Bilge & Ballast

(1)

Marine Oily Handling Devices

and Pollution Prevention

Chapter 1 Lesson 7

(2)

1.8 Bilge and ballast



_{A fire and bilge pump has suctions from sea,}

bilge main and engine room bilge, with

discharges to fire main, oily water separator and

overboard.



_{A ballast pump has suctions from sea, ballast}

main, engine room , bilge direct and bilge main

with discharges to overboard, the ballast main,

the oily water separator and possibly, the main

salt water circulating system.

(3)

1.8 Bilge and ballast



_{A general service pump has suctions from sea, ballast}

main, bilge main and engine room bilge with

discharges to the fire main, the ballast main, the oily

water separator and overboard. In this way, three

pumps provide effective alternatives for all essential

services in the event of breakdown of one or even two.



_{Many ships will have more generous provision and all}

passenger ships will have a submersible fire and bilge

pump, supplied with power from an emergency

(4)

1.8 Bilge and ballast

 _{There are many differences in arrangement; some ships will}

be fitted for oil or ballast in all double bottom tanks (except one or two, port and starboard for fresh water) some in only two or three.

 _{Other vessels will have one (or more) lower holds fitted as}

deep tanks and most will have peak ballast tanks forward and aft.

 _{Some ships will have a tunnel from the engine room to No.1}

hold aft bulkhead, for bilge, ballast and oil pipes and fittings and others will have a duct keel to carry the pipes forward.

(5)

1.8 Bilge and ballast

 _{In most other ships the bilge suction pipes will pass}

through the wings of the holds and the ballast pipes through the double bottom.

 _{In the two latter cases, the valve chests will be on the}

engine room (or boiler room) forward bulkhead or in a forward cofferdam.

 _{In all cases, the bilge suction valves will be screw-down,}

non-return, the oil and ballast valves, screw-lift.

 _{Ring and blank flanges will be fitted in deep tank suctions,}

so that ballast cannot be discharged inadvertently by a bilge pump not the hold be flooded when used for cargo.

 _{If liquid cargoes are carried, both will be blanked. Note}

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(7)

1.8 Bilge and ballast



_{The minimum number and capacity of bilge}

pumps and fire pumps and their dispersement

within the ship is governed by:



_{1 Classification Society Rules}



_{2 National requirements}



_{3 The IMCO International Convention for the}

Safety of Life at Sea, 1974(SOLAS 74).

(8)

1.8 Bilge and ballast

 _{The basic philosophy is similar in all three cases but SOLAS}

74 only defines bilge pump capacity for passenger ships and the Convention only applies to vessels trading

internationally; more-over it excludes cargo ships of less than 500 gross tons.

 _{The Classification Societies generally prescribe the bore of}

the main bilge line and branch bilge lines and relate the bilge pump capacity of each pump to that required to

maintain a minimum water speed in the line; the fire pump capacity is related to the capacity of the bilge pump thus defined e.g.

(9)

1.8 Bilge and ballast

Bilge main dia. d1=1.68 +25 mm Branch dia. d2=2.16 +25 mm

d2 not to be less than 50 mm and need not exceed 100 m. d1 must never be less than d2

where

L = length of ship in m; B = Breadth of ship in m;

D = Moulded depth at bulkhead deck in m; C = Length of compartment in m. ) (B D L(BD) L(BD) L(BD) L(BD) L  ) (B D L  ) (B D C  ) (B D C 

(10)

1.8 Bilge and ballast



_{Each pump should have sufficient}

capacity to give a water speed of 122

m/min through the Rule size mains of this

bore. Furthermore each bilge pump

should have a capacity of not less than



_d

₁₂

_m3/h

3 10 565 . 0

(11)

1.8 Bilge and ballast



_{The fire pumps, excluding any emergency fire}

pump fitted, must be capable of delivering a total

quantity of water at a defined head, not less than

two-thirds of the total bilge pumping capacity.



_{The defined head ranges from 3.2 bar in the case}

of passenger ships of 4000 tons gross or more to

2.4 bar for cargo ships of less than 1000 tons

(12)

1.8 Bilge and ballast



_{The following paragraphs are extracted from}

the International Convention for the Safety

of Life at Sea 1974 Chapter 11-1 Regulation

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1.8 Bilge and ballast



_{The arrangement of the bilge and ballast pumping}

system shall be such as to prevent the possibility of

water passing from the sea and from water ballast

spaces into the cargo and machinery spaces, or from

one compartment to another.



_{Special provision shall be made to prevent any deep}

tank having bilge and ballast connections being

inadvertently run up from the when containing

cargo, of pumped out through a bilge pipe when

containing water ballast.

(14)

1.8 Bilge and ballast



_{Provision shall be made to prevent the compartment}

served by any bile suction pipe being flooded in the

event of the pipe being severed, or otherwise damaged

by collision or grounding in any other compartment.



_{For this purpose, where the pipe is at any part situated}

nearer the side of the ship than one-fifth the breadth of

the ship (measured at right angles to the centre line at

the level of the deepest subdivision load line), or in a

duct keel, a non-return valve shall be fitted to the pipe

in the compartment containing the open end.

(15)

1.8 Bilge and ballast

 _{All the distribution boxes, cocks and valves in}

connetion with the bilge pumping arrangements shall be in positions which are accessible at all times under ordinary circumstances.

 _{They shall be so arranged that, in the event of}

flooding, one of the bilge pumps may be operative on any compartment; in addition, damage to a pump or its pipe connecting to the bilge main out board of a line drawn at one-fifth of the breadth of the ship shall not put the bilge system out of action.

 _{If there is only one system of pipes common to all the}

pumps, the necessary cocks or valves for controlling the bilge suctions must be capable of being operated from above the bulkhead deck.