EN ISO 19901-7:2026

SLOVENSKI STANDARD
01-oktober-2026
Posebne zahteve za naftne ploščadi - 7. del: Sistemi za vzdrževanje postaj na
plavajočih strukturah in premičnih enotah (ISO 19901-7:2026)
Specific requirements for offshore structures - Part 7: Stationkeeping systems for floating
offshore structures and mobile offshore units (ISO 19901-7:2026)
Öl- und Gasindustrie einschließlich kohlenstoffarmer Energieträger - Spezielle
Anforderungen für Offshore-Bauwerke - Teil 7: Positions-Erhaltungssysteme für
schwimmende Offshore-Bauwerke und mobile Offshore-Einheiten (ISO 19901-7:2026)
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-
7:2026)
Ta slovenski standard je istoveten z: EN ISO 19901-7:2026
ICS:
75.180.10 Oprema za raziskovanje, Exploratory, drilling and
vrtanje in odkopavanje extraction equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 19901-7
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2026
EUROPÄISCHE NORM
ICS 75.180.10 Supersedes EN ISO 19901-7:2013
English Version
Specific requirements for offshore structures - Part 7:
Stationkeeping systems for floating offshore structures
and mobile offshore units (ISO 19901-7:2026)
Exigences spécifiques relatives aux structures en mer - Öl- und Gasindustrie einschließlich kohlenstoffarmer
Partie 7: Systèmes de maintien en position des Energieträger - Spezielle Anforderungen für Offshore-
structures en mer flottantes et des unités mobiles en Bauwerke - Teil 7: Positions-Erhaltungssysteme für
mer (ISO 19901-7:2026) schwimmende Offshore-Bauwerke und mobile
Offshore-Einheiten (ISO 19901-7:2026)
This European Standard was approved by CEN on 5 June 2026.

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, Türkiye 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
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 19901-7:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 19901-7:2026) has been prepared by Technical Committee ISO/TC 67 "Oil and
gas industries including lower carbon energy" in collaboration with Technical Committee CEN/TC 12
“Oil and gas industries including lower carbon energy” the secretariat of which is held by NEN.
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 January 2027, and conflicting national standards shall
be withdrawn at the latest by January 2027.
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.
This document supersedes EN ISO 19901-7:2013.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
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, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 19901-7:2026 has been approved by CEN as EN ISO 19901-7:2026 without any
modification.
International
Standard
ISO 19901-7
Third edition
Specific requirements for offshore
2026-07
structures —
Part 7:
Stationkeeping systems for floating
offshore structures and mobile
offshore units
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 19901-7:2026(en) © ISO 2026

ISO 19901-7:2026(en)
© ISO 2026
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: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 19901-7:2026(en)
Contents Page
Foreword .vi
Introduction .vii
1 Scope . 1
2 Normative references . 2
3 Terms, definitions, symbols and abbreviated terms .3
3.1 Terms and definitions .3
3.2 Symbols . 12
3.3 Abbreviated terms . 13
4 Mooring hardware . 14
4.1 General .14
4.2 Off-vessel mooring line components . 15
4.2.1 General . 15
4.2.2 Anchors . 15
4.2.3 Chain . 15
4.2.4 Fibre rope. 15
4.2.5 Steel wire rope . 15
4.2.6 Connecting hardware .16
4.2.7 Buoys . .16
4.2.8 Clump weights .16
4.2.9 Mooring connectors . .16
4.2.10 Disconnectable turret buoy .17
4.3 On-vessel mooring line components .17
4.3.1 General .17
4.3.2 Fairleads . .17
4.3.3 Bending shoes .17
4.3.4 Chain stoppers .17
4.3.5 Uni-joints .17
4.3.6 Turret .17
4.4 On-vessel tensioning equipment .18
4.5 Monitoring equipment .18
4.5.1 General .18
4.5.2 Line tension or line payout .18
4.5.3 Floating structure position and heading .19
5 Metocean and other site data . 19
5.1 General .19
5.2 Metocean data .19
5.2.1 General .19
5.2.2 Wave data .19
5.2.3 Wind data . 20
5.2.4 Current data. 20
5.3 Bathymetry . 20
5.4 Geotechnical and geophysical data . 20
5.5 Marine growth .21
5.6 Physicochemical parameters .21
5.7 Ice-related .21
6 Design and site-specific assessment of stationkeeping systems .21
6.1 General .21
6.2 Functional requirements .21
6.3 Safety requirements . 22
6.4 Planning requirements . 23
6.4.1 General . 23
6.4.2 Design basis . 23
6.4.3 Design practices . 23

