ISO/TS 18683:2021
(Main)Guidelines for safety and risk assessment of LNG fuel bunkering operations
Guidelines for safety and risk assessment of LNG fuel bunkering operations
This document gives guidance on the risk-based approach to follow for the design and operation of the LNG bunker transfer system, including the interface between the LNG bunkering supply facilities and receiving LNG fuelled vessels. This document provides requirements and recommendations for the development of a bunkering site and facility and the LNG bunker transfer system, providing the minimum functional requirements qualified by a structured risk assessment approach taking into consideration LNG properties and behaviour, simultaneous operations and all parties involved in the operation. This document is applicable to bunkering of both seagoing and inland trading vessels. It covers LNG bunkering from shore or ship, mobile to ship and ship to ship LNG supply scenarios, as described in Clause 4.
Lignes directrices pour la sécurité et l'évaluation des risques des opérations de soutage de GNL
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Standards Content (Sample)
TECHNICAL ISO/TS
SPECIFICATION 18683
Second edition
2021-11
Guidelines for safety and risk
assessment of LNG fuel bunkering
operations
Lignes directrices pour la sécurité et l'évaluation des risques des
opérations de soutage de GNL
Reference number
ISO/TS 18683:2021(E)
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ISO/TS 18683:2021(E)
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ISO/TS 18683:2021(E)
Contents Page
Foreword .iv
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 4
4 Bunkering supply scenarios .5
5 Properties and behaviour of LNG .6
5.1 General . 6
5.2 Description and hazards of LNG . 6
5.3 Potential hazardous situations associated with LNG bunker transfer . 7
5.4 Composition of LNG as a bunker fuel . 8
6 Safety . 8
6.1 Objectives . 8
6.2 General safety principles . 8
6.3 Approach . 8
7 Risk assessment . 8
7.1 General . 8
7.2 Types of risk assessment . 9
7.3 Roles and responsibilities of stakeholders . 10
7.4 Approach, scope and basis . 11
7.5 Mitigation measures . 14
7.6 Reporting . 15
7.7 Safety Zone and controlled areas . 16
7.8 Safety zone determination . 17
7.9 Determination of monitoring and security areas . 18
7.10 Simultaneous Operations (SIMOPs) . 18
8 Functional requirements for LNG bunker transfer system .19
8.1 General . 19
8.2 Functional requirements . .20
9 Training .22
Annex A (informative) Risk acceptance criteria .23
Annex B (informative) Examples of safety zone calculations .28
Bibliography .37
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ISO/TS 18683:2021(E)
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
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore
structures for petroleum, petrochemical and natural gas industries, Subcommittee SC 9, Liquefied natural
gas installations and equipment.
This second edition cancels and replaces the first edition (ISO/TS 18683:2015), which has been
technically revised.
The main changes are as follows:
— title and scope restricted to Guidelines for safety and risk assessment of LNG fuel bunkering
operations;
— list of bunkering supply scenarios updated with experience gained since 2015 in Clause 4;
— addition of concept of design stage risk assessment and operational risk assessment in 7.1;
— addition of Quantitative Consequence Assessment in 7.2;
— addition of roles and responsibilities of stakeholders in 7.3;
— design requirements removed from Clause 8 to avoid duplication with ISO 20519;
— individual Risk Criteria added in Annex A;
— three methods added to determine safety zone in Annex B;
— to avoid duplication with ISO 20519, the following clauses and annexes have been removed:
— Clause 9 Requirements to components and systems;
— Clause 11 Requirements for documentation;
— Annex C Functional requirements;
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ISO/TS 18683:2021(E)
— Annex D Sample Ship supplier checklist;
— Annex E Sample LNG delivery note;
— Annex F Arrangement and types of presenting connection;
— Annex G Dry disconnect coupling.
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.
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ISO/TS 18683:2021(E)
Introduction
The properties, characteristics, and behaviour of LNG differ significantly from conventional marine
fuels, such as heavy fuel oils and distillate fuels as marine diesel oil (MDO) or marine gas oil (MGO).
For these reasons, it is essential that all LNG bunkering operations are undertaken with diligence and
due attention is paid to prevent leakage of LNG liquid or vapour and to control all sources of ignition.
Therefore, it is important that throughout the LNG bunkering chain, each element is carefully designed
and has dedicated safety and operational procedures executed by trained personnel.
It is important that the basic requirements laid down in this document are understood and applied to
each operation in order to ensure the safe, secure, and efficient transfer of LNG as a fuel to the ship.
The objective of this document is to provide guidance for the risk assessment of LNG fuel bunkering
operations and thereby ensuring that an LNG fuelled vessel and bunkering supply facilities are operating
with a high level of safety, integrity, and reliability regardless of the type of bunkering supply scenario.
