SIST EN ISO 19905-3:2022

Petroleum and natural gas industries - Site-specific assessment of mobile offshore units - Part 3: Floating units (ISO 19905-3:2021)

This document specifies requirements and recommendations for the site-specific assessment of mobile floating units for use in the petroleum and natural gas industries. It addresses the installed phase, at a specific site, of manned non-evacuated, manned evacuated and unmanned mobile floating units.
This document addresses mobile floating units that are monohull (e.g. ship-shaped vessels or barges); column-stabilized, commonly referred to as semi-submersibles; or other hull forms (e.g. cylindrical/conical shaped). It is not applicable to tension leg platforms. Stationkeeping can be provided by a mooring system, a thruster assisted mooring system, or dynamic positioning. The function of the unit can be broad, including drilling, floatel, tender assist, etc. In situations where hydrocarbons are being produced, there can be additional requirements.
This document does not address all site considerations, and certain specific locations can require additional assessment.
This document is applicable only to mobile floating units that are structurally sound and adequately maintained, which is normally demonstrated through holding a valid RCS classification certificate.
This document does not address design, transportation to and from site, or installation and removal from site.
This document sets out the requirements for site-specific assessments, but generally relies on other documents to supply the details of how the assessments are to be undertaken. In general:
-   ISO 19901 7 is referenced for the assessment of the stationkeeping system;
-   ISO 19904 1 is referenced to determine the effects of the metocean actions on the unit;
-   ISO 19906 is referenced for arctic and cold regions;
-   the hull structure and air gap are assessed by use of a comparison between the site-specific metocean conditions and its design conditions, as set out in the RCS approved operations manual;
-   ISO 13624 1 and ISO/TR 13624 2[1] are referenced for the assessment of the marine drilling riser of mobile floating drilling units. Equivalent alternative methodologies can be used;
-   IMCA M 220 is referenced for developing an activity specific operating guidelines. Agreed alternative methodologies can be used.
NOTE    RCS rules and the IMO MODU code[13] provide guidance for design and general operation of mobile floating units.

Erdöl- und Erdgasindustrie - Beurteilung von mobilen Offshore-Einheiten bezüglich ihres Einsatzgebietes - Teil 3: Schwimmende Einheiten (ISO 19905-3:2021)

Industries du pétrole et du gaz naturel - Évaluation spécifique au site d'unités mobiles en mer - Partie 3: Unités flottantes (ISO 19905-3:2021)

Le présent document spécifie les exigences et les recommandations pour l'évaluation spécifique au site d'unités mobiles flottantes destinées à être utilisées dans les industries du pétrole et du gaz naturel. Il traite de la phase en place, au niveau d'un site spécifique, d'unités mobiles flottantes occupées par du personnel non évacué, occupées par du personnel évacué et non occupées par du personnel.
Le présent document traite des unités mobiles flottantes monocoques (par exemple, structures à profil de bateau ou barges); stabilisées par des colonnes, souvent désignées par le terme «structures semi-submersibles»; ou ayant d'autres formes de coque (par exemple, cylindriques/coniques). Il n'est pas applicable aux plates-formes à lignes d'ancrage verticales tendues (TLP). Le maintien en position peut être assuré par un système d'ancrage, un système d'ancrage assisté par des propulseurs, ou un système de positionnement dynamique. L'unité peut avoir plusieurs fonctions, notamment des fonctions de forage, d'hôtel flottant, de barge, etc. Dans les situations où des hydrocarbures sont produits, des exigences supplémentaires peuvent s'appliquer.
Le présent document ne traite pas de toutes les considérations relatives au site, et certains emplacements peuvent nécessiter une évaluation supplémentaire.
Le présent document n'est applicable qu'aux unités mobiles flottantes dont la structure est saine et entretenue de manière adéquate, ce qui est normalement démontré par la tenue à jour d'un certificat de classification en cours de validité, délivré par une société de classification reconnue (RCS).
Le présent document ne traite pas de la conception, du transport vers et depuis un site ou de l'installation et du retrait du site.
Le présent document spécifie les exigences pour des évaluations spécifiques aux sites, mais s'appuie généralement sur d'autres documents pour fournir les informations détaillées sur la manière dont les évaluations doivent être effectuées. En général:
—          l'ISO 19901-7 est citée en référence pour l'évaluation du système de maintien en position;
—          l'ISO 19904-1 est citée en référence pour la détermination des effets des actions océano-météorologiques sur l'unité;
—          l'ISO 19906 est citée en référence pour les régions arctiques et froides;
—          la structure de la coque et la garde d'air sont évaluées en procédant à une comparaison entre les conditions océano-météorologiques spécifiques au site et les conditions de conception de la coque, comme indiqué dans le manuel d'exploitation approuvé par une société de classification reconnue (RCS);
—          l'ISO 13624-1 et l'ISO/TR 13624-2[1] sont citées en référence pour l'évaluation des tubes prolongateurs pour les forages en mer des unités de forage mobiles flottantes. D'autres méthodologies équivalentes peuvent être utilisées;
—          l'IMCA M 220 est citée en référence pour l'élaboration d'un document d'instructions d'exploitation spécifiques à l'activité. D'autres méthodologies approuvées peuvent être utilisées.
NOTE  Les règles RCS et le code MODU de l'OMI[13] fournissent des recommandations pour la conception et l'exploitation générale des unités mobiles flottantes.

