SIST EN ISO 19901-1:2006

SLOVENSKI STANDARD
SIST EN ISO 19901-1:2006
01-september-2006
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Petroleum and natural gas industries - Specific requirements for offshore structures -
Part 1: Metocean design and operating considerations (ISO 19901-1:2005)
Erdöl- und Erdgasindustrie - Spezielle Anforderungen für Offshore-Anlagen - Teil 1:
Grundsätze für die Auslegung und den Betrieb auf dem offenen Meer (ISO 19901-
1:2005)
Industries du pétrole et du gaz naturel - Exigences spécifiques relatives aux structures
en mer - Partie 1: Dispositions océano-météorologiques pour la conception et
l'exploitation (ISO 19901-1:2005)
Ta slovenski standard je istoveten z: EN ISO 19901-1:2005
ICS:
75.180.10 Oprema za raziskovanje in Exploratory and extraction
odkopavanje equipment
SIST EN ISO 19901-1:2006 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 19901-1:2006

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SIST EN ISO 19901-1:2006
EUROPEAN STANDARD
EN ISO 19901-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2005
ICS 75.180.10

English Version
Petroleum and natural gas industries - Specific requirements for
offshore structures - Part 1: Metocean design and operating
considerations (ISO 19901-1:2005)
Industries du pétrole et du gaz naturel - Exigences Erdöl- und Erdgasindustrie - Spezielle Anforderungen für
spécifiques relatives aux structures en mer - Partie 1: Offshore-Anlage - Teil 1: Grundsätze für die Auslegung und
Dispositions océano-météorologiques pour la conception et den Betrieb auf dem offenen Meer (ISO 19901-1:2005)
l'exploitation (ISO 19901-1:2005)
This European Standard was approved by CEN on 28 October 2005.
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 Central Secretariat 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 Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 19901-1:2005: E
worldwide for CEN national Members.

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SIST EN ISO 19901-1:2006

EN ISO 19901-1:2005 (E)





Foreword


This document (EN ISO 19901-1:2005) has been prepared by Technical Committee ISO/TC 67
"Materials, equipment and offshore structures for petroleum and natural gas industries" in
collaboration with Technical Committee CEN/TC 12 "Materials, equipment and offshore
structures for petroleum, petrochemical and natural gas industries", 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 May 2006, and conflicting national standards
shall be withdrawn at the latest by May 2006.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary,
Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.



Endorsement notice

The text of ISO 19901-1:2005 has been approved by CEN as EN ISO 19901-1:2005 without any
modifications.

2

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SIST EN ISO 19901-1:2006


INTERNATIONAL ISO
STANDARD 19901-1
First edition
2005-11-15

Petroleum and natural gas industries —
Specific requirements for offshore
structures —
Part 1:
Metocean design and operating
considerations
Industries du pétrole et du gaz naturel — Exigences spécifiques
relatives aux structures en mer —
Partie 1: Dispositions océano-météorologiques pour la conception et
l'exploitation




Reference number
ISO 19901-1:2005(E)
©
ISO 2005

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SIST EN ISO 19901-1:2006
ISO 19901-1:2005(E)
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©  ISO 2005
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ii © ISO 2005 – All rights reserved

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SIST EN ISO 19901-1:2006
ISO 19901-1:2005(E)
Contents Page
Foreword. v
Introduction . vii
1 Scope . 1
2 Normative references . 2
3 Terms and definitions. 2
4 Symbols and abbreviated terms . 9
4.1 Main symbols . 9
4.2 Abbreviated terms . 11
5 Determining the relevant metocean parameters . 11
5.1 General. 11
5.2 Expert interpretation of the metocean database . 12
5.3 Selecting appropriate parameters for determining design actions or action effects. 12
5.4 The metocean database . 13
5.5 Storm types in a region. 13
5.6 Directionality . 14
5.7 Extrapolation to rare conditions . 14
5.8 Metocean parameters for fatigue assessments . 14
5.9 Metocean parameters for short-term activities . 14
6 Water depth, tides and storm surges . 16
6.1 General. 16
6.2 Tides. 16
6.3 Storm surge. 16
7 Wind . 17
7.1 General. 17
7.2 Wind actions and action effects. 18
7.3 Wind profile and time-averaged wind speed . 19
7.4 Wind spectra . 19
8 Waves. 19
8.1 General. 19
8.2 Wave actions and action effects . 20
8.3 Intrinsic, apparent and encounter wave periods. 20
8.4 Two-dimensional wave kinematics . 21
8.5 Maximum height of an individual wave for long return periods . 21
8.6 Wave spectra. 21
8.7 Wave directional spreading function and spreading factor. 21
8.8 Wave crest elevation . 22
9 Currents . 22
9.1 General. 22
9.2 Current velocities. 22
9.3 Current profile . 23
9.4 Current profile stretching . 23
9.5 Current blockage . 23
10 Other environmental factors. 24
10.1 Marine growth . 24
10.2 Tsunamis . 24
10.3 Seiches . 25
10.4 Sea ice and icebergs . 25
© ISO 2005 – All rights reserved iii

