SIST EN ISO 20257-1:2020

Installation and equipment for liquefied natural gas - Design of floating LNG installations - Part 1: General requirements (ISO 20257-1:2020)

The objective of ISO 20257-1 is to provide functional guidelines and recommend practices for the design of floating liquefied natural gas (LNG) installations in order to have a safe and environmentally acceptable design and operation of floating LNG installations.
ISO 20257 gives functional guidelines for the design and operation of all floating LNG installations including those for the liquefaction, storage, vaporisation, transfer and handling of LNG.

Anlagen und Ausrüstung für Flüssigerdgas - Auslegung von schwimmenden Flüssigerdgas-Anlagen - Teil 1: Allgemeine Anforderungen (ISO 20257-1:2020)

Dieses Dokument legt Anforderungen und Anleitungen in Bezug auf die Auslegung und den Betrieb von schwimmenden Flüssigerdgasanlagen (en: liquefied natural gas, LNG) fest, einschließlich der Anlagen zur Verflüssigung, Speicherung, Verdampfung, Übergabe und Handhabung von LNG, damit Auslegung und Betrieb von schwimmenden LNG-Anlagen sicher und umweltfreundlich möglich sind.
Dieses Dokument ist anwendbar auf:
- schwimmende LNG-Verflüssigungsanlagen — FLNG;
- schwimmende LNG-Wiederverdampfungsanlagen — FSRU;
- schwimmende Speichereinheiten — FSU.
Dieses Dokument ist auf Offshore-Anlagen, Anlagen in Küstennähe oder angedockte schwimmende LNG Anlagen anwendbar.
Der Anwendungsbereich dieses Dokuments umfasst bei angedockten schwimmenden LNG Anlagen jegliche Piere im Hinblick auf die Vertäuung. Dieses Dokument beschreibt Vertäuungskonzepte für schwimmende LNG Anlagen.
Dieses Dokument gilt sowohl für neu gebaute als auch umgebaute schwimmende LNG Anlagen und behandelt spezielle Anforderungen.
Dieses Dokument ist nicht anwendbar auf:
- an Land befindliche Anlagen zur LNG-Speicherung, -Verflüssigung und/oder -Wiederverdampfung, mit Ausnahme von angedockten FSRU- und/oder FLNG Anlagen;
- Offshore LNG-Anlagen basierend auf nicht schwimmenden Strukturen (etwa das Prinzip auf Schwerkraft basierender Strukturen); und
- unterstützende Onshore-Anlagen (etwa Versorgungsschiffe, Schleppboote usw.).
Dieses Dokument ist nicht speziell für die Auslegung schwimmender Anlagen zur Stromerzeugung vorgesehen, relevante Teile dieses Dokumentes können jedoch verwendet werden.
Dieses Dokument ist nicht dazu vorgesehen, Anwendungen zum Bunkern von Kraftstoff für LNG abzudecken.

Installations et équipements de gaz naturel liquéfié - Conception des installations flottantes de GNL - Partie 1: Exigences générales (ISO 20257-1:2020)

Le présent document fournit des exigences et des recommandations concernant la conception et l'exploitation des installations flottantes de gaz naturel liquéfié (GNL), y compris les installations destinées à la liquéfaction, au stockage, à la vaporisation, au transfert et à la manipulation du GNL afin d'obtenir une conception et une exploitation sans danger et écologiquement acceptable des installations flottantes de GNL.
Le présent document est applicable :
—     aux terminaux flottants de liquéfaction de GNL (installation) ? FLNG ;
—     aux terminaux flottants de regazéification de GNL (installation) ? FSRU ;
—     aux unités flottantes de stockage ? FSU.
Le présent document est applicable aux installations flottantes de GNL en mer, à proximité de la côte ou à quai dans un port.
Le présent document inclut tous les appontements éventuels dans son domaine d'application dans le cas d'installations flottantes de GNL à quai pour ce qui est de l'amarrage. Le présent document décrit brièvement les concepts d'amarrage du GNL flottant.
Le présent document est applicable aux installations flottantes de GNL nouvellement construites aussi bien qu'aux installations converties et il couvre les exigences spécifiques.
Le présent document ne s'applique pas :
—     aux installations/terminaux terrestres de stockage, liquéfaction et/ou regazéification de GNL, à l'exception des installations de FSRU et/ou FLNG à quai ;
—     aux terminaux de GNL en mer basés sur une structure non flottante (comme le principe d'une structure gravitaire) ; ni
—     aux installations de soutien basées à terre (comme les navires de soutien, les remorqueurs, etc.).
Le présent document n'est pas destiné à la conception des installations flottantes d'alimentation en électricité bien que des parties pertinentes puissent être utilisées à ces fins.
Le présent document n'a pas vocation à traiter des GNL destinés aux applications de soutage de carburant.