Industrija za predelavo nafte in zemeljskega plina - Ocenjevanje premičnih naftnih ploščadi na področju postavitve - 3. del: Plavajoče enote (ISO 19905-3:2021)

Ta dokument določa zahteve in priporočila za ocenjevanje premičnih plavajočih enot na področju postavitve za uporabo v industriji za predelavo nafte in zemeljskega plina. Obravnava fazo postavitve na določenem področju za neevakuirane premične plavajoče enote s posadko, evakuirane premične plavajoče enote s posadko in za premične plavajoče enote brez posadke.
Ta dokument obravnava premične plavajoče enote, ki imajo en trup (npr. plovila v obliki ladje ali čolna); ki so stolpično stabilizirane in se običajno imenujejo enote, ki so pol pod vodo; ali ki imajo druge oblike trupa (npr. cilindrične ali stožčaste oblike). Ne uporablja se za navpično zasidrane ploščadi. Vzdrževalni sistemi se lahko zagotovijo s sistemi zasidranja, sistemi motorno podprtega zasidranja ali z dinamičnim pozicioniranjem. Enota lahko opravlja raznovrstne funkcije, vključno z vrtanjem, plovnimi hoteli, ponudniki pomoči itd. V primerih proizvodnje ogljikovodikov lahko obstajajo dodatne zahteve.
Ta dokument ne obravnava vseh pogojev področja postavitve in določene specifične lokacije lahko zahtevajo dodatno ocenjevanje.
Ta dokument se uporablja samo za premične plavajoče naftne enote, ki so strukturno trdne in ustrezno vzdrževane, kar se običajno izkazuje z veljavnim certifikatom klasifikacije RCS.
Ta dokument ne obravnava načrtovanja, prevoza na področje postavitve ali z njega ali namestitve na področje postavitve in odstranitve z njega.
Ta dokument podaja zahteve za oceno na področju postavitve, vendar se na splošno sklicuje na druge dokumente glede podajanja podrobnosti o tem, kako naj poteka ocenjevanje. Splošno:
–   sklic na standard ISO 19901-7 za ocenjevanje vzdrževalnega sistema;
–   sklic na standard ISO 19904-1 za določanje učinkov meteoroloških in oceanografskih vplivov na enoto;
–   sklic na standard ISO 19906 za arktična in hladna območja;
–   struktura trupa in zračna reža se ocenita na podlagi primerjave meteoroloških in oceanografskih pogojev, ki so specifični za področje postavitve, ter njihovih projektnih pogojev, kot je opredeljeno v s strani RCS odobrenih navodilih za uporabo;
–   sklic na standarda ISO 13624-1 in ISO/TR 13624-2[1] za ocenjevanje morskih dvižnih cevi za vrtanje na premičnih plavajočih vrtalnih enotah. Uporabijo se lahko tudi enakovredne nadomestne metodologije;
–   sklic na standard IMCA M 220 za razvoj smernic za delovanje, ki so specifične za dejavnost. Uporabijo se lahko tudi dogovorjene nadomestne metodologije.
OPOMBA:    Pravila RCS in kodeks IMO MODU[13] podajajo napotke za načrtovanje in upravljanje premičnih plavajočih enot.

