EN ISO 19904-1:2006

SLOVENSKI STANDARD
01-januar-2007
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Petroleum and natural gas industries - Floating offshore structures - Part 1: Monohulls,
semi-submersibles and spars (ISO 19904-1:2006)
Erdöl- und Erdgasindustrie - Schwimmende Offshore-Anlagen - Teil 1: Produktions- und
Lagerungsanlagen außer Tension-Leg-Anlagen (ISO 19904-1:2006)
Industries du pétrole et du gaz naturel - Structures en mer flottantes - Partie 1: Unités
monocoques, unités semi-submersibles et unités spars (ISO 19904-1:2006)
Ta slovenski standard je istoveten z: EN ISO 19904-1:2006
ICS:
75.180.10 Oprema za raziskovanje in Exploratory and extraction
odkopavanje equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 19904-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2006
ICS 75.180.10
English Version
Petroleum and natural gas industries - Floating offshore
structures - Part 1: Monohulls, semi-submersibles and spars
(ISO 19904-1:2006)
Industries du pétrole et du gaz naturel - Structures en mer Erdöl- und Erdgasindustrie - Schwimmende Offshore-
flottantes - Partie 1: Unités monocoques, unités semi- Anlagen - Teil 1: Produktions- und Lagerungsanlagen
submersibles et unités spars (ISO 19904-1:2006) außer Tension-Leg-Anlagen (ISO 19904-1:2006)
This European Standard was approved by CEN on 22 September 2006.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,
Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2006 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 19904-1:2006: E
worldwide for CEN national Members.

Foreword
This document (EN ISO 19904-1:2006) has been prepared by Technical Committee ISO/TC 67
"Materials, equipment and offshore structures for petroleum and natural gas industries" in
collaboration with Technical Committee CEN/TC 12 "Materials, equipment and offshore
structures for petroleum, petrochemical and natural gas industries", the secretariat of which is
held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of
an identical text or by endorsement, at the latest by May 2007, and conflicting national standards
shall be withdrawn at the latest by May 2007.

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

Endorsement notice
The text of ISO 19904-1:2006 has been approved by CEN as EN ISO 19904-1:2006 without any
modifications.
INTERNATIONAL ISO
STANDARD 19904-1
First edition
2006-11-01
Petroleum and natural gas industries —
Floating offshore structures —
Part 1:
Monohulls, semi-submersibles and spars
Industries du pétrole et du gaz naturel — Structures en mer flottantes —
Partie 1: Unités monocoques, unités semi-submersibles et unités spars

Reference number
ISO 19904-1:2006(E)
©
ISO 2006
ISO 19904-1:2006(E)
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ii © ISO 2006 – All rights reserved

ISO 19904-1:2006(E)
Contents Page
Foreword. vi
Introduction . viii
1 Scope . 1
2 Normative references . 2
3 Terms and definitions. 3
4 Symbols and abbreviated terms . 9
4.1 Symbols . 9
4.2 Abbreviated terms . 10
5 Overall considerations . 12
5.1 Functional requirements. 12
5.2 Safety requirements . 12
5.3 Planning requirements. 13
5.4 Rules and regulations . 14
5.5 General requirements. 14
5.6 Independent verification . 18
5.7 Analytical tools . 18
5.8 In-service inspection and maintenance. 18
5.9 Assessment of existing floating structures. 18
5.10 Reuse of existing floating structures . 19
6 Basic design requirements. 19
6.1 General. 19
6.2 Exposure levels. 19
6.3 Limit states . 22
6.4 Design situations. 23
7 Actions and action effects . 25
7.1 General. 25
7.2 Permanent actions (G). 25
7.3 Variable actions (Q) . 25
7.4 Accidental actions (A). 26
7.5 Environmental actions (E). 27
7.6 Other actions. 35
7.7 Repetitive actions . 35
7.8 Action combinations . 36
8 Global analysis. 36
8.1 General. 36
8.2 Static and mean response analyses. 36
8.3 Global dynamic behaviour. 37
8.4 Frequency domain analysis. 39
8.5 Time domain analysis. 39
8.6 Uncoupled analysis . 40
8.7 Coupled analysis . 40
8.8 Resonant excitation and response . 40
8.9 Platform offset. 40
8.10 Air gap. 40
8.11 Platform motions and accelerations. 41
8.12 Model tests . 41
8.13 Design situations for structural analysis . 42
ISO 19904-1:2006(E)
9 Structural considerations. 42
9.1 General . 42
9.2 Representative values of actions . 43
9.3 Design scantlings . 44
9.4 Modelling. 45
9.5 Structural analysis . 47
9.6 Structural strength. 49
9.7 Design checks . 50
9.8 Special design issues. 54
9.9 Material. 55
9.10 Corrosion protection of steel. 57
9.11 Fabrication and construction. 57
9.12 Marine operations . 58
9.13 Topsides/hull interface . 58
10 Fatigue analysis and design . 59
10.1 General . 59
10.2 Fatigue damage design safety factors. 60
10.3 Outline of approach . 61
10.4 Environmental data. 62
10.5 Structural modelling . 62
10.6 Hydrostatic analyses . 62
10.7 Response amplitude operators and combinations of actions . 62
10.8 Stresses and SCFs. 63
10.9 Stress range counting and distribution. 63
10.10 Fatigue resistance. 63
10.11 Damage accumulation . 63
10.12 Fracture mechanics methods . 64
10.13 Fatigue-sensitive components and connections. 64
11 Monohulls . 65
11.1 General . 65
11.2 General design criteria . 65
11.3 Structural strength. 66
12 Semi-submersibles . 69
12.1 General . 69
12.2 General design criteria . 69
12.3 Structural strength. 70
13 Spars . 70
13.1 General . 70
13.2 General design requirements . 71
13.3 Structural strength. 72
14 Conversion and reuse . 72
14.1 General . 72
14.2 Minimum design, construction and maintenance standards . 73
14.3 Pre-conversion structural survey. 73
14.4 Effects of prior service . 73
14.5 Corrosion protection and material suitability . 75
14.6 Inspection and maintenance. 75
15 Hydrostatic stability and compartmentation. 75
15.1 General . 75
15.2 Inclining test . 76
15.3 Compartmentation . 76
15.4 Watertight and weathertight appliances. 76
15.5 Special requirements for monohulls. 77
16 Mechanical systems . 77
16.1 General . 77
16.2 Hull systems . 77
iv © ISO 2006 – All rights reserved

