ISO 23314-2:2021

INTERNATIONAL ISO
STANDARD 23314-2
First edition
2021-11
Ships and marine technology —
Ballast water management systems
(BWMS) —
Part 2:
Risk assessment and risk reduction of
BWMS using electrolytic methods
Navires et technologie maritime — Systèmes de gestion de l'eau de
ballast (BWMS) —
Partie 2: Appréciation du risque et réduction du risque des BWMS qui
utilisent des procédés électrolytiques
Reference number
© ISO 2021
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ii
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Strategy for risk assessment and risk reduction . 3
5 Risk assessment process .4
5.1 General . 4
5.2 Information for risk assessment . 4
5.3 Determination of the limits . 5
5.3.1 General . 5
5.3.2 Use limits . 5
5.3.3 Space limits . 5
5.3.4 Time limits . 6
5.3.5 Environmental limits . 6
5.4 Hazard identification . 7
5.4.1 General . 7
5.4.2 Human interaction with the equipment over the entire life cycle of a BWMS
using the electrolytic method . 7
5.4.3 Possible states of BWMS using the electrolytic method . 8
5.4.4 Unintended behaviour of the operator or reasonably foreseeable misuse . 9
5.5 Risk estimation . 9
5.5.1 General . 9
5.5.2 Elements of risk . 9
5.5.3 Aspects to be considered during risk estimation . 10
5.6 Risk evaluation . 11
6 Risk reduction .12
6.1 General .12
6.2 Inherently safe design . 12
6.2.1 General .12
6.2.2 Considerations during the initial design .12
6.2.3 Choice of appropriate technology . 13
6.2.4 Applying inherently safe design measures to control systems .13
6.3 Safeguarding and/or complementary protective measures . 14
6.3.1 General . 14
6.3.2 Safeguarding measures . 14
6.3.3 Complementary protective measures . 14
6.4 Information for use . 16
6.4.1 General . 16
6.4.2 Installation guide . 16
6.4.3 Commissioning procedure . . 16
6.4.4 Operation, maintenance and safety manual (OMSM) . 17
6.4.5 Maintenance scheme . 17
6.4.6 Calibration manual . 17
6.4.7 Warning indication . 18
6.4.8 Training plan and documentation . 18
7 Documentation of risk assessment .18
Annex A (informative) Example of a risk estimation matrix table in accordance with ISO/
TR 14121-2 .19
Annex B (informative) Example of a risk assessment and risk reduction worksheet —
Filtration unit .20
iii
Annex C (informative) Example of a risk assessment and risk reduction worksheet —
Electrolysis unit .22
Annex D (informative) Example of a risk assessment and risk reduction worksheet –
Neutralization unit .26
Annex E (informative) Example of a training plan for BWMS using the electrolytic method .27
Bibliography .28
iv
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 8, Ships and marine technology.
A list of all parts in the ISO 23314 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
Introduction
A ballast water management system (BWMS) using the electrolytic method applies a combination
of filtration (if applicable), electrolysis and a neutralization process to treat ballast water to meet
[19]
Regulation D-2 of the International Maritime Organization (IMO) BWM Convention , or the ballast
water discharge standard (BWDS) requirements of port state administrations, e.g. the U.S. Coast Guard
[31]
(USCG) .
At the uptake of ballast water, the BWMS utilizes filtration (if applicable) and injection of active
substances (e.g. sodium hypochlorite) generated by an electrolysis process. The active substance can
be generated within the full flow of the ballast pipe (full stream) or generated from a smaller side
stream (either extracted from the ballast pipe or sourced from a brine tank) and then mixed with the
full ballast flow. The active substance in the ballast pipe is measured as total residual oxidants (TRO)
and the BWMS regulates the TRO level to ensure ballast water is treated to the threshold level. During
discharge, the residual TRO is monitored and neutralized prior to discharge overboard to ensure
that the amount of residual active substance entering the receiving environment is acceptable. The
treatment process is shown in Figure 1.
