1 INTRODUCTION
1.1 The purpose of these Guidelines is to provide shipowners and operators with general
guidance on the development of ship specific procedures for conducting ballast water
exchange. Whenever possible shipowners and operators should enlist the assistance of
classification societies or qualified marine surveyors in tailoring ballast exchange
practices for various conditions of weather, cargo and stability. The application of
processes and procedures concerning ballast water management are at the core of the
solution to prevent, minimize and ultimately eliminate the introduction of harmful
aquatic organisms and pathogens. Ballast water exchange offers a means, when used in
conjunction with good ballast water management practices, to assist in achieving this
solution.
1.2 Ballast water exchange introduces a number of safety issues, which
affect both the ship and its crew. These Guidelines are intended to provide guidance on
the safety and operational aspects of ballast water exchange at sea.
1.3 Given that there are different types of ships which may be required to
undertake ballast water exchange at sea, it is impractical to provide specific
guidelines for each ship type. Shipowners are cautioned that they should consider the
many variables that apply to their ships. Some of these variables include type and size
of ship, ballast tank configurations and associated pumping systems, trading routes and
associated weather conditions, port State requirements and manning.
Application
1.4 The Guidelines apply to all those involved with ballast water exchange, including
shipowners and operators, designers, classification societies and shipbuilders.
Operational procedures and guidance reflecting the issues raised in these Guidelines
should be reflected in the ship's ballast water management plan.
2 DEFINITIONS
For the purposes of these Guidelines, the definitions in the International Convention for
the Control and Management of Ships' Ballast Water and Sediments (the Convention) apply
and "ballast water tank" means any tank, hold or space used for the carriage of ballast
water.
3 RESPONSIBILITIES
3.1 Shipowners and operators should ensure, prior to undertaking ballast water exchange,
that all the safety aspects associated with the ballast water exchange method or methods
used on board have been considered and that suitably trained personnel are on board. A
review of the safety aspects, the suitability of the exchange methods being used and the
aspects of crew training should be undertaken at regular intervals.
3.2 The ballast water management plan should include the duties of key shipboard control
personnel undertaking ballast water exchange at sea. Such personnel should be fully
conversant with the safety aspects of ballast water exchange and in particular the
method of exchange used on board their ship and the particular safety aspects associated
with the method used.
3.3 In accordance with regulation B-4.4 of the Convention, if the master reasonably
decides that to perform ballast water exchange would threaten the safety or stability of
the ship, its crew or its passengers, because of adverse weather, the ship's design,
stress, equipment failure, or any other extraordinary condition, a ship shall not be
required to comply with regulations B-4.1 and B-4.2.
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.1 When a ship does not undertake ballast water exchange for the reasons stated
above, the reasons shall be entered in the ballast water record book.
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.2 The port or coastal State concerned may require that the discharge of ballast
water must be in accordance with procedures determined by them, taking into
account the Guidelines for additional measures including emergency situations
(G13).
3.4 Where a port State requires specific information regarding the management of ballast
water on a ship bound for a port, offshore terminal or anchorage area in that port
State, a completed ballast water reporting form as set out in the appendix may be
submitted prior to entry into that port State in a timeframe required by that port
State.
4 BALLAST WATER EXCHANGE REQUIREMENTS
4.1 Exchange of ballast water in deep ocean areas or open seas offers a means of limiting
the probability that harmful aquatic organisms and pathogens be transferred in ships'
ballast water.
4.2 Regulation D-1 of the Convention requires that:
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.1 ships performing ballast water exchange in accordance with this regulation
shall do so with an efficiency of at least 95% volumetric exchange of ballast
water; and
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.2 for ships exchanging ballast water by the pumping-through method, pumping
through three times the volume of each ballast water tank shall be considered to
meet the standard described in paragraph 1. Pumping through less than three
times the volume may be accepted provided the ship can demonstrate that at least
95% volumetric exchange is met.
4.3 There are three methods of ballast water exchange which have been evaluated and
accepted by the Organization. The three methods are the sequential method, the
flow-through method and the dilution method. The flow-through method and the dilution
method are considered as "pump through" methods.