General Information

• Status: Published
• Public Enquiry End Date: 03-May-2022
• Publication Date: 11-Jul-2022
• ICS: 75.180.10 - Exploratory, drilling and extraction equipment
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 07-Jul-2022
• Due Date: 11-Sep-2022
• Completion Date: 12-Jul-2022
• Ref Project: EN ISO 19905-3:2022 - Petroleum and natural gas industries - Site-specific assessment of mobile offshore units - Part 3: Floating units (ISO 19905-3:2021)

Relations

• Revised: SIST EN ISO 19905-3:2020 - Petroleum and natural gas industries - Site-specific assessment of mobile offshore units - Part 3: Floating unit (ISO 19905-3:2017)
• Effective Date: 10-Nov-2021
• Replaces: SIST EN ISO 19905-3:2020 - Petroleum and natural gas industries - Site-specific assessment of mobile offshore units - Part 3: Floating unit (ISO 19905-3:2017)
• Effective Date: 06-Jul-2022

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 19905-3:2022
01-september-2022
Nadomešča:
SIST EN ISO 19905-3:2020
Industrija za predelavo nafte in zemeljskega plina - Ocenjevanje premičnih naftnih
ploščadi na področju postavitve - 3. del: Plavajoče enote (ISO 19905-3:2021)
Petroleum and natural gas industries - Site-specific assessment of mobile offshore units -
Part 3: Floating units (ISO 19905-3:2021)
Erdöl- und Erdgasindustrie - Beurteilung von mobilen Offshore-Einheiten bezüglich ihres
Einsatzgebietes - Teil 3: Schwimmende Einheiten (ISO 19905-3:2021)
Industries du pétrole et du gaz naturel - Évaluation spécifique au site d'unités mobiles en
mer - Partie 3: Unités flottantes (ISO 19905-3:2021)
Ta slovenski standard je istoveten z: EN ISO 19905-3:2022
ICS:
75.180.10 Oprema za raziskovanje, Exploratory, drilling and
vrtanje in odkopavanje extraction equipment
SIST EN ISO 19905-3:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 19905-3:2022

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SIST EN ISO 19905-3:2022


EN ISO 19905-3
EUROPEAN STANDARD

NORME EUROPÉENNE

June 2022
EUROPÄISCHE NORM
ICS 75.180.10 Supersedes EN ISO 19905-3:2019
English Version

Petroleum and natural gas industries - Site-specific
assessment of mobile offshore units - Part 3: Floating units
(ISO 19905-3:2021)
Industries du pétrole et du gaz naturel - Évaluation Erdöl- und Erdgasindustrie - Beurteilung von mobilen
spécifique au site d'unités mobiles en mer - Partie 3: Offshore-Einheiten bezüglich ihres Einsatzgebietes -
Unités flottantes (ISO 19905-3:2021) Teil 3: Schwimmende Einheiten (ISO 19905-3:2021)
This European Standard was approved by CEN on 6 June 2022.

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

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

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





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 19905-3:2022 E
worldwide for CEN national Members.

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SIST EN ISO 19905-3:2022
EN ISO 19905-3:2022 (E)
Contents Page
European foreword . 3

2

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SIST EN ISO 19905-3:2022
EN ISO 19905-3:2022 (E)
European foreword
The text of ISO 19905-3:2021 has been prepared by Technical Committee ISO/TC 67 "Materials,
equipment and offshore structures for petroleum, petrochemical and natural gas industries” of the
International Organization for Standardization (ISO) and has been taken over as EN ISO 19905-3:2022
by Technical Committee CEN/TC 12 “Materials, equipment and offshore structures for petroleum,
petrochemical and natural gas industries” 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 December 2022, and conflicting national standards
shall be withdrawn at the latest by December 2022.
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 19905-3:2019.
Any feedback and questions on this document should be directed to the users’ national standards body.
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, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 19905-3:2021 has been approved by CEN as EN ISO 19905-3:2022 without any
modification.