Key
or treatment flow
feedback signal
Figure 1 — Overview of BWMS using the electrolytic method
vi
INTERNATIONAL STANDARD ISO 23314-2:2021(E)
Ships and marine technology — Ballast water management
systems (BWMS) —
Part 2:
Risk assessment and risk reduction of BWMS using
electrolytic methods
1 Scope
This document provides requirements and recommendations for designers of BWMS using electrolytic
methods to document the risk assessment and risk reduction process over the lifecycle of the
equipment, and to support its approval for use on ships by administrations and classification societies.
Specifically, this document provides basic terminology, principles and a methodology to identify
and subsequently minimize the risk of hazards in the design of BWMS using electrolytic methods. It
specifies the procedures for risk assessment and risk reduction following the guidance in ISO 12100.
Risks considered include: human health and safety; marine environment related to conditions on
board; and ship installation, operation, maintenance and structural integrity.
This document does not address the methodology for the risk assessment of corrosion effects, toxicity
and ecotoxicity of active substances, relevant chemicals and/or other chemicals generated or used
by BWMS using electrolytic methods, which is evaluated by the IMO GESAMP-Ballast Water Working
Group as prescribed in the document IMO GESAMP, Methodology for the Evaluation of Ballast Water
[26]
Management Systems using Active Substances .
This document does not address risks associated with the end of life disposition of the BWMS.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 12100:2010, Safety of machinery — General principles for design — Risk assessment and risk reduction
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 12100 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
active substance
substance or organism, including a virus or fungus, that has a general or specific action on or against
harmful organisms and pathogens
Note 1 to entry: For BWMS (3.3) using electrolytic methods (3.8), it means reaction products that are generated by
the electrolytic method for the ballast water treatment.
[SOURCE: IMO G9]
3.2
ballast water
water with its suspended matter taken on board a ship to control trim, list, draught, stability or stresses
of the ship
3.3
ballast water management system
BWMS
system that processes ballast water (3.2) such that it meets or exceeds the ballast water discharge
performance standard in Regulation D-2 of the BWM Convention
Note 1 to entry: A BWMS includes ballast water treatment equipment, all associated control equipment, piping
arrangements within the BWMS as specified by the manufacturer, control and monitoring equipment, and
sampling devices.
Note 2 to entry: A BWMS does not include the ship's ballast water fittings, which can include piping, valves,
pumps, etc. that would be required if the BWMS was not fitted.
Note 3 to entry: A ballast water treatment system (BWTS) defined in Environmental Technology Verification
(ETV) is considered the same as BWMS.
[SOURCE: IMO BWMS Code]
3.4
dangerous gas
gas that can develop an explosive and/or toxic atmosphere hazardous to the crew and/or the ship
EXAMPLE Hydrogen (H ), hydrocarbon gas, ozone (O ), chlorine (Cl ), chlorine dioxide (ClO ).
2 3 2 2
3.5
electrical distribution conductor
conductor intended for distributing the electricity, such as bus bars or conductors of insulated cables
3.6
electrolysis unit
unit that mainly consists of one or several chambers making use of an electrolytic method (3.8) to
produce active substances (3.1) for the treatment of ballast water (3.2), including ventilation components
for the safe handling of dangerous gases (3.4) if applicable, as well as relevant piping, valves, electrical
and electronic components
3.7
electrolytic chamber
chamber that contains one or several sets of electrodes and associated power connections, and that
makes use of the electrolytic method (3.8) for the production of active substances (3.1) when water flows
through it
3.8
electrolytic method
treatment process in which water flows through a set of special electrodes, producing active substances
(3.1) when an electric current is applied
3.9
flammable liquid
liquid having a flash point not exceeding 60 °C (closed cup test)
3.10
global integrated shipping information system
GISIS
public integrated information database developed by the IMO, which is composed of several modules
that deal with ship particulars, maritime safety, chemicals associated with treated ballast water (3.2)
and other shipping-related information
3.11
life cycle
entire lifespan from the design, manufacturing, storage, installation, to operation and disposal of a
BWMS (3.3)
3.12
maximum allowable discharge concentration
MADC
maximum allowable concentration of active substances (3.1) during discharge of ballast water (3.2) as
defined by port state control or local regulation
3.13
neutralization unit
unit that mainly consists of neutralizing agent preparation and dosing equipment for the purpose of
neutralizing active substances (3.1) by adding neutralizing agent into the de-ballast pipe so as to reduce
TRO (3.14) concentration to achieve compliance with the MADC (3.12)
3.14
total residual oxidant
TRO
sum of the effect of oxidizing chemicals, such as hypochlorous acid (HClO), hypochlorite (ClO), chlorine
(Cl ), hypobromous acid (HBrO), hypobromite (BrO), bromine (Br ), chloramine compounds, bromine
2 2
compound
4 Strategy for risk assessment and risk reduction
The process for risk assessment and risk reduction is based on guidance from ISO 12100 and is
summarized in Figure 2.
