Petroleum and natural gas industries - Site-specific assessment of mobile offshore units - Part 3: Floating unit (ISO 19905-3:2017)

ISO 19905-3 specifies requirements and gives guidance 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.
ISO 19905-3 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.
The requirements of ISO 19905-3 apply to the hull and stationkeeping system for all types of mobile units. The activity specific operating guideline document requirements can be modified to be appropriate to the situation being assessed.
ISO 19905-3 does not address all site considerations, and certain specific locations can require additional assessment.
ISO 19905-3 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.
ISO 19905-3 does not address design, transportation to and from site, or installation and removal from site.
ISO 19905-3 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 metocean actions on the unit;
- ISO 19906 is referenced for arctic and cold regions;
- the hull structure and airgap 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[5] is referenced for developing an activity specific operating guidelines. Agreed alternative methodologies can be used.
NOTE 1 The scope of ISO 19904‑1 specifically states that its requirements do not apply to mobile units, but the methodologies given for assessing metocean actions can be used.
NOTE 2 RCS rules and the IMO MODU code[4] 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 19905-3:2017)

Industries du pétrole et du gaz naturel - Évaluation spécifique au site d'unités mobiles en mer - Partie 3: Unité flottante (ISO 19905-3:2017)

ISO 19905-3:2017 spécifie les exigences et les lignes directrices pour l'évaluation spécifique au site d'unités mobiles flottantes à utiliser dans les industries du pétrole et du gaz naturel. Elle traite de la phase installée, au niveau d'un site spécifique, d'unités mobiles flottantes occupées par du personnel non évacuées, occupées par du personnel évacuées et non occupées par du personnel.
ISO 19905-3:2017 traite des unités mobiles flottantes monocoques (par exemple structures à profil de bateau ou barges); stabilisées par des colonnes, souvent désignées par structures semi-submersibles; ou ayant d'autres formes de coque (par exemple cylindriques/coniques). Elle n'est pas applicable aux plates-formes à ancrage tendu. 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, comprenant des fonctions de forage, d'hôtel flottant, de barge, etc. Dans les situations où des hydrocarbures sont produits, des exigences supplémentaires peuvent s'appliquer.
Les exigences du présent document s'appliquent à la coque et au système de maintien en position de tous les types d'unités mobiles. Il est possible de modifier les exigences du document d'instructions d'exploitation spécifiques à l'activité dans le but de les adapter à la situation faisant l'objet de l'évaluation.
ISO 19905-3:2017 ne traite pas de toutes les considérations du site, et il est possible que certains emplacements nécessitent une évaluation supplémentaire.
ISO 19905-3:2017 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).
ISO 19905-3:2017 ne traite pas de la conception, du transport vers et depuis un site ou de l'installation et du retrait du site.
ISO 19905-3:2017 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 actions océano-météorologiques sur l'unité;
- l'ISO 19906 est citée en référence pour les régions arctiques et froides;
- la structure et le tirant d'eau de la coque sont évalués en procédant à une comparaison entre les dispositions 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. Il est possible d'utiliser d'autres méthodologies équivalentes;
- l'IMCA M 220[5] est citée en référence pour l'élaboration d'un document d'instructions d'exploitation spécifique à l'activité. Il est possible d'utiliser d'autres méthodologies ayant fait l'objet d'un accord.
NOTE 1 Le domaine d'application de l'ISO 19904‑1 stipule spécifiquement que ses exigences ne s'appliquent pas aux unités mobiles, mais les méthodologies données pour l'évaluation des actions océano-météorolo

Industrija za predelavo nafte in zemeljskega plina - Ocenjevanje premičnih naftnih ploščadi na področju postavitve - 3. del: Plavajoča enota (ISO 19905-3:2017)

