SIST EN ISO 19901-7:2013

Petroleum and natural gas industries - Specific requirements for offshore structures - Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units (ISO 19901-7:2013)

This part of ISO 19901 specifies methodologies for
a) the design, analysis and evaluation of stationkeeping systems for floating structures used by the oil and gas industries to support
1) production,
2) storage,
3) drilling, well intervention and production,
4) production and storage,
5) drilling, well intervention, production and storage, and
b) the assessment of stationkeeping systems for site-specific applications of mobile offshore units (e.g. mobile offshore drilling units, construction units, and pipelay units). Most stationkeeping systems used with the class of floating structures covered by a) are termed “permanent mooring systems”, for which this part of ISO 19901 is applicable to all aspects of the life cycle and includes requirements relating to the manufacture of mooring components, as well as considerations for in-service inspections. Most stationkeeping systems used with mobile offshore units, the class covered by b), are termed “mobile mooring systems”. Throughout this part of ISO 19901, the term “floating structure”, sometimes shortened to “structure”, is used as a generic term to indicate any member of the two classes, a) and b). This part of ISO 19901 is applicable to the following types of stationkeeping systems, which are either covered directly in this part of ISO 19901 or through reference to other guidelines:
- spread moorings (catenary, taut-line and semi-taut-line moorings);
- single point moorings, anchored by spread mooring arrangements;
- dynamic positioning systems;
- thruster-assisted moorings.
Descriptions of the characteristics and of typical components of these systems are given in Annex A. The requirements of this part of ISO 19901 mainly address spread mooring systems and single point mooring systems with mooring lines composed of steel chain and wire rope. This part of ISO 19901 also provides guidance on the application of the methodology to synthetic fibre rope mooring systems, and includes additional requirements related to the unique properties of synthetic fibre ropes. This part of ISO 19901 is applicable to single anchor leg moorings (SALMs) and other single point mooring systems (e.g. tower soft yoke systems) only to the extent to which the requirements are relevant. This part of ISO 19901 is not applicable to the vertical moorings of tension leg platforms (TLPs). The methodology described in this part of ISO 19901 identifies a set of coherent analysis tools that, combined with an understanding of the site-specific metocean conditions, the characteristics of the floating structure under consideration, and other factors, can be used to determine the adequacy of the stationkeeping system to meet the functional requirements of this part of ISO 19901.

Erdöl- und Erdgasindustrie - Spezielle Anforderungen an Offshore-Bauwerke - Teil 7: Betriebssysteme für die Stationsunterhalte schwimmender Anlagen und mobiler Offshore-Einheiten (ISO 19901-7:2013)

Industries du pétrole et du gaz naturel - Exigences spécifiques relatives aux structures en mer - Partie 7: Systèmes de maintien en position des structures en mer flottantes et des unités mobiles en mer (ISO 19901-7:2013)

L'ISO 19901-7:2013 spécifie des méthodologies pour:
la conception, l'analyse et l'évaluation des systèmes de maintien en position des structures flottantes que les industries du pétrole et du gaz utilisent pour la production, le stockage, le forage, l'intervention sur un puits et la production, la production et le stockage, le forage, l'intervention sur un puits et la production et le stockage, et
l'évaluation des systèmes de maintien en position pour les applications spécifiques au site des unités mobiles en mer (unités mobiles de forage en mer, unités de construction et unités de pose de pipelines, par exemple).
L'ISO 19901-7:2013 est applicable aux types de systèmes suivants de maintien en position qui sont couverts soit directement dans l'ISO 19901-7:2013, soit par référence à d'autres lignes directrices:
ancrages étalés (ancrages caténaires, tendus et semi-tendus);
ancrages en un seul point, ancrés par des systèmes d'ancrage étalés;
systèmes de positionnement dynamique;
ancrages assistés par des propulseurs.
Une annexe informative décrit les caractéri      stiques et les composants classiques de ces systèmes.
Les exigences de l'ISO 19901-7:2013 concernent principalement les systèmes d'ancrage étalés et en un seul point dont les lignes d'ancrage sont composées de chaînes et de câbles en acier. L'ISO 19901-7:2013 fournit également des lignes directrices pour l'application de la méthodologie aux systèmes d'ancrage à cordage en fibres synthétiques, ainsi que des exigences supplémentaires liées aux propriétés spécifiques de ces cordages en fibres synthétiques.
L'ISO 19901-7:2013 s'applique aux ancrages sur point unique avec une seule tige d'ancre (SALM) et aux autres systèmes d'ancrage en un seul point (systèmes d'ancrage souple pour tours fixes, par exemple), uniquement dans la mesure où les exigences sont pertinentes pour ces systèmes.
L'ISO 19901-7:2013 ne s'applique pas aux ancrages verticaux des plates-formes à ancrage tendu (TLP).