4.4 The three accepted methods can be described as follows:
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.1 Sequential method – a process by which a ballast tank intended for the
carriage of ballast water is first emptied and then refilled with replacement
ballast water to achieve at least a 95% volumetric exchange.
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.2 Flow-through method – a process by which replacement ballast water is
pumped into a ballast tank intended for the carriage of ballast water, allowing
water to flow through overflow or other arrangements.
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.3 Dilution method – a process by which replacement ballast water is
filled through the top of the ballast tank intended for the carriage of ballast
water with simultaneous discharge from the bottom at the same flow rate and
maintaining a constant level in the tank throughout the ballast exchange
operation.
5 SAFETY PRECAUTIONS ASSOCIATED WITH BALLAST WATER EXCHANGE
5.1 Three methods of carrying out ballast water exchange at sea have been identified as
acceptable by the Organization. Each has particular safety aspects associated with it
that should be considered when selecting the method(s) to be used on a particular ship.
5.2 When identifying the ballast water exchange method(s) for the first time for a
particular ship, an evaluation should be made which should include:
- .1 the safety margins for stability and strength contained in allowable seagoing
conditions, as specified in the approved trim and stability booklet and the loading
manual relevant to individual types of ships. Account should also be taken of the
loading conditions and the envisaged ballast water exchange method or methods to be
used;
- .2 the ballast pumping and piping system taking account of the number of ballast
pumps and their capacities, size and arrangements of ballast water tanks; and
- .3 the availability and capacity of tank vents and overflow arrangements, for the
flow through method, the availability and capacity of tank overflow points,
prevention of under and over pressurization of the ballast tanks.
5.3 Particular account should be taken of the following:
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.1 stability which is to be maintained at all times and not less than those
values recommended by the Organization or required by the Administration;
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.2 longitudinal stress, and where applicable torsional stress values, not to
exceed permitted values with regard to prevailing sea conditions;
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.3 exchange of ballast in tanks where significant structural loads may be
generated by sloshing action in the partially filled tank to be carried out in
favourable sea and swell conditions such that the risk of structural damage is
minimized;
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.4 wave-induced hull vibrations when carrying out ballast water exchange;
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.5 limitations of the available methods of ballast water exchange in respect of
sea and weather conditions;
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.6 forward and aft draughts and trim, with particular reference to bridge
visibility, slamming, propeller immersion and minimum forward draft; and
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.7 additional workloads on the master and crew.
5.4 Having undertaken an evaluation for a particular ship and the exchange method or
methods to be used, the ship should be provided with procedures, advice and information
appropriate to the exchange method(s) identified and ship type in the ballast water
management plan. The procedures, advice and information in the ballast water management
plan may include but are not limited to the following:
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.1 avoidance of over and under-pressurization of ballast tanks;
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.2 free surface effects on stability and sloshing loads in tanks that may be
slack at any one time;
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.3 maintain adequate intact stability in accordance with an approved trim and
stability booklet;
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.4 permissible seagoing strength limits of shear forces and bending moments in
accordance with an approved loading manual;
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.5 torsional forces;
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.6 forward and aft draughts and trim, with particular reference to bridge
visibility, propeller immersion and minimum forward draft;
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.7 wave-induced hull vibrations when performing ballast water exchange;
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.8 watertight and weather-tight closures (e.g. manholes) which may have to be
opened during ballast exchange must be re-secured;
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.9 maximum pumping/flow rates – to ensure the tank is not subjected to a pressure
greater than that for which it has been designed;
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.10 internal transfers of ballast;
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.11 admissible weather conditions;
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.12 weather routeing in areas seasonably affected by cyclones, typhoons,
hurricanes, or heavy icing conditions;
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.13 documented records of ballasting and/or de-ballasting and/or internal
transfers of ballast;
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.14 contingency procedures for situations which may affect ballast water exchange
at sea, including deteriorating weather conditions, pump failure and loss of
power;
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.15 time to complete the ballast water exchange for each tank or an appropriate
sequence thereof;
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.16 continual monitoring of the ballast water operation; monitoring should
include pumps, levels in tanks, line and pump pressures, stability and stresses;
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.17 a list of circumstances in which ballast water exchange should not be
undertaken. These circumstances may result from critical situations of an
exceptional nature or force majeure due to stress of weather, known equipment
failures or defects, or any other circumstances in which human life or safety of
the ship is threatened;
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.18 ballast water exchange at sea should be avoided in freezing weather
conditions. However, when it is deemed absolutely necessary, particular
attention should be paid to the hazards associated with the freezing of
overboard discharge arrangements, air pipes, ballast system valves together with
their means of control, and the build-up of ice on deck; and
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.19 personnel safety, including precautions which may be required when personnel
are required to work on deck at night, in heavy weather, when ballast water
overflows the deck, and in freezing conditions. These concerns may be related to
the risks to the personnel of falling and injury, due to the slippery wet
surface of the deck plate, when water is overflowing on deck, and to the direct
contact with the ballast water, in terms of occupational health and safety.