Napeljave in oprema za utekočinjeni zemeljski plin - Načrtovanje plavajočih napeljav za utekočinjeni zemeljski plin - 1. del: Splošne zahteve (ISO 20257-1:2020)

General Information

• Status: Published
• Public Enquiry End Date: 04-Nov-2018
• Publication Date: 08-Jun-2020
• ICS: 75.200 - Petroleum products and natural gas handling equipment
• Technical Committee: DPL - Gas supply
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 20-May-2020
• Due Date: 25-Jul-2020
• Completion Date: 09-Jun-2020
• Ref Project: EN ISO 20257-1:2020 - Installation and equipment for liquefied natural gas - Design of floating LNG installations - Part 1: General requirements (ISO 20257-1:2020, Corrected version 2020-10)

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 20257-1:2020
01-julij-2020
Napeljave in oprema za utekočinjeni zemeljski plin - Načrtovanje plavajočih
napeljav za utekočinjeni zemeljski plin - 1. del: Splošne zahteve (ISO 20257-1:2020)
Installation and equipment for liquefied natural gas - Design of floating LNG installations
- Part 1: General requirements (ISO 20257-1:2020)
Anlagen und Ausrüstung für Flüssigerdgas - Auslegung von schwimmenden
Flüssigerdgas-Anlagen - Teil 1: Allgemeine Anforderungen (ISO 20257-1:2020)
Installations et équipements de gaz naturel liquéfié - Conception des installations
flottantes de GNL - Partie 1: Exigences générales (ISO 20257-1:2020)
Ta slovenski standard je istoveten z: EN ISO 20257-1:2020
ICS:
75.200 Oprema za skladiščenje Petroleum products and
nafte, naftnih proizvodov in natural gas handling
zemeljskega plina equipment
SIST EN ISO 20257-1:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 20257-1:2020

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SIST EN ISO 20257-1:2020


EN ISO 20257-1
EUROPEAN STANDARD

NORME EUROPÉENNE

May 2020
EUROPÄISCHE NORM
ICS 75.200
English Version

Installation and equipment for liquefied natural gas -
Design of floating LNG installations - Part 1: General
requirements (ISO 20257-1:2020)
Installations et équipements de gaz naturel liquéfié - Anlagen und Ausrüstung für Flüssigerdgas - Auslegung
Conception des installations flottantes de GNL - Partie von schwimmenden Flüssigerdgas-Anlagen - Teil 1:
1: Exigences générales (ISO 20257-1:2020) Allgemeine Anforderungen (ISO 20257-1:2020)
This European Standard was approved by CEN on 7 March 2020.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20257-1:2020 E
worldwide for CEN national Members.

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SIST EN ISO 20257-1:2020
EN ISO 20257-1:2020 (E)
Contents Page
European foreword . 3

2

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SIST EN ISO 20257-1:2020
EN ISO 20257-1:2020 (E)
European foreword
This document (EN ISO 20257-1:2020) has been prepared by Technical Committee ISO/TC 67
"Materials, equipment and offshore structures for petroleum, petrochemical and natural gas industries"
in collaboration with Technical Committee CEN/TC 282 “Installation and equipment for LNG” the
secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by November 2020, and conflicting national standards
shall be withdrawn at the latest by November 2020.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 20257-1:2020 has been approved by CEN as EN ISO 20257-1:2020 without any
modification.