Industrija za predelavo nafte in zemeljskega plina - Posebne zahteve za naftne ploščadi - 7. del: Sistemi za vzdrževanje postaj na plavajočih strukturah in premičnih enotah (ISO 19901-7:2013)

Ta del standarda ISO 19901 določa metodologije za:
a) načrtovanje, analizo in vrednotenje sistemov za vzdrževanje postaj na plavajočih strukturah, ki se uporabljajo vi industriji za predelavo nafte in zemeljskega plina za podporo
1. proizvodnje,
2. skladiščenja,
3. vrtanja, intervencij in proizvodnje v vrtinah,
4. proizvodnje in skladiščenja,
5. vrtanja, intervencij, proizvodnje in skladiščenja v vrtinah, ter
b) oceno vzdrževalnih sistemov za uporabo glede na lokacijo na premičnih priobalnih enot (npr. premične plavajoče vrtalne ploščadi, gradbene enote in enote za polaganje cevi). Večina vzdrževalnih sistemov, ki se uporabljajo pri razredu plavajočih struktur, zajetih v točki a), imenujemo »stalni sistemi za zasidranje«; zanje velja ta del standarda ISO 19901 za vse vidike življenjskega cikla, pri čemer so vključene zahteve v zvezi z izdelavo komponent za zasidranje ter upoštevana možnost inšpekcijskih pregledov med obratovanjem. Večina vzdrževalnih sistemov, ki se uporabljajo pri premičnih priobalnih enotah (ta razred zajema točka b)), se imenuje »premični sistemi za zasidranje«. V tem delu standarda ISO 19901 se izraz »plavajoča struktura«, ki je včasih skrajšan v »struktura«, včasih uporablja kot splošen izraz za katerega koli člana razredov a) in b). Ta del standarda ISO 19901 velja za naslednje vrste vzdrževalnih sistemov, ki so neposredno zajete v tem delu standarda ISO 19901 ali pa so zajete prek sklicevanja na druge smernice:
– razširitev zasidranja (vozna mreža, napeta linija in polnapeta linija);
– enotočkovno zasidranje z razširjenimi prilagoditvami;
– sistemi dinamičnega pozicioniranja;
– motorno podprto zasidranje.
Opisi lastnosti in tipičnih komponent teh sistemov so navedeni v dodatku A. Zahteve tega dela standarda ISO 19901 obravnavajo predvsem razširjene sisteme zasidranja in enotočkovne sisteme zasidranja z linijami, sestavljenimi iz jeklene verige in žičnate vrvi. Ta del standarda ISO 19901 zagotavlja tudi smernice za uporabo metodologije za sisteme zasidranja z vrvmi iz sintetičnih vlaken in vključuje dodatne zahteve v zvezi z edinstvenimi lastnostmi vrvi iz sintetičnih vlaken. Ta del standarda ISO 19901 velja za SALM in druge enotočkovne sisteme zasidranja (npr. sistemi TSY) samo do mere, do katere so zadevne zahteve še primerne. Ta del standarda ISO 19901 ne velja za navpično zasidranje TLP. V tem delu standarda ISO 19901 opisana metodologija določa zbirko skladnih orodij za analizo, ki se v kombinaciji z razumevanjem meteoroloških in oceanografskih pogojev glede na lokacijo, lastnostmi obravnavane plavajoče konstrukcije in drugih dejavnikov lahko uporabljajo za določitev primernosti vzdrževalnih sistemov, da se zadovoljijo funkcionalne zahteve tega dela standarda ISO 19901.

General Information

• Status: Published
• Public Enquiry End Date: 24-Jun-2011
• Publication Date: 13-May-2013
• ICS: 75.180.10 - Exploratory, drilling and extraction equipment
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 10-May-2013
• Due Date: 15-Jul-2013
• Completion Date: 14-May-2013
• Ref Project: EN ISO 19901-7:2013 - Petroleum and natural gas industries - Specific requirements for offshore structures - Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units (ISO 19901-7:2013)