3

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SIST EN ISO 19905-3:2022

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SIST EN ISO 19905-3:2022
INTERNATIONAL ISO
STANDARD 19905-3
Second edition
2021-03
Petroleum and natural gas
industries — Site-specific assessment
of mobile offshore units —
Part 3:
Floating units
Industries du pétrole et du gaz naturel — Évaluation spécifique au
site d'unités mobiles en mer —
Partie 3: Unités flottantes
Reference number
ISO 19905-3:2021(E)
©
ISO 2021

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SIST EN ISO 19905-3:2022
ISO 19905-3:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

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SIST EN ISO 19905-3:2022
ISO 19905-3:2021(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3  Terms and definitions . 2
4 Abbreviated terms . 4
5 Overall considerations . 5
5.1 General . 5
5.1.1 Competency . 5
5.1.2 Planning . 5
5.1.3 Reporting . 5
5.1.4 Regulations . 5
5.1.5 Classification of unit . 5
5.2 Assessment . 6
5.3 Exposure levels . 6
5.4 Selection of limit states . 6
5.5 Determination of assessment situations . 7
5.5.1 General. 7
5.5.2 Arctic operations and ice . 8
5.5.3 Earthquake . 8
5.6 Models and analytical tools . 8
6 Data to be assembled for each site . 8
6.1 Applicability . 8
6.2 Mobile floating unit data . 8
6.3 Stationkeeping data . 9
6.3.1 General. 9
6.3.2 Moored units . 9
6.3.3 Moored units with thruster assist. 9
6.3.4 Dynamically positioned units . 9
6.4 Site data .10
6.5 Data on activity/use limitations .10
6.5.1 General.10
6.5.2 Reassessment or modification of activity/use limitations .11
6.5.3 Sources of data and types of activity/use limitations .11
6.6 Post installation data .11
7 Actions .11
8 Hull of unit .12
8.1 Strength .12
8.1.1 General.12
8.1.2 Monohull .12
8.1.3 Semi-submersible .12
8.1.4 Other hull forms .12
8.2 Air gap and freeboard .12
8.2.1 General.12
8.2.2 Monohull .13
8.2.3 Semi-submersible .13
8.2.4 Other hull forms .13
8.3 Temperature .13
8.4 Stability .14
9 Stationkeeping system .14
9.1 General .14
© ISO 2021 – All rights reserved iii

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SIST EN ISO 19905-3:2022
ISO 19905-3:2021(E)

9.2 Moored .14
9.3 Thruster assisted mooring .14
9.4 Dynamic positioning systems .14
10  Activity specific assessments .14
10.1 General .14
10.2 Assessment of site-specific activities and equipment .15
10.2.1 General.15
10.2.2 Marine drilling riser assessment .15
10.3 Risk assessment .15
10.4 Activity specific operating guidelines .15
11  Confirmation of compatibility between analysis and as-installed condition .16
Annex A (informative) Outline of an activity specific operating guideline document for a
dynamically positioned unit and a moored unit .17
Annex B (informative) Suggested process for completing a site-specific assessment of a
mobile floating unit .20
Bibliography .22
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SIST EN ISO 19905-3:2022
ISO 19905-3:2021(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.
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 documents 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).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
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, 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 19905-3:2017), which has been
technically revised.
The main changes compared to the previous edition are as follows:
— removed definitions of drift off and drive off in Clause 3 and consolidated under loss of position;
— Table 1 in Clause 5 removed and reference made to ISO 19900;
— FLS removed from 8.1.2 and 8.1.3;
— air gap requirements modified in 8.2;
— ISO 35104 referenced in 10.4;
— editorial revision.
A list of all parts in the ISO 19905 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.
© ISO 2021 – All rights reserved v

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SIST EN ISO 19905-3:2022
ISO 19905-3:2021(E)