Figure 2 — General procedure of risk assessment and risk reduction for BWMS using
the electrolytic method
5 Risk assessment process
5.1 General
The risk assessment for BWMS using the electrolytic method is comprised of risk analysis and risk
evaluation.
Risk analysis consists of determining the limits, identifying the hazards, and estimating risk over the
whole lifespan of a BWMS, as considered in 5.3 to 5.5. Risk analysis provides the information required
for the risk evaluation (see 5.6), which in turn allows judgment to be made about whether or not risk
reduction (see Clause 6) is required.
5.2 Information for risk assessment
The information for the risk assessment of a BWMS using the electrolytic method shall consider the
documentation described in the following list.
a)  System description:
— documents related to installation guidance; the operation, maintenance and safety manual
(OMSM); schematic diagrams; process flow diagrams; and applicable test reports.
b)  Regulations, standards and other applicable documents:
[19]
— ISO and IEC standards (e.g. IEC 60079), IMO regulations or circulars (e.g. BWM Convention ,
[21] [20] [27]
BWMS Code , Procedure G9 ), IACS Unified requirements (e.g. IACS UR M74 ), port state
[31]
administration rules (e.g. USCG 46 CFR 162.060 ), and classification society rules;
— safety data sheets (SDSs) of the active substance, neutralizing agent, TRO measurement reagent,
and dangerous gas (e.g. hydrogen);
— database of chemicals commonly associated with treated ballast water in the IMO GISIS.
c)  Related to experience of use:
— known accidents, incidents or malfunction history of the actual or similar electrochlorination
systems (from database of marine incidents, e.g. GISIS):
— the potential for adverse effects from human exposure (e.g. to active substances);
— the experience of users of similar system e.g. electrochlorination system in power plant, waterworks,
etc.
The information used in the risk assessment shall be updated throughout the design process or when
modifications to the BWMS are required.
5.3 Determination of the limits
5.3.1 General
Risk assessment begins with the determination of the limits of the BWMS, taking into account all the
phases over the lifespan of the BWMS. This means considering the characteristics and performances
of both subsystems and the overall system as an integrated process. Characteristics of the system,
including its relationship with humans, the environment, and other products shall be identified in
terms of the limits of the BWMS as given in 5.3.2 to 5.3.5.
The purpose of this step is to identify all key parameters and their associated performance limits. These
parameters pertain to installation, operation, maintenance, personnel and the environment.
5.3.2 Use limits
Use limits include the intended use and the reasonably foreseeable misuse of the BWMS. Aspects to
account for include the following.
— The anticipated levels of training, experience or ability of the people who carry out installation,
commissioning, operation, and maintenance of the BWMS, e.g. unexpected system shutdown can be
activated due to misuse by an operator who is improperly trained or unfamiliar with the BWMS.
— Exposure of other persons to the hazards associated with the system that can be reasonably be
predicted, e.g. crew for other duties, administration officer or service personnel for other equipment
adjacent to the BWMS.