Relations

• Revised: SIST EN ISO 19901-7:2006 - Petroleum and natural gas industries - Specific requirements for offshore structures - Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units (ISO 19901-7:2005)
• Effective Date: 12-Feb-2011
• Revises: oSIST prEN ISO 19901-7:2018 - Petroleum and natural gas industries - Specific requirements for offshore structures - Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units (ISO/DIS 19901-7:2017)
• Effective Date: 18-Jan-2023
• Revises: oSIST prEN ISO 19901-7:2018 - Petroleum and natural gas industries - Specific requirements for offshore structures - Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units (ISO/DIS 19901-7:2017)
• Effective Date: 19-Jan-2023
• Replaces: SIST EN ISO 19901-7:2006 - Petroleum and natural gas industries - Specific requirements for offshore structures - Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units (ISO 19901-7:2005)
• Effective Date: 01-Jun-2013
• Revised: oSIST prEN ISO 19901-7:2018 - Petroleum and natural gas industries - Specific requirements for offshore structures - Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units (ISO/DIS 19901-7:2017)
• Effective Date: 01-Jan-2014
• Replaces: SIST EN ISO 19901-7:2006 - Petroleum and natural gas industries - Specific requirements for offshore structures - Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units (ISO 19901-7:2005)
• Effective Date: 08-Jun-2022

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 19901-7:2013
01-junij-2013
1DGRPHãþD
SIST EN ISO 19901-7:2006
,QGXVWULMD]DSUHGHODYRQDIWHLQ]HPHOMVNHJDSOLQD3RVHEQH]DKWHYH]DQDIWQH
SORãþDGLGHO6LVWHPL]DY]GUåHYDQMHSRVWDMQDSODYDMRþLKVWUXNWXUDKLQ
SUHPLþQLKHQRWDK,62
Petroleum and natural gas industries - Specific requirements for offshore structures -
Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units
(ISO 19901-7:2013)
Erdöl- und Erdgasindustrie - Spezielle Anforderungen an Offshore-Bauwerke - Teil 7:
Betriebssysteme für die Stationsunterhalte schwimmender Anlagen und mobiler Offshore
-Einheiten (ISO 19901-7:2013)
Industries du pétrole et du gaz naturel - Exigences spécifiques relatives aux structures
en mer - Partie 7: Systèmes de maintien en position des structures en mer flottantes et
des unités mobiles en mer (ISO 19901-7:2013)
Ta slovenski standard je istoveten z: EN ISO 19901-7:2013
ICS:
75.180.10 Oprema za raziskovanje in Exploratory and extraction
odkopavanje equipment
SIST EN ISO 19901-7:2013 en,fr
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 19901-7:2013

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SIST EN ISO 19901-7:2013


EUROPEAN STANDARD
EN ISO 19901-7

NORME EUROPÉENNE

EUROPÄISCHE NORM
May 2013
ICS 75.180.10 Supersedes EN ISO 19901-7:2005
English Version
Petroleum and natural gas industries - Specific requirements for
offshore structures - Part 7: Stationkeeping systems for floating
offshore structures and mobile offshore units (ISO 19901-
7:2013)
Industries du pétrole et du gaz naturel - Exigences Erdöl- und Erdgasindustrie - Spezielle Anforderungen an
spécifiques relatives aux structures en mer - Partie 7: Offshore-Anlagen - Teil 7: Betriebssysteme für das
Systèmes de maintien en position des structures en mer Positionshalten schwimmender Anlagen und mobiler
flottantes et des unités mobiles en mer (ISO 19901-7:2013) Offshore-Einheiten (ISO 19901-7:2013)
This European Standard was approved by CEN on 5 January 2013.

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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 19901-7:2013: E
worldwide for CEN national Members.

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SIST EN ISO 19901-7:2013
EN ISO 19901-7:2013 (E)
Contents Page
Foreword .3
2

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SIST EN ISO 19901-7:2013
EN ISO 19901-7:2013 (E)
Foreword
This document (EN ISO 19901-7:2013) 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 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 November 2013, and conflicting national standards shall be withdrawn
at the latest by November 2013.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 19901-7:2005.
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, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 19901-7:2013 has been approved by CEN as EN ISO 19901-7:2013 without any modification.
3

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SIST EN ISO 19901-7:2013

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SIST EN ISO 19901-7:2013

INTERNATIONAL ISO
STANDARD 19901-7
Second edition
2013-05-01

Petroleum and natural gas industries —
Specific requirements for offshore
structures —
Part 7:
Stationkeeping systems for floating
offshore structures and mobile offshore
units
Industries du pétrole et du gaz naturel — Exigences spécifiques
relatives aux structures en mer —
Partie 7: Systèmes de maintien en position des structures en mer
flottantes et des unités mobiles en mer




Reference number
ISO 19901-7:2013(E)
©
ISO 2013

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SIST EN ISO 19901-7:2013
ISO 19901-7:2013(E)