The LNG bunkering interface comprises the area of LNG transfer and includes manifold, valves, safety
and security systems and other equipment, and the personnel involved in the LNG bunkering operations.
This document is based on the assumption that the receiving ships and LNG bunkering supply facilities
are designed according to the relevant and applicable codes, regulations, and guidelines such as the
International Maritime Organization (IMO), ISO, EN, and NFPA standards and the Society for Gas as a
Marine Fuel (SGMF) and other recognized documents during LNG bunkering. Relevant publications by
these and other organizations are listed in the Bibliography.
This document should be combined with the requirements set on ISO 20519.
In cases where the distance to third parties is too close and the risk exceeds acceptance criteria, the
bunkering location should not to be considered.
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TECHNICAL SPECIFICATION ISO/TS 18683:2021(E)
Guidelines for safety and risk assessment of LNG fuel
bunkering operations
1 Scope
This document gives guidance on the risk-based approach to follow for the design and operation of the
LNG bunker transfer system, including the interface between the LNG bunkering supply facilities and
receiving LNG fuelled vessels.
This document provides requirements and recommendations for the development of a bunkering site
and facility and the LNG bunker transfer system, providing the minimum functional requirements
qualified by a structured risk assessment approach taking into consideration LNG properties and
behaviour, simultaneous operations and all parties involved in the operation.
This document is applicable to bunkering of both seagoing and inland trading vessels. It covers LNG
bunkering from shore or ship, mobile to ship and ship to ship LNG supply scenarios, as described in
Clause 4.
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/IEC Guide 73, Risk management — Vocabulary
ISO 31010, Risk management — Guidelines on principles and implementation of risk management
ISO 20519, Ships and marine technology — Specification for bunkering of liquefied natural gas fuelled
vessels
IMO, IGF Code of Safety for Ships using Gases or other Low flashpoint fuels
IMO, IGC International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in
Bulk
IMO, International Convention on Standards of Training, Certification and Watchkeeping for Seafarers
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC Guide 73 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/
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ISO/TS 18683:2021(E)
3.1.1
as low as reasonably practical
ALARP
reducing a risk to a level that represents the point, objectively assessed, at which the time, trouble,
difficulty, and cost of further reduction measures become unreasonably disproportionate to the
additional risk reduction obtained
3.1.2
boiling liquid expanding vapour explosion
BLEVE
sudden release of the content of a vessel containing a pressurized flammable liquid followed by a fireball
3.1.3
bunkering
process of transferring fuel to a ship
3.1.4
bunkering facility
system designed to be used to transfer/bunker liquefied gas as fuel to a gas-fuelled vessel
Note 1 to entry: It may consist of a floating, shore-based, fixed or mobile fuel-supply facility, such as a bunker
vessel, terminal or road tanker.
3.1.5
bunkering site
location dedicated for bunkering comprising the bunkering installations, port and jetty, and other
facilities and equipment that should be considered in the planning of bunkering
3.1.6
competent authority
organization or organizations that implement the requirements of legislation and regulate installations
that must comply with the requirements of legislation
3.1.7
consequence
outcome of an event
3.1.8
drip tray
spill containment manufactured of material that can tolerate cryogenic temperatures
3.1.9
emergency shut-down
ESD
method that safely and effectively stops the bunker/transfer of natural gas and vapour between the
supply facilities and receiving ship
3.1.10
gas-fuelled vessel
GFV
vessel using gas as marine fuel
3.1.11
hazard
potential source of harm
3.1.12
hazard identification
HAZID
brainstorming exercise using checklists where the potential hazards in a project are identified and
gathered in a risk register for follow up in the project
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ISO/TS 18683:2021(E)
3.1.13
impact assessment
assessment of how consequences (fires, explosions, etc.) affect people, structures the environment, etc.
3.1.14
individual risk
probability on an annual basis for an individual to be killed due to accidental events arising from the
activity
3.1.15
mist
fog
cloud that will be generated by condensing humidity in air when in contact with cold surfaces during
bunkering
Note 1 to entry: This mist will reduce visibility and can mask minor leaks.
3.1.16
monitoring and security area
area around the bunkering facility and ship where ship traffic and other activities are monitored (and
controlled) to mitigate harmful effects
3.1.17
probability
extent to which an event is likely to occur
3.1.18
rapid phase transition
RPT
shock wave forces generated by instantaneous vaporization of LNG upon coming in contact with water
3.1.19
receiver
one or more organizations with ownership, operational and/or legal interests in a gas-fuelled vessel
Note 1 to entry: The receiver can be the vessel owner(s), the charterer or the operator.
