Wind energy generation systems - Part 3-1: Design requirements for fixed offshore wind turbines

This part of IEC 61400 specifies additional requirements for assessment of the external conditions at an offshore wind turbine site and specifies essential design requirements to ensure the engineering integrity of fixed offshore wind turbines. Its purpose is to provide an appropriate level of protection against damage from all hazards during the planned lifetime. This document focuses on the engineering integrity of the structural components of an offshore wind turbine but is also concerned with subsystems such as control and protection mechanisms, internal electrical systems and mechanical systems. A wind turbine shall be considered as a fixed offshore wind turbine if the support structure is subject to hydrodynamic loading and it is founded on the seabed. The design requirements specified in this document are not sufficient to ensure the engineering integrity of floating offshore wind turbines. For floating installations, reference is made to IEC 61400-3-2. In the remainder of this document, the term "offshore wind turbine" is assumed to refer to those that are fixed to the seabed. This document should be used together with the appropriate IEC and ISO standards mentioned in Clause 2. In particular, this document is fully consistent with the requirements of IEC 61400-1. The safety level of the offshore wind turbine designed according to this document shall be at or exceed the level inherent in IEC 61400-1. In some clauses, where a comprehensive statement of requirements aids clarity, replication of text from IEC 61400-1 is included.

Windenergieanlagen - Teil 3-1: Auslegungsanforderungen für gegründete Offshore-Windenergieanlagen

Systèmes de génération d’énergie éolienne - Partie 3-1 : Exigences de conception des éoliennes fixes en pleine mer

l'IEC 61400-3-1:2019 spécifie des exigences complémentaires d'évaluation des conditions externes sur un site d'éoliennes en mer, ainsi que les exigences essentielles de conception, afin d'assurer l'intégrité technique des éoliennes en mer fixes. Elle a pour objet de fournir un niveau de protection approprié contre les dommages causés par tous les dangers pendant la durée de vie prévue. Le présent document se concentre sur l'intégrité technique des éléments de structure d'une éolienne en mer, mais concerne également les sous-systèmes, tels que les mécanismes de commande et de protection, les systèmes électriques internes et les systèmes mécaniques. Cette édition annule et remplace la première édition de l'IEC 61400-3 parue en 2009. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à la première édition de l'IEC 61400-3: a) Le tableau des charges de conception a été révisé afin de simplifier l'approche par vagues, à la fois pour plusieurs cas de rafales avec l'état de mer normale et pour de nombreux cas avec l'état de mer extrême. Les recommandations concernant les calculs de charge ont été modifiées en conséquence; b) Pour les facteurs de sécurité de charge, il est désormais fait directement référence à l'IEC 61400-1; c) Le système de commande a été aligné sur les dernières mises à jour de l'IEC 61400-1; d) La première édition consacrée aux spectres d'ondes a été remplacée par une référence à l'ISO 19901-1; e) L'annexe consacrée aux surcharges de glace a été révisée et mise à jour f) Deux annexes informatives concernant les cyclones tropicaux ont été introduites: g) Les autres parties du texte ont été alignées sur l'IEC 61400-1.

Sistemi za proizvodnjo energije na veter - 3-1. del: Zahteve za načrtovanje fiksnih vetrnih turbin na morju (IEC 61400-3-1:2019)

Ta dokument določa dodatne zahteve za ocenjevanje zunanjih pogojev na območju vetrnih turbin na morju in temeljne zahteve za načrtovanje, s katerimi se zagotovi inženirska celovitost fiksnih vetrnih turbin na morju. Njegov namen je zagotoviti ustrezno raven zaščite pred poškodbami zaradi vseh nevarnosti v predvideni življenjski dobi. Ta dokument se osredotoča na inženirsko celovitost sestavnih delov konstrukcije vetrne turbine na morju, obravnava pa tudi podsisteme, kot so nadzorni in zaščitni mehanizmi, notranji električni sistemi ter mehanski sistemi. Vetrno turbino je treba obravnavati kot fiksno vetrno turbino na morju, če je podporna konstrukcija podvržena hidrodinamični obremenitvi in ima temelje na morskem dnu. Zahteve za načrtovanje, ki so določene v tem dokumentu, ne zadostujejo za zagotovitev inženirske celovitosti plavajočih vetrnih turbin na morju. Za plavajoče namestitve je omenjen standard IEC 61400-3-2. V nadaljevanju tega dokumenta se izraz »vetrna turbina na morju« navezuje na vetrne turbine, ki so pritrjene na morsko dno. Ta dokument naj se uporablja skupaj z ustreznimi standardi IEC in ISO, omenjenimi v točki 2. Ta dokument je v celoti skladen z zahtevami iz standarda IEC 61400-1. Varnostna stopnja vetrne turbine na morju, načrtovane v skladu s tem dokumentom, mora biti enaka stopnji iz standarda IEC 61400-1 ali jo presegati. V nekaterih točkah, pri katerih obsežen opis zahtev pripomore k jasnosti, se ponavlja besedilo iz standarda IEC 61400-1.

