PREVENTION OF MARINE
POLLUTION FROM SHIPS
Preventing Marine Pollution from Ship
• Identify various ship operations generating
• Distinguish tank operations resulting in
• State the hazards involved in handling
• Explain safety measures in handling petroleum
In order to avoid marine pollution from
ships, activities on board vessels should be
taken with extreme care. Lack of safety measures
increases the chance of spilling oil or harmful
substances. This chapter deals with ship’s
operational activities that generate marine
pollution. Emphasis on standard safety operating
procedures in the handling of petroleum cargo is
given in this chapter
SHIPS OPERATIONS GENERATING POLLUTION
The common causes of pollution from routine shipboard
operations are as follows:
• Ships taking in or transferring bunkers or disposing of or
transferring fuel, fuel residues and oily bilge water
• Tanker operations such as cargo loading/discharging, tank
cleaning, ballasting operations
• Discharge of hold bilges or ballast water on vessels other than
• Washing of decks covered with cargo remnants or hydraulic oil
which has leaked from deck machinery
• Discharge of sewage
• Disposal of galley and other garbage
-the operation of taking on board fuel.
- in most cases, bunkering is a major cause of operational oil
spills for all types of vessels. The ship’s officer-in-charge of
monitoring this task has to be alert and experienced in this field.
The areas of safety concern are as follows:
• The position of overflow and air pipes
• Overflow tank and sounding pipes
• Depth indicators of all fuel tanks
• Overflow alarm system
MEASURES TO PREVENT OIL SPILL DURING OPERATIONS
a. Fitting of scupper plugs and checking that drain plugs of
bunker, manifold and fuel tank air pipe containment “save-
alls” are in place
b. Establishing communication with supply control position and
agreeing on maximum pumping rate and pressure. Ensure that
any signals to be used are thoroughly understood
c. Checking the conditions of hoses and couplings before and
d. Checking blanks available and hose string of sufficient length
to allow for normal for normal movement of vessel.
e. Checking all valves in required position and tank vent pipes
free from obstruction before bunkering commences.
f. Taking accurate sounding of all tanks before and on
completion of bunkering in oreder to verify the amount of fuel
g) Barge/ shore tank sounding and/or meter readings should also
be checked before and after bunkering to help resolve any
problem concerning quantity.
h) Taking frequent sounding during bunkering and rate of
delivery slowed down during topping of.
i) Ample warning should be given to supplier of need to reduce
delivery rate and the final shutting off.
j) Vessel should be upright and even keel throughout the
TRANSFERRING OF FUEL
-Transferring is done either within the ship or from ship-to-ship
Ship-to-ship > transfer or lightening may occur either in a port area
or at sea
If transfer is from one ship to another ship, risk is also considerable.
Safety measures should be undertaken to prevent the release of
oil into the water. The measures are as follows:
a. Fenders are properly placed when a vessel is to be positioned
alongside the damaged vessel for the transfer of oil (in case of
b. Before transfer begins, a lightening plan must be detailed so that
vessel shall stay at even keel.
c. Clear languages or communication instructions and signals must
be adopted by both ships.
d) All pieces of equipment must be in good condition, this includes
the hoses, couplings, etc.
e) Experienced personnel who have the skills in the delicate
operations must be deployed.
f) Emergency procedures must be adopted by both vessels.
BILGE WATER DISCHARGE OPERATIONS AND
>Bilge water discharge should be done to shore facilities. However
in order to discharge water from bilges at sea, a series of
conditions are provided by technical Annex I of MARPOL
73/78. For the purpose of monitoring discharge of oily ballast
water or tank washings from cargo tanks, installations of an oil
discharge monitoring and control system is required together
with fitting of oil/water interface detector.
For the purpose of monitoring discharge of oily bilge water and
oily ballast water from fuel tanks, installation of oil filtering
equipment is required. Different equipment should be attached
to oil-filtering equipment depending on the gross registered
tonnage of the ship.
Regulation 14 of the revised Technical Annex I reuires that any
ship off 400 GT and above but less than 10,000 GT shall be fitted
with oil filtering euipment, which design is approved by the
administration. It should be noted before the revision of
technical Annex I of MARPOL 73/78, the oil filtering equipment
requirement was within Regulation 16 of Technical Annex I
The equipment requirements for oil-water separating equipment
and oil filtering equipment are as follows:
a) Oil-water separating equipment – It may include any
combination of a separator, filter, or coalescer and also a single
unit designed to produce an effluent with oil content of less than
b) Oil filtering Equipment- It includes any combintaion of a
separator, filter or coalescer and also a single unit designed to
produce an effluent with oil content no exceeding 15ppm. It is
intended to use equipment attached to oily-water separating
equipment certified for an effluent of less than 100ppm
The following are the regulations relative to fitting the filtering
• When the level of effluents discharge more than the required
15ppm, the bilge alarm system activates.