iii
ISO 19901-7:2026(en)
6.4.4 Installation considerations at design stage .24
6.4.5 Integrity management strategy .24
6.5 Rules and regulations . 25
6.6 Independent verification for permanent systems . 25
6.7 Numerical tools . 25
6.8 Design situations . 25
6.8.1 Limit states . 25
6.8.2 Analysis cases for ultimate limit state . 26
6.8.3 Analysis cases for serviceability limit state . 28
6.8.4 Analysis cases for fatigue limit state. 29
6.8.5 Analysis cases for abnormal and accidental limit states . 30
6.8.6 Analysis cases for temporary phases . 30
7 Design and site-specific assessment criteria .31
7.1 Safety factors for mooring component strength .31
7.1.1 Line tensions .31
7.1.2 Safety factors for buoyancy elements . 33
7.1.3 Anchor holding capacity safety factors . 33
7.2 Vessel offsets and heading . 35
7.3 Requirements for clearances . 35
7.3.1 General . 35
7.3.2 Mooring line with seabed (thrash zone) . 35
7.3.3 Mooring line with sea surface . 36
7.3.4 Mooring line with hull . 36
7.3.5 Mooring line with riser, umbilical, mooring line, pipeline, seabed assets and
exclusion zones . 36
7.3.6 Submerged turret buoy .37
7.3.7 Anchor with mooring line, pipeline, seabed assets and exclusion zones .37
7.4 Safety factors for mooring component fatigue resistance .37
8 Analysis . .40
8.1 General . 40
8.2 Analysis methods .41
8.3 Coupling effects .41
8.4 Environmental loads on the floating structure .42
8.4.1 General .42
8.4.2 Wave forces .42
8.4.3 Wind forces .42
8.4.4 Current forces and VIM .43
8.5 Environmental loads on mooring lines and risers .43
8.6 Mooring analysis for strength, offsets and clearances .43
8.6.1 Basic considerations .43
8.6.2 Extreme value statistics .43
8.6.3 Design values for responses to transient wind squalls . 44
8.6.4 Mitigating mooring line trenching effects on AHC . 44
8.7 Mooring analysis for fatigue. 44
8.7.1 Basic considerations . 44
8.7.2 Analysis approach . 44
8.7.3 Fatigue damage calculation methods .45
8.8 Response based analysis .47
9 Dynamic positioning and thruster-assisted mooring. 47
9.1 General .47
9.1.1 Dynamic positioning .47
9.1.2 Thruster assisted mooring. 48
9.2 DP and TAM equipment classes . 48
9.3 Available effective thrust . 49
9.4 Determination of allowable thrust . 49
9.5 Load sharing of TAM system . 49
9.5.1 General . 49

iv
ISO 19901-7:2026(en)
9.5.2 Mean load reduction method . 49
9.5.3 Weathervaning structures . 50
9.5.4 System dynamic analysis . 50
9.6 Failure mode and effects analysis . 50
9.7 Design, test and maintenance .51
9.8 Operating personnel .51
9.9 Determination of stationkeeping capability .51
10 Installation, test load and as-installed survey . 51
10.1 General .51
10.2 Installation considerations and storm-safe criteria .52
10.3 Mooring line handling and installation procedure .52
10.4 Test loading requirements . 53
10.4.1 General . 53
10.4.2 Anchor test load for permanent mooring systems . 53
10.4.3 Anchor test load for mobile mooring systems . 53
10.5 Installation tolerances . 53
10.6 Traceability records . 54
10.7 As-installed survey and establishment of as-installed capacity . 54
11 Integrity management, survey and inspection, and monitoring .55
11.1 Integrity management . 55
11.2 Surveys and inspections . 55
11.2.1 In-service inspection program . 55
11.2.2 As-built inspection . 55
11.2.3 Annual survey . 55
11.2.4 5-year survey . 56
11.3 Conformity assessment .57
11.4 Monitoring . 58
11.4.1 Position and heading monitoring . 58
11.4.2 Line failure detection . 58
Annex A (informative) Additional information and guidance .59
Annex B (normative) Regional requirements and supporting information .140
Bibliography .185

v
ISO 19901-7:2026(en)
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.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 67, Oil and gas industries including lower
carbon energy, Subcommittee SC 7, Offshore structures, in collaboration with the European Committee for
Standardization (CEN) Technical Committee CEN/TC 12, Oil and gas industries including lower carbon energy,
in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 19901-7:2013), which has been technically
revised.
The main changes are as follows:
— addition of requirements for a mooring integrity management system;
— emphasis on the definition of the operator's expectations on the performance standard;
— inclusion of fibre ropes as a standard material such as chain and steel wire ropes;
— alignment of text relating to the geotechnical design of anchors with ISO 19901-4;
— inclusion of guidance on OPB (out of plane bending) fatigue and squall design cases.
A list of all parts in the ISO 19901 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