Standard ISO 19905-3 določa zahteve in podaja smernice 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. Standard ISO 19905-3 obravnava premične plavajoče enote, ki imajo en trup (npr. plovila v obliki plavila ali plovila); ki so stolpično stabilizirana 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. Vzdrževalne sisteme se lahko zagotovi 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. Zahteve iz standarda ISO 19905-3 veljajo za trupe in vzdrževalne sisteme za vse vrste premičnih enot. Zahteve dokumenta za delovanje, ki je specifično za dejavnost, je mogoče spremeniti tako, da ustrezajo primeru, ki se jo ocenjuje.
Standard ISO 19905-3 ne obravnava vseh pogojev mesta uporabe in določene specifične lokacije lahko zahtevajo dodatno ocenjevanje.
Standard ISO 19905-3 se uporablja samo za premične plavajoče enote, ki so strukturno trdne in ustrezno vzdrževane, kar se običajno izkazuje z veljavnim certifikatom klasifikacije RCS.
Standard ISO 19905-3 ne obravnava načrtovanja, prevoza na mesto ali z njega ali namestitve na mesto in odstranitve z njega.
Standard ISO 19905-3 podaja zahteve za oceno na mestu 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 meteoroloških in oceanografskih ukrepov za enoto;
– sklic na standard ISO 19906 za arktična in hladna območja;
– struktura trupa in zračna reža se ocenita s primerjavo med meteorološkimi in oceanografskimi pogoji, ki so specifični za mesto postavitve, ter njihovimi določenimi pogoji, 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[5] za razvoj smernic za delovanje, ki so specifične za dejavnost. Uporabijo se lahko tudi dogovorjene nadomestne metodologije.
OPOMBA 1: Področje uporabe standarda ISO 19904‑1 izrecno navaja, da zahteve standarda ne veljajo za premične enote, vendar je mogoče uporabiti metodologije, ki so podane za ocenjevanje meteoroloških in oceanografskih dejanj.
OPOMBA 2: Pravila RCS in kodeks IMO MODU [4] podajajo napotke za načrtovanje in upravljanje premičnih plavajočih enot.

General Information

Status
Withdrawn
Public Enquiry End Date
31-Jul-2019
Publication Date
05-Nov-2019
Withdrawal Date
10-Jul-2022
Technical Committee
Current Stage
9900 - Withdrawal (Adopted Project)
Start Date
08-Jul-2022
Due Date
31-Jul-2022
Completion Date
11-Jul-2022

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SLOVENSKI STANDARD
SIST EN ISO 19905-3:2020
01-januar-2020
Industrija za predelavo nafte in zemeljskega plina - Ocenjevanje premičnih naftnih
ploščadi na področju postavitve - 3. del: Plavajoča enota (ISO 19905-3:2017)
Petroleum and natural gas industries - Site-specific assessment of mobile offshore units
- Part 3: Floating unit (ISO 19905-3:2017)
Erdöl- und Erdgasindustrie - Beurteilung von mobilen Offshore Einheiten bezüglich ihres
Einsatzgebietes - Teil 3: Schwimmende Einheiten (ISO 19905-3:2017)
Industries du pétrole et du gaz naturel - Évaluation spécifique au site d'unités mobiles en
mer - Partie 3: Unité flottante (ISO 19905-3:2017)
Ta slovenski standard je istoveten z: EN ISO 19905-3:2019
ICS:
75.180.10 Oprema za raziskovanje, Exploratory, drilling and
vrtanje in odkopavanje extraction equipment
SIST EN ISO 19905-3:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 19905-3:2020

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SIST EN ISO 19905-3:2020


EN ISO 19905-3
EUROPEAN STANDARD

NORME EUROPÉENNE

October 2019
EUROPÄISCHE NORM
ICS 75.180.10
English Version

Petroleum and natural gas industries - Site-specific
assessment of mobile offshore units - Part 3: Floating unit
(ISO 19905-3:2017)
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 -
Unité flottante (ISO 19905-3:2017) Teil 3: Schwimmende Einheiten (ISO 19905-3:2017)
This European Standard was approved by CEN on 9 September 2019.

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
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 19905-3:2019 E
worldwide for CEN national Members.

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SIST EN ISO 19905-3:2020
EN ISO 19905-3:2019 (E)
Contents Page
European foreword . 3

2

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SIST EN ISO 19905-3:2020
EN ISO 19905-3:2019 (E)
European foreword
The text of ISO 19905-3:2017 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 19905-3:2019
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 April 2020, and conflicting national standards shall be
withdrawn at the latest by April 2020.
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.
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 19905-3:2017 has been approved by CEN as EN ISO 19905-3:2019 without any
modification.