General Information

Status
Published
Publication Date
19-Sep-2019
Technical Committee
Drafting Committee
Current Stage
6060 - Document made available
Due Date
20-Sep-2019
Completion Date
20-Sep-2019

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SLOVENSKI STANDARD
SIST EN IEC 61400-3-1:2019
01-december-2019

Sistemi za proizvodnjo energije na veter - 3-1. del: Zahteve za načrtovanje fiksnih

vetrnih turbin na morju (IEC 61400-3-1:2019)

Wind energy generation systems - Part 3-1: Design requirements for fixed offshore wind

turbines (IEC 61400-3-1:2019)

Windenergieanlagen - Teil 3-1: Auslegungsanforderungen für Windenergieanlagen auf

offener See (IEC 61400-3-1:2019)

Systèmes de génération d’énergie éolienne - Partie 3-1 : Exigences de conception des

éoliennes fixes en pleine mer (IEC 61400-3-1:2019)
Ta slovenski standard je istoveten z: EN IEC 61400-3-1:2019
ICS:
27.180 Vetrne elektrarne Wind turbine energy systems
SIST EN IEC 61400-3-1:2019 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN IEC 61400-3-1:2019
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SIST EN IEC 61400-3-1:2019
EUROPEAN STANDARD EN IEC 61400-3-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2019
ICS 27.180
English Version
Wind energy generation systems - Part 3-1: Design
requirements for fixed offshore wind turbines
(IEC 61400-3-1:2019)

Systèmes de génération d’énergie éolienne – Partie 3-1 : Windenergieanlagen - Teil 3-1: Auslegungsanforderungen

Exigences de conception des éoliennes fixes en pleine mer für Windenergieanlagen auf offener See

(IEC 61400-3-1:2019) (IEC 61400-3-1:2019)

This European Standard was approved by CENELEC on 2019-05-10. CENELEC 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 CENELEC 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 CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the

same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,

Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden,

Switzerland, Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2019 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN IEC 61400-3-1:2019 E
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SIST EN IEC 61400-3-1:2019
EN IEC 61400-3-1:2019 (E)
European foreword

The text of document 88/708/FDIS, future edition 1 of IEC 61400-3-1, prepared by IEC/TC 88 "Wind

energy generation systems" was submitted to the IEC-CENELEC parallel vote and approved by

CENELEC as EN IEC 61400-3-1:2019.
The following dates are fixed:

• latest date by which the document has to be implemented at national (dop) 2020-03-20

level by publication of an identical national standard or by endorsement

• latest date by which the national standards conflicting with the (dow) 2022-09-20

document have to be withdrawn

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

Endorsement notice

The text of the International Standard IEC 61400-3-1:2019 was approved by CENELEC as a

European Standard without any modification.

In the official version, for Bibliography, the following notes have to be added for the standards

indicated:
IEC 60034 (series) NOTE Harmonized as EN 60034-9:2005/A1 (series)
IEC 60038 NOTE Harmonized as EN 60038
IEC 60146 (series) NOTE Harmonized as EN 60146 (series)
IEC 60204-1 NOTE Harmonized as EN 60204-1
IEC 60204-11:2000 NOTE Harmonized as EN 60204-11:2000 (not modified)
IEC 60269 (series) NOTE Harmonized as EN 60269 (series)
IEC 60364 (series) NOTE Harmonized as HD 60364 (series) (modified)
IEC 60439 (series) NOTE Harmonized as EN 60439 (not modified)
IEC 60446:2007 NOTE Harmonized as EN 60446:2007 (not modified)
IEC 60529:1989 NOTE Harmonized as EN 60529:1991 (not modified)
IEC 60755:2008 NOTE Harmonized as EN 60755:—
IEC 60898 NOTE Harmonized as EN IEC 60898 (not modified)
IEC 61000-6-1 NOTE Harmonized as EN IEC 61000-6-1
IEC 61000-6-4 NOTE Harmonized as EN 61000-6-4
IEC 61310-1:2007 NOTE Harmonized as EN 61310-1:2008 (not modified)
IEC 61310-2:2007 NOTE Harmonized as EN 61310-2:2008 (not modified)
IEC 61400-13 NOTE Harmonized as EN 61400-13
IEC 61400-21 NOTE Harmonized as EN 61400-21
IEC 61400-24 NOTE Harmonized as EN 61400-24
Under preparation. Stage at the time of publication: prEN 60755:2016.
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SIST EN IEC 61400-3-1:2019
EN IEC 61400-3-1:2019 (E)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.

NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod), the relevant

EN/HD applies.

NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:

www.cenelec.eu.
Publication Year Title EN/HD Year

IEC 60721 series Classification of environmental conditions EN IEC 60721 series

IEC 61400-1 2019 Wind energy generation systems - Part 1: EN IEC 61400-1 2019
Design requirements
ISO 2394 1998 General principles on reliability for structures - -
ISO 2533 1975 Standard Atmosphere - -
ISO 19900 2002 Petroleum and natural gas industries - General - -
requirements for offshore structures

ISO 19901-1 2015 Petroleum and natural gas industries - Specific EN ISO 19901-1 2015

requirements for offshore structures - Part 1:
Metocean design and operating conditions
ISO 19901-4 2003 Petroleum and natural gas industries - Specific - -
requirements for offshore structures - Part 4:
Geotechnical and foundation design
considerations
ISO 19902 2007 Petroleum and natural gas industries - Fixed EN ISO 19902 2007
steel offshore structures
ISO 19903 2006 Petroleum and natural gas industries - Fixed EN ISO 19903 2006
concrete offshore structures
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SIST EN IEC 61400-3-1:2019
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SIST EN IEC 61400-3-1:2019
IEC 61400-3-1
Edition 1.0 2019-04
INTERNATIONAL
STANDARD
colour
inside
Wind energy generation systems –
Part 3-1: Design requirements for fixed offshore wind turbines
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.180 ISBN 978-2-8322-6600-7

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
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SIST EN IEC 61400-3-1:2019
– 2 – IEC 61400-3-1:2019 © IEC 2019
CONTENTS

FOREWORD ........................................................................................................................... 7

INTRODUCTION ..................................................................................................................... 9

1 Scope ............................................................................................................................ 10

2 Normative references .................................................................................................... 10

3 Terms and definitions .................................................................................................... 11

4 Symbols and abbreviated terms ..................................................................................... 19

4.1 Symbols and units................................................................................................. 19

4.2 Abbreviations ........................................................................................................ 20

5 Principal elements ......................................................................................................... 21

5.1 General ................................................................................................................. 21

5.2 Design methods .................................................................................................... 21

5.3 Safety classes ...................................................................................................... 22

5.4 Quality assurance ................................................................................................. 22

5.5 Rotor–nacelle assembly markings ......................................................................... 23

6 External conditions – definition and assessment ............................................................ 23

6.1 General ................................................................................................................. 23

6.2 Wind turbine classes ............................................................................................. 24

6.3 Definition of external conditions at an offshore wind turbine site ........................... 24

6.3.1 General ......................................................................................................... 24

6.3.2 Wind conditions ............................................................................................. 25

6.3.3 Marine conditions .......................................................................................... 25

6.3.4 Electrical power network conditions ............................................................... 32

6.3.5 Other environmental conditions ..................................................................... 32

6.4 Assessment of external conditions at an offshore wind turbine site ....................... 33

6.4.1 General ......................................................................................................... 33

6.4.2 The metocean database ................................................................................ 33

6.4.3 Assessment of wind conditions ...................................................................... 34

6.4.4 Assessment of marine conditions ................................................................... 36

6.4.5 Assessment of other environmental conditions .............................................. 40

6.4.6 Assessment of electrical network conditions .................................................. 41

6.4.7 Assessment of soil conditions ........................................................................ 41

7 Structural design ........................................................................................................... 42

7.1 General ................................................................................................................. 42

7.2 Design methodology ............................................................................................. 42

7.3 Loads.................................................................................................................... 42

7.3.1 General ......................................................................................................... 42

7.3.2 Gravitational and inertial loads ...................................................................... 42

7.3.3 Aerodynamic loads ........................................................................................ 43

7.3.4 Actuation loads .............................................................................................. 43

7.3.5 Hydrodynamic loads ...................................................................................... 43

7.3.6 Sea/lake ice loads ......................................................................................... 43

7.3.7 Other loads .................................................................................................... 44

7.4 Design situations and load cases .......................................................................... 44

7.4.1 General ......................................................................................................... 44