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 addressing design requirements and assessments of all types of offshore structures used by the
petroleum and natural gas industries worldwide.
NOTE These are sometimes referred to as the ISO 19900 series on offshore structures.
Through their application, the intention is to achieve adequate structural integrity and performance
based on reliability levels appropriate for manned and unmanned offshore structures, whatever the
nature or combination of the materials used.
Structural integrity is an overall concept comprising: models for describing actions; structural
analyses; design or assessment rules; safety elements; workmanship; quality management; and
national requirements, all of which are mutually dependent. The modification of any of these elements
in isolation can cause an imbalance or inconsistency, with possible impact on the reliability inherent in
the offshore structure. The implications involved in modifying one element, therefore, are considered
in relation to all the elements and the overall reliability of the offshore structure.
The International Standards on offshore structures prepared by TC 67 are intended to provide latitude
in the choice of structural configurations, materials and techniques and to allow for innovative
solutions. Sound engineering judgement is, therefore, necessary in the use of these documents.
This document states the general principles and basic requirements for the site-specific assessment of
mobile floating units. The technical information used in the assessment primarily resides in documents
referenced herein. This document is intended to be used for assessment and not for design.
Site-specific assessment is normally carried out when an existing mobile floating unit is to be installed
at a specific site. The assessment is not intended to provide a full evaluation of the unit; it is assumed
that aspects not addressed herein have been addressed at the design stage using other practices and
standards.
The purpose of the site-specific assessment is to demonstrate the adequacy of the mobile floating
unit, its stationkeeping system and any connected systems for the applicable assessment situations
and defined limit states, taking into account the consequences of failure. The results of a site-specific
assessment should be appropriately recorded and communicated to those persons required to know or
act on the conclusions and recommendations. Alternative approaches to the site-specific assessment
can be used provided that they have been shown to give a level of reliability equivalent, or superior, to
that implicit in this document.
In this document, the following verbal forms are used:
— “shall” indicates a requirement;
— “should” indicates a recommendation;
— “can” indicates a possibility or a capability;
— “may” indicates a permission.
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SIST EN ISO 19905-3:2022
INTERNATIONAL STANDARD ISO 19905-3:2021(E)
Petroleum and natural gas industries — Site-specific
assessment of mobile offshore units —
Part 3:
Floating units
1 Scope
This document specifies requirements and recommendations for the site-specific assessment of mobile
floating units for use in the petroleum and natural gas industries. It addresses the installed phase, at a
specific site, of manned non-evacuated, manned evacuated and unmanned mobile floating units.
This document addresses mobile floating units that are monohull (e.g. ship-shaped vessels or barges);
column-stabilized, commonly referred to as semi-submersibles; or other hull forms (e.g. cylindrical/
conical shaped). It is not applicable to tension leg platforms. Stationkeeping can be provided by a
mooring system, a thruster assisted mooring system, or dynamic positioning. The function of the unit
can be broad, including drilling, floatel, tender assist, etc. In situations where hydrocarbons are being
produced, there can be additional requirements.
This document does not address all site considerations, and certain specific locations can require
additional assessment.
This document is applicable only to mobile floating units that are structurally sound and adequately
maintained, which is normally demonstrated through holding a valid RCS classification certificate.
This document does not address design, transportation to and from site, or installation and removal
from site.
This document sets out the requirements for site-specific assessments, but generally relies on other
documents to supply the details of how the assessments are to be undertaken. In general:
— ISO 19901-7 is referenced for the assessment of the stationkeeping system;
— ISO 19904-1 is referenced to determine the effects of the metocean actions on the unit;
— ISO 19906 is referenced for arctic and cold regions;
— the hull structure and air gap are assessed by use of a comparison between the site-specific
metocean conditions and its design conditions, as set out in the RCS approved operations manual;
[1]
— ISO 13624-1 and ISO/TR 13624-2 are referenced for the assessment of the marine drilling riser of
mobile floating drilling units. Equivalent alternative methodologies can be used;
— IMCA M 220 is referenced for developing an activity specific operating guidelines. Agreed alternative
methodologies can be used.
[13]
NOTE RCS rules and the IMO MODU code provide guidance for design and general operation of mobile
floating units.
2 Normative references
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.
© ISO 2021 – All rights reserved 1

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SIST EN ISO 19905-3:2022
ISO 19905-3:2021(E)

ISO 13624-1, Petroleum and natural gas industries — Drilling and production equipment — Part 1: Design
and operation of marine drilling riser equipment
ISO 19900, Petroleum and natural gas industries — General requirements for offshore structures
ISO 19901-1, Petroleum and natural gas industries — Specific requirements for offshore structures —
Part 1: Metocean design and operating considerations
ISO 19901-7, Petroleum and natural gas industries — Specific requirements for offshore structures —
Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units
ISO 19904-1, Petroleum and natural gas industries — Floating offshore structures — Part 1: Ship-shaped,
semi-submersible, spar and shallow-draught cylindrical structures
ISO 19906:2019, Petroleum and natural gas industries — Arctic offshore structures
ISO 35104, Petroleum and natural gas industries — Arctic operations — Ice
...