3

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SIST EN ISO 20257-1:2020

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SIST EN ISO 20257-1:2020
INTERNATIONAL ISO
STANDARD 20257-1
First edition
2020-04
Installation and equipment for
liquefied natural gas — Design of
floating LNG installations —
Part 1:
General requirements
Installations et équipements de gaz naturel liquéfié — Conception des
installations flottantes de GNL —
Partie 1: Exigences générales
Reference number
ISO 20257-1:2020(E)
©
ISO 2020

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SIST EN ISO 20257-1:2020
ISO 20257-1:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

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SIST EN ISO 20257-1:2020
ISO 20257-1:2020(E)

Contents Page
Foreword .vii
Introduction .viii
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 3
3.1 Terms and definitions . 3
3.2 Abbreviated terms . 8
4 Basis of design .11
4.1 Site and meteocean conditions .11
4.1.1 Site study .11
4.1.2 Earthquake .13
4.1.3 Location .13
4.1.4 Other studies .14
4.2 Design criteria .14
4.2.1 General.14
4.2.2 Topsides .15
4.2.3 Transfer systems .16
4.2.4 Hull . .20
4.2.5 LNG storage .22
4.2.6 Mooring .23
4.2.7 Pipe-work .25
5 Health, safety and the environment .26
5.1 General .26
5.1.1 Main objectives .26
5.1.2 Main principles .26
5.2 Identification of safety and environmental barriers and design requirements .27
5.2.1 General.27
5.2.2 Purpose .27
5.2.3 Safety and environmental barriers .28
5.2.4 Generic barriers .28
5.2.5 Safety and environmental barriers identification process .29
5.2.6 Safety and environmental barriers design requirements .30
5.2.7 Safety and environmental barriers design requirements certification .30
5.3 Environmental considerations .31
5.3.1 General.31
5.3.2 Floating LNG installations specificities .31
5.3.3 Environmental aspects identification .31
5.3.4 Environmental design review . .32
5.3.5 Environmental design requirements .32
5.4 Safety considerations .39
5.4.1 General.39
5.4.2 Safety strategies and philosophies .39
5.4.3 Safety reviews .40
5.4.4 Qualitative risk assessment, QRA and specific safety studies.42
5.4.5 Risk prevention measures (typical list) .46
5.4.6 Emergency response .59
5.5 Occupational health and industrial hygiene considerations .61
5.5.1 Occupational health and industrial hygiene aspects identification .61
5.5.2 Chemical exposure .61
5.5.3 Biological factor .62
5.5.4 Legionella .63
5.5.5 Thermal stress .63
© ISO 2020 – All rights reserved iii

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SIST EN ISO 20257-1:2020
ISO 20257-1:2020(E)

5.5.6 Hot/cold surfaces .64
5.5.7 Support functions to operators - Project with permanent operators on-
board or in the facility .64
5.5.8 Lighting .64
5.5.9 Water availability and quality intended for human consumption .65
5.5.10 Noise and vibration .65
5.6 Ergonomics and human factor .66
6 Mooring and stationkeeping .66
6.1 General .66
6.2 Permanent stationkeeping in open waters .67
6.2.1 Stationkeeping concepts .67
6.2.2 Design requirements .68
6.3 Permanent stationkeeping in nearshore or docked conditions .68
6.3.1 Stationkeeping concepts .68
6.3.2 Design requirements .69
6.3.3 Emergency departure of floating LNG installation.70
6.4 Mooring systems for special project design conditions .71
6.4.1 Disconnectable mooring .71
6.4.2 Permanent mooring for a limited project life .71
6.5 Short-duration mooring of a visiting LNGC for loading/unloading .72
6.5.1 General.72
6.5.2 Ship-to-ship mooring in open waters .72
6.5.3 Mooring in docked or nearshore conditions .72
6.5.4 Mooring to an SPM terminal .72
6.5.5 Design requirements .73
6.6 Infrastucture design for jetty moorings .73
6.6.1 General.73
6.6.2 Jetty elevation .74
6.6.3 Corrosion protection of the marine infrastructure .74
6.6.4 LNG spillage containment .74
6.6.5 Power supply from/to jetty to the FSRU/FLNG .74
6.6.6 Navigation aids .74
6.6.7 Emergency response and evacuation route .74
6.7 Transfer of material and personnel .75
7 Hull design .75
7.1 Hull structural design .75
7.1.1 Design philosophy .75
7.1.2 Design methods .76
7.1.3 Codes and standards .76
7.1.4 Limit states for floating structures .76
7.1.5 Design situations for ULS .76
7.1.6 Design situations for SLS .77
7.1.7 Design situations for FLS .77
7.1.8 Design situations for ALS .77
7.1.9 Site-specific design . . .78
7.1.10 Cargo containment loads .78
7.1.11 Fatigue .78
7.1.12 Slamming .79
7.1.13 Green water .79
7.1.14 Topsides and external loads .79
7.1.15 Accidental loads .79
7.2 Stability and watertight integrity.80
7.2.1 General.80
7.2.2 Stability .80
7.2.3 Watertight and weathertight integrity.80
8 LNG storage .81
8.1 General .81
iv © ISO 2020 – All rights reserved