• The oil filtering equipment should be strongly suited for
The equipment requirements for oil-water separating equipment
and oil filtering equipment are as follows:
• It is fitted in areas where flammable atmosphere may be present
• Electrical support attachment should be equipped with safety
equipment and installed in the safe areas.
• The equipment is designed to function automatically but
manual control is also provided in case of emergency.
• The system should be able to operate at least 24 hours of
normal duty without attention.
• The bilge alarm has an oil content meter. The meter can
withstand corrosion arising from saltwater. The meter is fitted
with an alarm device, which is set automatically to alert crew of
the ship. The alarm activates when the effluent exceeds 15ppm.
The alarm also operates automatically when the meter fails to
function during a warm up period or de-energized.
Tankers carry a variety of petroleum products. Tankers are
considered as the single largest contributor of marine pollution.
The introduction of supertankers created public concerns in
both developing and advanced countries. Oil pollution from
tankers originate from two principal sources. These are as
1. Various types of tanker accidents.
2. Normal tanker operations(i.e. tank cleaning, ballasting, and
other operational activities involving discharge of oil overboard)
Aside from the tanker accidents and normal tanker operations, the
dry-docking activities of these types of ships also add to the oil
pollution. However, the normal tanker operation is considered
as the main source of marine pollution from tankers.
In this regard, it is extremely important that all loading and
unloading operations are done with all the necessary
precautions. This practice reduces the risk of unnecessary oil
release into the water that pollutes the sea but also ascertains
that lives and properties are not endangered.
STANDARD SAFETY PROCEDURES FOR TANKER
The standard safety proceduresin the following tanker operations
are normally followed to avoid accidents that may entail marine
A. Pre-loading Operations
i. Before loading, a communication and signaling system
should be agreed upon between the ship and shore
personnel. For a standard ship, a shore safety checklist is
used and the items on it are checked.
ii. A loading plan is drawn between the ship and the shore
wherein loading sequence, stoppages, etc. are stated. The
ullage is calculated to which the cargo is to be loaded
iii. Fire fighting equipment and gears are placed close to the
manifold and ready for immediate use. Measures are taken
to prevent oil from flowing overboard in case of leakage of
hose couplings, etc. the tank lids are closed gastight and the
tank vent risers are put in loading position.
iv. The ullage meters are lowered to their lowest position. The
ships cargo lines are set right as in the case with tank valves.
If only one product is to be loaded, the valves in the main
and the crossover lines may all be kept open. The suction
and discharge valves of all pumps are shut.
v. The cargo line valves in the pump room are to be set right.
The terminal will connect their lines to the ship’s manifold
by means of hoses or steel pipes. After all the checking, the
ship can indicate to terminal that their valve/s now may be
opened and loading can start. The time the ship is ready to
load is noted on time sheet. Inert gas installation should be
v. …installation should be shut off. The gases in the tanks are
blown out during loading and dislodged by cargoes.
B. During Loading Operations
i. Loading should start slowly to check if connections are oil
tight and also to avoid static accumulation. Checks should
be made if oil flows overboard via the seachests in the
pump room and the cargo in indeed flowing into the tanks.
ii. The speed of loading may rise gradually to an agreed speed
or allowable hose or chicksan pressure. Soon after loading
has begun, the terminal and ship will take samples of the
tanks that are being loaded to check the temperature of the
iii. During loading,rounds are made regularly to check the
moorings, emergency, towing wire, etc. the loading speed is
checked. The calculated ullage is checked if nearly reached.
The tank valve is closed. The regular intervals are checked
iii. if sheer forces and bending moments reach the maximum.
If so, steps are to be taken to reduce them. Near the end of
loading, speed must be reduced to diminish the chance of
an overflow from the tank, as this may entail a heavy fine on
C. POST LOADING OPERATIONS
i. After completion of loading, the ship’s manifld valves are
only to be closed after the shore valves have been closed.
The tank valve is to be closed last. After completion of
loading, the hoses or loading arms should be emptied into a
drip tray prior to disconnecting.
ii. After disconnecting the hose and loading arms, blind
flanges are to be connected to the manifold valves. All main
and crossovers valves are shut.
iii. All openings of the tanks are closed gas tight, except P/V
breakers. The whessoe gauges are to be raised up to the
D. DISCHARGING OPERATIONS
i. Of every cargo tank,