[SOURCE: Reference [24]]
3.1.20
risk
combination of the probability of occurrence of harm and the severity of that harm
3.1.21
risk analysis
systematic use of information to identify sources and to estimate the risk
3.1.22
risk assessment
overall process of risk analysis and risk evaluation
3.1.23
risk contour
two-dimensional representation of risk (e.g. individual risk on a map)
3.1.24
risk evaluation
procedure based on the risk analysis to determine whether the tolerable risk has been achieved
3.1.25
safety
freedom from unacceptable risk
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ISO/TS 18683:2021(E)
3.1.26
safety zone
area around the bunkering station where only dedicated and essential personnel and activities are
allowed during bunkering
3.1.27
stakeholder
individual, group, or organization that can affect, be affected by, or perceive itself to be affected by a
risk
3.28
supplier
one or more organizations with ownership, operational and/ or legal interests in a bunkering facility
Note 1 to entry: The supplier can be the bunker vessel owner, charterer or operator; the LNG bunkering terminal
owner or operator; the road tanker fleet manager; the LNG producer; and so on.
[SOURCE: Reference [24]]
3.1.29
tolerable risk
risk that is accepted in a given context based on the current values of society
3.1.30
topping up
final sequence of LNG transfer to ensure correct filling level in receiving tank
3.1.31
water curtain
sprinkler arrangement to protect steel surfaces from direct contact with LNG
3.2 Abbreviated terms
BASiL bunkering area safety information for LNG
ERC emergency release coupling
ERS emergency release system
HFO heavy fuel oil
HSE health, safety, and environment
IMO international maritime organization
LNG liquefied natural gas
MGO marine gas oil
PPE personal protective equipment
QualRA qualitative risk assessment
QCA quantitative consequence assessment
QRA quantitative risk assessment
SGMF society for gas as marine fuel
SIMOPS simultaneous operations
STCW seafarers’ training, certification and watch-
keeping
NOTE LNG is defined in ISO 16903.
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ISO/TS 18683:2021(E)
4 Bunkering supply scenarios
Selection of the bunkering supply scenario should consider the following factors:
a) LNG process conditions (e.g. LNG bunkering volumes, transfer rates and LNG pressure and
temperature);
b) simultaneous operations (e.g. loading/unloading cargo, embarkation of passengers, transfer of
other bunker fuels);
c) possible interference with other activities in the bunkering location (e.g. port area);
d) bunker transfer equipment;
e) type of receiving LNG fuelled ship and bunkering facility;
f) safety studies undertaken for the bunkering operations (e.g. risk assessment and safety zone
defined in Clause 7);
g) local conditions (e.g. weather, traffic).
Three typical LNG bunkering supply scenarios have been considered in this document (see Figure 1):
— Mobile-to-Ship: An LNG bunkering operation to a gas-fuelled vessel from a mobile bunkering facility
located onshore. Mobile bunkering facilities can consist of a truck, rail car or other mobile device
(including portable tanks) used to bunker LNG (see Figure 1).
— Shore-to-Ship: An LNG bunkering operation to a gas-fuelled vessel from a fixed bunkering facility or
terminal (see Figure 1).
— Ship-to-Ship: An LNG bunkering operation to a gas-fuelled vessel from a floating storage or bunker
vessel (see Figure 1).
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ISO/TS 18683:2021(E)
Receiver Supplier Receiver Supplier
Gas-fuelled vessel Bunkering facility Gas-fuelled vessel Bunkering facility
Mobile to Ship bunkering from a truck Mobile to Ship bunkering from multiple trucks/port-
able tanks, throughout a jointed manifold/pumping
station
Receiver Supplier Receiver Supplier
Gas-fuelled vessel Bunkering facility Gas-fuelled vessel Bunkering facility
Ship to ship bunkering from a floating storage or bun- Shore to ship bunkering from a fixed bunkering facili-
ker vessel ty/terminal
Figure 1 — Typical LNG supply bunkering scenarios
5 Properties and behaviour of LNG
5.1 General
The properties, characteristics and behaviour of LNG differ significantly from conventional marine
fuels for example HFO and MGO, etc. For these reasons, it is essential that all LNG bunkering operations
are undertaken with diligence, that due attention is paid to prevent leakage of LNG liquid or vapour and
that sources of ignition in the vicinity (i.e. inside the safety zone) of the bunkering operation are strictly
controlled. Therefore, it is necessary that throughout the LNG bunkering supply chain, each element
is carefully designed and has dedicated safety operational and maintenance procedures executed by
trained and competent personnel.
5.2 Description and hazards of LNG
Description of LNG is fully covered in ISO 16903 but for the purposes of LNG bunkering, the most
important characteristics compared with marine gas fuel are described in this subclause.