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SIST EN ISO 20257-1:2020
ISO 20257-1:2020(E)

8.2 Sloshing loads .81
8.2.1 Intermediate filling levels: Operating conditions of FSRU/FLNG .81
8.2.2 Intermediate filling levels: Operating conditions of cargo transfers (STS) .82
8.3 Boil-off gas management .83
8.4 Rollover prevention management .83
8.4.1 Background.83
8.4.2 Detection and prevention .83
8.5 Vent systems for LNG storage.84
8.5.1 General.84
8.5.2 Pressure relief systems.84
8.5.3 Vacuum relief systems . . .85
9 LNG transfer system .85
9.1 Functional requirements .85
9.2 Design of transfer systems .86
9.2.1 Operating envelope . .86
9.2.2 Transfer system design .87
10 Boil-off gas handling and recovery .89
10.1 General .89
10.2 BOG collection system .89
10.3 System of gas return to LNGC or to FLNG facility.90
10.4 Boil-off gas recovery .90
10.5 Gas compressor .90
10.6 Flare/vent .91
11 Low temperature pipework .
...

SLOVENSKI STANDARD
oSIST prEN ISO 20257-1:2018
01-oktober-2018
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QDSHOMDY]DXWHNRþLQMHQL]HPHOMVNLSOLQGHO6SORãQH]DKWHYH,62',6

Installation and equipment for liquefied natural gas - Design of floating LNG installations -
Part 1: General requirements (ISO/DIS 20257-1:2018)
Anlagen und Ausrüstung für Flüssigerdgas - Teil 1: Allgemeine Anforderungen an
schwimmende Flüssigerdgas-Anlagen (ISO/DIS 20257-1:2018)
Installations et équipements de gaz naturel liquéfié - Conception des installations en mer
- Partie 1: Exigences générales pour installations flottantes de GNL (ISO/DIS 20257-
1:2018)
Ta slovenski standard je istoveten z: prEN ISO 20257-1
ICS:
75.200 2SUHPD]DVNODGLãþHQMH Petroleum products and
QDIWHQDIWQLKSURL]YRGRYLQ natural gas handling
]HPHOMVNHJDSOLQD equipment
oSIST prEN ISO 20257-1:2018 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 20257-1:2018

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oSIST prEN ISO 20257-1:2018
DRAFT INTERNATIONAL STANDARD
ISO/DIS 20257-1
ISO/TC 67/SC 9 Secretariat: AFNOR
Voting begins on: Voting terminates on:
2018-08-20 2018-11-12
Installation and equipment for liquefied natural gas —
Design of floating LNG installations —
Part 1:
General requirements
Installations et équipements de gaz naturel liquéfié — Conception des installations en mer —
Partie 1: Exigences générales pour installations flottantes de GNL
ICS: 75.200
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 20257-1:2018(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2018

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oSIST prEN ISO 20257-1:2018
ISO/DIS 20257-1:2018(E)
ISO 20257-1:2018(DIS)