ISO 19904-1:2006(E)
16.3 Import and export systems. 85
16.4 Fire protection systems . 87
17 Stationkeeping systems. 88
17.1 General. 88
17.2 Mooring equipment. 89
17.3 Turret. 90
18 In-service inspection, monitoring and maintenance. 92
18.1 General. 92
18.2 Structural integrity management system philosophies. 92
18.3 Planning considerations . 95
18.4 Implementation issues . 96
18.5 Minimum requirements . 99
Annex A (informative) Additional information and guidance . 104
A.1 Scope . 104
A.2 Normative references . 106
A.3 Terms and definitions. 106
A.4 Symbols and abbreviated terms . 106
A.5 Overall considerations . 107
A.6 Basic design requirements. 111
A.7 Actions and action effects . 113
A.8 Global analysis. 125
A.9 Structural considerations . 128
A.10 Fatigue analysis and design. 134
A.11 Monohulls . 137
A.12 Semi-submersibles. 141
A.13 Spars . 142
A.14 Conversion and reuse . 143
A.15 Hydrostatic stability and compartmentation . 144
A.16 Mechanical systems . 144
A.17 Stationkeeping systems. 154
A.18 In-service inspection, monitoring and maintenance. 155
Bibliography . 172

ISO 19904-1:2006(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 19904-1 was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore structures
for petroleum, petrochemical and natural gas industries, Subcommittee SC 7, Offshore structures.
ISO 19904 consists of the following parts, under the general title Petroleum and natural gas industries —
Floating offshore structures:
⎯ Part 1: Monohulls, semi-submersibles and spars
Tension leg platforms is to form the subject of a future Part 2.
ISO 19904 is one of a series of standards for offshore structures. The full series consists of the following
International Standards.
⎯ ISO 19900, Petroleum and natural gas industries — General requirements for offshore structures
⎯ ISO 19901 (all parts), Petroleum and natural gas industries — Specific requirements for offshore
structures
1)
⎯ ISO 19902, Petroleum and natural gas industries — Fixed steel offshore structures
1)
⎯ ISO 19903, Petroleum and natural gas industries — Fixed concrete offshore structures
⎯ ISO 19904-1, Petroleum and natural gas industries — Floating offshore structures — Part 1: Monohulls,
semi-submersibles and spars
⎯ ISO 19904-2, Petroleum and natural gas industries — Floating offshore structures — Part 2: Tension leg
2)
platforms
⎯ ISO 19905-1, Petroleum and natural gas industries — Site-specific assessment of mobile offshore units
2)
— Part 1: Jack-ups
1)
To be published.
2)
Under preparation.
vi © ISO 2006 – All rights reserved

ISO 19904-1:2006(E)
⎯ ISO/TR 19905-2, Petroleum and natural gas industries — Site-specific assessment of mobile offshore
3)
units — Part 2: Jack-ups commentary
3)
⎯ ISO 19906, Petroleum and natural gas industries — Arctic offshore structures

