Gp80. Ship Common Sys

5/26/2018 Gp80. Ship Common Sys

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SUPERINTENDENTs MANUAL

Super-Man

Part II - Technical Part

Main Group 8 - Ship Common Systems

Gp 80 - Ballast and Bilge Systems

Super-Man/Basic Edition/Part II Copyright NSA


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SUPERINTENDENTs MANUAL PART II - TECHNICAL PART

Table of Contents Page

80 BALLAST AND BILGE SYSTEMS 1

800 GENERAL 1

800.0 General Guidelines 1

800.01 Abbreviations 1

800.1 Ballasting of Vessels 1

800.10 General 1

800.11 Ballast water management 2

800.12 Exchange of ballast water 4

800.2 Tankers 5

800.20 General 5

800.21 Ballasting procedures 6800.22 Overpumping 8

800.23 Ballast arrangement 8

800.3 Bulk Carriers 9

800.30 General 9

800.31 Ballasting procedures 9

800.32 Overpumping 9

800.33 Ballast arrangement 9

801 BALLAST SYSTEMS 11


801.1 Piping System 11801.10 General 11

801.11 Pipes 11

801.12 Valves 12

801.13 Valve control systems 13

801.2 Ballast Pumps and Ejectors 13

801.20 General 13

801.3 Filters and Strainers 15

801.30 General 15

801.4 Fitting of Ballast System on Board 15

801.40 General 15

801.5 Maintenance of Ballast Systems 15

801.50 General 15

802 HEATING COILS IN BALLAST TANKS 16

(Not included in Basic Edition) 16

803 BILGE SYSTEMS 17


803.1 Piping System 17

803.10 General 17

803.11 Engine room bilge arrangement 18

803.12 Cargo hold bilge arrangement 20

803.13 Drainage of cargo deck spaces ('Tween decks) 21



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803.14 Pipes 22

803.15 Valves 23

803.16 Valve control systems 24

803.2 Bilge Pumps and Ejectors 24

803.20 General 24

803.21 Bilge pumps 24803.3 Filters 26

803.30 General 26

803.4 Bilge Water Separators 26

803.40 General 26

803.5 Bilge Sludge Tanks 27

803.50 General 27

List of Figures

Fig.no Title Page

800.12 A Ballast Water Exchange-Start and Finish Condition 28

800.12 B Ballast Water Exchange-Bending Moments for Intermediate Conditions 28

800.33 A Details of Ballast/Bilge Piping, Bilge Wells and Venting 29



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80 BALLAST AND BILGE SYSTEMS

800 GENERAL

800.0 General Guidelines

Group (Gp) 80 contains the following Sub-Groups (SGps):

* 800 - General

* 801 - Ballast systems

* 803 - Bilge systems

SGp 802 - Heating coils in ballast tanks, and 804 - Gutter pipes outside accommodation, are

not included in Basic Edition.

SGps 805-809 are vacant numbers.

General items related to piping arrangements, bending and welding of pipes, pipe materials,

types of pumps, inspection and testing, general operating procedures and safety requirements

are dealt with in MGp 1/Gp 17. Hence, Gp 17 should be studied in parallel with Gp 80.

Figures and diagrams are either located at the end of Gp 80 or inserted in the text where

practical.

800.01 Abbreviations

* MARPOL 73/78 : International Convention for the Regulation of Pollution from Ships

Protocol of 1973 and 1978.

* ICS : International Chamber of Shipping

* INTERTANKO : International Association of Independent Tanker Owners

* IMO : International Maritime Organization

* WHO : World Health Organization

* SOLAS : International Convention for the Safety of Life at Sea

800.1 Ballasting of Vessels

800.10 General

Ballasting, by filling sea water or river water into specially designated tanks (i.e. segregated

ballast tanks or the vessels cargo tanks), is generally performed for following purposes:

* To bring the ship down from a light loadline when carrying none or little cargo, to a draft

and trim that will ensure sufficient seaworthiness, handling capabilities and propulsion

efficiency for the upcoming voyage (normally ballast voyage).

* To reduce the air draft sufficiently while loading or discharging to permit a safe overhead

clearance to the loading/discharging devices of the cargo terminal.



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* To regulate the air draft in areas with height limitations (e.g. bridges).

* To regulate draft and trim as required in case of multi-port loading or discharging.

* To obtain a satisfactory metacentric height and stability as well as trim in case of

unfavourable cargo distribution.

* To reduce the strain on the vessel in case of unfavourable cargo distribution, in particular

in connection with multi-port loading or discharging and/or light cargo conditions.

* To reduce the strain and sea impact on the vessel in general, caused by heavy weather and

in particular reduce impact forces in the bottom area forward.

These basic reasons for introducing ballast systems in ships are basically the same for tankers,

bulk carriers and dry cargo vessels. However, capacities and procedures may vary

considerably.

The rules of the classification societies are regulating design, construction and materials of

ballast systems, whereas IMO is regulating aspects related to pollution (MARPOL 73/78)

which will include regulations to minimize transfer of harmful organisms and pathogens

found in the ballast water (see also MGp1/Gp10). Ballast water management is further

described in 800.11.

A general concern related to ballast water handling is the possibility of rupturing/damaging

tanks due to over-pressure caused by the relatively smaller dimension of air venting/overflow

pipes compared to inlet pipes. This is particularly important to have in mind on older vessels.

Over-pumping must therefore be avoided. (See also 800.11 as well as Gp 82).

800.11 Ballast water management

The following guidelines are mainly quoted from the Model Ballast Water Management

Plan presented by ICS and INTERTANKO. The Plan is based on IMOs Assembly

Resolution A.868(20) - Guidelines for the control and management of ships' ballast water to

minimize the transfer of harmful aquatic organisms, which should be studied for further

guidance. IMO is currently working on international regulations concerning transfer of ballast

water, and adoption of the final convention is expected early 2004. The following description

is based on the present situation with no international regulations but several national regimesregulating transfer of ballast water.

(1) General

Studies carried out in several countries have shown that many species of bacteria, plants, and

animals can survive in a viable form in ballast water and sediment carried in ships, even after

journeys of several weeks duration. Subsequent discharge of ballast water or sediment into the

waters of port states may result in establishment of colonies of harmful species and pathogens

which can seriously upset the existing ecological balance. Although other methods have been

identified by which organisms are transferred between geographically separated sea areas,

ballast water discharge from ships appears to have been prominent among those identified.



