LNG bunkering ship
October 2015
Rule Note
NR 620 DT R00 E
Marine & Offshore Division
92571 Neuilly sur Seine Cedex – France
Tel: + 33 (0)1 55 24 70 00 – Fax: + 33 (0)1 55 24 70 25
Website: http://www.veristar.com
Email: [email protected]
 2015 Bureau Veritas - All rights reserved
MARINE & OFFSHORE DIVISION
GENERAL CONDITIONS
ARTICLE 1
1.1. - BUREAU VERITAS is a Society the purpose of whose Marine & Offshore Division (the "Society") is
the classification (" Classification ") of any ship or vessel or offshore unit or structure of any type or part of
it or system therein collectively hereinafter referred to as a "Unit" whether linked to shore, river bed or sea
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• "prepares and publishes Rules for classification, Guidance Notes and other documents (" Rules ");
• "issues Certificates, Attestations and Reports following its interventions (" Certificates ");
• "publishes Registers.
1.2. - The Society also participates in the application of National and International Regulations or Standards, in particular by delegation from different Governments. Those activities are hereafter collectively referred to as " Certification ".
1.3. - The Society can also provide services related to Classification and Certification such as ship and
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ARTICLE 2
2.1. - Classification is the appraisement given by the Society for its Client, at a certain date, following surveys by its Surveyors along the lines specified in Articles 3 and 4 hereafter on the level of compliance of
a Unit to its Rules or part of them. This appraisement is represented by a class entered on the Certificates
and periodically transcribed in the Society's Register.
2.2. - Certification is carried out by the Society along the same lines as set out in Articles 3 and 4 hereafter
and with reference to the applicable National and International Regulations or Standards.
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the Unit for surveys and to inform the Society without delay of circumstances which may affect the
given appraisement or cause to modify its scope.
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performance of the requested Services. The Client is the sole responsible for the conditions of presentation of the Unit for tests, trials and surveys and the conditions under which tests and trials are carried out.
ARTICLE 3
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preparation the state of currently available and proven technical knowledge of the Industry. They
are a collection of minimum requirements but not a standard or a code of construction neither a
guide for maintenance, a safety handbook or a guide of professional practices, all of which are
assumed to be known in detail and carefully followed at all times by the Client.
Committees consisting of personalities from the Industry contribute to the development of those documents.
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has no effect unless it involves the Society's intervention.
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Rules and to the Code of Ethics of the Society. Surveyors have authority to decide locally on matters related to classification and certification of the Units, unless the Rules provide otherwise.
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ARTICLE 4
4.1. - The Society, acting by reference to its Rules:
• "reviews the construction arrangements of the Units as shown on the documents presented by the Client;
• "conducts surveys at the place of their construction;
• "classes Units and enters their class in its Register;
• "surveys periodically the Units in service to note that the requirements for the maintenance of class are
met.
The Client is to inform the Society without delay of circumstances which may cause the date or the
extent of the surveys to be changed.
ARTICLE 5
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on the Society to obtain a result or as a warranty.
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or repair checks, neither in the operation of the Units or in their trade, neither in any advisory services, and cannot be held liable on those accounts. Its certificates cannot be construed as an implied or express warranty of safety, fitness for the purpose, seaworthiness of the Unit or of its value
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ARTICLE 6
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provided for the purpose by the Society or with its assistance.
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ARTICLE 7
7.1. - Requests for Services are to be in writing.
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the other party thirty days' written notice, for convenience, and without prejudice to the provisions
in Article 8 hereunder.
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date of effect of the notice issued according to 7.2. here above subject to compliance with 2.3. here above
and Article 8 hereunder.
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ARTICLE 8
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notification to pay.
ARTICLE 9
9.1. - The documents and data provided to or prepared by the Society for its Services, and the information
available to the Society, are treated as confidential. However:
• "Clients have access to the data they have provided to the Society and, during the period of classification of the Unit for them, to the classification file consisting of survey reports and certificates which
have been prepared at any time by the Society for the classification of the Unit ;
• "copy of the documents made available for the classification of the Unit and of available survey reports
can be handed over to another Classification Society, where appropriate, in case of the Unit's transfer
of class;
• "the data relative to the evolution of the Register, to the class suspension and to the survey status of
the Units, as well as general technical information related to hull and equipment damages, may be
passed on to IACS (International Association of Classification Societies) according to the association
working rules;
• "the certificates, documents and information relative to the Units classed with the Society may be
reviewed during certificating bodies audits and are disclosed upon order of the concerned governmental or inter-governmental authorities or of a Court having jurisdiction.
The documents and data are subject to a file management plan.
ARTICLE 10
10.1. - Any delay or shortcoming in the performance of its Services by the Society arising from an event
not reasonably foreseeable by or beyond the control of the Society shall be deemed not to be a breach of
contract.
ARTICLE 11
11.1. - In case of diverging opinions during surveys between the Client and the Society's surveyor, the Society may designate another of its surveyors at the request of the Client.
11.2. - Disagreements of a technical nature between the Client and the Society can be submitted by the
Society to the advice of its Marine Advisory Committee.
ARTICLE 12
12.1. - Disputes over the Services carried out by delegation of Governments are assessed within the
framework of the applicable agreements with the States, international Conventions and national rules.
12.2. - Disputes arising out of the payment of the Society's invoices by the Client are submitted to the Court
of Nanterre, France, or to another Court as deemed fit by the Society.
12.3. - Other disputes over the present General Conditions or over the Services of the Society are
exclusively submitted to arbitration, by three arbitrators, in London according to the Arbitration
Act 1996 or any statutory modification or re-enactment thereof. The contract between the Society
and the Client shall be governed by English law.
ARTICLE 13
13.1. - These General Conditions constitute the sole contractual obligations binding together the
Society and the Client, to the exclusion of all other representation, statements, terms, conditions
whether express or implied. They may be varied in writing by mutual agreement. They are not varied by any purchase order or other document of the Client serving similar purpose.
13.2. - The invalidity of one or more stipulations of the present General Conditions does not affect the validity of the remaining provisions.
13.3. - The definitions herein take precedence over any definitions serving the same purpose which may
appear in other documents issued by the Society.