SLOVENSKI STANDARD
oSIST prEN ISO 19905-3:2022
01-april-2022
Industrija za predelavo nafte in zemeljskega plina - Ocenjevanje premičnih naftnih
ploščadi na področju postavitve - 3. del: Plavajoče enote (ISO 19905-3:2021)
Petroleum and natural gas industries - Site-specific assessment of mobile offshore units
- Part 3: Floating units (ISO 19905-3:2021)
Erdöl- und Erdgasindustrie - Beurteilung von mobilen Offshore-Einheiten bezüglich ihres
Einsatzgebietes - Teil 3: Schwimmende Einheiten (ISO 19905-3:2021)
Industries du pétrole et du gaz naturel - Évaluation spécifique au site d'unités mobiles en
mer - Partie 3: Unités flottantes (ISO 19905-3:2021)
Ta slovenski standard je istoveten z: prEN ISO 19905-3
ICS:
75.180.10 Oprema za raziskovanje, Exploratory, drilling and
vrtanje in odkopavanje extraction equipment
oSIST prEN ISO 19905-3:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 19905-3:2022

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oSIST prEN ISO 19905-3:2022
INTERNATIONAL ISO
STANDARD 19905-3
Second edition
2021-03
Petroleum and natural gas
industries — Site-specific assessment
of mobile offshore units —
Part 3:
Floating units
Industries du pétrole et du gaz naturel — Évaluation spécifique au
site d'unités mobiles en mer —
Partie 3: Unités flottantes
Reference number
ISO 19905-3:2021(E)
©
ISO 2021

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oSIST prEN ISO 19905-3:2022
ISO 19905-3:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
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
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ISO copyright office
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Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