7.4.2 Power production (DLC 1.1 to 1.6) ................................................................. 50

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7.4.3 Power production plus occurrence of fault or loss of electrical network

connection (DLC 2.1 – 2.5) ............................................................................ 51

7.4.4 Start up (DLC 3.1 to 3.3)................................................................................ 53

7.4.5 Normal shutdown (DLC 4.1 to 4.2) ................................................................. 54

7.4.6 Emergency stop (DLC 5.1) ............................................................................. 54

7.4.7 Parked (standstill or idling) (DLC 6.1 to 6.4) .................................................. 55

7.4.8 Parked plus fault conditions (DLC 7.1 to 7.2) ................................................. 56

7.4.9 Transport, assembly, maintenance and repair (DLC 8.1 to 8.4) ...................... 57

7.4.10 Sea/lake ice design load cases ...................................................................... 60

7.5 Load and load effect calculations .......................................................................... 61

7.5.1 General ......................................................................................................... 61

7.5.2 Relevance of hydrodynamic loads .................................................................. 61

7.5.3 Calculation of hydrodynamic loads ................................................................. 62

7.5.4 Calculation of sea/lake ice loads .................................................................... 62

7.5.5 Overall damping assessment for support structure response evaluations ....... 62

7.5.6 Simulation requirements ................................................................................ 64

7.5.7 Other requirements ........................................................................................ 65

7.6 Ultimate limit state analysis................................................................................... 66

7.6.1 Method .......................................................................................................... 66

7.6.2 Ultimate strength analysis .............................................................................. 68

7.6.3 Fatigue failure ............................................................................................... 68

7.6.4 Special partial safety factors .......................................................................... 69

7.6.5 Assessment of cyclic loading for foundation assessment ............................... 69

8 Control system .............................................................................................................. 69

9 Mechanical systems ...................................................................................................... 70

10 Electrical system ........................................................................................................... 70

11 Foundation and substructure design .............................................................................. 70

12 Assembly, installation and erection ................................................................................ 71

12.1 General ................................................................................................................. 71

12.2 Planning ............................................................................................................... 72

12.3 Installation conditions ........................................................................................... 72

12.4 Site access ........................................................................................................... 72

12.5 Environmental conditions ...................................................................................... 73

12.6 Documentation ...................................................................................................... 73

12.7 Receiving, handling and storage ........................................................................... 73

12.8 Support structure systems .................................................................................... 73

12.9 Assembly of offshore wind turbine ......................................................................... 73

12.10 Erection of offshore wind turbine ........................................................................... 74

12.11 Fasteners and attachments ................................................................................... 74

12.12 Cranes, hoists and lifting equipment ..................................................................... 74

13 Commissioning, operation and maintenance .................................................................. 74

13.1 General ................................................................................................................. 74

13.2 Design requirements for safe operation, inspection and maintenance ................... 75

13.3 Instructions concerning commissioning ................................................................. 76

13.3.1 General ......................................................................................................... 76

13.3.2 Energization .................................................................................................. 76

13.3.3 Commissioning tests ...................................................................................... 76

13.3.4 Records ......................................................................................................... 76

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SIST EN IEC 61400-3-1:2019
– 4 – IEC 61400-3-1:2019 © IEC 2019

13.3.5 Post commissioning activities ........................................................................ 76

13.4 Operator’s instruction manual ............................................................................... 76

13.4.1 General ......................................................................................................... 76

13.4.2 Instructions for operations and maintenance record ....................................... 77

13.4.3 Instructions for unscheduled automatic shutdown .......................................... 77

13.4.4 Instructions for diminished reliability .............................................................. 77

13.4.5 Work procedures plan .................................................................................... 77

13.4.6 Emergency procedures plan .......................................................................... 78

13.5 Maintenance manual ............................................................................................. 78

Annex A (informative) Key design parameters for an offshore wind turbine .......................... 80

A.1 Offshore wind turbine identifiers ............................................................................ 80

A.1.1 General ......................................................................................................... 80

A.1.2 Rotor-nacelle assembly (machine) parameters .............................................. 80

A.1.3 Support structure parameters ........................................................................ 80

A.1.4 Wind conditions (based on a 10-min reference period and including

wind farm wake effects where relevant) ......................................................... 80

A.1.5 Marine conditions (based on a 3-hour reference period where relevant) ........ 81

A.1.6 Electrical network conditions at turbine .......................................................... 81

A.2 Other environmental conditions ............................................................................. 82

A.3 Limiting conditions for transport, erection and maintenance .................................. 82

Annex B (informative) Shallow water hydrodynamics and breaking waves ............................ 83