BV Mod. Ad. ME 545 L - 7 January 2013
RULE NOTE NR 620
NR 620
LNG bunkering ship
SECTION 1
GENERAL
SECTION 2
SHIP ARRANGEMENT
SECTION 3
HULL AND STABILITY
SECTION 4
TRANSFER SYSTEMS
SECTION 5
INERT GAS SYSTEMS
SECTION 6
ELECTRICAL INSTALLATIONS AND INSTRUMENTATION
SECTION 7
AUTOMATION SYSTEMS
SECTION 8
FIRE SAFETY
SECTION 9
ADDITIONAL SERVICE FEATURES
APPENDIX 1
RISK ANALYSIS
October 2015
Section 1
General
1
General
1.1
1.2
1.3
1.4
2
2
9
LNG transfer system trials in working condition
3
4
10
LNG bunkering station
Bunkering control station
Ventilation in closed or semi- enclosed spaces
4.1
10
General
Arrangement of bunkering system
3.1
3.2
10
Risk analysis
Hazardous area
Material requirements
2.1
11
General
Hull and Stability
1
Location of cargo tanks
1.1
12
General
Transfer Systems
1
General
1.1
1.2
2
13
Application
Requirements
Hoses
2.1
2.2
2.3
2
General
General design requirements
1.1
1.2
Section 4
9
Ship Arrangement
1
Section 3
Acronyms
Definitions
Referenced documents
Tests and trials
4.1
Section 2
7
Document to be submitted
3.1
4
Application
Scope
Exclusion
Classification notations
References
2.1
2.2
2.3
3
7
13
General
Design requirements
Type approval of bunkering hose
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October 2015
2.4
2.5
2.6
2.7
3
Quick connect disconnect coupler (QCDC)
3.1
3.2
3.3
4
6
7
8
16
General
16
General
LNG transfer system
9.1
9.2
10
General
Transfer arm
Auxiliary equipment
8.1
9
16
Swivels
7.1
15
General
Supports
6.1
6.2
15
General
Type approval of break-away and ERC
Type testing
Workshop testing
Electrical isolation flanges
5.1
15
Type approval of QCDC
Type testing
Workshop testing
Break-away and emergency release coupling (ERC)
4.1
4.2
4.3
4.4
5
Type approval testing
Workshop Testing
Survey requirements
Hoses onboard
16
General
Testing of the complete system
Bunkering transfer rate
16
10.1 General
10.2 Sampling
11
Arrangement for draining the LNG transfer lines
17
11.1 General
12
Compatibility between receiving ship and bunkering ship
17
12.1 General
Section 5
Inert Gas Systems
1
General
1.1
1.2
Section 6
Application
Requirements
Electrical Installations and Instrumentation
1
General
1.1
1.2
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18
19
Application
System of supply
Bureau Veritas
3
2
Earth detection
2.1
3
Monitoring of circuits in hazardous areas
Gas detection
3.1
3.2
4
19
19
Gas detection in enclosed spaces
Gas detection in open areas
Emergency shut-down systems (ESD)
20
4.1
Section 7
Automation Systems
1
General
1.1
1.2
1.3
1.4
Section 8
21
Application
Emergency shut-down systems (ESD)
Alarms and safety actions
Communication systems
Fire Safety
1
General
1.1
1.2
1.3
2
22
Application
Water Spray systems
Dry chemical powder
Fire protection
22
2.1
3
Fire extinction
3.1
3.2
Section 9
Water spray systems
Dry chemical powder fire-extinguishing system
Additional Service Features
1
Additional service feature RE
1.1
2
3
4
23
General
Additional service feature BOG
4.1
4.2
23
General
Additional service feature Initial-CD
3.1
23
General
Additional service feature IG-Supply
2.1
4
22
23
General
Vapour return line
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October 2015
Appendix 1 Risk Analysis
1
General
1.1
1.2
1.3
1.4
2
24
General
LNG transfer system
Gas detection system
Control monitoring and safety systems
Unexpected events to be analysed
3.1
3.2
3.3
October 2015
Purpose of this appendix
Form of the risk analysis
Single failure concept
Scope of the risk analysis
Systems to be analysed
2.1
2.2
2.3
2.4
3
24
24
LNG leakage
Risk related to the receiving ship
Black-out
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6
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October 2015
NR 620, Sec 1
SECTION 1
1
GENERAL
General
1.1
1.3
Application
1.1.1 The present Rule Note applies to ships carrying liquefied natural gas (LNG) and intended to ensure the transfer of
LNG to ships using LNG as fuel.
Ships complying with this Rule Note may be assigned classification notations defined in [1.4].
1.1.2 In general, this Rule Note applies to bunkering and gas
transfer systems of the ship, which is additionally to comply
with the applicable requirements indicated in Tab 1.
Table 1 : Additional applicable requirements
Item
Reference
Ship arrangement
NR467, Part B
Hull
NR467, Part B
Stability
NR467, Part B
Machinery and cargo system
NR467, Part C
Electrical installations
NR467, Part C
Automation
NR467, Part C
Fire protection, detection and
extinction
NR467, Part C
Carriage of liquefied gases
NR467, Part D, Chapter 9
1.3.1 This Rule Note does not cover the LNG storage tanks,
associated piping and process systems which are to comply
with the requirements of IGC Code and Ship Rules, Part D,
Chapter 9.
1.4
1.4.2 Additional service features
The service notation LNG bunkering ship may be completed by the following additional service features, as applicable:
• RE, where the ship is designed to receive LNG from a
gas fuelled ship for which the LNG fuel tanks have to be
emptied.
• Initial-CD, where the ship is designed for initial cooling
down of the gas fuelled ship LNG fuel tank.
• IG-Supply, where the ship is designed to supply inert gas
and dry air, to ensure gas freeing and aeration, to a gas
fuelled ship complying with IGF Code, paragraph 6.10.4.
• BOG, where the ship is designed to recover and manage
the boil-off gas generated during the bunkering operation.
2.1
1.1.3 Ships complying with the requirements of this Rule
Note are to comply with IGC Code except otherwise specified.
This Rule Note provides additional requirements and interpretations of IGC Code, which are also mandatory class
requirements. The society may refer to IGC Code when
deemed necessary.
1.2
Scope
1.2.1 This Rule Note covers:
• the design and installation of the LNG transfer systems
from bunkering ship to the receiving ship and the
vapour transfer system from the receiving ship to bunkering ship, including LNG hoses, transfer arms and
auxiliary equipment for handling the LNG system
• the design and installation of the equipment intended
for the boil-off gas management of the bunkering ship
• the design and installation of the gas piping system of
the bunkering ship
• the safety arrangements.
October 2015
Classification notations
1.4.1 Service notation
Ships complying with the requirements of this Rule Note
are to be granted the service notation LNG bunkering ship.
2
Note 1: NR467: Rules for the Classification of Steel Ships
(hereafter referred as Ship Rules)
Exclusion
References
Acronyms
2.1.1 The following acronyms are used:
BOG
: Boil-Off Gas
ERC
: Emergency Release Coupling
ESD
: Emergency Shut-Down systems
LNG
: Liquefied Natural Gas
MAAT : Maximum Allowable Applied Twist
MBR
: Minimum Bend Radius
QCDC : Quick Connect/Disconnect Couplers.
2.2
Definitions
2.2.1 Auxiliary equipment
Auxiliary equipment for handling the LNG transfer system
refer to the following equipment:
• Hydraulic systems
• Power supply
• Inert gas systems
• Supporting equipment
• Water curtains
• etc ...