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SIST EN ISO 19901-1:2006
ISO 19901-1:2005(E)
10.5 Snow and ice accretion . 25
10.6 Miscellaneous. 25
Annex A (informative) Additional information and guidance. 26
A.1 Scope. 26
A.2 Normative references . 26
A.3 Terms and definitions. 26
A.4 Symbols and abbreviations . 26
A.5 Determining the relevant metocean parameters. 26
A.6 Water depth, tides and storm surges. 35
A.7 Wind. 36
A.8 Waves. 41
A.9 Currents . 57
A.10 Other environmental factors. 61
Annex B (informative) Discussion of wave frequency spectra. 64
B.1 The Pierson-Moskowitz spectrum. 64
B.2 The JONSWAP spectrum . 67
B.3 Comparison of Pierson-Moskowitz and JONSWAP spectra . 68
B.4 Ochi-Hubble spectra . 70
Annex C (informative) Regional information . 74
C.1 General . 74
C.2 North-west Europe . 74
C.3 West coast of Africa. 84
C.4 US Gulf of Mexico . 94
C.5 US Coast of California . 112
C.6 East coast of Canada. 118
Bibliography . 130

iv © ISO 2005 – All rights reserved

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SIST EN ISO 19901-1:2006
ISO 19901-1:2005(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 19901-1 was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore structures
for petroleum, petrochemical and natural gas industries, Subcommittee SC 7, Offshore structures.
ISO 19901 consists of the following parts, under the general title Petroleum and natural gas industries —
Specific requirements for offshore structures:
⎯ Part 1: Metocean design and operating considerations
⎯ Part 2: Seismic design procedures and criteria
⎯ Part 4: Geotechnical and foundation design considerations
⎯ Part 5: Weight control during engineering and construction
⎯ Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units
The following parts are under preparation:
⎯ Part 3: Topsides structure
⎯ Part 6: Marine operations
ISO 19901 is one of a series of standards for offshore structures. The full series consists of the following
International Standards.
⎯ ISO 19900, Petroleum and natural gas industries — General requirements for offshore structures
⎯ ISO 19901 (all parts), Petroleum and natural gas industries — Specific requirements for offshore
structures
1)
⎯ ISO 19902, Petroleum and natural gas industries — Fixed steel offshore structures
1)
⎯ ISO 19903, Petroleum and natural gas industries — Fixed concrete offshore structures

1) To be published.
© ISO 2005 – All rights reserved v

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SIST EN ISO 19901-1:2006
ISO 19901-1:2005(E)
⎯ ISO 19904-1, Petroleum and natural gas industries — Floating offshore structures — Part 1: Monohulls,
2)
semi-submersibles and spars
⎯ ISO 19904-2, Petroleum and natural gas industries — Floating offshore structures — Part 2: Tension leg
3)
platforms
⎯ ISO 19905-1, Petroleum and natural gas industries — Site-specific assessment of mobile offshore
3)
units — Part 1: Jack-ups
⎯ ISO/TR 19905-2, Petroleum and natural gas industries — Site-specific assessment of mobile offshore
3)
units — Part 2: Jack-ups commentary
3)
⎯ ISO 19906, Petroleum and natural gas industries — Arctic offshore structures