B.1 Selection of suitable wave theories ....................................................................... 83

B.2 Modelling of irregular wave trains.......................................................................... 84

B.3 Wave height distributions ...................................................................................... 84

B.3.1 General ......................................................................................................... 84

B.3.2 The Goda model for maximum wave height ................................................... 84

B.3.3 The Battjes and Groenendijk wave height distribution .................................... 87

B.3.4 The Forristall wave and crest height distributions .......................................... 90

B.4 Breaking waves .................................................................................................... 92

B.5 Reference documents ........................................................................................... 95

Annex C (informative) Guidance on calculation of hydrodynamic loads ................................ 96

C.1 General ................................................................................................................. 96

C.2 Morison’s equation ................................................................................................ 97

C.3 Diffraction ............................................................................................................. 98

C.4 Slap and slam loading ........................................................................................... 99

C.5 Vortex-induced vibrations.................................................................................... 102

C.5.1 General ....................................................................................................... 102

C.5.2 Critical velocities for cross-flow motion ........................................................ 103

C.5.3 Critical velocities for in-line motion .............................................................. 104

C.6 Appurtenances .................................................................................................... 105

C.6.1 General ....................................................................................................... 105

C.6.2 Alternative method for estimating hydrodynamic coefficients accounting

for appurtenances and marine growth .......................................................... 105

C.7 Calculation methods ........................................................................................... 112

C.7.1 General ....................................................................................................... 112

C.7.2 Explicit approach ......................................................................................... 113

C.7.3 Constrained wave approach......................................................................... 113

C.8 Reference documents ......................................................................................... 113

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SIST EN IEC 61400-3-1:2019
IEC 61400-3-1:2019 © IEC 2019 − 5 −

Annex D (informative) Recommendations for design of offshore wind turbine support

structures with respect to ice loads ..................................................................................... 115

D.1 Introductory remarks ........................................................................................... 115

D.2 General ............................................................................................................... 115

D.3 Choice of ice thickness ....................................................................................... 116

D.4 Load cases ......................................................................................................... 117

D.4.1 General ....................................................................................................... 117

D.4.2 Horizontal load from fast ice cover originating from temperature

fluctuations (DLC D1) .................................................................................. 117

D.4.3 Horizontal load from fast ice cover originating from water level

fluctuations and arch effect (DLC D2) .......................................................... 118

D.4.4 Horizontal load from moving ice (DLC D3, D4, D7 and D8) .......................... 118

D.4.5 Vertical load from fast ice cover (DLC D5) ................................................... 122

D.4.6 Pressure from ice ridges (DLC D6) .............................................................. 123

D.4.7 Dynamic loading (DLC D3, D4, D7, and D8)................................................. 123

D.5 Requirements on stochastic simulation ............................................................... 126

D.6 Requirements on model testing ........................................................................... 126

D.7 Reference documents ......................................................................................... 127

D.8 Databases for ice conditions ............................................................................... 129

Annex E (informative) Offshore wind turbine foundation and substructure design ............... 130

Annex F (informative) Statistical extrapolation of operational metocean parameters

for ultimate strength analysis .............................................................................................. 131

F.1 General ............................................................................................................... 131

F.2 Use of IFORM to determine 50-yr significant wave height conditional on

mean wind speed ................................................................................................ 131

F.3 Examples of joint distributions of V and H and approximations to the

environmental contour ........................................................................................ 133

F.4 Choice of sea state duration ............................................................................... 135

F.5 Determination of the extreme individual wave height to be embedded in SSS ..... 135

F.6 Reference documents ......................................................................................... 136

Annex G (informative) Corrosion protection ....................................................................... 137

G.1 General ............................................................................................................... 137

G.2 The marine environment ..................................................................................... 137

G.3 Corrosion protection considerations .................................................................... 138

G.4 Corrosion protection systems – Support structures ............................................. 138

G.5 Corrosion protection in the rotor–nacelle assembly ............................................. 139

G.6 Reference documents ......................................................................................... 140

Annex H (informative) Prediction of extreme wave heights during tropical cyclones ........... 141

H.1 General ............................................................................................................... 141

H.2 Wind field estimation for tropical cyclones ........................................................... 141

H.3 Wave estimation for tropical cyclones ................................................................. 142

H.4 Reference documents ......................................................................................... 142

H.5 Databases for tropical storms conditions ............................................................. 143

Annex I (informative) Recommendations for alignment of safety levels in tropical

cyclone regions ................................................................................................................... 144

I.1 General ............................................................................................................... 144

I.2 Global robustness le
...

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