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NR 620, Sec 1
2.2.2 LNG bunkering station
LNG bunkering station means the following equipment:
• hoses and piping connections used for liquid and
vapour return lines, including the isolating valves and
the emergency shut-down valves
• Automation and alarms systems
• the drip tray with its draining arrangement and other
arrangements intended for the ship structure protection
• the gas and leak detection systems
• the associated firefighting installations
• Zone 2:
• the monitoring systems (i.e. thermic camera).
• rigid pipes, hoses, swivels, valves, couplings
2.2.3
• supporting structure
Bunkering emergency shut-down system
(ESD)
An ESD is a system that safely and effectively stops the
transfer of LNG (and vapour as applicable) between the
receiving ship and the bunkering ship in the event of an
emergency during the bunkering operation, and puts the
system in a safe condition.
Note 1: In addition to the ESD required by IGC Code, if a separate
transfer system is provided.
2.2.4 Bunkering connections
Bunkering connections correspond to the end of the fixed
piping to the bunkering ship (i.e. manifold for a system with
flexible hose and before the swivel for a system with transfer
arm).
2.2.5 Emergency release coupling (ERC)
An ERC is a coupling located on the receiving ship bunkering manifold or on the LNG transfer system, which separates at a predetermined section, when required, each
separated section containing a self-closing shut-off valve,
which seals automatically.
An emergency release coupling can be activated:
• by maximal allowable forces applied to the predetermined section
• by manual or automatic control, in case of emergency.
2.2.6 Enclosed space
Enclosed space means any space within which, in the
absence of artificial ventilation, the ventilation will be limited and any explosive atmosphere will not be dispersed
naturally.
2.2.7 Hazardous area
According to IGC Code, hazardous area means an area in
which an explosive gas atmosphere is or may be expected
to be present, in quantities such as to require special precautions for the construction, installation and use of electrical apparatus.
Hazardous areas are divided into Zone 0, 1 and 2 as
defined below and according to the area classification specified in Sec 2, [1.2]:
• Zone 0:
Area in which an explosive gas atmosphere is present
continuously or is present for long periods
• Zone 1:
Area in which an explosive gas atmosphere is likely to
occur in normal operation
8
Area in which an explosive gas atmosphere is not likely
to occur in normal operation and, if it does occur, is
likely to do so only infrequently and will exist for a short
period only.
2.2.8 LNG transfer system
A LNG transfer system is a system used to connect the bunkering ship and the receiving ship in order to transfer LNG
only or both LNG and LNG vapour.
The LNG transfer system includes:
• handling system and its control/monitoring system.
It also includes the compressors or blowers intended for the
boil-off gas pressure management, when required.
2.2.9 LNG vapour return lines
A LNG vapour return line is a connection between the bunkering ship and the receiving ship to prevent pressure
increase in the receiving tank due to liquid transfer and
associated boil-off.
2.2.10 Non-hazardous area
Non-hazardous area means an area in which an explosive
gas atmosphere is not expected to be present in quantities
such as to require special precautions for the constructions,
installation and use of electrical apparatus.
2.2.11 Open deck
Open deck means a deck that is open on both ends, or is
open on one end equipped with adequate natural ventilation that is effective over the entire length of the deck
through permanent openings distributed in the side panels
or in the deck above.
2.2.12 Quick connect disconnect coupler (QCDC)
A QCDC is a manual or hydraulic mechanical device used
to connect the LNG transfer system to the receiving ship
manifold.
2.2.13 Receiving ship
A receiving ship is a ship receiving LNG as fuel.
2.2.14 Safety zone
The safety zone is a zone around the bunkering ship, the
bunkering station of the receiving ship and the LNG transfer
system, where the only activities performed are the bunkering operations and related activities and where measures
are taken to prevent leakage of LNG or LNG vapour and to
control sources of ignition.
2.2.15 Semi-enclosed space
Semi-enclosed space means a space limited by decks and
or bulkheads in such manner that the natural conditions of
ventilation are notably different from those obtained on
open deck.
2.2.16 Transfer arm
Transfer arm refers to any system allowing supporting a
hoses or rigid pipes during bunkering operations.
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October 2015
NR 620, Sec 1
2.3
2.3.1
Referenced documents
Ship Rules
Ship Rules means Rules for the Classification of Steel Ships
(NR467).
2.3.2
2.3.7 IEC 60092-502
IEC 60092-502 means the International Electrotechnical
Commission standard: Electrical installations in ships (Part
502: Tankers - Special features).
3
Document to be submitted
NR320
NR320 means the latest version of NR320 Certification
Scheme of Materials and Equipment for the Classification of
Marine Units.
3.1
2.3.3
3.1.2 The operating manuals and procedures to be submitted are listed in Tab 3.
NR216
NR216 means the latest version of NR216 Rules on Materials and Welding for the Classification of Marine Units.
2.3.4
IGC Code means the International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in
Bulk, published by the International Maritime Organization.
2.3.5
3.1.1 The drawing and related information to be submitted
are listed in Tab 2, and, as relevant, in Sec 9.
4
IGC Code
IGF Code
IGF Code means the International Code of Safety for Ship
using Gases or other Low-flashpoint Fuels, published by the
International Maritime Organization.
General
4.1
Tests and trials
LNG transfer system trials in working
condition
4.1.1 LNG transfer system, defined in [2.2.8], is to be
examined by Surveyor during the first LNG bunkering operation.
The following examinations are to be conducted during the
first LNG transfer:
The society may refer to IGF Code when deemed necessary.
a) Examination of transfer piping systems including supporting arrangements.
2.3.6
b) Witness satisfactory operation of the following:
• Control and monitoring systems
• Connections systems (QCDC).
SOLAS Convention
SOLAS Convention means the International Convention for
the Safety of Life at Sea, 1974, as subsequently amended.
Table 2 : Documentation to be submitted
No
A/I
1
A
General arrangement of the ship showing the location of the bunkering station and bunkering control station
Documents
2
I
Risk analysis - LNG transfer system (see App 1) and the follow up report
3
A
Details of maximum bunkering flow and maximum pressure (see Sec 4)
4
A
Details of LNG transfer system (see Sec 4)
5
A
Details of ESD Bunkering system (see Sec 4)
6
I
Safety certificates for electrical equipment, concerning the bunkering, located in hazardous areas, where applicable
7
A
Instrumentation list
8
A
Drawing of transfer arm
Note 1:
A : To be submitted for approval
I : To be submitted for information
Table 3 : Operating manuals and procedures to be submitted
No
A/I
1
I
Bunkering procedure, including inerting and gas freeing
Documents
2
I
BOG management procedure
3
I
Operating envelop of the bunkering ship
4
I
Risk analysis of the bunkering operations
Note 1:
A : To be submitted for approval
I : To be submitted for information
October 2015
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NR 620, Sec 2
SECTION 2
1
SHIP ARRANGEMENT
The LNG bunkering station is to be physically separated or
structurally shielded from accommodation and control stations.
