3.2.1 A plan
showing the location of manholes and access openings within the double
bottom is to be submitted. Attention is to be given to any relevant
Statutory Requirements of the National Authority of the country in
which the craft is to be registered.
3.2.2 The number
and positioning of manholes are to be such that access under service
conditions is neither difficult nor dangerous. Attention is to be
given to any relevant international regulations regarding the minimum
size of access openings.
3.2.3 Manholes
and their covers are to be of an approved design or in accordance
with a recognised National or International Standard.
3.2.4 The size
of opening is not, in general, to exceed 50 per cent of the double
bottom depth, unless edge reinforcement is provided. In way of outboard
ends of floors and fore and aft girders at transverse bulkheads, the
number and size of holes are to be kept to a minimum, and the openings
are to be circular or elliptical. Edge stiffening may be required
in these positions.
3.2.5 Manholes,
lightening holes and other cut-outs are to be avoided in way of concentrated
loads and areas of high shear. In particular, manholes and similar
openings are not to be cut in vertical or horizontal diaphragm plates
in narrow cofferdams or double plate bulkheads within one-third of
their length from either end, nor in floors or double bottom girders
close to their span ends, below the heels of pillars, nor in way of
mast steps, unless the stresses in the plating and the panel buckling
characteristics have been calculated and found satisfactory.
3.2.6 Manholes,
lightening holes and other openings are to be suitably framed and
stiffened where necessary.