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The potential for ballast water discharge to cause harms has been recognized not only by

IMO, but also by WHO, which is concerned about the role of ballast water in spreading

epidemic disease bacteria.

(2) Requirements

Some states have established control of discharge of ships' ballast water that will minimize thepotential for colonization of their rivers and estuaries by non-native species. The preferred

option in this regard is mid-ocean ballast water exchange prior to arrival. Accordingly, the

countries most concerned have promulgated advice to ships for ballast management, together

with a request for their cooperation in applying the techniques voluntarily. Standard

procedures have been developed that will be accepted by quarantine authorities as achieving

the level of acceptability desired by the port state.

(3) Safety

Unless applied carefully, some of the measures being urged for ballast management can affect

a ship's safety adversely, either by creating forces in the hull greater than the design

parameters or by compromising the stability of the vessel. It is because of concern about theseproblems IMO became involved in what would otherwise be a purely quarantine matter. It is

recognized by governments and the shipping industry that the needs of individual countries

should be harmonized with the need for ensuring the safety of ships, crews and passengers.

IMO therefore recommends that each vessel should be provided with a Ballast Water

Management Plan, detailing how the ship can comply with any measures demanded by a port

state. Once it has been established that the management of ballast is necessary to meet the

quarantine requirements of a port state, preparations for proper ballasting should be treated

with the same seriousness as preparation of a cargo plan. Everybody concerned with the

operation and safe passage of the ship can thereby be assured that they are protecting the

marine environment as well as the safety of vessel and crew.

A ballast handling plan for a ballast voyage should be prepared in advance, as the preparation

of a cargo plan for a loaded voyage, and with the same degree of thoroughness. This

preplanning is necessary in order to maintain safety, in case compliance with ballast exchange

or other ballast water treatment or control options, are required.

As part of the environmental function, the plan will provide information to quarantine officers

who whish to learn about a ship's ballast handling system, or to confirm that ballast

management has been effectively planned. The plan should not be used or regarded as a guide

to ballasting. Training and shipboard operational practices should already be well established.

(4) Records required

To be able to demonstrate at the arrival port that correct measures have been completed, it

will be necessary to maintain a full and accurate ballast log. A suitable outline for such a log

is provided in Section 9 of the ICS/INTERTANKO Plan. Even if a ship is not trading in an

area where ballast water information is required, it may later prove worthwhile to have a

history of what ballast water has been carried.

(5) Reporting to port states

Several countries have become aware of the potential, for transfer into their coastal areas of

harmful aquatic organisms, through discharge of ships' ballast water. Governments have



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recognized the necessity of knowing ongoing ballasting procedures, before devising

mandatory controls on ships.

Concerned countries have therefore introduced requirements, generally calling for ships to

report in advance to the national monitoring authority the amount of ballast water onboard on

arrival, where it was taken onboard and whether a ballast management procedure has beenfollowed. In most cases it is mandatory to present such report, even if the actual ballast

exchange in mid-ocean (or other management procedure) remains voluntary.

800.12 Exchange of ballast water

(1) General

Ballast water exchange implies replacement of ballast water from port/coastal areas with

sea water at sea , assuming that organisms taken on board in coastal areas will not survive

when released in open sea, (and vice versa).

There are mainly three different methods for exchanging ballast water:

* The sequential method (re-ballasting)

* The flow through method (overflowing of tanks)

* The (Brazilian) dilution method

These methods are further described below.

(2) The sequential method

This method is in principle possible for all ships provided the relevant safety and hazard

aspects are taken into account. The ballast tanks are emptied and re-filled sequentially through

the suction/delivery pipes, which requires removal of very large weights from the ship in a

dynamic condition. This implies new procedures and is different from ballasting in port.

Important aspects and hazards are:

* Stability of the ship during ballast operations.

* Excessive hull girder bending moments or shear forces.

* Excessive torsional stresses due to twisting of the hull caused by unsymmetrical

conditions.

* Structural damage of tanks and holds due to over/under pressuring and sloshing forcesdue to slack tanks in a dynamic condition.

* Impact forces in the foreship bottom area due to changes in forward draught.

* Loss of manoeuvreability and/or ability to make headway.

* Propeller and rudder immersion as well as bridge visibility due to changes in trim.

* Changes in GM and rolling period and effect on stresses in cargo lashing equipment

(e.g. containers).

* Intact stability requirements taking into account free surface effect due to slack tanks as

well as changes in GM.

* Operator performance during the procedure as well as personnel safety.



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Typical sequence for replacing the ballast water in a 149.100 dwt bulk carrier is shown in Fig.

800.12 A and B , and same principle will apply to other ship types as well. The sketches

describe some of the sequences from original to final condition.

The sequence is highly dependent on ship type and the above-mentioned aspects. Some steps

may involve restoring to the original condition, or emptying/filling one tank at the time ratherthan several tanks simultaneously. Before initiating a next step in the procedure, a positive

decision should be made, taking into account the ship's position, weather forecast, machinery

performance and degree of crew fatigue. If any factors are considered unfavourable, the

ballast exchange should be suspended or halted.

(3) The flow-through method

The flow-through method may involve some modifications to existing vessels, depending on

the air vents as well as structural strength of the tanks/holds. The tanks used for ballast are

overfilled by pumping in additional water, offering the advantage that the method can be used

in weather conditions, which would be marginal for use of the sequential method, since there

is little change to the condition of the ship. However, the flow-through method introducescertain other risks and problems which must be considered.

Air pipes of tanks, which can be overfilled by pumping, shall normally be dimensioned so

that the sum of the static and dynamic pressure will not exceed the design pressure of the

tank. See also 800.22.

Typically three times the volume of the tank needs to be pumped in to achieve 95 % change

of water. Pumping in only once the volume produces 63 % exchange, twice the volume 86 %

and four times the volume 98 % water exchange.

(4) The (Brazilian) dilution method

This method will normally imply modifications to the pipe and pump system, and is

consequently more applicable to newbuildings. Ballast water enters via pipes, is pumped

through a ballast pipeline on the weather deck to each tank, and is removed from the bottom

of the tanks via a separate set of pumps. The method involves a closed system that maintains

stability and avoids discharge of water on deck.