General design requirements
1.1
Risk analysis
1.1.1 LNG transfer system
The design and the installation of the LNG transfer system
are to be substantiated by a risk analysis to be performed in
accordance with App 1.
1.2
Hazardous area
1.2.1 General
The hazardous areas are to be in accordance with IGC
Code, regulation 1.3.17.
1.2.2 Zone 1
This zone includes in addition to IGC Code:
• areas on the open deck within spillage coamings surrounding gas bunkering manifold valves and 3 m
beyond these, up to a height of 2,4 m above the deck
Hazardous area created during bunkering
operations
A particular attention is to be paid to the hazardous areas
created during the bunkering operations and to restrict the
access in order to avoid the presence of unauthorized persons in the vicinity of these hazardous areas and the possibility to create source of ignition.
Drip trays
Drip trays are to be fitted below the liquid bunkering connections and where leakage may occur which can cause
damage to the ship structure.
Thermal sensors are to be positioned in way of bunkering
connections in the drip tray.
• when applicable, transfer arm operating amplitude.
1.2.3
Classification of spaces adjacent to
hazardous areas
A space separated by gastight boundaries (with or without
opening) from an hazardous area may be classified as zone
1, 2 or considered as hazardous, taking into account the
sources of release inside that space, the type and arrangements of openings and the conditions of ventilation, as per
IEC Publication 60092-502, paragraph 4.1.
A type approved gastight bulkhead penetration device is not
considered as a source of release.
2.1
3.1.2
3.1.3
• LNG bunkering station
2
Structural strength calculations and drawings manifolds are
to be submitted to the Society and stated on the manifolds.
Material requirements
The drip trays are to be made of stainless steel, and capable
of being remotely drained over the ship’s side without risk
of damage to the ship structure and to the receiving ship.
A water piping system is to be fitted in way of the hull under
the bunkering manifold to provide low-pressure water curtain for additional protection of the hull steel and the ship’s
structure. This system is to be in operation when transfer
system is in progress. Other solutions are acceptable with
justification.
3.1.4
General
2.1.1 Materials used in LNG transfer systems, piping system for liquefied gas and other systems or components in
contact with gas are to be in accordance with IGC Code,
Chapter 6 and Ship Rules, Pt D, Chapter 9.
Bow and stern arrangements
LNG bunkering station may be accepted at the ship bow
and stern provided that the relevant requirements of IGC
Code, paragraph 3.8, are satisfied.
3.2
Bunkering control station
Materials are in general to be in accordance with NR216.
3
3.1
3.2.1 The bunkering control station is to be considered as a
control station with regard to requirements of Steel Ships,
Part C and Part D and of the IGC Code.
Arrangement of bunkering system
LNG bunkering station
3.1.1 General
The LNG bunkering station is to be located in a area with
sufficient natural ventilation. Closed or semi-enclosed bunkering stations will be subject to special consideration.
10
3.2.2 Control of the bunkering operation should be possible from a safe location with regards to bunkering operations and may be from the cargo control room. At this
location, overfilling alarm, automatic and manual shutdown are be indicated.
Bureau Veritas
October 2015
NR 620, Sec 2
4
4.1
Ventilation in closed or semienclosed spaces
General
4.1.1 Ventilation of closed or semi-enclosed space is to be
of mechanical type and take place in the lower part of the
compartment. Furthermore a gas detection system is to be
fitted.
4.1.2 Any ducts used for the ventilation of hazardous areas
are to be separated from that used for the ventilation of non-
October 2015
hazardous areas. The ventilation is to be capable of functioning at all temperature conditions the ship is designed to
operate in. Electric fan motors are not to be located in ventilation ducts for hazardous areas unless the motor is certified
for the same area classification and operating conditions as
the space served.
4.1.3 Ventilation ducts shall have the same area classification as the ventilated space.
4.1.4 Ventilation capacity is to be in accordance with paragraph 12.1.2 of IGC Code.
Bureau Veritas
11
NR 620, Sec 3
SECTION 3
1
1.1
HULL AND STABILITY
Location of cargo tanks
General
1.1.1 The location of cargo tanks are to be in accordance
with requirements of IMO resolution MSC.370(93),
Chapter 2, paragraph 2.4.
12
Bureau Veritas
October 2015
NR 620, Sec 4
SECTION 4
1
TRANSFER SYSTEMS
General
1.1
2.2.2 Maximum design pressure
The maximum design pressure is not to be less than 10 bar
in accordance with paragraph 5.7.3 of IGC Code.
Application
1.1.1 This Section covers the LNG transfer systems, LNG
vapour return transfer systems and their mandatory associated systems including:
• Hoses
2.2.3 Materials
All materials are to be compatible with each other and with
the fluid conveyed (LNG and LNG vapours).
2.2.4 End connection and coupling
The end fittings are to be made of stainless steel and be in
accordance with IGC Code or NR216.
• QCDC
• Break-away
• Isolation flanges.
2.3
Type approval of bunkering hose
This Section also covers the following systems:
2.3.1 Bunkering hoses are to be type approved by the Society.
• ERC
• Support
2.3.2 All hoses are to be tested at the plant of manufacturer
in the presence of the Surveyor. An alternative survey
scheme, BV Mode I as per Rule Note NR320 as amended,
may be agreed with the Society.
• Swivels
• Auxiliary equipment.
1.2
Requirements
1.2.1 The LNG transfer system is to include a Quick Connect Disconnect Coupler (QCDC), a Break-away coupling
or a ERC and insulation flanges.
1.2.2 Transfer systems and their associated systems are to
be considered as essential services as defined in Ship Rules,
Part A, Ch 1, Sec 1, [1.2.1].
1.2.3 The transfer system is to be designed to avoid the
release of gas or liquid to the atmosphere during bunkering
operations.
2
Hoses
2.1
General
2.1.1 The requirements of IGC Code, in particular paragraph 5.7, are to be fulfilled.
2.2
2.2.1
Design requirements
General
The following characteristics are to be defined by the
designer and submitted to the Society:
• Extreme service temperature
• Maximum working load
• Maximum design pressure
• Minimum bend radius (MBR)
• Maximum allowable applied twist (MAAT).
October 2015
2.4
Type approval testing
2.4.1 Validation test
After type approval testing, as defined in [2.4.2] to [2.4.9],
the hose assembly is to be subjected to a hydraulic pressure
test to a pressure not less than 1,5 times the nominal pressure, to demonstrate that the hose assembly is capable of
withstanding these tests without leaking.