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oSIST prEN ISO 19905-3:2022
ISO 19905-3:2021(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3  Terms and definitions . 2
4 Abbreviated terms . 4
5 Overall considerations . 5
5.1 General . 5
5.1.1 Competency . 5
5.1.2 Planning . 5
5.1.3 Reporting . 5
5.1.4 Regulations . 5
5.1.5 Classification of unit . 5
5.2 Assessment . 6
5.3 Exposure levels . 6
5.4 Selection of limit states . 6
5.5 Determination of assessment situations . 7
5.5.1 General. 7
5.5.2 Arctic operations and ice . 8
5.5.3 Earthquake . 8
5.6 Models and analytical tools . 8
6 Data to be assembled for each site . 8
6.1 Applicability . 8
6.2 Mobile floating unit data . 8
6.3 Stationkeeping data . 9
6.3.1 General. 9
6.3.2 Moored units . 9
6.3.3 Moored units with thruster assist. 9
6.3.4 Dynamically positioned units . 9
6.4 Site data .10
6.5 Data on activity/use limitations .10
6.5.1 General.10
6.5.2 Reassessment or modification of activity/use limitations .11
6.5.3 Sources of data and types of activity/use limitations .11
6.6 Post installation data .11
7 Actions .11
8 Hull of unit .12
8.1 Strength .12
8.1.1 General.12
8.1.2 Monohull .12
8.1.3 Semi-submersible .12
8.1.4 Other hull forms .12
8.2 Air gap and freeboard .12
8.2.1 General.12
8.2.2 Monohull .13
8.2.3 Semi-submersible .13
8.2.4 Other hull forms .13
8.3 Temperature .13
8.4 Stability .14
9 Stationkeeping system .14
9.1 General .14
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oSIST prEN ISO 19905-3:2022
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9.2 Moored .14
9.3 Thruster assisted mooring .14
9.4 Dynamic positioning systems .14
10  Activity specific assessments .14
10.1 General .14
10.2 Assessment of site-specific activities and equipment .15
10.2.1 General.15
10.2.2 Marine drilling riser assessment .15
10.3 Risk assessment .15
10.4 Activity specific operating guidelines .15
11  Confirmation of compatibility between analysis and as-installed condition .16
Annex A (informative) Outline of an activity specific operating guideline document for a
dynamically positioned unit and a moored unit .17
Annex B (informative) Suggested process for completing a site-specific assessment of a
mobile floating unit .20
Bibliography .22
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oSIST prEN ISO 19905-3:2022
ISO 19905-3:2021(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.
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 documents 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).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
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, 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 19905-3:2017), which has been
technically revised.
The main changes compared to the previous edition are as follows:
— removed definitions of drift off and drive off in Clause 3 and consolidated under loss of position;
— Table 1 in Clause 5 removed and reference made to ISO 19900;
— FLS removed from 8.1.2 and 8.1.3;
— air gap requirements modified in 8.2;
— ISO 35104 referenced in 10.4;
— editorial revision.
A list of all parts in the ISO 19905 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.
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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 addressing design requirements and assessments of all types of offshore structures used by the
petroleum and natural gas industries worldwide.
NOTE These are sometimes referred to as the ISO 19900 series on offshore structures.
Through their application, the intention is to achieve adequate structural integrity and performance
based on reliability levels appropriate for manned and unmanned offshore structures, whatever the
nature or combination of the materials used.
Structural integrity is an overall concept comprising: models for describing actions; structural
analyses; design or assessment rules; safety elements; workmanship; quality management; and
national requirements, all of which are mutually dependent. The modification of any of these elements
in isolation can cause an imbalance or inconsistency, with possible impact on the reliability inherent in
the offshore structure. The implications involved in modifying one element, therefore, are considered
in relation to all the elements and the overall reliability of the offshore structure.
The International Standards on offshore structures prepared by TC 67 are intended to provide latitude
in the choice of structural configurations, materials and techniques and to allow for innovative
solutions. Sound engineering judgement is, therefore, necessary in the use of these documents.
This document states the general principles and basic requirements for the site-specific assessment of
mobile floating units. The technical information used in the assessment primarily resides in documents
referenced herein. This document is intended to be used for assessment and not for design.
Site-specific assessment is normally carried out when an existing mobile floating unit is to be installed
at a specific site. The assessment is not intended to provide a full evaluation of the unit; it is assumed
that aspects not addressed herein have been addressed at the design stage using other practices and
standards.
The purpose of the site-specific assessment is to demonstrate the adequacy of the mobile floating
unit, its stationkeeping system and any connected systems for the applicable assessment situations
and defined limit states, taking into account the consequences of failure. The results of a site-specific
assessment should be appropriately recorded and communicated to those persons required to know or
act on the conclusions and recommendations. Alternative approaches to the site-specific assessment
can be used provided that they have been shown to give a level of reliability equivalent, or superior, to
that implicit in this document.
In this document, the following verbal forms are used:
— “shall” indicates a requirement;
— “should” indicates a recommendation;
— “can” indicates a possibility or a capability;
— “may” indicates a permission.
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oSIST prEN ISO 19905-3:2022
INTERNATIONAL STANDARD ISO 19905-3:2021(E)
Petroleum and natural gas industries — Site-specific
assessment of mobile offshore units —
Part 3:
Floating units
1 Scope
This document specifies requirements and recommendations for the site-specific assessment of mobile
floating units for use in the petroleum and natural gas industries. It addresses the installed phase, at a
specific site, of manned non-evacuated, manned evacuated and unmanned mobile floating units.
This document addresses mobile floating units that are monohull (e.g. ship-shaped vessels or barges);
column-stabilized, commonly referred to as semi-submersibles; or other hull forms (e.g. cylindrical/