800.2 Tankers

800.20 General

Oil tankers above 20.000 dwt, and product carriers above 30.000 dwt delivered after 1 June

1982 are built with segregated ballast tanks, pumps, and pipe lines. These vessels should

accordingly not have any pollution problems even when handling cargo and ballast

simultaneously.

For older tankers from 5000 dwt and upwards, IMO has established a phasing out scheme

starting 1 January 2007. In the meantime some of these vessels will need to work ballast

before leaving port, immediately upon finishing the unloading; for somewhat more modern

ships also during discharging. In order to avoid oil pollution, certain procedures must be

followed in such cases.



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Ballast water amounting to approx. 20 % of the ship's summer deadweight, has usually proved

to be sufficient for satisfactory handling of the ship when entering and leaving port and for

passages in calm water. However, port authorities may demand more than this minimum, and

adverse weather may also require more ballast. In such circumstances, even on ships with

segregated ballast system, it may become necessary to use one or more of the vessels cargo

tanks for this purpose, and great care has to be taken to prevent any oil pollution whendischarging the ballast from the cargo tanks.

800.21 Ballasting procedures

Older, single hull oil tankers, utilize the cargo tanks for carrying ballast. Prior to commencing

the ballasting operation on these ships, all pumps and associated pipelines must be set up and

the tank ventilation system realigned to the loading mode. If inert gas has been used during

discharge of the cargo, the system may be shut down or put in standby position during

ballasting. When setting up the pipeline system it is of utmost importance that the sea valves

are not opened until the moment the operation commences. Neglecting this important stepwill invariably result in a certain quantity of oil running back through the pump room lines

and over the side into the sea. The result could be a pollution incident and the affected shore

authorities imposing a substantial fine and clear-up costs on the ship.

As for loading oil cargo, the normal procedure for ballasting is to start the pumps at slow

speed, open the relevant sea valves and check that the water is entering the designated tanks,

before going on to full pumping rate. When ballasting tanks having previously contained a

volatile cargo, it is inevitable that large quantities of flammable gas will be driven out from

the tank. The ballasting operation must therefore be treated with exactly the same attention

and caution as when loading cargo, if dangerous situations shall be avoided. For some

inexplicable reasons, the most conscientious ship officers tend to relax when ballast is being

loaded, probably because one tends to think that water being taken on board presents no

comparable problems to those encountered with oil. However, it is absolutely essential that

careful watch is kept on the rising liquid level in the tanks, as failure to do this can result in an

overflow and possible structural damages from hydraulic pressure (see also 800.10).

Upon completion of ballasting operations, all tank openings, which may have been used for

ullage, should be closed, mast riser bypass valves shut down, and the pressure/vacuum valves

reset. If an inert gas system is fitted, it should once more be brought up to correct pressure to

prevent the ingress of any unwanted air.

Ballasting of cargo tanks takes place during or immediately upon completion of unloading,

and invariably in ports where discharge of oil is prohibited. This makes the first opening of

the cargo system to the sea an extremely critical operation. Every precaution must therefore

be taken to ensure that no oil escapes overboard when the sea suction is opened. Procedures

will vary depending on the vessels design/arrangement; however, the following procedures

illustrate the precautions needed for avoiding accidental oil discharge through the sea suction

during start-up of ballasting:

* For the system to be used for ballasting, strip the suction and discharge lines to a slop

tank, vent the lines as necessary.



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* After the lines have been well stripped, line up the system so that all valves upstream of

the pump are open. The sea suction valve remains closed.

* Have a person ready for opening sea suction valve.

* Make sure that the person starting the pump(s) is aware that the pump is going to bestarted for ballasting operations, and that once running, the pump should not be

immediately shut down.

* Start the pump and make sure it is on line.

* Once the pump is observed to be on line and running and suction is observed on the pump

suction gauge, open the sea valve.

When shutting down the pump upon completion of ballasting, the sea suction valve should be

closed before stripping the pump.

The above description mainly deals with methods used on older ship types in which ballasting

is only performed after the complete oil cargo has been discharged.

Some, more modern ships, not required by regulations to be fitted with permanent/segregated

ballast systems, have a facility to load ballast water simultaneously with the discharge of

cargo. This system, which of necessity utilizes the cargo pipeline system, has one major

drawback. If, due to human error, any valves are wrongly set when commencing the

ballasting operation, the following incidents may occur, either singly or together:

* The cargo may flow back to the tanks, which have just been emptied, and thereby mix

with the incoming ballast water.

* Ballast water may find its way into the shore tanks via the vessel's discharge lines.

* Cargo may return over the side, causing pollution.

When realizing that these defects can be caused through simple human error or wrongful

manipulation of only one valve, the need for checking and rechecking the pipeline system will

be clearly understood.

Attention should further be drawn to the danger of loading ballast by hose into non-gas free

tanks. It has been proved by laboratory tests that water falling from a height is capable of

generating static electric charges, which under certain conditions may generate a spark thatcould ignite flammable vapours present in the tank. If it for any urgent operational reasons,

becomes essential to load ballast by this method into a tank that has contained volatile cargo,

the following precautions must be strictly observed:

* Cargo residue remaining in the tank should be stripped out before water is introduced.

* The hose to be used for ballasting should then be lowered into the tank until it is

actually rests on the tank bottom.

* The hose should have a special bonding wire passing through it to ensure that any static

charges generated by the water flow are carried away from the danger area and safelyearthed to the ship's structure.



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* The ballast water should initially be introduced at a slow rate until the end of the hose is

well immersed in the water.

It should be duly noted, that the practice of allowing liquid to enter a cargo tank by any means

other than the permanent pipeline system is attended with danger and should not be adopted

unless there is no alternative.

Once at sea on the loaded voyage, all cargo systems will be shut down. On ballast voyages,

however, tank cleaning and ballast changing activities will be taking place. The same

precautions to prevent overfilling ballast or slop tanks, apply at sea as they do in port. All

discharges overboard must be via the oil detection monitoring equipment (ODME) and in

compliance with MARPOL 73/78 regulations regarding permissible quantities and

geographical areas. Same apply to discharge of machinery space bilges. Whenever discharges

overboard are made in compliance with MARPOL 73/78, the discharge should still be

monitored visually for oil in case the relevant equipment is not functioning correctly.