At atmospheric pressure, depending upon composition, LNG boils at approximately ‒160 °C. Released
LNG will form a boiling pool on the ground or on the water where the evaporation rate (and vapour
generation) depends on the heat transfer to the pool.
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ISO/TS 18683:2021(E)
LNG for fuel supply may be delivered at an elevated pressure and at a temperature exceeding its boiling
point at atmospheric conditions (e.g. at 5 bar and at ‒155 °C). Release of LNG under such conditions will
result in instantaneous flashing and larger vapour release compared to evaporation from liquid pools.
The vapour release will form a flammable cloud which at these temperatures is denser than air. The
dispersing gas becomes lighter than air (buoyant) at approximately ‒110 °C so will drift with wind and
be diluted by atmospheric turbulence and diffusion. The coldness of the gas will condense moisture in
the air making the dispersing gas visible as a white cloud.
Cold surfaces in the bunker transfer system can also cause mist or fog by condensing humidity in the
air that might mask a release.
LNG can cause brittle fracture if spilled on unprotected carbon steel.
Natural gas has a flammable range between 5 % and 15 % when mixed with air.
Natural gas has a flashpoint of ‒187 °C and a high self-ignition temperature (theoretically, approximately
540 °C. The properties of traditional fuels are different; MGO has a flashpoint in excess of 60 °C and a
self-ignition temperature of 300 °C for MGO or a gas oil vapour/aerosol air mixture.
The ignition energy of natural gas/air mixtures is 0,25 mJ, which is lower than most other hydrocarbons.
Natural gas releases are not easily ignited by hot surfaces that ignite most conventional fuel oil fires in
engine rooms, but low energy sparks represent a higher risk.
Methane has a high greenhouse gas potential and venting to the atmosphere shall not be part of normal
operations.
The following are the main hazards associated with LNG applicable to bunkering operations:
— fire (pool fire, jet/torch fire, flash fire) explosion (in confined spaces) from ignited natural gas
evaporating from spilled LNG;
— vapour dispersion;
— brittle fracture of the steel structure exposed to LNG spills;
— frostbite or cold burn from liquid or cold vapour spills;
— asphyxiation from vapour release;
— over-pressure or pressure surge of the bunker system caused by thermal expansion or vaporization
of trapped LNG;
NOTE The thermal expansion coefficient of LNG is high.
— release in confined spaces causing over-pressure due to vaporization of liquid;
— possible RPT (rapid phase transition from liquid to gas);
— possible stratification with existing LNG in tanks (might later lead to inadvertent venting of gas);
— possible BLEVE of a pressurized tank subjected to a fire.
5.3 Potential hazardous situations associated with LNG bunker transfer
The planning, design, and operation should focus on preventing release of LNG and vapour and avoiding
occupational accidents related to the handling of equipment. The risk and hazards related to the LNG
bunkering are closely linked to the potential rate of release in accidental situations and factors such as
transfer rates, inventories in hoses and piping, protective systems such as detection systems, ESD, and
spill protection are essential.
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ISO/TS 18683:2021(E)
5.4 Composition of LNG as a bunker fuel
The specification of the LNG supplied as fuel is defined in ISO 23306.
The composition will change with ageing also known as weathering (due to preferential evaporation),
commingling from different sources/suppliers and will modify the fuel composition.
6 Safety
6.1 Objectives
Safety shall be the primary objective for the planning, design, and operation of facilities for the delivery
of LNG as marine fuel taking into consideration simultaneous operations and the interaction with third
parties.
LNG bunkering might be carried out without simultaneous operations (SIMOPS), but more often some
SIMOPS such as cargo operations, bunkering with passengers on-board or embarking/disembarking is
occurring at the same time and these need acceptance by all parties involved as competent authority,
port authorities, terminal, ship and bunkering operator, and supplier operator.
Furthermore, in all LNG bunkering cases a risk assessment must be performed for the specific
bunkering operations, location, bunkering scenario and process conditions. This risk assessment should
be appropriate to the operation and risks and it should provide evidence that risks have been identified
and sufficiently mitigated to allow their acceptance by the competent authority. Risk assessment
methodology for the different conditions as described in factors above are recommended in Clause 7.
The safety of the bunkering operation shall not be compromised by commercial requirements.
6.2 General safety principles
The planning, design, procurement, construction, and operation should be implemented through
quality, health, safety, and environmental management systems.
6.3 Approach
The safety targets for the operation of the bunkering scenarios shall be demonstrated by meeting the
requirements as defined in Clause 8, and supported by a risk assessment as outlined in Clause 7.
7 Risk assessment
7.1 General
An assessment of risk to individuals, local populations, assets and the environment shall be undertaken
as a part of the development of the bunkering facility and the gas fuelled vessel and their operati
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