Contents
This template allows you to work with default MS Word functions and styles. You can use these if you want
to maintain the Table of Contents automatically and apply auto-numbering.
To update the Table of Contents please select it and press "F9".
Foreword . viii
Introduction. ix
1 Scope . 1
2 Normative references . 2
2.1 Local Regulations . 2
2.2 List of Standards . 3
3 Terms and definitions . 7
4 Basis of Design . 18
4.1 Site and Meteocean Conditions . 18
4.1.1 Site study . 18
4.1.2 Earthquake . 19
4.1.3 Location . 20
4.1.4 Other studies . 21
4.2 Design Criteria . 21
4.2.1 Introduction . 21
4.2.2 Topsides . 22
4.2.3 Transfer Systems . 23
4.2.4 Hull . 30
4.2.5 LNG storage . 31
4.2.6 Mooring . 33
4.2.7 Pipe-work . 34
5 Health, Safety and Environment . 35
5.1.1 Main objectives. 35
5.1.2 Main principles. 35
5.2 Identification of Safety and Environmental Barriers and design requirements . 36
5.2.1 Introduction . 36
5.2.2 Purpose . 37
5.2.3 Safety and Environmental Barriers definition . 37
5.2.4 Generic list of barriers . 38
5.2.5 Safety and Environmental barriers identification process . 38
5.2.6 Safety and Environmental Barriers design requirements . 39
5.2.7 Safety and Environmental barriers design requirements certification . 40
5.3 Environmental Considerations . 40
COPYRIGHT PROTECTED DOCUMENT
5.3.1 Floating LNG Installations specificities . 41
© ISO 2018
5.3.2 Environmental Aspects Identification . 41
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
5.3.3 Environmental Design Review . 42
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
5.3.4 Environmental Design Requirements . 42
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
5.4 Safety Considerations . 50
below or ISO’s member body in the country of the requester.
5.4.1 Safety Strategies and Philosophies . 51
ISO copyright office
5.4.2 Safety Reviews . 51
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
5.4.3 Qualitative Risk Assessment, Quantitative Risk Assessment (QRA) and Safety Studies . 54
Phone: [phone]
5.4.4 Risk Prevention Measures (Typical list) . 58
Fax: [phone]
5.4.5 Emergency Response . 75
Email: [e-mail]
Website: www.iso.org
5.5 Occupational Health and Industrial Hygiene Considerations . 76
Published in Switzerland
ii © ISO 2018 – All rights reserved
© ISO 2017 – All rights reserved iii

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oSIST prEN ISO 20257-1:2018
ISO/DIS 20257-1:2018(E)
ISO 20257-1:2018(DIS)
Contents
This template allows you to work with default MS Word functions and styles. You can use these if you want
to maintain the Table of Contents automatically and apply auto-numbering.
To update the Table of Contents please select it and press "F9".
Foreword . viii
Introduction. ix
1 Scope . 1
2 Normative references . 2
2.1 Local Regulations . 2
2.2 List of Standards . 3
3 Terms and definitions . 7
4 Basis of Design . 18
4.1 Site and Meteocean Conditions . 18
4.1.1 Site study . 18
4.1.2 Earthquake . 19
4.1.3 Location . 20
4.1.4 Other studies . 21
4.2 Design Criteria . 21
4.2.1 Introduction . 21
4.2.2 Topsides . 22
4.2.3 Transfer Systems . 23
4.2.4 Hull . 30
4.2.5 LNG storage . 31
4.2.6 Mooring . 33
4.2.7 Pipe-work . 34
5 Health, Safety and Environment . 35
5.1.1 Main objectives. 35
5.1.2 Main principles. 35
5.2 Identification of Safety and Environmental Barriers and design requirements . 36
5.2.1 Introduction . 36
5.2.2 Purpose . 37
5.2.3 Safety and Environmental Barriers definition . 37
5.2.4 Generic list of barriers . 38
5.2.5 Safety and Environmental barriers identification process . 38
5.2.6 Safety and Environmental Barriers design requirements . 39
5.2.7 Safety and Environmental barriers design requirements certification . 40
5.3 Environmental Considerations . 40
5.3.1 Floating LNG Installations specificities . 41
5.3.2 Environmental Aspects Identification . 41
5.3.3 Environmental Design Review . 42
5.3.4 Environmental Design Requirements . 42
5.4 Safety Considerations . 50
5.4.1 Safety Strategies and Philosophies . 51
5.4.2 Safety Reviews . 51
5.4.3 Qualitative Risk Assessment, Quantitative Risk Assessment (QRA) and Safety Studies . 54
5.4.4 Risk Prevention Measures (Typical list) . 58
5.4.5 Emergency Response . 75
5.5 Occupational Health and Industrial Hygiene Considerations . 76
© ISO 2017 – All rights reserved iii
© ISO 2018 – All rights reserved