Well planned and practiced procedures and frequent equipment checks are the hallmarks of awell-run tanker operation. Discuss the transfer operation with everybody concerned and go

through the check list prior to cargo and/or ballast handling. When topping-off, slow down the

loading rate well in advance and make sure there are enough personnel available for the task

at hand.

Whether in port or at sea, the risk of oil spill can be significantly reduced by good planning

and organization and ensuring proper communication between all personnel involved.

800.22 Overpumping

For newer ships the cross section of air pipes to be dimensioned so that the structure of the

ship is not exposed to unacceptable stress if the tank is over-pumped with the largest available

pumps. Documentation of calculated pressure drops caused by overflow, is to be submitted

for approval to the Class, see 800.12 (3). Alternatively, arrangements for prevention of over-

pumping of tanks may be accepted. For short air pipes of gooseneck type, a max. water

velocity of 4 m/s may normally be acceptable, but if an automatic type air vent is fitted, the

flow resistance increases and the water velocity must be lower. In no case the cross sectional

area is to be less than 125 % of that of the filling pipe.

On older ships, however, these criteria are often not fulfilled. In such cases the pressure rise incase of overflow may be very rapid. Even if the pumps are stopped at the very moment water

is observed emerging from a tank, it is probably too late to prevent damage to the tank

structure.

800.23 Ballast arrangement

For future newbuildings, it is important to take into account the upcoming regulations for

ballast water management, and design the ballast water system and tanks to be effective in

ballast water exchange operations.



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800.3 Bulk Carriers

800.30 General

In MGp 2/Gp 23 is shown a typical structural transverse section of a bulk carrier with single

sides, double bottom, hopper and top wing tanks. Usually there may also be stool tankssupporting the transverse bulkheads. The ballast is usually carried in all the top wing tanks

and in some of the hopper and double bottom tanks. In addition, one of the cargo holds may

be equipped for extra ballast capacity in case of heavy weather (the ballast hold).

The normal way of filling the top wing tanks would be through a separate ballast line on each

side of the vessel. For bulk carriers with independent bilge systems, the filling of these tanks

can also easily be connected to the fire and wash line on deck, but emptying must always take

place through the ballast lines or direct drain overboard.

800.31 Ballasting procedures

When ballasting dry cargo holds, some important issues are worth noting:

* Separation between the ballast system and the bilge system by two non-return valves in

series.

* Air venting of hold in ballast mode

For the last item, following issues are important:

* Manual opening and closing of air vent involve the risk of operational mistakes, causing

over/under pressure damages.

* Air vents with floats do not prevent problems with free surface and sloshing forces.

* Manually operated air vents with vacuum valve will prevent operational mistakes causing

underpressure damages (sucking-in of hatches) when emptying the hold.

800.32 Overpumping

Principally the same precautions and deliberations mentioned for oil tankers in 800.22 arevalid for bulk carriers. The above comments concerning ballasting procedures should be

noted.

800.33 Ballast arrangement

The Class rules (DNV) state that ballast tanks exceeding 35 m length shall normally have

(bilge) suction at forward and aft end, to attain improved safety and redundancy for large

ballast tanks.

A ballast arrangement with independent pipelines for each tank will give the most flexiblesystem for different ballast conditions. However, the solution requires substantial piping.



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Most newbuildings today (2002) have very simple ballast systems with a minimum of piping,

but still maintaining flexibility and safety. For future newbuildings, it is important to take into

account the upcoming regulations for ballast water management, and thus design the ballast

water system and tanks to be effective in ballast water exchange operations.

Filling of top wing tanks is normally carried out with separate pipelines in the wing tanks.

Favourable arrangement is a connection trunk between the top wing and hopper tank. The

advantage is that the top wing tanks become pipe-free; the disadvantage is less flexibility in

ballast discharge operations.

For bulk carriers with independent bilge systems, the filling of top wing tanks can easily be

carried out through the fire main and wash line on deck.

Fig. 800.33 A (Source: DNV) shows details of ballast/bilge piping, bilge wells, and venting.



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801 BALLAST SYSTEMS


The ballast system includes suction pipes with valves etc. from seawater intakes/chests,

ballast pumps, pressure pipes to ballast tanks and overboard piping/pump system, as well asconnection to bilge systems.

Further is included all associated/connected equipment and fittings, such as control

equipment, filters/strainers, clamping etc.

Permanent ballast tanks may be filled by pumping or by opening inlet valves to sea.

801.1 Piping System

801.10 General

For a simplified diagram for a complete, combined ballast- and bilge system see 801.20.

801.11 Pipes

Pipe material is generally either plastic (GRP) or steel or equivalent material. Mild steel pipes

are generally more expensive to renew/repair in way of double bottom spaces, but allows

fitting at the block building stage and are less sensitive to impact/handling damages compared

to plastic pipes. Applying plastic pipes, however, eliminates corrosion problems, and enables

more easy replacement of damaged parts.

For newbuildings, plastic pipes are more complicated/difficult to fit at block building stage. In

addition the joining and alignment are more difficult and the supports have to be of special

saddle type.

Plastic pipes of approved type can be used for ballast lines situated inside the ballast tank, in

cofferdams, void spaces, pipe tunnels and ducts. Bulkhead penetrations are to be fitted with a

metallic spool piece. Due to large difference of temperature coefficient between steel and

GRP pipes, expansion elements are required at bulkhead penetrations.

Typically, the straight main line and branch line before suction valves may be of GRP and the

suction branch after the valves as well as all fittings may be of steel or equivalent material

with anti-corrosion measures (e.g. aluminising).

According to the Class Rules (DNV), grey cast iron is not to be used for bilge and ballast

pipes in pipe tunnels in the double bottom or in ballast lines for forward tanks passing through

cargo oil tanks. The reason is that grey cast iron is very brittle and sensitive to impacts. For

such pipes the bending of the lines has to be absorbed by connection flanges on the pipe.

For double bottom designs with centre FO (Fuel Oil) tanks, the ballast pipes have to be lead

through the tanks, implying high installation and maintenance costs. To minimise such costs,the ballast pipelines in the tanks may be made of plastic materials.



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801.12 Valves

(1) General

Valves in ballast systems should be of butterfly type with body of ductile cast iron and disc of

Al-bronze. All valves with cast iron or cast steel body for handling of sea water and bilge

water, should be coated internally with tar epoxy. Butterfly valves to have NBR seat.