2.4.2 Temperature and pressure cycle test
The hose assembly is to be subjected to a pressure cycle test
at ambient temperature to demonstrate that the hose is
capable of withstanding 2 000 pressure cycle test from zero
to at least twice the specified maximum working pressure.
The hose assembly is also to be subjected to a cryogenic
temperature and pressure cycle test with a minimum of 200
combined test cycles.
2.4.3 Burst pressure test
After the pressure cycle test, as defined in [2.4.2], has been
carried out, the prototype test is to demonstrate a bursting
pressure of at least 5 times its specified maximum working
pressure at the upper and lower extreme service temperature.
2.4.4 Bending cycle fatigue test
The hose assembly is to be subjected to a bending cycle
fatigue test, at ambient and cryogenic temperature, with
400 000 cycles without failure.
The fatigue bend radius is to be in accordance with designer
recommendation.
Bureau Veritas
13
NR 620, Sec 4
2.4.5
Crushing test
The hose assembly is to be subjected to a crushing test at
ambient temperature and cryogenic temperature without
damage. The hose assembly is to be held between two rigid
plates (an area equivalent to the diameter of the hose) and a
force of 1000N is to be applied ten times at the same location in the middle of each flexible hose.
2.4.6
Impact test
The hose assembly is to be subjected to an impact test to
ensure that the hose is capable of withstanding loads without damage at ambient and cryogenic temperature.
2.4.7
Tensile test
The hose assembly is to be subjected to a tensile test at
ambient and cryogenic temperature to ensure that the hose
is capable of withstanding the maximum working load.
2.4.8
Bending test to minimum bend radius (MBR)
The hose assembly is to be subjected to a bending test at
ambient and cryogenic temperature to ensure that the hose
is capable of withstanding the maximum working pressure
at minimum working bend radius.
Hose should be gradually bent to the MBR and then pressurized to the maximum working pressure. Hose shall be
examined for leaks whilst being held for 15 min at MBR and
no damage should be evident on return pre-test conditions.
2.4.9
Maximum allowable applied twist (MAAT) test
The hose assembly is to be subjected to a ambient and cryogenic twist test to ensure that the hose is capable of withstanding its maximum working load whilst at MAAT.
The hose assembly is to be gradually twisted to the MAAT
and then pressurized to the maximum working pressure.
The hose is to be examined for leaks whilst being held for
15 min at MAAT and no damage should be evident on
return pre-test conditions.
2.4.10 Electrical testing
The hose assembly is to be subjected to a electrical test.
The hose assembly is to be drained and supported above
ground by non-conductive means and the resistance measured between the two end fittings (connection face). Electrically continuous hoses shall have a resistance of less than
10 Ω. Electrically discontinuous hoses shall have a resistance of not less than 25 000 Ω.
2.5.2 Pressure test
The hose assembly shall be subjected to a hydraulic pressure test at ambient temperature and a pressure test at cryogenic temperature, to a pressure not less than 1,5 times the
nominal pressure, but not more than two fifths of its bursting pressure, to demonstrate that the hose assembly is capable of withstanding its pressure without leaking.
2.5.3 Leak test
The hose assembly shall be subjected to a pneumatic pressure test, at ambient temperature, to a pressure not less than
1,1 times the design pressure, to demonstrate that the hose
assembly is capable of withstanding its pressure without
leaking.
2.5.4 Inspection of welds
Welds of the hose assembly are to be subjected to non
destructive testing (NDT).
When applicable, all butt welds of the hose assembly with
connections systems are to be subjected to a 100% radiography examination.
2.6
Survey requirements
2.6.1 Survey
The products are to be manufactured, examined and tested
by the manufacturer. Arrangements shall be made for a
Society's Surveyor to attend the relevant tests and examinations at manufacturer's works or to perform the relevant
audits when an alternative survey scheme (BV Mode I) has
been agreed.
2.6.2 Certification
When the design assessment and testing are successfully
completed and the documentation (study and test reports)
are examined, a type approval certificate is issued and
given a validity period of 5 years.
2.7
Hoses onboard
2.7.1 General
Transfer hose manufacturer’s instructions regarding testing,
storage and number of temperature and pressure operating
cycles before removal from service are to be strictly followed.
The maximum service life of the hose assembly should not
exceed 5 years and hoses are to be inspected periodically
during the annual survey of the LNG bunkering ship.
2.7.2 Documents
A document containing the following information is to be
kept on board:
• Hose identification number
2.5
2.5.1
• Type approval certificate
Workshop Testing
• Date of initial entry into service
• Initial test and certificates
Application
Each produced length of cargo hose completed with end-fittings is to be tested as defined in [2.5.2] to [2.5.4] (hoses
used for prototype testing are not to be used onboard).
14
• Records of all transfer operations.
This document is to be made available during any survey by
the Port Administration.
Bureau Veritas
October 2015
NR 620, Sec 4
2.7.3
4.1.3 ERC is to be designed for:
Marking of products
Each hose is to be permanently marked with at least the following information:
• Remote and local manual activation
• Manufacturer's name or logo
• Automatic activation in case the safe working envelope
of the loading arm is exceeded.
• Hose designation and size
• Maximum working pressure
4.1.4 In the event of activation of the break-away or the
ERC, the hoses are to be adequately supported and protected to prevent potential damage, spark or rupture due to
mechanical shocks.
• Maximum and minimum working temperature
• Overall weight of the hose and end fittings assembly
• Date of manufacture
4.1.5 All electrical components of the emergency release
coupling actuator are to be of a suitable safe type.
• Society's brand as relevant
• Date of last inspection and testing.
3
When applicable, the availability of hydraulic power is to
be monitored. If the power supply of ERC by the hydraulic
source is no longer available, bunkering operation is to be
stopped.
Quick connect disconnect coupler
(QCDC)
3.1
4.2
Type approval of QCDC
3.1.2 All QCDC are to be tested at the plant of manufacturer in the presence of the Surveyor. An alternative survey
scheme, BV Mode I as per Rule Note NR320, may be
agreed with the Society.
Each produced QCDC is to be tested as defined in [3.3.1]
(QCDC used for prototype testing are not to be used
onboard).
Type testing
Workshop testing
3.3.1
Pressure test
The QCDC is to be subjected to a hydraulic pressure test, at
ambient temperature, to a pressure not less than 1,5 times
the design pressure, to demonstrate that the QCDC is capable of withstanding its pressure without leaking.
4
4.1
4.2.2 All break-away and ERC are to be tested at the plant
of manufacturer in the presence of the Surveyor. An alternative survey scheme, BV Mode I as per Rule Note NR320,
may be agreed with the Society.
Each produced break-away and ERC are to be tested as
defined in [4.3.1] (break-away and ERC used for prototype
testing are not to be used onboard).
4.3
3.2.1 The QCDC is to be subjected to a type test to confirm
the release performance under ice built up condition.