5.3.3 Space limits
Aspects of space limits shall address the requirements for safe installation, operation, and maintenance
of the BWMS. Considerations shall include:
— power supply and cabling;
— cooling water or ventilation air;
— operation and maintenance space;
— space for chemical storage (e.g. neutralizing agent, TRO measurement reagent);
— space for dangerous gas exhaust on open deck;
— installation location (e.g. hazardous area).
5.3.4 Time limits
Aspects of time limits shall consider specific operating and maintenance factors, including:
— life limit of parts that can wear due to corrosion, or life of critical components where a decline in
efficiency affects performance capabilities (e.g. electrode);
— recommended service and calibration intervals;
— holding time (minimum for efficacy and maximum based on regrowth);
NOTE The holding time can be dependent on water salinity, water temperature and TRO concentration.
— TRO measurement reagent service life/neutralizing agent shelf life in both solid (if applicable) and
aqueous forms (stored in ready to use form).
5.3.5 Environmental limits
Environmental limits shall consider the range of uptake water chemistries to be treated, operational
limits of process variables within the BWMS, limitations imposed by the shipboard environment on the
BWMS, hazardous by-products of the electrolytic process, and any environmental constraints on the
storage and use of chemicals associated with the BWMS. At a minimum, the following limits shall be
considered:
— recommended minimum salinity and temperature of the ballast water;
— recommended minimum salinity and minimum and maximum temperature of the electrolytic unit
feed water;
— recommended minimum inlet pressure of the filtration unit (if applicable);
— treatment rated capacity (TRC);
— maximum allowable discharge concentration (MADC), related to potential toxicity to the receiving
environment;
— lower TRO limit for treatment efficacy;
— upper TRO limit for the potential corrosive effects on ballast tanks;
— ambient marine environment related to locations on board;
— potential flammable and explosive atmospheres that can be created on board the vessel;
— potential health risks to personnel due to exposure to dangerous gas, and flammable and explosive
environments;
— personnel exposure to active substances or other relevant chemicals;
— TRO measurement waste (if applicable).
NOTE The limits including water salinity, water temperature, holding time, and TRO concentration are also
identified as representative system design limitations (SDL) for a BWMS using the electrolytic method as per the
[21]
BWMS Code .
5.4 Hazard identification
5.4.1 General
After determination of the limits of the BWMS, the next essential step is to identify the reasonably
foreseeable hazards (permanent hazards), unexpected hazards, hazardous situations, and hazardous
events during all lifecycle phases of the system, including:
— design;
— transportation, storage and installation;
— commissioning;
— operation;
— maintenance.
Only when hazards have been identified can steps be taken to eliminate them or to reduce risks.
Hazard identification shall identify the hazards associated with the operations to be performed by the
BWMS and the tasks to be performed by persons who interact with it while considering the different
components, mechanisms or functions of the system, and the environment in which the system can be
operated.
In addition to general mechanical and electrical hazards, the designer of the BWMS shall identify
hazards specific to the electrolytic method while considering the items in 5.4.2 to 5.4.4.
5.4.2 Human interaction with the equipment over the entire life cycle of a BWMS using
the electrolytic method
Over the course of building, installation, operation, maintenance and removal of a BWMS, personnel
can be exposed to a number of hazards. These can be a result of normal operation, or consequences of
maintenance or repair activities. Hazards shall be considered for the following conditions or activities.
a) Health effects due to contact with active substances or other relevant chemicals.
b) Start-up/shutdown of systems (i.e. electrical shock, water hammer, etc.).
c) In the case of an operator initiating emergency shutdown, hazards can be dependent on the reason
for the shutdown and the ballasting stage. Potential hazards include:
— explosion, fire, smoke, or ruptured piping due to dangerous gas accumulation;
— treatment failure;
— potential toxicity to the environment;
— fire or smoke generation;
— stored energy (i.e. electric or hydraulic).
d) Preparation of the neutralizing agent solution or TRO measurement reagent, if applicable (e.g. injury
due to direct contact with chemicals such as neutralizing agents or TRO measurement reagents).
e) Incorrect mechanical connection or electrical wiring during installation and commissioning.
f) Incorrect operating sequences in manual/override and maintenance modes that can override
computer-based control safety devices and shutdowns.
g) Inappropriate maintenance or troubleshooting of the BWMS.
