Bilge system /MiMi
DNV rules January 2013
Pt.4 Ch.6 Sec.4 – Page 19
201 Two non-return valves in series shall be installed between sea or ballast system and bilge
suctions in compartments
203 Bilge distribution chest valves shall be screw-down non-return valves.
204 All direct bilge suctions, and branch suctions not leading to a bilge distribution chest shall be fitted
with screw-down non-return valves.
Pt.4 Ch.6 Sec.4 – Page 19
C103 For cargo holds with double bottom the bilge suctions shall be led from bilge wells with a
capacity of at least 0.15 m3 each. Wells of less capacity may be accepted for small compartments.
D 109 The bilge water tank shall be connected to the vessel's bilge system. The suction pipe from the
tank shall have a diameter not less than that of the main bilge line.
Pt.4 Ch.6 Sec.4 – Page 21
D203 Where the water is discharged by means of pumps pumping directly from bilge wells or bilge
tanks, the capacity of the bilge pumps shall be at least 125% of the combined capacity of both the
water-spraying system pumps and the required number of fire hose nozzles.
E101 Dry compartments shall be connected to the bilge system or to be drained by separate bilge
pumps. For small compartments hand pumps may be accepted.
Pt.4 Ch.6 Sec.4 – Page 22
F 200 Branch bilge suctions
201 At least three branch bilge suctions shall be fitted. The suctions shall be arranged forward and aft
at bothsides of the engine room.
F 300 Direct bilge suctions
301 Separate bilge suctions shall be lead directly to the bilge pumps from each side of the engine
room in addition to the branch bilge suctions.
302 If an emergency bilge suction is arranged to a self-priming pump (as required by SOLAS for
passenger vessels), the direct bilge suction may be omitted on the side where the emergency suction
is fitted.
F401 Where the machinery space is divided into compartments separated by watertight bulkheads,
the number and position of the branch bilge suctions in boiler rooms, auxiliary engine rooms etc shall
be the same as for cargo holds. In addition a direct bilge suction shall be arranged for each
compartment to an independent pump.
Pt.4 Ch.6 Sec.4 (H. Bilge Pumping and Piping)
H 100 General
101 At least two bilge pumping units shall be provided. For ships with length 90 m and less, one of
these may be driven by the main engine. In larger ships, both units shall be independently driven.
102 Each pumping unit may consist of one or more pumps connected to the main bilge line, provided
their combined capacity is sufficiently large.
103 One of the bilge pumps may be a bilge ejector if there is a separate pump delivering sufficient
water for operating the ejector.
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Bilge system /MiMi
105 In vessels arranged with inboard drainage of cargo deck spaces which have access openings in
the shell plating or which have fixed water-spraying fire fighting systems, one of the bilge pumping
units shall not be connected to more than one additional system in which the number and capacity of
pumping units already satisfy the Rules.
106 For ships of less than 100 gross tonnage with the service area restriction notations R0, R1, R2,
R3 or R4, one bilge pump driven by the main engine and one manual pump of sufficient capacity will
be accepted. This arrangement presumes that the main engine can be disconnected from the
propeller shafting, and the cooling water pumps driven by the main engine shall be able to drain
directly from the engine room.
H 300 Bilge pumping arrangement
301 All bilge pump connections to the main bilge line shall be fitted with stop valves.
302 The bilge pumps shall be so arranged that either can be used while the other is being overhauled.
303 The direct bilge suctions from machinery spaces shall be so arranged that they can be used at the
same time as the other bilge pumping unit is drawing from the main bilge line.
304 Centrifugal bilge pumps shall be located as low as possible in the ship.
305 Centrifugal bilge pumps shall be arranged in such a way that any suction line is not led through
more than two non-return valves, preferably not more than one.
Bilge calculations
From:
DNV Pt.4 Ch.6 Sec.4 H400 (Piping systems- Page 24/25)
H400-401 The internal diameter of the main bilge line shall not be less than given by the following
formula, to the nearest 5 mm
-Sizes of bilge suctions:
d=1.68 √ L ( B+ D )+ 25 mm
where:
L=lenght of ship (m)
B= breadth of ship (m)
D=depth of ship to bulkhead deck (m)
For example:General arrangement (P12-7210 UT 535E Alianca)
L
B
D
d=1.68 √ 53.95 ( 14+ 6 ) +25 mm=55.184+25=80.18 mm
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Bilge system /MiMi
To the nearest 5 mm- bilge main=> DN80 => 88.9 x 5.5 (ASTM A53/A106 B STEEL PIPES)
Main bilge line:
d u=88.9−( 2∗5.5 )=77.9 mm
DNV Pt.4 Ch.6 Sec.4 H200 (Page 23)
201 Each bilge-pumping unit shall be capable of giving a water velocity of at least 2 m/s through a rule
size main bilge pipe.
202 Where the capacity of one bilge pumping unit is somewhat less than required, the deficiency may
be made up for by the other bilge pumping unit. However, the capacity of the smaller bilge-pumping
unit shall not be less than one third of the combined pumping capacity.
203 Pumping unit capacity determined from pipe diameter given in 400 is specified in Table H1.
The pump capacity Q in m3/hour may also be determined from the formula::
2
5.75 d
Q= 3
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or from Table H1 (Page 24)
Bilge pump capacity:37 m3/h / each pump
403 The internal diameter of branch bilge suctions to cargo holds, machinery and boiler spaces shall
not beless than stipulated by the following formula, to the nearest 5 mm
- Branch bilge pipe:
d=2.15 √ lx ( B+ D ) +25
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where: l -lenght of compartment (m)
404 Direct bilge suctions shall have an internal diameter of not less than 1.4 d1 but need not exceed
the diameter given in 401.