2) To be published.
3) Under preparation.
vi © ISO 2005 – All rights reserved

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SIST EN ISO 19901-1:2006
ISO 19901-1:2005(E)
Introduction
The series of International Standards applicable to types of offshore structure, ISO 19900 to ISO 19906,
constitutes a common basis covering those aspects that address design requirements and assessments of all
offshore structures used by the petroleum and natural gas industries worldwide. Through their application the
intention is to achieve reliability levels appropriate for manned and unmanned offshore structures, whatever
the type of structure and the nature or combination of the materials used.
It is important to recognize that structural integrity is an overall concept comprising models for describing
actions, structural analyses, design rules, safety elements, workmanship, quality control procedures and
national requirements, all of which are mutually dependent. The modification of one aspect of design in
isolation can disturb the balance of reliability inherent in the overall concept or structural system. The
implications involved in modifications, therefore, need to be considered in relation to the overall reliability of all
offshore structural systems.
The series of International Standards applicable to types of offshore structure is intended to provide a wide
latitude in the choice of structural configurations, materials and techniques without hindering innovation.
Sound engineering judgement is therefore necessary in the use of these International Standards.
The overall concept of structural integrity is described above. Some additional considerations apply for
metocean design and operating conditions. The term “metocean” is short for “meteorological and
oceanographic” and refers to the discipline concerned with the establishment of relevant environmental
conditions for the design and operation of offshore structures. A major consideration in the design and
operation of such a structure is the determination of actions on, and the behaviour of, the structure as a result
of winds, waves and currents.
Environmental conditions vary widely around the world. For the majority of offshore locations there are little
numerical data from historic conditions; comprehensive data often only start being collected when there is a
specific need, for example, when exploration for hydrocarbons is being considered. Despite the usually short
duration for which data are available, designers of offshore structures need estimates of extreme and
−2
abnormal environmental conditions (with an individual or joint probability of the order of 1 × 10 / year and
−3 −4
1 × 10 to 1 × 10 / year, respectively).
Even for areas like the Gulf of Mexico, offshore Indonesia and the North Sea, where there are up to 30 years
of fairly reliable measurements available, the data are insufficient for rigorous statistical determination of
appropriate extreme and abnormal environmental conditions. The determination of relevant design
parameters has therefore to rely on the interpretation of the available data by specialists, together with an
assessment of any other information, such as prevailing weather systems, ocean wave creation and regional
and local bathymetry, coupled with consideration of data from comparable locations. It is hence important to
employ specialists from both the metocean and structural communities in the determination of design
parameters for offshore structures, particularly since setting of appropriate environmental conditions depends
on the chosen option for the offshore structure.
This part of ISO 19901 provides procedures and guidance for the determination of environmental conditions
and their relevant parameters. Requirements for the determination of the actions on, and the behaviour of, a
structure in these environmental conditions are given in ISO 19901-3, ISO 19901-6, ISO 19901-7, ISO 19902,
ISO 19903, ISO 19904, ISO 19905 and ISO 19906.
Some background to, and guidance on, the use of this part of ISO 19901 is provided in informative Annex A.
The clause numbering in Annex A is the same as in the normative text to facilitate cross-referencing.
A discussion on wave spectra is provided in informative Annex B.
Regional information, where available, is provided in informative Annex C.
© ISO 2005 – All rights reserved vii

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SIST EN ISO 19901-1:2006

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SIST EN ISO 19901-1:2006
INTERNATIONAL STANDARD ISO 19901-1:2005(E)

Petroleum and natural gas industries — Specific requirements
for offshore structures —
Part 1:
Metocean design and operating considerations
1 Scope
This part of ISO 19901 gives general requirements for the determination and use of meteorological and
oceanographic (metocean) conditions for the design, construction and operation of offshore structures of all
types used in the petroleum and natural gas industries.
The requirements are divided into two broad types:
a) those that relate to the determination of environmental conditions in general, together with the metocean
parameters that are required to adequately describe them;
b) those that relate to the characterization and use of metocean parameters for the design, the construction
activities or the operation of offshore structures.
The environmental conditions and metocean parameters discussed comprise
⎯ extreme and abnormal values of metocean parameters that recur with given return periods that are
considerably longer than the design service life of the structure,
⎯ long-term distributions of metocean parameters, in the form of cumulative, conditional, marginal or joint
statistics of metocean parameters, and
⎯ normal environmental conditions that are expected to occur frequently during the design service life of the
structure.
Metocean parameters are applicable to
⎯ the determination of actions and action effects for the design of new structures,
⎯ the determination of actions and action effects for the assessment of existing structures,
⎯ the site-specific assessment of mobile offshore units,
⎯ the determination of limiting environmental conditions, weather windows, actions and action effects for
pre-service and post-service situations (i.e. fabrication, transportation and installation or decommissioning
and removal of a structure), and
⎯ the operation of the platform, where appropriate.
[1]
NOTE Specific metocean requirements for tension leg platforms are to be contained in ISO 19904-2 , for site-
[2] [3]
specific assessment of jack-ups in ISO 19905-1 , for arctic structures in ISO 19906 and for topsides structures in
[4]
ISO 19901-3 .
© ISO 2005 – All rights reserved 1

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SIST EN ISO 19901-1:2006
ISO 19901-1:2005(E)
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 19900, Petroleum and natural gas industries — General requirements for offshore structures
4)
ISO 19902, Petroleum and natural gas industries — Fixed steel offshore structures
ISO 19903, Petroleum and natural gas industries — Fixed concrete offshore structures
ISO 19904-1, Petroleum and natural gas industries — Floating offshore structures — Part 1: Monohulls, semi-
submersibles and spars
3 Terms and definitions
For the purpose of this document, the terms and definitions given in ISO 19900 and the following apply.
3.1
abnormal value
design value of a parameter of abnormal severity used in accidental limit state checks in which a structure is
intended not to suffer complete loss of integrity
−3 −4
NOTE Abnormal events have probabilities of the order of 10 to 10 per annum. In the limit state checks, some or
all of the partial factors are set to 1,0.
3.2
chart datum
local datum used to fix water depths on a chart or tidal heights over an area
NOTE Chart datum is usually an approximation to the level of the lowest astronomical tide.
3.3
conditional distribution
conditional probability
statistical distribution (probability) of the occurrence of a variable A, given that other variables B, C, … have
certain assigned values
NOTE The conditional probability of A given that B, C, …
...