5.4.3 Possible states of BWMS using the electrolytic method
Both normal and abnormal states of equipment conditions should be considered during the identification
of reasonably foreseeable hazards. At a minimum, the following conditions should be considered.
a) Flooding from burst components due to water hammer or fire.
b) Potential respiratory hazards due to inhalation of toxic compounds from plastic components and
other materials involved in fires.
c) Potential respiratory hazards due to inhalation of active substances.
d) Blockage in filtration unit due to dirty load of ballast water or insufficient filter cleaning.
e) Corrosion due to incorrect material selection.
f) Dangerous gas leakage from electrolysis unit and the piping where dangerous gas can be present
due to welding joint breaking or sealing failure, e.g. improper gasket sealing between the flanges.
g) High temperature arcing or sparking conditions created by improper or loose electrical connections.
h) Explosion or fire due to non-rated hazardous electrical equipment installed in designated
hazardous zones.
i) Inoperability of the BWMS due to environmental conditions outside of the intended operation
ranges, including salinity, temperature, ballast pump capacity, etc.
j) Potential release of dangerous gas into the ballast tank.
NOTE 1 A hazardous condition exists any time the concentration of dangerous gas inside the ballast tank
(or other potential gas release locations) exceeds the lower explosive limit (LEL).
k) Electrical and electronic component failure due to shipboard environment (e.g. vibration,
temperature).
l) Excessive electrical harmonics reflected to the ship's electrical distribution system.
[28]
NOTE 2 See IACS UR E24 and vessel-specific requirements by classification societies.
m) In the case of interruptions in ship's power supply (e.g. loss of power, electrical fault), potential
hazards include:
— treatment failure;
— residual dangerous gas in electrolysis unit and associated piping or duct;
— stored energy (i.e. electric or hydraulic) after shutdown of BWMS;
— seized valves allowing inadvertent discharge of non-compliant ballast water to the environment
(exceeding D-2 performance standard or excessive TRO);
— failure of performance of critical components for the handling of dangerous gas.
n) In the case of an automated shutdown, hazards can be dependent on the reason for shutdown and
the ballasting stage. Potential hazards include:
— explosion, fire, smoke, or ruptured piping due to dangerous gas accumulation;
— treatment failure;
— potential toxicity to the environment;
— fire, smoke, or electric short due to water intrusion into the electric control or power supply;
— stored energy (i.e. electric or hydraulic) after automated shutdown;
— operator awareness to respond;
— effect on active cargo operations and to stresses on ship.
o) Treatment capacity decreasing due to low salinity or low water temperature or excessively aged
electrode conditions.
p) Potential ingress of a flammable liquid into a non-hazardous space from a hazardous location.
5.4.4 Unintended behaviour of the operator or reasonably foreseeable misuse
Operator controls include provisions for maintenance and checkout of BWMS functions, which can have
unintended consequences if the operator conducts actions that fall outside the expected sequence of
commands. Hazards resulting from such actions shall be considered, including the following.
a) Dangerous gas accumulation due to faulty operation, safeguard failure or poor maintenance of
danger gas removal module (if applicable) in the electrolysis unit.
b) Loss of treatment performance due to bypass or overriding of the BWMS.
c) Loss of treatment performance due to improper maintenance of the filter elements (if applicable).
d) Loss of instrument's utility due to improper maintenance or calibration (e.g. TRO analyser
maintenance, calibration and maintenance of dangerous gas monitoring equipment).
e) Improper valve line up during ballast system operations that cause:
— low flow rate through the electrolytic chamber;
— high pressure in the electrolytic chamber or other relevant equipment (e.g. TRO analyser);
— high temperature in the electrolytic chamber.
f) Fire/explosion at the dangerous gas exhaust outlet at open deck.