3.3
Type approval of break-away and ERC
4.2.1 Break-away and ERC are to be type approved by the
Society.
3.1.1 QCDC are to be type approved by the Society.
3.2
• Automatic activation in case of excessive forces
Break-away and emergency release
coupling (ERC)
4.3.1 The break-away or the ERC are to be subjected to a
type test to confirm the values of axial and shear forces at
which it automatically separates. The tightness of the selfclosing shut-off valves after separation is to be checked.
4.3.2 The break-away or the ERC are to be subjected to a
type test to confirm the release performance under ice built
up condition.
4.3.3 When applicable, the ERC is to be subjected to a type
test to confirm the automatic release in case of activation.
4.4
General
4.1.1 The bunkering line is to be designed and arranged to
withstand the surge pressure that may result from the activation of the break-away or the ERC.
Type testing
Workshop testing
4.4.1 Pressure test
The break-away or the ERC are to be subjected to a hydraulic pressure test, at ambient temperature, to a pressure not
less than 1,5 times the design pressure, to demonstrate that
the break-away or the ERC are capable of withstanding its
pressure without leaking.
4.1.2 Justifications are to be submitted regarding the compatibility with hoses and the maximum axial and shear
forces likely to be exerted on the break-away or the ERC
during the bunkering operations.
5
Alternatively the manifold area may be suitably reinforced.
Details of the manifold loads are to be submitted to the
society for information.
5.1.1 Each insulation flange is to be subjected to a test of
electrical resistance in air and the resistance is to be not less
than 10 000Ω.
October 2015
5.1
Bureau Veritas
Electrical isolation flanges
General
15
NR 620, Sec 4
5.1.2 The resistance of each insulation flange is to be measured after installation in the complete LNG transfer system
and the resistance is to be not less than 1000Ω.
9
LNG transfer system
9.1
6
Supports
6.1
General
6.1.1 Hoses are to be suitably supported in such a way that
the allowable bending radius is satisfied. They should normally not lay directly on the ground. They are to be
arranged with enough slack to allow for all possible movements between the receiving ship and the bunkering ship.
6.2
Transfer arm
6.2.1 When applicable, the maximum allowable operating
amplitude for the system is to be defined and hose handling
arm shall be approved by the Society.
9.1.1 The requirements [9.2.1] and [9.2.2] apply to complete LNG transfer systems including additional safety
devices such as dry break-away coupling/self-sealing quick
release, ERC, swivels, etc. (i.e: all parts which are after the
bunkering manifold).
9.2
9.2.1
General
7.1.1
Pressure test
Inspection of welds
When applicable, the welds of the LNG transfer system
with connections systems are to be subjected to a nondestructive examination (NDE) test and all butt welds of the
LNG transfer system with connections systems are to be
subjected to a 100% radiography examination.
Swivels
7.1
Testing of the complete system
The LNG transfer system is to be subjected to a hydraulic
pressure test, at ambient temperature, to a pressure not less
than 1,5 times the nominal pressure, to demonstrate that the
hose assembly is capable of withstanding its pressure without leaking.
9.2.2
7
General
Pressure swivels
The pressure parts of a pressure swivel are to be designed
and manufactured according to the requirements of Pt C,
Ch 1, Sec 3 of the Ship Rules or other recognised pressure
vessel code.
10 Bunkering transfer rate
A pressure swivel is to be isolated from the structural loads
due to the connection with the receiving ship.
10.1.1 The bunkering transfer rate is to be kept within the
capabilities of the receiving ship.
Means are to be provided to collect and safely dispose of
liquid leaks.
10.1.2 The maximum LNG transfer rate is to be justified,
taking into consideration:
7.1.2
• The management of the BOG generated during bunkering operation
Static resistance test
Pressure swivels are to be subjected to a pressure resistance
static test, according to its design code.
7.1.3
At least two complete rotations, or equivalent, in each
direction are to be performed.
8.1
Auxiliary equipment
General
• The maximum flow permitted by the ERC
• The maximum flow permitted by the hose
• The maximum flow permitted by the QCDC.
10.1.3 The LNG velocity in the piping system is not to
exceed 10m/s in order to avoid the generation of static electricity and to limit the heat transfer due to friction inside the
pipes.
10.2 Sampling
8.1.1 The auxiliary equipment, as defined in Sec 1, [2.2.1]
are to be in accordance with Ship Rules.
16
• The temperature of the LNG supplied to the ship
• Characteristics of the receiving tank
Dynamic test
Rotation and oscillation test including rest periods are to be
performed at design pressure with measurement of starting
and running moments.
8
10.1 General
10.2.1 Connections for taking LNG samples are to be in
accordance with IGC Code and Ship Rules.
Bureau Veritas
October 2015
NR 620, Sec 4
• Draught and freeboard difference between the receiving
ship and the LNG bunkering ship
11 Arrangement for draining the LNG
transfer lines
• Compatibility of the bunkering arm or hose operating
amplitude with the bunkering station location
11.1 General
11.1.1 In order to prevent cryogenic liquid spills, the
design of the transfer system is to be such that the lines can
be drained before disconnection and purged after an emergency disconnection.
12 Compatibility between receiving ship
and bunkering ship
• Pressure and temperature difference between the LNG
tanks of receiving ship and bunkering ship
• Vapour management
• Vapour return line (pressure and temperature)
• Delivery flow rate (maximum and minimum)
• Type and size of hose connections systems.
12.1 General
12.1.1 The ship working limits of bunkering are to be
checked with regards to at least the following aspects:
October 2015
• Compatibility of the ESD link
• Mooring arrangement.
Bureau Veritas
17
NR 620, Sec 5
SECTION 5
1
1.1
INERT GAS SYSTEMS
General
1.2
1.2.1 The inert gas systems are to be in accordance with
the requirements 9.5 of the IGC Code.
Application
1.1.1 This Section covers the inert gas systems for purging
the bunkering lines.
18
Requirements
1.2.2 The inerting capacity is to be designed according the
bunkering operations and it is not to be less than 5 times the
volume of the hose and pipes to be purged.
Bureau Veritas
October 2015
NR 620, Sec 6
SECTION 6
1
ELECTRICAL INSTALLATIONS AND
INSTRUMENTATION
General
1.1
1.2.3
Application
1.1.1 The requirements of IGC Code, as amended, relating
to electrical installations are to be complied with.
The present Section includes additional requirements and
interpretations of IGC Code, which are to be considered
mandatory for class.
1.1.2 In case of conflict between this Section and IGC
Code, the Society is to be consulted for clarification.