3

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SIST EN ISO 19905-3:2020
INTERNATIONAL ISO
STANDARD 19905-3
First edition
2017-10
Petroleum and natural gas
industries — Site-specific assessment
of mobile offshore units —
Part 3:
Floating unit
Industries du pétrole et du gaz naturel — Évaluation spécifique au
site d'unités mobiles en mer —
Partie 3: Unité flottante
Reference number
ISO 19905-3:2017(E)
©
ISO 2017

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SIST EN ISO 19905-3:2020
ISO 19905-3:2017(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved

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SIST EN ISO 19905-3:2020
ISO 19905-3:2017(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 2
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 . 5
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 . 7
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 . 9
6.5 Data on activity use limitations .10
6.5.1 General.10
6.5.2 Reassessment or modification of activity use limitations .10
6.5.3 Sources of data and types of activity use limitations .10
6.6 Post installation data .11
7 Actions .11
8 Hull of unit .11
8.1 Strength .11
8.1.1 General.11
8.1.2 Monohull .11
8.1.3 Semi-submersible .12
8.1.4 Other hull forms .12
8.2 Airgap and freeboard .12
8.2.1 General.12
8.2.2 Monohull .12
8.2.3 Semi-submersible .12
8.2.4 Other hull forms .13
8.3 Temperature .13
8.4 Stability .13
9 Stationkeeping system .13
9.1 General .13
© ISO 2017 – All rights reserved iii

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9.2 Moored .13
9.3 Thruster assisted mooring .13
9.4 Dynamic positioning systems .13
10  Activity specific assessments .14
10.1 General .14
10.2 Assessment of site-specific activities and equipment .14
10.2.1 General.14
10.2.2 Marine drilling riser assessment .14
10.3 Risk assessment .14
10.4 Activity specific operating guidelines .14
11  Confirmation of compatibility between analysis and as-installed condition .15
Annex A (informative) Outline of an activity specific operating guideline document for a
dynamically positioned unit and a moored unit .16
Annex B (informative) Suggested process for completing a site-specific assessment of a
mobile floating unit .19
Bibliography .21
iv © ISO 2017 – All rights reserved

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SIST EN ISO 19905-3:2020
ISO 19905-3:2017(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 on 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 the following
URL: 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.
A list of all parts in the ISO 19905 series can be found on the ISO website.
© ISO 2017 – All rights reserved v

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Introduction
The series of International Standards applicable to types of offshore structure, ISO 19900 to ISO 19906,
addresses design requirements and assessments for all offshore structures used by the petroleum and
natural gas industries worldwide. Through their application, the intention is to achieve reliability levels
appropriate for manned and unmanned offshore structures, whatever the type of structure and the
nature or combination of the materials used.
It is important to recognize that structural integrity is an overall concept comprising models for
describing actions, structural analyses, design or assessment rules, safety elements, workmanship,
quality control procedures and national requirements, all of which are mutually dependent. The
modification of one aspect of the design or assessment 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 offshore structural systems.
The series of International Standards applicable to the various types of offshore structure is intended
to provide a wide latitude in the choice of structural configurations, materials and techniques
without hindering innovation. Sound engineering judgement is therefore necessary in the use of these
International Standards.
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 International Standards, the following verbal forms are used:
— “shall” and “shall not” are used to indicate requirements strictly to be followed in order to conform
to the document and from which no deviation is permitted;
— “should” and “should not” are used to indicate that, among several possibilities, one is recommended
as particularly suitable, without mentioning or excluding others, or that a certain course of action is
preferred but not necessarily required, or that (in the negative form) a certain possibility or course
of action is deprecated but not prohibited;
— “may” is used to indicate a course of action permissible within the limits of the document;
— “can” and “cannot” are used for statements of possibility and capability, whether material, physical
or causal.
vi © ISO 2017 – All rights reserved

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SIST EN ISO 19905-3:2020
INTERNATIONAL STANDARD ISO 19905-3:2017(E)
Petroleum and natural gas industries — Site-specific
assessment of mobile offshore units —
Part 3:
Floating unit
1 Scope
This document specifies requirements and gives guidance 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.
The requirements of this document apply to the hull and stationkeeping system for all types of
mobile units. The activity specific operating guideline document requirements can be modified to be
appropriate to the situation being assessed.
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 metocean actions on the unit;
— ISO 19906 is referenced for arctic and cold regions;
— the hull structure and airgap 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;
[5]
— IMCA M 220 is referenced for developing an activity specific operating guidelines. Agreed
alternative methodologies can be used.
NOTE 1 The scope of ISO 19904-1 specifically states that its requirements do not apply to mobile units, but the
methodologies given for assessing metocean actions can be used.
[4]
NOTE 2 RCS rules and the IMO MODU code provide guidance for design and general operation of mobile
floating units.
© ISO 2017 – All rights reserved 1

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ISO 19905-3:2017(E)

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 13624-1:2009, Petroleum and natural gas industries — Drilling and production equipment — Part 1:
Design and operation of marine drilling riser equipment
ISO 19900:2013, 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 19901-7:2013, 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: Monohulls,
semi-submersibles and spars
1)
ISO 19906:— , Petroleum and natural gas industries — Arctic offshore structures
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
...