5.5 Risk estimation
5.5.1 General
Following the identification of specific hazards, an estimation of the risk associated with each hazardous
situation shall be determined by assessing the elements of risk as defined in 5.5.2. When assessing each
element of risk, the aspects given in 5.5.3 shall be considered for each element. These aspects consider
potential protective measures and risk mediation strategies that can be available.
NOTE See ISO 12100:2010, 5.5.1.
The purpose of this step is to determine the severity of harm and its probability occurrence for a BWMS
using the electrolytic method. The goal of the estimation is to evaluate possible scenarios, from low risk
and low severity of harm to high risk and high severity of harm.
Methods for risk estimation can be qualitative (defining the level of risk such as "high", "medium" and
"low") and can incorporate consequence and probability to evaluate the resultant level of risk against
qualitative criteria. Several tools or models are available for risk estimation. An example of a risk
estimation tool is shown in Annex A.
5.5.2 Elements of risk
The risk associated with a particular hazardous situation depends on the following elements, as defined
in ISO 12100:2010, 5.5.2.
a) Severity of harm.
b) Probability of occurrence of that harm, which is a function of:
— persons exposed to the hazard,
— occurrence of a hazardous event, and
— technical and human possibilities to avoid or limit the harm.
5.5.3 Aspects to be considered during risk estimation
5.5.3.1 Persons exposed
Risk estimation shall account for reasonably foreseeable hazards during installation, commissioning,
operation and maintenance of a BWMS to all personnel (operators and others) that use this equipment.
5.5.3.2 Type, frequency and duration of exposure
A BWMS utilizing the electrolytic method provides the potential for exposure to chemicals used for
disinfection treatment and neutralization, as well as electrical and hydraulic energy hazards. Exposure
to any of these can result in injury. Estimation of exposure to each of these hazards shall be evaluated
for a) all modes of operation, and b) during maintenance to the BWMS. In particular, the analysis
shall account for the need for access during ballasting or de-ballasting treatment, maintenance,
troubleshooting and chemical handling. When estimating risk of exposure to dangerous gases, time
weighted average and short-term exposure limits shall be considered for both normal operating
conditions and in the case of an emergency.
NOTE 1 The exposure limit to dangerous gas and chemicals can be found in relevant SDSs.
The risk estimation shall consider those tasks for which it is necessary to suspend protective measures,
e.g. bypassing the BWMS in case of emergencies on board the ship to ensure the safety of the ship and
crews.
NOTE 2 Five human exposure scenarios to active substances, relevant substances and by-products have been
identified for BWMS in section 7.2.3 of IMO BWM.2/Circ.13/Rev.4.
5.5.3.3 Relationship between exposure and effects
The relationship between an exposure to a hazard and its effects shall be taken into account for each
hazardous situation considered. The effects of accumulated exposure and combinations of hazards
shall also be considered. When considering these effects, risk estimation shall, as far as practicable, be
based on appropriate recognized data.
NOTE See ISO 12100:2010, 5.5.3.3.
5.5.3.4 Human factors
A BWMS using the electrolytic method is a complicated integrated system that is related to many
human activities. Risk estimation from human factors shall consider the following:
— the interaction of a person(s) with the BWMS, e.g. operation, maintenance, troubleshooting and
reagent preparation of the BWMS;
— interactions between persons, e.g. shift change during the operation and the maintenance of the
BWMS;
— stress-related aspects, e.g. due to fire, bad weather, or other emergent situations;
— the capacity of persons to be aware of risks depending on their training, experience and ability;
— fatigue aspects (e.g. on duty for continuous long-time ballasting/de-ballasting treatment); and
— aspects of limited abilities (e.g. unfamiliarity with BWMS due to lack of experience or training).
NOTE See ISO 12100:2010, 5.5.3.4.