Butterfly valves should generally be of wafer type, except valves fitted on shore connection

or at side ships which should be of lugged type.

All shore connection and ships side valves should have ductile cast iron or cast steel body.

Butterfly valves' spindle to be of one piece, going through the disc.

(2) Ballast valves in double bottom tanks

For tank arrangement with FO tanks in centre and one main ballast line in loop to which the

tank suctions are connected, the ballast valves are generally located inside the tanks.

In case of remote-controlled valves for the ballast system, a portable hand pump can be

accepted as a secondary means of operation

To ensure high safety of the ballast system, the suction valves to be accessible in all loading

conditions. It is often recommended that tank valves in the double bottom are located in a

valve chest with opening to the hopper space (bulk carriers). Generally speaking, submerged

valves should be located in adjacent tanks, ref below sketch:

(3) Ballast tank vents

The capacity of vents must allow overpumping without over-pressurising the ballast tanks.

DNV requires sizing of vents to allow overpumping of any ballast tank with the largest ballast

pump connected. In addition capacity calculations (pressure drop) is required for verification,

see 800.22.



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801.13 Valve control systems

Remotely controlled valves shall be provided with indication for open and closed valve

positions at the control stations. In cases where local manual operation is required in addition

to the remote control, means of observing the valve position at the valve shall be provided.

Valve control systems shall be designed so that any possible failure does not cause critical

conditions for the vessel, such as opening of closed valves or closing of valves which should

be open.

801.2 Ballast Pumps and Ejectors

801.20 General

All ships shall be provided with a ballast piping system so arranged that any tank can be de-

ballasted or ballasted by either of at least two independently driven pumps or by controlledfree flow. If only one pump is installed, an emergency solution is normally provided, e.g. a

temporary connection to a cargo pump.

Ballast pumps are normally of centrifugal type. The maximum suction height of a fully

primed centrifugal pump is approximately 4 m. The centrifugal ballast pumps shall be located

as low as possible. The priming function is normally carried out by ejectors.

The ballast pumps may either have steam drive or electric drive or a combination of these, e.g

one of each. Important to note is that steam turbine driven pumps require activation of the

steam producing plant when conducting ballast water exchange (see 800.12). Electric driven

pumps are more critical with respect to water hammering problems unless a "soft start"

arrangement is provided.

Sufficient stripping capacity of pumps and system may be obtained by:

* Stripping ejectors

* Vacuum strip

* Additional small diameter stripping suctions

The below sketches illustrate the above listed options.

The top figure shows a typical ballast system with two pumps and stripping ejectors, and the

lower figure shows a ballast system with two pumps, ejectors and vacuum stripping system.

Remotely controlled bilge and ballast pumps to be provided with operating instructions at the

(remote) manoeuvring panel.



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801.3 Filters and Strainers

801.30 General

Ref. SGp 803 (Bilge systems).

801.4 Fitting of Ballast System on Board

801.40 General

In addition to the guidelines given in MGp 3/Gp 35, following check points are important:

* Possibilities of proper draining, in particular where danger of freezing.

* On tankers, the possibilities of discharging water from the pump room by operating

pumps and valves from upper deck, to be closely followed up.

* Joints/angle links on spindle extensions etc. to be fitted in such a way that the valve

control wheel on upper deck can be operated easily without nearby obstructions.

* Bilge systems, for stern well and chain lockers to be checked for easy control/operation.

* See also Class/authorities regulations for practical advice concerning ballast- and bilge

systems.

801.5 Maintenance of Ballast Systems

801.50 General

Main branch lines, direct and emergency pipes for bilge suction, filters, mud and rose boxes

to be thoroughly checked for corrosion, leaking and clogging. Correct functioning of suction

valves, including emergency bilge suction, to be confirmed. This is applicable for bilge

systems but should also be observed for ballast systems.

Remotely controlled valves (hydraulic or pneumatic) are to be tested, i.e. by direct activation

or by hand pump connected to the control system. Position indicating system of these valvesalso to be confirmed.

Water hammering problems are important to be aware of. Generally these may occur at:

* Sudden closing of valve(s) while ballast pump(s) is running. Opening and closing time

of valves to be checked.

* Starting of ballast pump for filling. Electrically driven pumps are more critical in this

regard unless a soft starting arrangement is provided.



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Important measures for avoiding water hammering problems are:

* Robust axial supports

* Alignment of sliding supports and sufficient transverse strength

* Location of supports relative to expansion joints

* Avoid soft joints, e.g. bellows, as far as practicable* Correct adjustment of closing speed of valves

* Soft starting arrangement for electric pump motor

802 HEATING COILS IN BALLAST TANKS

(Not included in Basic Edition)

(Note that heating coils in ballast tanks will increase corrosion).



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803 BILGE SYSTEMS


The main principles concerning bilge system are laid down in SOLAS Reg. 21 and MARPOL

Reg. 15, 16, and 17.

An efficient drainage system is to be provided for all tanks and watertight compartments such

as engine room, pump room(s), pipe tunnels etc.

The bilge system normally includes two pumps, suction pipes with non-return valves, mud

boxes and pipes for overboard discharge with non-return valves. Two non-return valves in

series are to be installed between sea and the bilge suction, in order to protect against leakage

of sea water. The bilge pumps shall be of the self-priming type. One of the pumps may be an

ejector.

Further is included equipment and systems for cleaning of bilge water, i.e. bilge water

separators and filtering systems with piping, valves etc.

803.1 Piping System

803.10 General

To attain redundancy by simple means the service of bilge, general service and fire pumps

may be combined in such a way that the system still maintains an equivalent safety level.

The Class normally requires minimum three pump units for covering the requirement to bilge

and fire systems. The general service pump will cover the requirement for fire and bilge

pumps. For guidance, see below sketch:

Bilge suction pipes are, as far as practicable, not to be carried through double bottom tanks.

In deep tanks used for water ballast or fuel oil, the bilge pipes to be led through pipe tunnels

or made of steel with an increased wall thickness and if possible, to consist of a single pipe

length, or be welded together.



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Non-metallic pipes may in some cases be used in lieu of steel pipes. Expansion bends or

approved expansion bellows to be fitted to bilge pipes inside tanks. Open ends of these

suction pipes in cargo holds to be provided with non-return valves.