5.5 During ballast water exchange sequences there may be times when, for a transitory
period, one or more of the following criteria cannot be fully met or are found to be
difficult to maintain:
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.1 bridge visibility standards (SOLAS regulation V/22);
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.2 propeller immersion; and
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.3 minimum draft forward.
5.6 As the choice of acceptable ballast water exchange sequences is limited for most
ships, it is not always practicable to dismiss from consideration those sequences where
transitory non-compliance may occur. The practical alternative would be to accept such
sequences provided an appropriate note is placed in the ballast water management plan to
alert the ship's master. The note would advise the master of the nature of the
transitory non-compliance, that additional planning may be required and that adequate
precautions need to be taken when using such sequences.
5.7 In planning a ballast water exchange operation that includes sequences which involve
periods when the criteria for propeller immersion, minimum draft and/or trim and bridge
visibility cannot be met, the master should assess:
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.1 the duration(s) and time(s) during the operation that any of the criteria will
not be met;
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.2 the effect(s) on the navigational and manoeuvring capabilities of the ship;
and
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.3 the time to complete the operation.
5.8 A decision to proceed with the operation should only be taken when it is anticipated
that:
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.1 the ship will be in open water;
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.2 the traffic density will be low;
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.3 an enhanced navigational watch will be maintained including if necessary an
additional look out forward with adequate communications with the navigation
bridge;
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.4 the manoeuvrability of the vessel will not be unduly impaired by the draft and
trim and or propeller immersion during the transitory period; and
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.5 the general weather and sea-state conditions will be suitable and unlikely to
deteriorate.
5.9 On oil tankers, segregated ballast and clean ballast may be discharged below the
water line at sea by pumps if the ballast water exchange is performed under the
provisions of regulation D-1.1 of the Convention, provided that the surface of the
ballast water has been examined either visually or by other means immediately before the
discharge to ensure that no contamination with oil has taken place.
6 CREW TRAINING AND FAMILIARIZATION
6.1 Appropriate training for ships' masters and crews should include instructions on the
safety issues associated with ballast water exchange based upon the information
contained in these Guidelines. Instruction should be provided on the ships' ballast
water management plan including the completion of required records.
6.2 Ships' officers and crew engaged in ballast water exchange at sea should be trained
in and be familiar with the following as appropriate:
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.1 the ship's ballast pumping and piping arrangements, positions of associated
air and sounding pipes, positions of all compartment and tank suctions and
pipelines connecting them to ship's ballast pumps and, in the case of use of the
flow through method of ballast water exchange, the openings used for release of
water from the top of the tank together with overboard discharge arrangements;
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.2 the method of ensuring that sounding pipes are clear, and that air pipes and
their non-return devices are in good order; .3 the different times required to
undertake the various ballast water exchange operations including the time to
complete individual tanks;
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.4 the method(s) in use for ballast water exchange at sea if applicable with
particular reference to required safety precautions; and
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.5 the need to continually monitor ballast water exchange operations.
7 FUTURE CONSIDERATIONS IN RELATION TO BALLAST WATER EXCHANGE
These Guidelines may be revised and updated in the light of possible technical evolutions
with the ballast water exchange methods and of new ballast water management options.