5.5.3.5 Suitability of protective measures
Risk estimation of BWMS using the electrolytic method shall take into account the suitability of
protective measures and shall:
— identify the circumstances that can result in harm, e.g. using appropriate warning indication of
dangerous gas or chemical, activation of an alarm with suitable settings for detection of dangerous
gas and active substances;
— whenever appropriate, be carried out using quantitative methods to compare alternative protective
measures, e.g. comparison rate of different materials that can be used in the BWMS, comparison of
toxicity and corrosion characteristics of different neutralizing agents, which are used in the BWMS;
— provide information that can assist with the selection of appropriate protective measures, e.g. the
SDSs of active substances, dangerous gases, and neutralizing agents, which are used or generated in
the BWMS.
When estimating risk, special attention shall be paid to components that increase risk or directly
affect treatment performance in case of failure, such as critical monitoring instruments, e.g. TRO
measurement instrument, dangerous gas detectors, sensors for electrolysis reaction.
Protection to ship and crew can be improved by implementing inherently safe chemical handling and
gas venting designs.
NOTE See ISO 12100:2010, 5.5.3.5.
5.5.3.6 Feasibility of protective measures
For the continued safe operation of the BWMS using the electrolytic method, the feasibility of the
protective measures shall be considered. Protective measures that are inconvenient or difficult to
implement can be overridden or ignored by the operators. For example, a protective measure (per
the OMSM) to mitigate water hammers with slow opening or closing of manually operated valves
can be overlooked by the crew during start-up or shutdown of the BWMS. This can be prevented by
incorporating valves having an automated slow opening or closing function.
5.5.3.7 Sustainability of protective measures
The risk estimation shall take account of the sustainability of protective measures to ensure they
are able to maintain the safe operation of the BWMS, e.g. automatic control to maintain the desired
concentration of active substances during ballasting or de-ballasting treatment is required.
5.5.3.8 Information for use
Risk estimation shall consider the available information for use, e.g. installation guidance,
commissioning procedures, and operating and maintenance procedures per the OMSM. See also 6.4.
5.6 Risk evaluation
After completion of the risk estimation, risk evaluation shall be performed to determine whether risk
reduction is required.
Complete a risk evaluation according to ISO 12100:2010, 5.6.
6 Risk reduction
6.1 General
Risk reduction simultaneously reduces the severity of harm and the probability of occurrence, and shall
follow protective measures as recommended by ISO 12100:
— incorporate inherently safe design measures;
— incorporate safeguards and complementary protective measures;
— provide information for use.
Standardized methods shall be used when applicable. Use existing information about a prototype or
existing system to aid in risk reduction. This makes it possible for the designer to:
— estimate the risk associated with the potential hazards;
— evaluate the effectiveness of the protective measures implemented at the design stage;
— provide ship owners with quantitative information on potential hazards in the technical
documentation;
— provide operators with quantitative information on potential hazard in the information for use.
6.2 Inherently safe design
6.2.1 General
Recognition and elimination of hazards during the design is the first and most important step in the
risk reduction process, and offers an opportunity for an inherently safe design. Specific to BWMS using
electrolytic methods, the designer shall address hazards following the guidance of ISO 12100 as listed
in 6.2.2 to 6.2.4.
6.2.2 Considerations during the initial design
— Selection of materials and components that are resistant to corrosion including, but not limited to,
filter elements, electrodes, piping to and from the electrolysis unit, and neutralizing pipeline.
— Selection of piping and materials that are suitable with respect to fire endurance and flammable
spread requirements.
— Utilization of environmentally safe chemicals including, but not limited to, the neutralizer and TRO
measurement reagent.
— Selection of electrode materials with a long service life based on test results, public information, or
literature (e.g. per ISO 19097-2).
— Consideration of the expected dosage of the active substance and its effect on corrosion of materials
and coatings used in ballast piping and ballast tanks in accordance with recognized methods (e.g.
ISO 15711).
NOTE 1 An additional methodology for corrosion effect evaluation of active substances is prescribed in
IMO G9 methodology (see BWM.2/Circ.13 a
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