1.2
1.2.1
Earthed system without hull return
Earthed systems without hull return are not permitted, with
the following exceptions:
System of supply
Acceptable systems of supply
a) earthed intrinsically safe circuits and the following other
systems to the satisfaction of the Society
b) power supplies, control circuits and instrumentation circuits in non-hazardous areas where technical or safety
reasons preclude the use of a system with no connection to earth, provided the current in the hull is limited
to not more than 5 A in both normal and fault conditions, or
c) limited and locally earthed systems, such as power distribution systems in galleys and laundries to be fed
through isolating transformers with the secondary windings earthed, provided that any possible resulting hull
current does not flow directly through any hazardous
area, or
d) alternating current power networks of 1,000 V root
mean square (line to line) and over, provided that any
possible resulting current does not flow directly through
any hazardous area; to this end, if the distribution system is extended to areas remote from the machinery
space, isolating transformers or other adequate means
are to be provided.
The following systems of generation and distribution of
electrical energy are acceptable:
a) direct current:
• two-wire insulated
b) alternating current:
• single-phase, two-wire insulated
2
• three-phase, three-wire insulated.
In insulated distribution systems, no current carrying part is
to be earthed, other than:
a) through an insulation level monitoring device
b) through components used for the suppression of interference in radio circuits.
1.2.2
Earthed system with hull return
Earthed systems with hull return are not permitted, with the
following exceptions to the satisfaction of the Society:
2.1
Earth detection
Monitoring of circuits in hazardous
areas
2.1.1 The devices intended to continuously monitor the
insulation level of all distribution systems are also to monitor all circuits, other than intrinsically safe circuits, connected to apparatus in hazardous areas or passing through
such areas.
An audible and visual alarm is to be given, at a manned
position, in the event of an abnormally low level of insulation.
a) impressed current cathodic protective systems
b) limited and locally earthed systems, such as starting and
ignition systems of internal combustion engines, provided that any possible resulting current does not flow
directly through any hazardous area
c) insulation level monitoring devices, provided that the
circulation current of the device does not exceed 30 mA
under the most unfavourable conditions.
October 2015
3
3.1
Gas detection
Gas detection in enclosed spaces
3.1.1 Permanently installed gas detectors are to be fitted in
all hazardous areas including bunkering station, bunkering
process room and other enclosed spaces containing gas
piping or other equipment without ducting.
Bureau Veritas
19
NR 620, Sec 6
3.1.2 The number of detectors in each space is to be considered taking into account the size, layout and ventilation
of the space. At least two independent gas detectors are
required in each hazardous area.
3.1.3 The detection equipment is to be located where gas
may accumulate and in the ventilation outlets. Gas dispersion analysis or a physical smoke test is to be used to find
the best arrangement.
3.1.4 An audible and visual alarm is to be activated before
the vapour concentration reaches 30% of the lower explosive limit (LEL).
3.1.5 Audible and visual alarms from the gas detection
equipment are to be located on the bridge and in the bunkering control room.
20
3.2
Gas detection in open areas
3.2.1 Permanently installed thermal imaging camera are to
be fitted for the following hazardous areas when located on
open areas:
• Bunkering station
• Bunkering process systems.
Monitoring of thermal imaging camera is to be possible
from a safe location with regards to bunkering operations
and with a permanent observation during transfer operations.
4
Emergency shut-down systems (ESD)
4.1
4.1.1 All electrical components of the ESD systems are to
be of suitable safe type.
Bureau Veritas
October 2015
NR 620, Sec 7
SECTION 7
1
1.1
AUTOMATION SYSTEMS
1.2.5 Any pipeline or component containing liquid, which
may be isolated due to the ESD activation, shall be provided
with pressure relief valve.
General
Application
1.3
1.1.1 This section provides requirements for the automation systems of the LNG transfer system.
1.2
Alarms and safety actions
1.3.1 If the ventilation in closed or semi-enclosed bunkering station stops during bunkering operations, a visual and
audible alarm is to be provided at bunkering control location and the ESD shall be activated.
Emergency shut-down systems (ESD)
1.2.1 The design of the ESD systems is to take into account
the possible excessive bunkering ship (or receiving ship)
motions.
1.3.2 The alarms and safety function actions required for
the transfer system are given in Tab 1.
1.2.2 Any activation of the ESD systems is to be implemented simultaneously on both bunkering facility and
receiving ship. The timing sequence is to ensure that the
involved pumps and vapour return compressors (if any) stop
before the closure of any manifold valves.
1.4
Communication systems
1.4.1 A communication system with back-up is to be provided between the bunkering ship and the receiving ship.
This may be achieved by electric, fibre-optic or pneumatic
links, or a combination of these systems.
1.2.3 The bunkering line is to be designed and arranged to
withstand the surge pressure that may result from the activation of the emergency release coupling and quick closing of
ESD valves. If not demonstrated to be required at a higher
value due to pressure surge considerations, a default time of
5 seconds from the trigger of the alarm to full closure of the
ESD valves is to be adjusted, in accordance with IGF Code.
1.4.2 Communications are to be maintained between the
bunkering ship and the receiving ship at all times during the
bunkering operation. In the event that communications cannot be maintained, bunkering is to be stopped and not
resumed until communications are restored.
1.2.4 At least one local manual activation position for the
ESD system is to be at a safe distance from the manifold and
is to have a clear view of the manifold area.
1.4.3 The components of the communication system
located in hazardous and safety zones are to be of a suitable safe type.
Table 1 : Alarms and safety actions required for the transfer system
Alarm
Activation of the
ESD systems
Low pressure in the supply tank
X
X
Sudden pressure drop at the transfer pump discharge
X
X
Parameters
High level in the receiving tank
X
X
High pressure in the receiving tank
X
X
LNG leak detection or vapour detection (anywhere)
X
X
Gas detection around the bunkering lines
X
X
Manual activation of the emergency release coupling
X
X
Safe working envelope of the loading arm exceeded
X
X
Disconnection of the ERC
X
X
October 2015
Bureau Veritas
Automatic activation of the
emergency release coupling
X
21
NR 620, Sec 8
SECTION 8
1
1.1
FIRE SAFETY
General
Application
1.1.1 This section provides requirements for the fire safety
system in the safety zone.
1.2
Water Spray systems
1.2.1 Water spray systems are to comply with the requirements of Ship Rules, Pt D, Chapter 9.
1.3
Dry chemical powder
1.3.1 Dry chemical powder fire-extinguishing systems are
to comply with the requirements of Ship Rules, Pt D, Chapter 9.
2
3.1.3 For the purpose of isolating damage sections, stop
valves are to be fitted at least every 40 m or the system may
be divided into two or more sections with control valves
located in a safe and readily accessible position not likely to
be cut-off in case of fire.
Fire protection
2.1
2.1.1 When applicable, the bunkering station is to be separated by class A-60 insulation towards other spaces, except
for spaces such as tanks, voids, auxiliary machinery spaces
of no fire risk, sanitary and similar spaces where insulation
standard may be reduced to class A-0.
