3.4.1 Cargo tanks should be at least of the type
required for the cargo by the International Bulk Chemical Code or
the International Gas Carrier Code, as applicable.
3.4.2 Instead of the use of permanently attached
deck-tanks, portable tanks meeting the requirements of the International
Maritime Dangerous Goods (IMDG) Code or other portable tanks specifically
approved by the Administration may be used for cargoes indicated in
paragraph 1.2.2, provided that the tanks are properly located and
secured to the vessel.
3.4.3 Except for the tank connections to cargo
pump-rooms, all tank openings and connections to the tank should terminate
above the weather deck and should be located in the tops of the tanks.
Where cofferdams are provided over integral tanks, small trunks may
be used to penetrate the cofferdam.
3.4.4 The greater of the following design pressures
(gauge) should be used for determining scantlings of independent pressure
tanks:
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.1 0.07 MPa;
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.2 the vapour pressure of the cargo at 45°C;
-
.3 the vapour pressure of the cargo at 15°C
above the temperature at which it is normally carried; or
-
.4 the pressure which occurs in the tank during
the loading or unloading.
The design of the tanks should comply with standards acceptable
to the Administration taking into account the carriage temperature
and relative density of cargo. Due consideration should also be given
to dynamic forces and any vacuum pressure to which the tanks may be
subjected.
3.4.5 Integral and independent gravity tanks should
be constructed and tested according to standards of the Administration
taking into account the carriage temperature and relative density
of cargo.
3.4.6 For pollution hazard only substances having
a flashpoint exceeding 60°C, the requirements of 3.4.3 need not
be applied.