vi
ISO 19901-7:2026(en)
Introduction
The International Standards on offshore structures prepared by TC 67 (i.e. ISO 19900, the ISO 19901 series,
ISO 19902, ISO 19903, ISO 19904-1, the ISO 19905 series, ISO 19906) constitute a common basis covering
those aspects that address design requirements and assessments of offshore structures used by the oil and
gas industries worldwide. The intention in their application is to achieve reliability levels appropriate for
manned and unmanned offshore structures, irrespective type of structure and the nature or combination of
materials used.
It is important to recognize that structural integrity is a concept comprised of models that describe 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 design or structural system. The implications
involved in modifications therefore should be considered in relation to the overall reliability of all offshore
structural systems.
The International Standards on offshore structures prepared by TC 67 are intended to provide a wide
breadth of choice for structural configurations, materials and techniques without hindering innovation.
Informed engineering judgement is therefore necessary in the use of these International Standards.
This document 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 energy production platforms (with and without storage) 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 and flotels) and construction units (such as heavy lift vessels and
pipelay units).
This document assumes that permanently moored hydrocarbon production systems that are equipped
with stationkeeping systems as a minimum have the ability to both shut-in wells and the facility in case of
emergency (e.g. emergency shut-down valves on the seabed), otherwise the consequence of mooring failure
can be significantly different.
Stationkeeping is a generic term covering systems for keeping a floating structure, which is under the
constant influence of external actions, either at a pre-defined location or at a pre-defined heading or both
with limited excursions. Stationkeeping systems resist external actions by means of any of the following:
— mooring systems (e.g. spread mooring systems or single point mooring systems);
— dynamic positioning systems (generally consisting of thrusters)
— a combination of mooring system and thrusters (thruster assisted mooring systems).
The external actions generally consist of wind, wave, current and ice actions on the floating structure,
mooring and risers.
The procedures for the design of permanent or site-specific assessment of mobile mooring systems specified
in this document are based on a deterministic approach where mooring system responses (such as line
tensions, vessel offsets, and anchor loads) are evaluated for a design environment defined by an annual
probability of exceedance or return period. Mooring system responses are then checked against specified
requirements for mooring strength, offsets and orientation, clearances, anchor capacity, fatigue resistance,
etc. The minimum specified requirements are defined either in this document or by the operator if more
stringent.
NOTE Stationkeeping systems designed based on this deterministic approach can have differing levels of
reliability.
For moored structures (vessels), system responses are calculated and compared to minimum specified
requirements for:
— Ultimate limit states (ULS): mooring component strength. Vessel offset, orientation, and clearance
constraints. Herein the ULS includes both intact and single failure condition for stationkeeping systems.

vii
ISO 19901-7:2026(en)
— Serviceability limit states (SLS): vessel offset, orientation, and clearance constraints. For mooring
components this includes clearances with the vessel, risers, umbilicals, seabed, water surface, field
infrastructure, exclusion zones, etc.
— Fatigue limit states (FLS) : cumulative mooring component fatigue damage.
— Accidental and abnormal limit state (ALS): no criteria are given for accidental or abnormal limit state
which are left to operator decision or local authorities requirements.
The methodology described in this document identifies a set of coherent analysis techniques 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 specified in this document.
Descriptions of characteristics and typical components found in these systems are given in Annex A.
Some background to, and guidance on, the use of this document is provided in Annex A. The clause numbering
in Annex A is the same as in the main text to facilitate cross-referencing.
Regional information, where available, is provided in Annex B.

viii
International Standard ISO 19901-7:2026(en)
Specific requirements for offshore structures —
Part 7:
Stationkeeping systems for floating offshore structures and
mobile offshore units
1 Scope
This document specifies methodologies for:
a) the design, analysis and evaluation of stationkeeping systems for floating offshore structures;
b) the assessment of stationkeeping systems for site-specific applications of mobile offshore units and
construction units.
Originally developed for floating structures used in the oil and gas industry, this document is now also used
in the renewable energy sector. The extent of application of this document to floating structures used in
other industries is at the discretion of the relevant standard entity and its users. For example, IEC 61400-3-2
for floating wind applies this document to determine stationkeeping system responses while incorporating
its own load conditions, safety factors, and environmental return periods.
This document is applicable to the following types of stationkeeping systems, which are either covered
directly in this document or through reference to other guidelines:
— spread mooring syste
...