3.1.4 The capacity of the water spray pump is to be sufficient to deliver the required amount of water to the hydraulically most demanding area as specified in [3.1.3] in the
areas protected.
3.1.5 Remote start of pumps supplying the water spray system and remote operation of any normally closed valves to
the system is to be located in a readily accessible position
which is not likely to be cut off in case of fire in the areas
protected.
3.1.6 The nozzles are to be of an approved full bore type
and they are to be arranged to ensure an effective distribution of water throughout the space being protected.
3.1.7 An equivalent system to the water spray system may
be fitted provided it has been tested.
3.2
3
3.1
Fire extinction
Water spray systems
3.1.1 The water spray system is to be fitted to protect the
bunkering manifold, associated piping installations and the
transfer area.
3.1.2 The system is to be designed to cover all areas as
specified in [3.1.1] with an application rate of 10 l/min/m²
for horizontal projected surfaces and 4 l/min/m² for vertical
surfaces.
22
Dry chemical powder fire-extinguishing
system
3.2.1 In the bunkering station area a permanently installed
dry chemical powder extinguishing system is to cover all
possible leak points. The capacity is to be at least 3,5 kg/s
for a maximum of 45 s discharges. The system is to be
arranged for easy manual release from a safe location outside of the protected area.
3.2.2 One portable dry powder extinguisher of at least 5 kg
capacity is to be located near the bunkering station.
Bureau Veritas
October 2015
NR 620, Sec 9
SECTION 9
1
1.1
ADDITIONAL SERVICE FEATURES
Additional service feature RE
3.1.2 Document to be submitted
The following documents are to be submitted to the Society
for information in addition to the information required in
Sec 1, [3.1]:
General
1.1.1 Handling system
The BOG handling system of the LNG bunkering ship is to
be sized to handle the extra vapours generated during this
operation taking into account the fact that the level in the
receiving cargo tanks is increasing.
• Procedure for initial cooling down.
4
4.1
1.1.2 Document to be submitted
The following documents are to be submitted to the Society
for information in addition to the information required in
Sec 1, [3.1]:
• Bunkering procedure for LNG receiving from a gas
fuelled ship.
2
2.1
Additional service feature IG-Supply
General
Additional service feature BOG
General
4.1.1 The bunkering ship is to be capable of handling all or
part of the boil-off gas from receiving ship, in addition to its
own boil-off, generated during the LNG bunkering operation without release to the atmosphere. The boil-off gas
handling capacity of the bunkering ship is to be indicated
and justified.
4.1.2 Different ways to dispose of the BOG may to be considered:
• liquefaction
2.1.1 Piping system
The lines used for the inert gas are to be independent from
the liquid and vapour lines used for normal operation.
• cooling
2.1.2 Document to be submitted
The following documents are to be submitted to the Society
for review in addition to the information required in Sec 1,
[3.1]:
• Diagram of the gas freeing system
• Procedure for gas freeing.
• gas combustion unit.
3
3.1
Additional service feature Initial-CD
A combination of these means is possible for the BOG and
other solutions may be accepted if they are duly justified to
the Society.
4.1.3 Document to be submitted
The following documents are to be submitted to the Society
for information in addition to the information required in
Sec 1, [3.1]:
• Bunkering procedure for boil-off gas management.
General
3.1.1 The bunkering ship is to be capable of handling all or
part of the boil-off gas from receiving ship, in addition to its
own boil-off, generated during the initial cooling down
without release to the atmosphere. The boil-off gas handling
capacity of the bunkering ship is to be indicated and justified.
October 2015
• utilization by the gas consuming equipment of the ship
(e.g. gas or dual-fuel engines or boilers)
4.2
Vapour return line
4.2.1 The system is to be operational and capable of
accepting the maximum vapour flow rate generated at loading rate defined by the designer. The maximum vapour flow
rate is to be indicated and justified to the Society.
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NR 620, App 1
APPENDIX 1
1
RISK ANALYSIS
General
1.1
2
2.1
Purpose of this appendix
1.1.1 The purpose of this Appendix is to define the scope of
the risk analysis which is required for the LNG transfer system and the bunkering operation to assess the consequences of:
• A failure affecting the concerned systems
Systems to be analysed
General
2.1.1 The risk analysis is to be performed at least for the
systems and functions defined in [2.2] to [3.3].
2.2
LNG transfer system
2.2.1 Function
The function of the LNG transfer system is to connect the
bunkering ship to the receiving ship and transfer the LNG.
• A LNG leakage
• A tank over-pressurization
• ...
1.1.2 Detailed follow-up report of actions and mitigation
measures taken in response to risk analysis findings is to be
submitted to the society for information.
1.2
Form of the risk analysis
1.2.1 The required analysis can be a HAZOP analysis or
another type of analysis providing equivalent information
for the LNG transfer system.
1.3
Single failure concept
1.3.1 The required analysis is to be based on the single failure concept, which means that only one failure needs to be
considered at the same time. Both detectable and nondetectable failures are to be considered. Consequences failures, i.e failures of any component directly caused by a single failure of another component, are also to be considered.
2.3
Gas detection system
2.3.1 Definition
Gas detection systems includes:
• The gas detection sensors
• The centralized monitoring unit and its power supply
• The wiring between the sensors and the centralized
monitoring unit.
2.3.2 Function
The function of gas detections systems is to detect any gas
leakage by measuring gas concentration in air taking into
account the actual air parameters at the measuring point (in
particular air velocity).
2.4
Control monitoring and safety systems
1.4.1 The scope of the risk analysis is to:
2.4.1 Definition
Control, monitoring and safety systems include the relevant
equipment serving:
• LNG transfer systems
• Gas detection systems.
• Identify all the possible failures in the concerned systems which could lead to a loss of assigned function
3
1.4
Scope of the risk analysis
• Evaluate the consequences
3.1
• Identify the failure detection method
• Identify the corrective measures.
The results of the risk analysis are to be documented.
1.4.2 The means of protection to prevent failures are to be
defined.
Unexpected events to be analysed
LNG leakage
3.1.1 The consequences of a LNG leakage are to be analysed. The following sources of leakage are to be considered:
• Leakage of hoses
• Leakage within the piping enclosure.
a) In the system design, such as:
• redundancies
3.2
• safety devices, monitoring or alarm provisions
which permit restricted operation of the system
3.2.1 The risk related to the receiving ship should include,
but is not limited to:
• Unexpected overpressure on the receiving ship
• Unexpected venting on the receiving ship
• Unexpected movement of the receiving ship.
b) in the system operation, such as:
• initiation of redundancy
• activation of an alternative mode operation.
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Risk related to the receiving ship
October 2015
NR 620, App 1
3.3
Black-out
3.3.1 The risk analysis referred to in [1.1.1] is also to cover
the consequences of a black-out during the bunkering operation.
October 2015
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