COPYRIGHT PROTECTED DOCUMENT


©  ISO 2013
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56  CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland

ii © ISO 2013 – All rights reserved

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SIST EN ISO 19901-7:2013
ISO 19901-7:2013(E)
Contents Page
Foreword . v
Introduction . vii
1  Scope . 1
2  Normative references . 2
3  Terms and definitions . 2
4  Symbols and abbreviated terms . 7
4.1  Symbols . 7
4.2  Abbreviated terms . 8
5  Overall considerations . 9
5.1  Functional requirements. 9
5.2  Safety requirements . 9
5.3  Planning requirements . 10
5.4  Inspection and maintenance requirements . 10
5.5  Analytical tools . 10
6  Design requirements . 10
6.1  Exposure levels . 10
6.2  Limit states . 11
6.3  Defining design situations . 11
6.4  Design situations . 12
7  Actions. 14
7.1  General . 14
7.2  Site-specific data requirements . 14
7.3  Environmental actions on mooring lines . 15
7.4  Indirect actions . 16
8  Mooring analysis . 18
8.1  Basic considerations . 18
8.2  Floating structure offset . 19
8.3  Floating structure response . 20
8.4  Mooring line response . 25
8.5  Line tension . 26
8.6  Line length and geometry constraints . 26
8.7  Anchor forces . 27
8.8  Typical mooring configuration analysis and assessment . 27
8.9  Thruster-assisted moorings . 28
8.10  Transient analysis of floating structure motions . 29
9  Fatigue analysis . 30
9.1  Basic considerations . 30
9.2  Fatigue resistance . 30
9.3  Fatigue analysis procedure . 32
10  Design criteria . 37
10.1  Floating structure offset . 37
10.2  Line tension limit . 38
10.3  Grounded line length . 38
10.4  Anchoring systems . 38
10.5  Fatigue safety factor . 41
10.6  Corrosion and wear . 41
10.7  Clearances . 42
© ISO 2013 – All rights reserved iii

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SIST EN ISO 19901-7:2013
ISO 19901-7:2013(E)
10.8  Supporting structures .42
11  Mooring hardware .42
11.1  Mooring line components .42
11.2  Winching equipment .43
11.3  Monitoring equipment .43
12  In-service inspection, monitoring and maintenance .44
12.1  General .44
12.2  Mobile moorings .44
12.3  Permanent moorings .44
13  Dynamic positioning system .46
13.1  Basic considerations .46
13.2  Design and analysis .47
13.3  Design, test and maintenance .48
13.4  Operating personnel .48
13.5  Determination of stationkeeping capability .48
14  Synthetic fibre rope mooring .48
14.1  Basic considerations .48
14.2  Fibre rope mooring analysis .49
14.3  Fatigue analysis .50
14.4  Creep analysis .50
14.5  Design criteria .50
14.6  Model testing .51
Annex A (informative) Additional information and guidance .52
Annex B (informative) Regional information . 169
Bibliography . 176

iv © ISO 2013 – All rights reserved

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SIST EN ISO 19901-7:2013
ISO 19901-7:2013(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 19901-7 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.
This second edition cancels and replaces the first edition (ISO 19901-7:2005), which has been technically
revised.
This second edition of ISO 19901-7 includes several major additions and changes, primarily to Annex A
(informative). The largest change is the addition of detailed informative text incorporated directly from API RP
2SK on all types of anchor design. In the first edition of this International Standard, this material was
previously addressed only by reference to API RP 2SK. Informative material has also been added from
API RP 2SK regarding the analysis and mitigation of vortex-induced motions of large cylindrical hulls.
Consequently, the normative text has been modified to remove reference to API RP 2SK and to cross-
reference portions of the expanded informative annex.
The other significant change is the updating of guidance on polyester rope mooring design to conform to the
provisions of the recent amendment to API RP 2SM. The changes include new definitions of stiffness,
recognition of effective filter barriers, removal of the prohibition against the rope touching the sea floor, and
more detail on minimum tension requirements, among others. Additionally, minor corrections were made to
the text in 7.4.4 (Wind actions) and 8.3.4 (Riser considerations), and the terminology "most probable
maximum" has been standardized throughout. Finally, the Norwegian clause of Annex B has been updated at
the request of Norway, and a new Canadian clause has been added.
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 3: Topsides structure
 Part 4: Geotechnical and foundation design considerations
 Part 5: Weight control during engineering and construction
 Part 6: Marine operations
 Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units
© ISO 2013 – All rights reserved v