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oSIST prEN ISO 20257-1:2018
ISO/DIS 20257-1:2018(E)
ISO 20257-1:2018(DIS)
5.5.1 Occupational Health and Industrial Hygiene Aspects Identification . 76
5.5.2 Chemical Exposure . 77
5.5.3 Biological Factor . 78
5.5.4 Legionella . 79
5.5.5 Thermal Stress . 79
5.5.6 Hot/ Cold Surfaces . 80
5.5.7 Support functions to operators . 80
5.5.8 Lighting . 81
5.5.9 Water quality & availability intended for human consumption . 81
5.5.10 Noise & Vibration . 82
5.6 Ergonomics and Human Factor . 84
6 Mooring and station keeping . 84
6.1 Introduction. 84
6.2 Station keeping and Mooring concepts . 85
6.2.1 Station keeping. 85
6.2.2 Ship to Ship Mooring (LNG moored to FSU, FSRU or FLNG ) . 87
6.2.3 Dynamic positioning . 87
6.3 Station Keeping and Mooring Design . 87
6.4 Specific Requirements for Floating LNG Installations moored to berth/ jetties . 88
6.4.1 General . 88
6.4.2 Dynamic Mooring Analysis . 88
6.4.3 Vessel Compatibility Study . 89
6.4.4 Infrastructure design . 89
6.4.5 Navigation Aids . 90
6.4.6 Power supply from/to jetty to the FSRU/FLNG / Safety guidance . 90
6.4.7 Specific requirements for nearshore or dockside jetties (safety criteria) . 90
6.5 Transfer of material and personnel . 91
7 Hull Design . 92
7.1 Hull Structural Design . 92
7.1.1 Design Philosophy . 92
7.1.2 Design methods . 92
7.1.3 Codes and Standards . 93
7.1.4 Limit states for floating structures . 93
7.1.5 Design situations for ULS . 93
7.1.6 Design situations for SLS . 93
7.1.7 Design situations for FLS . 94
7.1.8 Design situations for ALS . 94
7.1.9 Site Specific Design . 95
7.1.10 Cargo Containment Loads . 95
7.1.11 Fatigue . 95
7.1.12 Slamming . 96
7.1.13 Green Water . 96
7.1.14 Topsides and External Loads . 96
7.1.15 Accidental Loads . 97
7.2 Stability and Watertight Integrity . 97
7.2.1 General . 97
7.2.2 Stability . 97
7.2.3 Watertight and Weathertight Integrity . 98
8 LNG Storage . 99
8.1 Sloshing loads . 99
8.1.1 Intermediate Filling levels: Operating Conditions of FSRU/FLNG . 99
8.1.2 Intermediate Filling levels: Operating Conditions of cargo transfers (STS) . 100
8.2 BOG management . 101
iv © ISO 2018 – All rights reserved
© ISO 2018 – All rights reserved

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oSIST prEN ISO 20257-1:2018
ISO/DIS 20257-1:2018(E)
ISO 20257-1:2018(DIS)
8.3 Rollover Prevention Management . 101
8.3.1 Background: . 101
8.3.2 Detection and Prevention: . 101
9 LNG transfer system . 102
9.1 Functional Requirements . 102
9.2 Design of transfer systems . 103
9.2.1 Operating envelope . 103
9.2.2 Operating Envelope for Transfer System in Non dynamic sensitive areas . 103
9.2.3 Transfer System Design . 104
10 BOG handling and recovery . 106
10.1 General . 106
10.2 Boil-off collection systems . 107
10.3 System of gas return to tanker(s) or to FLNG facility . 107
10.4 Boil off gas recovery . 107
10.5 Gas compressor . 108
10.6 Flare/vent . 108
11 Low temperature Pipework . 108
11.1 Introduction . 108
11.2 Piping components . 108
11.2.1 General . 108
11.3 Pipe .
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