10.1 Tanks for separated sludge and their pipework
Tanks for separated sludge, their pipework and pumps should
be designed as follows:
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10.1.1 Size of tanks
See subparagraph 8.
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10.1.2 Design of tanks and tank heating systems
The tanks and tank heating systems should be designed to the
satisfaction of the Administration.
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10.1.3 Tank heating system
Tanks for separated sludge should be equipped with tank heating
systems. The heating pipes should be arranged such that, seen from
the heating inlet, to start with they are arranged in a way of the
boundaries and then across the whole bottom area sufficiently high,
in order to avoid being covered totally by sediments in the tank;
The tank heating system should be designed such as to enable
heating of the oil sludge up to 60°C.
The suction line from the sludge tank to the pump should be
provided with heat tracing.
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10.1.4 Pipelines from the heavy fuel oil purifier
to the tank
Whenever possible, the sludge tank should be locted below the
heavy fuel oil purifier. If this is not possible, the sludge tank
should be situated close to the heavy fuel oil purifier in such a
way that the discharge line to the tank can be installed at the maximum
gradient. The pipelines should, wherever possible, be straight or
fitted with large radius elbows.
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10.1.5 The submersible pump or opening of the
suction line should be arranged so that the oil sludge's path to the
suction opening is as short as possible, or the sludge tank should
be mounted or designed, so that the oil sludge moves down a slope
towards the suction opening. The openings should be placed as wide
as possible in the frames above the tank bottom in such a way that
the oil sludge has free access to the suction line.
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10.1.6 Pump and pressure lines
The pump should be suitable for use with high viscosity oil
sludge, e.g. “self-priming displacement pump”, with suitable
means for protection against dry running. It should have a total head
of at least 4 bar, and the delivery rate should be determined by applying
the formula:
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where V is the volume of the sludge tank as
calculated by the interpretation to regulation
17. Four hours should be substituted for the time t.
However, the pumping capacity should be not less than 2.0 m3/h.
The geodetic suction head of the pump should not exceed 3.0
m for ships with main engine rating up to 15,000 kW and 3.5 m for
ships greater than 15,000 kW.
The pressure side of the pump should only be connected to the
transfer line on deck, to sludge tanks and to the incineration equipment,
if provided.
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10.1.7 Sludge tank design to facilitate cleaning
Access holes should be arranged so that all areas of the tank
can be cleaned. An access hole should be sited on top of the tank
to facilitate the use of a portable pump.
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10.1.8 Steaming-out lines
The top of sludge tanks should be fitted with steaming-out lines
for cleaning.