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SIST EN ISO 19901-7:2013
ISO 19901-7:2013(E)
The following parts are under preparation:
 Part 8: Marine soil investigations
ISO 19901 is one of a series of International 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
 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
 ISO 19905-1, Petroleum and natural gas industries — Site-specific assessment of mobile offshore
units — Part 1: Jack-ups
 ISO/TR 19905-2, Petroleum and natural gas industries — Site-specific assessment of mobile offshore
units — Part 2: Jack-ups commentary and detailed sample calculation
 ISO 19905-3, Petroleum and natural gas industries — Site-specific assessment of mobile offshore
1)
units — Part 3: Floating units
 ISO 19906, Petroleum and natural gas industries — Arctic offshore structures

1) Under preparation.
vi © ISO 2013 – All rights reserved

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SIST EN ISO 19901-7:2013
ISO 19901-7:2013(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, petrochemical and natural gas industries worldwide. Through their
application, the intention is to achieve reliability levels appropriate for manned and unmanned offshore
structures, whatever type of structure and nature or combination of 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 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.
This part of ISO 19901 was developed in response to the worldwide offshore industry’s demand for a coherent
and consistent definition of methodologies to analyse, design and evaluate stationkeeping systems used for
floating production and/or storage platforms of various types (e.g. semi-submersibles, spar platforms, ship-
shaped structures) and to assess site-specific applications of mobile offshore units (such as mobile offshore
drilling units, pipelay units, construction units).
Stationkeeping is a generic term covering systems for keeping a floating structure, which is under the constant
influence of external actions, on a pre-defined location and/or heading with limited excursions. Stationkeeping
systems resist external actions by means of any combination of the following:
 mooring systems (e.g. spread moorings or single point moorings);
 dynamic positioning systems (generally consisting of thrusters).
The external actions generally consist of wind, wave, current and ice actions on the floating structure, mooring
and/or risers.
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.
Regional information, where available, is provided in informative Annex B.

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SIST EN ISO 19901-7:2013

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SIST EN ISO 19901-7:2013
INTERNATIONAL STANDARD ISO 19901-7:2013(E)

Petroleum and natural gas industries — Specific requirements
for offshore structures —
Part 7:
Stationkeeping systems for floating offshore structures and
mobile offshore units
1 Scope
This part of ISO 19901 specifies methodologies for
a) the design, analysis and evaluation of stationkeeping systems for floating structures used by the oil and
gas industries to support
1) production,
2) storage,
3) drilling, well intervention and production,
4) production and storage,
5) drilling, well intervention, production and storage, and
b) the assessment of stationkeeping systems for site-specific applications of mobile offshore units (e.g.
mobile offshore drilling units, construction units, and pipelay units).
Most stationkeeping systems used with the class of floating structures covered by a) are termed “permanent
mooring systems”, for which this part of ISO 19901 is applicable to all aspects of the life cycle and includes
requirements relating to the manufacture of mooring components, as well as considerations for in-service
inspections. Most stationkeeping systems used with mobile offshore units, the class covered by b), are termed
“mobile mooring systems”. Throughout this part of ISO 19901, the term “floating structure”, sometimes
shortened to “structure”, is used as a generic term to indicate any member of the two classes, a) and b).
This part of ISO 19901 is applicable to the following types of stationkeeping systems, which are either covered
directly in this part of ISO 19901 or through reference to other guidelines:
 spread moorings (catenary, taut-line and semi-taut-line moorings);
 single point moorings, anchored by spread mooring arrangements;
 dynamic positioning systems;
 thruster-assisted moorings.
Descriptions of the characteristics and of typical components of these systems are given in Annex A.
The requirements of this part of ISO 19901 mainly address spread mooring systems and single point mooring
systems with mooring lines composed of steel chain and wire rope. This part of ISO 19901 also provides
© ISO 2013 – All rights reserved 1

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SIST EN ISO 19901-7:2013
ISO 19901-7:2013(E)
guidance on the application of the methodology to synthetic fibre rope mooring systems, and includes
additional requirements related to the unique properties of synthetic fibre ropes.
This part of ISO 19901 is applicable to single anchor leg moorings (SALMs) and other single point mooring
systems (e.g. tower soft yoke systems) only to the extent to which the requirements are relevant.
This part of ISO 19901 is not applicable to the vertical moorings of tension leg platforms (TLPs).
The methodology described in this part of ISO 19901 identifies a set of coherent analysis tools that, combined
with an understanding of the site-specific metocean conditions, the characteristics of the floating structure
under consideration, and other factors, can be used to determine the adequacy of the stationkeeping system
to meet the functional requirements of this part of ISO 19901.
NOTE For moorings deployed in ice-prone environments, additional requirements are given in ISO 19906.
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 amendment
...