sounding
pipes, may result in serious problems regarding weather/watertightness
and/or fire-fighting.
4.1.7 The general
condition with regard to corrosion of the deck structure may be observed
by visual inspection. Special attention should be paid to areas where
pipes, e.g. fire main, hydraulic pipes, pipes for compressed air,
are fitted close to structure, making proper maintenance of the protective
coating difficult to carry out. Grooving corrosion may occur at the
transition between the varying thicknesses of deck plating, especially
when the difference in plate thickness causes water to gather in this
area.
4.1.8 Plate buckling
(between stiffeners) may occur in areas subjected to compressive stresses,
particularly if corrosion is evident. Special attention should be
paid to areas where the compressive stresses are perpendicular to
the direction of the stiffening system. Such areas may be in the foreship
where deck longitudinals are terminated and replaced by transverse
beams.
4.1.9 Damaged structure
may be observed in areas of the deck where stores have been handled
and in particularly exposed areas of deck in heavy weather. It is
essential that an under-deck inspection is carried out to assess the
extent of such damage.
4.1.10 Naval ships
tend to have a large number of discontinuities on the upper deck which
are due to superstructure and deck-house connections. Where a lack
of alignment occurs with the under-deck structure, severe stresses
can occur leading to defects in the connection.On all ships, these
areas need particular examination and discussion with the Owner/Naval
Authority to resolve the matter with an acceptable solution.