Branch bilge pipes for drainage of machinery spaces and shaft tunnels to be led to mud boxes.

The mud boxes to have straight tail pipes to the bilges and to be arranged for easy inspectionand cleaning.

Strums or rose boxes (i.e. filter plates with holes) not to be fitted to the lower end of these

pipes or to emergency bilge suctions. Generally, mud boxes should be aimed at being fitted to

the main bilge line on the suction side of the pumps.

Strums or rose boxes are to be fitted to the ends of bilge suction pipes in cargo holds and

arranged for easy inspection and cleaning (i.e. at the bottom of the bilge or wells and to be

adequate to allow full flow of water and to facilitate cleaning).

Pumping arrangements for seawater cooling of machinery units to be independent andseparate from the ballast/bilge pumping functions. This to protect the system against

explosive liquids that may be pumped into a closed system.

Bilge ejectors should be provided for following spaces (example):

* 1 set, 5 m3/h in chain lockers and deck stores

* 1 set, 5 m3/h in bow thruster room and forward pump room

* 2 sets, each 40 m3/h in pipe duct forward and aft

Bilges in the steering gear compartment, emergency fire pump space and aft rope space

should be led to bilge well in the engine room through self-closing valve. Bilge wells (2 aft, 2

fwd) should be provided in the steering gear compartment.

Driving water for ejectors may be supplied from fire/wash deck system; materials should be

bronze body and stainless steel nozzle.

Each cofferdam should be provided with 2 bilge wells (one port and one starboard) at the

bottom.

An international flange connection for discharging engine room bilge to shore to be provided

at each side of the deck house. The connection to be blanked off with blind flange.

A water detecting system to be provided in engine and pump rooms.

803.11 Engine room bilge arrangement

The principal feature of this system is the main bilge line to which bilge suctions from the

various compartments are connected.

At least 3 branch bilges to be fitted in the engine room. The suctions to be arranged forward,

aft, and at both sides of the engine room. Where rise of floor (bottom) is more than 5 , onebranch suction near the centre line will be acceptable.



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Arrangements to be such that any water, which may enter this compartment, can be pumped

out through at least two bilge suctions when the ship is on even keel, and is either upright or

having a list of not more than 5 . One of these suctions to be a branch bilge suction connected

to the main bilge line and the other to be a direct bilge suction, i.e. a suction led directly to an

independently powered pump.

In addition to the branch bilge suctions, separate bilge suctions are to be led directly to the

bilge pump from each side of the engine room. (For passenger vessels emergency bilge

suction to be arranged in addition to the bilge suction forward in the engine room, i.e.

according to SOLAS. In such case the direct bilge suction may be omitted on the side where

the emergency suction is fitted). The diameter of the emergency suction to be equal to that of

the suction side of the pump, but does not need to exceed 400 mm.

A typical bilge/sludge system for engine room is shown below:

The sketch shows the minimum requirements of MARPOL 73/78 regarding prevention of oil

pollution from the engine room, as well as SOLAS Reg. 21 regarding bilge-pumping

requirements.

Any ship of 400 GRT and above shall be fitted with oil filtering equipment. Ships larger than

10.000 GRT shall in addition be provided with arrangement for an alarm and for automatic

stopping any discharge of oily mixture when the oil content in the effluent exceeds 15 ppm

(parts per million).

Under normal conditions, MARPOL does not accept use of the bilge pumps for pumping oily

water over board.



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SOLAS Reg. 21 requires that an efficient bilge pumping system shall be provided, capable of

pumping from and draining any watertight dry compartment. At least two pumps connected to

the main bilge system shall be provided. One of the bilge pumps may be ballast or general

service pump.

One of the direct bilge suctions may be replaced by emergency bilge suction connected to sea-water cooling pump.

The purpose of the main bilge pumping arrangement is to protect the engine room against

flooding; hence regular service of the bilge well must be carried out. Connection of the

emergency bilge suction to be arranged so that only two valve operations are necessary to

bring the suction into operation.

If the machinery space is divided into compartments separated by watertight bulkheads, the

drainage system is to be as for cargo holds, and it is to be connected to two mutually

independent bilge pumping units, situated in different compartments. In addition, a direct

bilge suction to be arranged to an independent pump for each compartment.

Specially formed parts of the machinery space, e.g. fly wheel wells and hotwell of main

condensers, to be fitted with branch suctions with internal diameter not less than 50 mm.

803.12 Cargo hold bilge arrangement

For bulk carriers the main bilge line is generally located in a pipe duct to which the bilge

suction pipes from each bilge well is connected. The double bottom tanks to be arranged so

that bilge suction pipes through FO tanks are avoided. If this is impracticable, the bilge pipe

should be in one continuous length or connected by welded joints.

Where bilge pipes are led through cargo holds, they are to be efficiently protected by cover

plates or built in.

One bilge suction normally to be fitted at each side of the holds. If rise of the floor/bottom of

the hold/tank is more than 5 , one suction near the centre line may be accepted. For such

tanks, filling and suction pipes for liquid cargo and ballast to be arranged for blank flanging.

Bilge suction pipes are also to be arranged for blank flanging at the tank bulkheads.

Vessels with one cargo hold only to have suctions at fore and aft ends of the hold. Shipshaving two or more holds to have suction at fore and aft end of holds with length exceeding

0,2 L. Holds of length less than 35 m may have only one suction (0,2 175 = 35)

Double bottom bilge suctions in cargo holds are to be arranged with bilge wells having a

capacity of at least 0,15 m3 each. Wells of less capacity may be accepted for small

compartments. Cargo holds for dry cargo in bulk to be provided with arrangements giving

satisfactory drainage when bulk cargoes are carried.

Sliding type expansion joints in bilge lines in way of ballast tanks are not to be used.

Expansion bellows of stainless steel are not suitable due to pitting corrosion from sea water.

Titanium or reinforced rubber compensators should be used instead. Further, if possible,flexibility of the piping should be ensured by means of loops or offsets.



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803.13 Drainage of cargo deck spaces ('Tween decks)

All cargo decks are to be fitted with an appropriate number of drainage openings at each side

of the vessel for drainage of small leakages. Cargo decks with a length of less than 70 m to

have minimum one drainage on each side forward and aft. For cargo decks with length above

70 m, one additional drainage on each side is to be arranged. The drains to be positionedwithin an area of 50 % of the length, around the middle of the cargo deck. These are typical

Class requirements.