SLOVENSKI STANDARD
oSIST prEN ISO 19905-3:2019
01-julij-2019
Industrija za predelavo nafte in zemeljskega plina - Ocenjevanje premičnih naftnih
ploščadi na področju postavitve - 3. del: Plavajoča enota (ISO 19905-3:2017)
Petroleum and natural gas industries - Site-specific assessment of mobile offshore units
- Part 3: Floating unit (ISO 19905-3:2017)
Industries du pétrole et du gaz naturel - Évaluation spécifique au site d'unités mobiles en
mer - Partie 3: Unité flottante (ISO 19905-3:2017)
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 19905-3:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 19905-3:2019
INTERNATIONAL ISO
STANDARD 19905-3
First edition
2017-10
Petroleum and natural gas
industries — Site-specific assessment
of mobile offshore units —
Part 3:
Floating unit
Industries du pétrole et du gaz naturel — Évaluation spécifique au
site d'unités mobiles en mer —
Partie 3: Unité flottante
Reference number
ISO 19905-3:2017(E)
©
ISO 2017

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ISO 19905-3:2017(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved

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Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 2
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 . 5
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 . 7
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 . 9
6.5 Data on activity use limitations .10
6.5.1 General.10
6.5.2 Reassessment or modification of activity use limitations .10
6.5.3 Sources of data and types of activity use limitations .10
6.6 Post installation data .11
7 Actions .11
8 Hull of unit .11
8.1 Strength .11
8.1.1 General.11
8.1.2 Monohull .11
8.1.3 Semi-submersible .12
8.1.4 Other hull forms .12
8.2 Airgap and freeboard .12
8.2.1 General.12
8.2.2 Monohull .12
8.2.3 Semi-submersible .12
8.2.4 Other hull forms .13
8.3 Temperature .13
8.4 Stability .13
9 Stationkeeping system .13
9.1 General .13
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9.2 Moored .13
9.3 Thruster assisted mooring .13
9.4 Dynamic positioning systems .13
10  Activity specific assessments .14
10.1 General .14
10.2 Assessment of site-specific activities and equipment .14
10.2.1 General.14
10.2.2 Marine drilling riser assessment .14
10.3 Risk assessment .14
10.4 Activity specific operating guidelines .14
11  Confirmation of compatibility between analysis and as-installed condition .15
Annex A (informative) Outline of an activity specific operating guideline document for a
dynamically positioned unit and a moored unit .16
Annex B (informative) Suggested process for completing a site-specific assessment of a
mobile floating unit .19
Bibliography .21
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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 on 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 the following
URL: 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.
A list of all parts in the ISO 19905 series can be found on the ISO website.
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Introduction
The series of International Standards applicable to types of offshore structure, ISO 19900 to ISO 19906,
addresses design requirements and assessments for all offshore structures used by the petroleum and
natural gas industries worldwide. Through their application, the intention is to achieve reliability levels
appropriate for manned and unmanned offshore structures, whatever the type of structure and the
nature or combination of the materials used.
It is important to recognize that structural integrity is an overall concept comprising models for
describing actions, structural analyses, design or assessment rules, safety elements, workmanship,
quality control procedures and national requirements, all of which are mutually dependent. The
modification of one aspect of the design or assessment 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 offshore structural systems.
The series of International Standards applicable to the various types of offshore structure is intended
to provide a wide latitude in the choice of structural configurations, materials and techniques
without hindering innovation. Sound engineering judgement is therefore necessary in the use of these
International Standards.
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 International Standards, the following verbal forms are used:
— “shall” and “shall not” are used to indicate requirements strictly to be followed in order to conform
to the document and from which no deviation is permitted;
— “should” and “should not” are used to indicate that, among several possibilities, one is recommended
as particularly suitable, without mentioning or excluding others, or that a certain course of action is
preferred but not necessarily required, or that (in the negative form) a certain possibility or course
of action is deprecated but not prohibited;
— “may” is used to indicate a course of action permissible within the limits of the document;
— “can” and “cannot” are used for statements of possibility and capability, whether material, physical
or causal.
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INTERNATIONAL STANDARD ISO 19905-3:2017(E)
Petroleum and natural gas industries — Site-specific
assessment of mobile offshore units —
Part 3:
Floating unit
1 Scope
This document specifies requirements and gives guidance 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.
The requirements of this document apply to the hull and stationkeeping system for all types of
mobile units. The activity specific operating guideline document requirements can be modified to be
appropriate to the situation being assessed.
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 metocean actions on the unit;
— ISO 19906 is referenced for arctic and cold regions;
— the hull structure and airgap 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;
[5]
— IMCA M 220 is referenced for developing an activity specific operating guidelines. Agreed
alternative methodologies can be used.
NOTE 1 The scope of ISO 19904-1 specifically states that its requirements do not apply to mobile units, but the
methodologies given for assessing metocean actions can be used.
[4]
NOTE 2 RCS rules and the IMO MODU code provide guidance for design and general operation of mobile
floating units.
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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 13624-1:2009, Petroleum and natural gas industries — Drilling and production equipment — Part 1:
Design and operation of marine drilling riser equipment
ISO 19900:2013, 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 19901-7:2013, 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: Monohulls,
semi-submersibles and spars
1)
ISO 19906:— , Petroleum and natural gas industries — Arctic offshore structures
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 http://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
3.1
activity specific operating guidelines
ASOG
document that sets out the activity specific actions to be taken at specific alert level thresholds (3.3)
Note 1 to entry: The ASOG for drilling operations is often called the well specific operating guideline document.
Note 2 to entry: An example ASOG for DP and moored units is given in Annex A.
3.2
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, or red alert. Parameters affecting the change of colour-coded alert levels can be, for
example, limiting metocean conditions are reached, loss of equipment function, reduced power levels, offset
limits are reached [watch circles (3.17)], vessel motions, etc. Actions that need to be taken can include, for
example, discontinue drilling, disconnect riser, suspend lifts, etc.
3.3
alert level threshold
boundary between alert levels (3.2) which is crossed when certain parameters reach or exceed specific
limits and that triggers actions
1) To be published. Stage at time of publication ISO/DIS 19906:2017.
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3.4
assessment
site-specific assessment
evaluation of a mobile floating unit and activity specific equipment to determine compliance with the
requirements of this document
[SOURCE: ISO 19905-1:2016, 3.4, modified — the definition has been revised.]
3.5
assessment situation
mobile floating unit configuration together with the metocean and ice actions to be assessed
[SOURCE: ISO 19905-1:2016, 3.5, modified — the definition has been revised.]
3.6
assessor
entity performing the site-specific assessment
[SOURCE: ISO 19905-1:2016, 3.6]
3.7
drift-off
unintended move of a dynamically positioned or thruster-assisted vessel off its intended location [watch
circle (3.17)] relative to its set point, generally caused by loss of stationkeeping control or propulsion
[SOURCE: ISO 13624-1:2009, 3.1.25, modified — the definition has been revised.]
3.8
drive-off
unintended move of a dynamically positioned or thruster-assisted vessel off its intended location [watch
circle (3.17)] relative to its set point, driven by the vessel's main propulsion or stationkeeping thrusters
[SOURCE: ISO 13624-1:2009, 3.1.27, modified — the definition has been revised.]
3.9
extreme storm event
extreme combination of wind, wave and current conditions to which the structure can be subjected
during its deployment
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 airgap.
[SOURCE: ISO 19905-1:2016, 3.17, modified — Note 1 to entry has been revised.]
3.10
operating manual
marine operations manual
manual that defines the operational characteristics and capabilities of the mobile floating unit
Note 1 to entry: The assessor (3.6) is advised to ensure that the operations manual referenced is the latest
revision and that any updated weight data are provided.
[SOURCE: ISO 19905-1:2016, 3.45, modified — “jack-up” has been replaced by “mobile floating unit”.]
3.11
operator
representative of the companies leasing the site
Note 1 to entry: The operator is normally the oil company acting on behalf of co-licensees.
[SOURCE: ISO 19905-1:2016, 3.46]
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3.12
recognized classification society
RCS
member of the International Association of Classification Societies (IACS), with recognized and relevant
competence and experience in mobile floating units, and with established rules and procedures for
classification/certification of such units used in petroleum-related activities
[SOURCE: ISO 19901-7:2013, 3.23, modified — the definition has been revised.]
3.13
set point position
inte
...

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