If an emergency suction is fitted, the diameter shall be taken equal to that of the suction side of the
pump, but need not exceed 400 mm.
405 The sizes of direct bilge suctions in smaller separated machinery spaces will be considered in
each case.
406 The sectional area of a suction pipe from a bilge distribution chest shall not be less than the
combined area of the two largest branch bilge suctions connected to that chest, but it need not exceed
that required above for the main bilge line.
407 The internal diameter of the bilge suction pipes to the fore and after peaks and to the tunnel well
shall not be less than 63 mm for ships exceeding 61 m in length and 50 mm for ships under 61 m.
Diameter of Bilge Branch Line:
For example:General arrangement (P12-7210 UT 535E Alianca)
√
Machinery space (ER): d=2.15 13.8 x (14 +6 )+25=60.71 mm
Nearest commercial size: DN65
√
Bow thruster room: d=2.15 3.6 x ( 14+6 )+ 25=43.24 mm
Nearest commercial size: DN50
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Bilge system /MiMi
Propulsion room:
d=2.15 √ 7.8 x ( 14 +6 ) +25=51.85 mm
Nearest commercial size: DN50
Aft Cargo pump room:
d=2.15 √ 18.75 x ( 14 +6 ) +25=66.63 mm
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Bilge system /MiMi
Nearest commercial size: DN80
Cargo pump room:
d=2.15 √ 3.75 x (14 +6 )+25=43.6 mm
Nearest commercial size: DN50
Entrance Main Propulsion room: (stairs from tank top to tween deck - Prop.room)
d=2.15 √ 5.4 x ( 14+6 ) +25=47.3 mm
Nearest commercial size: DN50
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Bilge system /MiMi
From:
SOLAS Chapter II-2, Reg 10 2.2.4.1 Total capacity of required fire pumps .2 . (pumps in cargo ships,
other than any emergency pump: the quantity of water is not less than four thirds of the quantity
required under regulation II-1/21 to be dealt with by each of the independent bilge pumps in a
passenger ship of the same dimension when employed in bilge pumping, provided that in no cargo
ship need the total required capacity of the fire pumps exceed 180 m3/h. )
Capacity of fire pump:
4
Q FIRE= QBILGE
3
4
Q FIRE= ∗37=49~50 m3/h
3
From:
SOLAS Chapter II-2, Reg 10 2.2.4.2. Capacity of each fire pump
(Each of the required fire pumps shall have a capacity not less than 80% of the total required capacity
divided by the minimum number of required fire pumps but in any case not less than 25 m3/h and
each such pump shall in any event be capable of delivering at least the two required jets of water.)
Emergency fire pump: 40% * QFIRE=0.4*50=20 m3/h
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Bilge system /MiMi
Sludge tank capacity:
DNV Pt.4 Ch.6 Sec.6 A20
203 Collecting tank(s) for oil residues including sludge, waste oil, drain oil, etc. shall be arranged with
a minimum aggregate capacity of:
V = K ∙C ∙D (m3)
K = 0.015 for ships where heavy fuel oil is purified for main engine use, or
= 0.005 for ships using diesel oil or heavy fuel oil which does not require purification before use
C = daily fuel oil consumption (m3)
D = length of voyage in days, but no less than 30 unless restricted service notation.
K=0.005
C=3∙0.452∙24=32.5 m3/day CI=c x P x 1/ρ [m3/h]
c - specific consumption (kg/kWh)
br. sati
CI P - power (kW)
br.motora ρ - fuel density (kg/m3)
CI=c x P x 1/ρ =0.205∙1840∙1/835=0.452 [m3/h]
[kg/kWh] [kW] [kg/m3]
c - specific consumption (kg/kWh)
P - power (kW)
ρ - fuel density (kg/m3) → ρ =835kg/m3 for gasoline or diesel
D=30
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Bilge system /MiMi
From MTU (Main engines-Product data) for P12-7210 UT 535E Alianca :
V = K ∙C ∙D=0.05∙32.5∙30=4.875 ≈ 4.9 m3
SEL (Example)
H 600 Bilge wells, mud boxes
601 The bilge wells are normally to have a capacity of at least 0.15 m3.
602 Branch bilge pipes for drainage of machinery spaces and shaft tunnels shall be led to mud boxes.
The mud boxes shall have straight tail pipes to the bilges and shall be arranged for easy inspection
and cleaning.
Mud boxes
Mud boxes are fitted into the machinery space bilge suction piping. The mud box is a coarse strainer
with a straight tailpipe down to the bilge . To enable the internal perforated plate to be cleaned when
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Bilge system /MiMi
necessary, the lid of the mud box is easily removed without disconnecting any pipework.
Fig:Mud box
603 Strums or rose boxes shall be fitted to the ends of bilge suction pipes in cargo holds, and
arranged for easy inspection and cleaning. The open area shall be at least twice the internal sectional
area of the pipe. The diameter of the holes shall be approximately 10 mm.
604 The distance between the open ends of the bilge suction pipes and the bottom of the bilge or
wells shall be adequate to allow a full flow of water and to facilitate cleaning.
605 Valves, cocks and mud boxes shall be located in readily accessible positions above or on the
same level as the floor plates. Where this is not practicable, they may be placed immediately below,
provided that the floor plates in question can easily be removed and are fitted with a name plate which
indicates the presence of these fittings.
Tickness wall for pipes:
Pt.4 Ch.6 Sec.7 – Page 50
203 Bilge and ballast pipes and fittings of nodular cast iron shall have minimum wall thickness not less
than:
t = K (0.5 + 0.001 DN) (mm)
DN = nominal diameter in mm
K = 9 for pipes
= 12 for fittings other than tees
= 14 for tees.
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