The total drainage capacity of each part of the deck (for cargo spaces protected by a

pressurised water spraying system or a high expansion foam system, see below and Gp 81) to

have a capacity greater than the quantity of water supplied from two nozzles (four nozzles for

cargo spaces intended for carriage of dangerous goods), with size and pressure according to

the Class rules.

The cross-sectional area of each drainage opening not to be less than that corresponding to a

pipe diameter of 100 mm. Each opening to have a drain-off grating with total area ofopening not less than 4 times the drainage opening.

The outlets may be led overboard if the drainage openings in the deck are not below the

waterline when the vessel is loaded to the summer load line and has a list of 5 . If the

drainage openings in the deck are lower in this condition, the outlets to be led down to the

bilge wells in the inner bottom or to a separate bilge water tank.

Drainage water pipes from different watertight subdivisions leading to a common bilge water

tank are to have automatic non-return valves. The bilge water tank to be connected to the

vessels bilge system, and the suction pipe from the tank to have a diameter not less than the

main bilge line. The bilge tank volume to be min. 1/3 of the total drainage capacity per hour

of each part of the deck(s). Air pipes from the bilge tank to be led to open air above the

freeboard deck.

Bilge water tanks and bilge wells collecting drainage water from cargo spaces are to be

arranged with alarm to the bridge, indicating ingress of water.

Where cargo spaces are protected against fire by pressurised water spraying system or a high

expansion foam system, drainage openings to be arranged as follows:

* The cargo deck area to be divided into 4 areas, 2 on each side of the ship.

* One area to cover the forward half of the deck length, and the other to cover the aft half

of the deck length.

* Each of the four areas to have two or more drainage openings with a combined capacity

at least equal to the total capacity of the water spraying system or the high expansion

foam system. For the latter, the total capacity of the drainage openings to be determined

considering the water content of the high expansion foam only. However, the drainage

capacity not to be less than as defined above for each part of the deck.

Required diameter of drainage openings may be found in the Class rules.



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Where drainage is by means of pumping directly from the bilge wells, the capacity of the

bilge pumps to be at least 1/3 in excess of the sprinkler pumps. If pumped from a bilge tank,

the bilge pumps are to have at least the same capacity as the sprinkler pumps.

803.14 Pipes

Plastic pipes are not accepted for bilge and fire lines.

As stated in 801.11, grey cast iron is not to be used for bilge and ballast pipes in pipe tunnels

in the double bottom or for ballast lines to forward tanks when led through cargo oil tanks.

According to SOLAS and USCG (Coast Guard) requirements, bilge pipes are to be of steel or

other equivalent material. Stainless steel is generally not recommended due to risk of pitting

corrosion in case of stagnant sea water.

The min. internal diameter of the main bilge line is calculated by a formula given in the Classrules, based on vessels length/breadth (L/B in m) and depth (D in m) to the bulkhead deck:

)(25)(68.1 mmDBLd ++=

Min. internal diameter of branch bilge suctions to cargo holds, machinery and boiler spaces is

given by:

)(25)(15.21 mmDBld ++=

l = length of compartment (m)

The internal diameter of any branch suction not to be less than 50 mm.

For vessels where pumps in the machinery spaces are not used for bilge drainage outside the

machinery space, the size of the main line may be less than stipulated by Class. However, the

cross-sectional area of the pipe is not to be less than twice the area required for the branch

bilge suction pipes in the engine room, see below.

Direct bilge suctions are to have a diameter of not less than 1,4 d 1but does not need to exceed

the diameter of the main bilge line (d). For smaller separated machinery spaces the sizes of

the direct bilge suctions may be considered especially.

The cross-sectional area of a suction pipe from a bilge distribution chest is not to be less than

the combined area of the two largest branch bilge suctions connected to that chest. However,

it does not have to exceed what is required for the main bilge line (d).

The internal diameter of the bilge suction pipes to the fore and aft peak tanks and to the tunnel

well is not to be less than 63 mm for ships exceeding 61 metres in length and 50 mm for

shorter ships.



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803.15 Valves

Valves, cocks and mud boxes to be located at readily accessible positions above or on the

same level as the floor plates. Bilge branch valves should be located in an accessible, dry

compartment or the bilge system should be arranged with redundancy (two main bilge lines).

Where this is not practicable, they may be placed immediately below the floor level, providedthe floor plates in question can be easily removed and are fitted with nameplates indicating

the fittings that are located below the plates.

According to e.g. DNV rules, two non-return valves in series are to be installed between sea

or ballast system and bilge suction in compartments such as engine room, pump room(s), pipe

tunnels etc. These valves to be of screw-down, non-return type.

For direct emergency bilge suctions in the machinery space, one non-return valve between sea

or ballast system and bilge suctions will generally be accepted. All direct bilge suctions and

branch suctions not leading to a bilge distribution chest, are to be fitted with same type of

valves (screw-down, non-return valves). For arrangements with a main bilge line, it isessential that each suction is controlled by such valves to prevent intercommunication

between the compartments. Branch bilge suction for drainage of cargo holds and machinery

spaces to be separated from sea inlet valves and pipes used for filling or emptying of holds or

tanks intended to carry water or oil.

Bilge valves must at any time be accessible and arranged for manual operation in addition to

remote control. Manual operation by means of a portable hand pump is not acceptable.

All bilge valves located in pipe tunnels to have local, manual control in addition to any

remote control (see below sketch):

Valves in the bilge system should be of globe and screw-down, non-return type with body of

cast iron and disc of bronze. Such valves of 40 mm and below, should be of bronze body and

disc.



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Further, as for ballast system valves, all valves with cast iron or cast steel body for handling

sea water and bilge water should be coated internally with tar epoxy.

803.16 Valve control systems

Main bilge lines for cargo holds generally to be placed in a pipe tunnel, and branch bilge

suctions to be fitted with remotely controlled valves. The main line is to be dimensioned as

the machinery space main bilge line and to be placed as high as possible in the pipe tunnel.