conical shaped). It is not applicable to tension leg platforms. Stationkeeping can be provided by a
mooring system, a thruster assisted mooring system, or dynamic positioning. The function of the unit
can be broad, including drilling, floatel, tender assist, etc. In situations where hydrocarbons are being
produced, there can be additional requirements.
This document does not address all site considerations, and certain specific locations can require
additional assessment.
This document is applicable only to mobile floating units that are structurally sound and adequately
maintained, which is normally demonstrated through holding a valid RCS classification certificate.
This document does not address design, transportation to and from site, or installation and removal
from site.
This document sets out the requirements for site-specific assessments, but generally relies on other
documents to supply the details of how the assessments are to be undertaken. In general:
— ISO 19901-7 is referenced for the assessment of the stationkeeping system;
— ISO 19904-1 is referenced to determine the effects of the metocean actions on the unit;
— ISO 19906 is referenced for arctic and cold regions;
— the hull structure and air gap are assessed by use of a comparison between the site-specific
metocean conditions and its design conditions, as set out in the RCS approved operations manual;
[1]
— ISO 13624-1 and ISO/TR 13624-2 are referenced for the assessment of the marine drilling riser of
mobile floating drilling units. Equivalent alternative methodologies can be used;
— IMCA M 220 is referenced for developing an activity specific operating guidelines. Agreed alternative
methodologies can be used.
[13]
NOTE RCS rules and the IMO MODU code provide guidance for design and general operation of mobile
floating units.
2 Normative references
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.
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ISO 13624-1, Petroleum and natural gas industries — Drilling and production equipment — Part 1: Design
and operation of marine drilling riser equipment
ISO 19900, Petroleum and natural gas industries — General requirements for offshore structures
ISO 19901-1, Petroleum and natural gas industries — Specific requirements for offshore structures —
Part 1: Metocean design and operating considerations
ISO 19901-7, Petroleum and natural gas industries — Specific requirements for offshore structures —
Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units
ISO 19904-1, Petroleum and natural gas industries — Floating offshore structures — Part 1: Ship-shaped,
semi-submersible, spar and shallow-draught cylindrical structures
ISO 19906:2019, Petroleum and natural gas industries — Arctic offshore structures
ISO 35104, Petroleum and natural gas industries — Arctic operations — Ice management
International Marine Contractors Association, “Guidance on Operational Activity Planning”, IMCA M 220
3  Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 19900, ISO 19901-1,
ISO 19901-7, ISO 19904-1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
activity specific operating guidelines
ASOG
document that sets out the activities that need to be undertaken at specific alert level thresholds (3.4)
for specified changes in conditions
Note 1 to entry: These guidelines are in a document that sets out high level actions to be undertaken at specific
alert level thresholds.
Note 2 to entry: The ASOG for drilling operations is often called the well specific operating guideline
document (WSOG).
Note 3 to entry: An example ASOG for DP (dynamic positioning) and moored units is given in Annex A.
3.2
air gap
distance between the highest water elevation and the lowest exposed part of the primary deck structure
and permanent equipment not designed to withstand associated environmental action effects
[SOURCE: ISO 19900:2019, 3.5, modified — “structure” and “action effects” not defined herein, “and
permanent equipment” added and “for defined return period” deleted.]
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3.3
alert level
condition when certain parameters are below the lower limit, or between limits, or above the upper limit
Note 1 to entry: Alert levels are often colour-coded. The colour-coding will often be green for normal, blue for
advisory, yellow alert for reduced status, and red alert for emergency status. Parameters affecting the change
of colour-coded alert levels can be, for example, approach of limiting metocean conditions, loss of equipment
function, reduced available power levels, offset limits are reached [watch circles (3.17)], excessive vessel motions
are predicted, etc. Actions to be taken can include, for example, discontinue drilling, disconnect riser, suspend
lifts, etc.
3.4
alert level threshold
boundary between alert levels (3.3)
3.5
assessment
site-specific assessment
evaluation of a mobile floating unit and activity specific equipment to determine conformity with
specific requirements
Note 1 to entry: The specific requirements are the requirements of this document (i.e. 19905-3).
Note 2 to entry: Definition derived from ISO 19905-1:2016, 3.4.
3.6
assessment situation
mobile floating unit configuration together with the metocean and ice actions that need to be assessed
3.7
assessor
entity performing the site-specific assessment (3.5)
[SOURCE: ISO 19905-1:2016, 3.6]
3.8
extreme storm event
extreme combination of wind, wave and current conditions used for the assessment (3.5) of the mobile
floating unit
Note 1 to entry: This is the metocean event used for ULS storm assessment and varies depending on what is being
assessed. For example, the metocean event for the ULS assessment of the mooring system can be different from
that used in the ULS assessment of the hull strength or air gap.
3.9
loss of position
unintended move of a dynamically positioned or thruster-assisted vessel from its intended location
[watch circle (3.17)] relative to its set point position (3.13), generally caused by loss of stationkeeping
control or propulsion
Note 1 to entry: Loss of position can take on three main forms drift off, drive off, or force off.
3.10
operating manual
marine operations manual
latest approved document that defines the operational characteristics and capabilities of the mobile
floating unit
[SOURCE: ISO 19905-1:2016, 3.45, modified — “jack-up” has been replaced by “mobile floating unit”,
Note 1 to entry has been deleted, and “manual” replaced by “latest approved document”.]
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3.11
operator
representative of the company or companies leasing the site
Note 1 to entry: The operator is normally the oil company acting on behalf of co-licensees.
Note 2 to entry: The operator can be termed the owner or the duty holder.
[SOURCE: ISO 19900:2019, 3.35]
3.12
recognized classifi
...