Alternatively, the main bilge line may be arranged as follows::

* Through double bottom ballast tanks, with branch line valves located in accessible, dry

compartments, or

* Two main bilge lines can be arranged, with branch line valves located in double bottom

ballast tanks. Each cargo hold then to have branch suctions connected to the main lines,i.e. two bilge suctions per hold.

Main bilge line for cargo holds further to be fitted with a shut-off valve in the machinery

space. In addition, remotely controlled valves in branch bilge suction lines to be screw-down,

non-return valves or shut-off and non-return valves connected in series. The manoeuvring

panel for remotely controlled valves in bilge and ballast systems shall indicate whether the

valves are open or closed.

803.2 Bilge Pumps and Ejectors

803.20 General

For double bottoms without pipe duct, the installation of bilge pipes in the double bottom is

complicated and expensive. A bilge system with two bilge ejectors for each cargo hold is then

recommended, driven by water from the fire main/wash line on deck. Each ejector to have

independent, overboard discharge, non-return valves.

Load Line regulations require that discharge pipes are led overboard 920 mm above the

freeboard deck and provided with closing valve, e.g. gate valve. For further details, see Gp

82.

When cargo holds are cleaned with HP water guns driven from the main fire line, the ejector

capacity to be about 20 % larger than the cleaning gun capacity.

Ejectors used for draining of cargo holds may be accepted, provided the arrangement offers

safety against ingress of water.

803.21 Bilge pumps

Two mutually independent pump units are required. For vessels with length up to 90 m, oneof the pumps may be driven from the main engine.



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Each pumping unit may consist of one or more pumps connected to the main bilge line,

provided their combined capacity is sufficient.

One of the pump units may be a bilge ejector, if a separate pump is delivering sufficient water

for operation of the ejector. This arrangement has the advantage that the ejector can also be

used for stripping of ballast tanks and for priming of the ballast pumps.

On vessels with inboard drainage of cargo deck spaces having access openings in the shell

plating or fixed water spraying fire fighting systems, one of the bilge pumping units is not to

be connected to more than one additional system, for which the number and capacity of the

pumping units already satisfy the Class rules . The inboard drainage is discharges led from one

deck to a space below the freeboard deck, with bilge suctions.

Bilge pumps of centrifugal type either to be of the self-priming type or connected to a central

priming system. Centrifugal bilge pumps to be arranged in such a way that no suction line is

led through more than two non-return valves, preferably only one. At least one of the bilge

pumps should be of the reciprocating type.

Where pumps, necessary for propulsion machinery or for ballasting, are connected to a

common suction or discharge chest or other piping, the arrangement to be such that the

functioning of any pump is not affected by other pumps in operation at the same time.

The capacity of each bilge pumping unit to be sufficiently large to give the water under

ordinary working conditions a velocity of at least 2-3 m/s (to avoid clogging of pipes).

If the capacity of one pump is somewhat smaller than required, the deficiency may be

compensated for by increasing the capacity of the other pump. The smaller pump is not to

have a capacity less than one third of the total combined pumping capacity.

E.g. for a handy size bulk carrier, the ballast pumps can be combined with bilge ejector and

fire pumps. For this arrangement one of the ballast pumps must be of two-step type with

capacity approximately 1000 m3 at 2 bar or 200 m

3 at 10 bar. Capacity for the two-step

fire/general service pump to be approx. 200 m3at 2 bar or 100 m

3at 10 bar.

For a Panmax bulk carrier, the capacity of the ballast pumps is generally too large to be

combined with other systems. However, a bilge ejector driven by the ballast pumps can be

combined with the bilge pump function.

Remotely controlled bilge and ballast pumps to be provided with operating indications at the

remote, manoeuvring panel.

All bilge pump connections to the main bilge line are to be fitted with stop valves. Further,

the bilge pumps are to be arranged so that either one can be used while the other is being

overhauled.

Direct bilge suctions from machinery spaces to be arranged so that they can be used

simultaneously with other bilge pumps, drawing from any other compartments.



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Pipe diameters and corresponding bilge pump capacities are given in the below table:

Bore of bilge pipe

[mm]

Capacity of each

pump [m3/hour]

Bore of bilge pipe

[mm]

Capacity of each

pump [m3/hour]

50 15 130 97

55 18 135 10560 21 140 113

65 25 145 121

70 29 150 130

75 33 155 138

80 37 160 147

85 42 165 157

90 47 170 166

95 52 175 176

100 58 180 186

105 64 185 197110 70 190 208

115 76 195 219

120 83 200 230

125 90 205 246

210 254

803.3 Filters

803.30 General

Branch bilge pipes for drainage of machinery spaces and shaft tunnels are to be led to mud

boxes. The mud boxes to be arranged for easy inspection and cleaning.

Strums or rose boxes, which may be filter box or a steel plate with holes, are to be fitted to the

ends of bilge suction pipes in cargo holds.

803.4 Bilge Water Separators

803.40 General

According to MARPOL 73/78, Reg. 15 and 16, any ship of 400 GRT and above, shall be

provided with approved oil filtering equipment or bilge water separator ensuring that any oil

mixture discharged into the sea, has oil content not exceeding 15 ppm (parts per million).

For ship of 10.000 GRT or more, discharge into the sea shall be monitored by an alarm, and

automatically stopped when the oil content exceeds 15 ppm.



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803.5 Bilge Sludge Tanks

803.50 General

According to MARPOL Reg. 17, every ship of 400 GRT and above shall be provided with atank of adequate capacity, to receive oil residues (sludge) from oil leakages, fuel and lube oil

separators.

___________



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0.214 L0.214 L

Trim = 0.36 mWB TK

4

WB TK

3 Tf= 7.10

m

WB 1WB TK

2Ta= 7.46 mWB TK 5

0.214 L0.214 L

Trim = 0.36 mWB TK

4

WB TK

3 Tf= 7.10

m

WB 1WB TK

2Ta= 7.46 mWB TK 5

Fig. 800.12 A Ballast Water Exchange Start and Finish Condition

-50000

0

50000

100000

150000

200000

250000

300000

350000

400000

0 50 100 150 200 250

Distance from AP [m]

Ben

ding

Momen

[tm

]

Fig. 800.12 B Ballast Water Exchange Bending Moments for Intermediate Conditions



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Fig. 800.33 A Details of Ballast/Bilge Piping, Bilge Wells and Venting


Documents

Gp80. Ship Common Sys