3)
Under preparation.
ISO 19904-1:2006(E)
Introduction
The series of International Standards applicable to types of offshore structure, ISO 19900 to ISO 19906,
constitutes a common basis covering those aspects that address design requirements and assessments of all
offshore structures used by the petroleum, petrochemical and natural gas industries worldwide. Through their
application the intention is to achieve reliability levels appropriate for manned and unmanned offshore
structures, whatever the type of structure and the nature or combination of materials used.
It is important to recognize that structural integrity is an overall concept comprising models for describing
actions, structural analyses, design rules, safety elements, workmanship, quality control procedures and
national requirements, all of which are mutually dependent. The modification of one aspect of design in
isolation can disturb the balance of reliability inherent in the overall concept or structural system. The
implications involved in modifications, therefore, need to be considered in relation to the overall reliability of all
offshore structural systems.
The series of International Standards applicable to types of offshore structure is intended to provide wide
latitude in the choice of structural configurations, materials and techniques without hindering innovation.
Sound engineering judgement is therefore necessary in the use of these International Standards.
International Standard ISO 19904 was developed in response to the offshore industry’s demand for a
coherent and consistent definition of methodologies to design, analyse and assess floating offshore structures
of the class described in Clause 1. In particular, this part of ISO 19904 addresses monohulls, semi-
submersibles and spars.
Some background to, and guidance on, the use of this part of ISO 19904 is provided in informative Annex A.
The clause numbering in Annex A is the same as in the normative text to facilitate cross-referencing.

viii © ISO 2006 – All rights reserved

INTERNATIONAL STANDARD ISO 19904-1:2006(E)

Petroleum and natural gas industries — Floating offshore
structures —
Part 1:
Monohulls, semi-submersibles and spars
1 Scope
This part of ISO 19904 provides requirements and guidance for the structural design and/or assessment of
floating offshore platforms used by the petroleum and natural gas industries to support the following functions:
⎯ production;
⎯ storage and/or offloading;
⎯ drilling and production;
⎯ production, storage and offloading;
⎯ drilling, production, storage and offloading.
NOTE 1 Floating offshore platforms are often referred to using a variety of abbreviations, e.g. FPS, FSU, FPSO, etc.
(see Clauses 3 and 4), in accordance with their intended mission.
NOTE 2 In this part of ISO 19904, the term “floating structure”, sometimes shortened to “structure”, is used as a
generic term to indicate the structural systems of any member of the classes of platforms defined above.
NOTE 3 In some cases, floating platforms are designated as “early production platforms”. This term relates merely to
an asset development strategy. For the purposes of this International Standard, the term “production” includes “early
production”.
Its requirements do not apply to the structural systems of mobile offshore units (MOUs). These include,
among others:
⎯ floating structures intended primarily to perform drilling and/or well intervention operations (often referred
to as MODUs), even when used for extended well test operations;
⎯ floating structures used for offshore construction operations (e.g. crane barges or pipelay barges), for
temporary or permanent offshore living quarters (floatels), or for transport of equipment or products (e.g.
transportation barges, cargo barges), for which structures reference is made to relevant recognized
classification society (RCS) rules.
Its requirements are applicable to all possible life-cycle stages of the structures defined above, such as
⎯ design, construction and installation of new structures, including requirements for inspection, integrity
management and future removal,
⎯ structural integrity management covering inspection and assessment of structures in-service, and
⎯ conversion of structures for different use (e.g. a tanker converted to a production platform) or reuse at
different locations.
ISO 19904-1:2006(E)
The following types of floating structure are explicitly considered within the context of this part of ISO 19904:
a) monohulls (ship-shaped structures and barges);
b) semi-submersibles;
c) spars.
In addition to the structural types listed above, this part of ISO 19904 covers other floating platforms intended
to perform the above functions, consisting of partially submerged buoyant hulls made up of any combination of
plated and space frame components and used in conjunction with the stationkeeping systems covered in
ISO 19901-7. These other structures can have a great range of variability in geometry and structural forms
and, therefore, can be only partly covered by the requirements of this part of ISO 19904. In other cases,
specific requirements stated in this part of ISO 19904 can be found not to apply to all or part of a structure
under design.
In all the above cases, conformity with this part of ISO 19904 will require that the design is based upon its
underpinning principles and achieves a level of safety equivalent, or superior, to the level implicit in it.
NOTE 4 The speed of evolution of offshore technology often far exceeds the pace at which the industry achieves
substantial agreement on innovation in structural concepts, structural shapes or forms, structural components and
associated analysis and design practices, which are continuously refined and enhanced. On the other hand, International
Standards can only capture explicit industry consensus, which requires maturation and acceptance of new ideas.
Consequently, advanced structural concepts can, in some cases, only be partly covered by the provisions of this part of
ISO 19904.
This part of ISO 19904 is applicable to steel floating structures. The principles documented herein are,
however, considered to be generally applicable to structures fabricated in materials other than steel.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 13702, Petroleum and natural gas industries — Control and mitigation of fires and explosions on offshore
production installations — Requirements and guidelines
ISO 19900:2002, 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 19901-7:2005, Petroleum and natural gas industries — Specific requirements for offshore structures —
Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units
4)
ISO 19902:— , Petroleum and natural gas industries — Fixed steel offshore structures

4)
To be published.
2 © ISO 2006 – All rights reserved

ISO 19904-1:2006(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
abnormal
condition that exceeds conventionally specified design conditions and which is used to mitigate against very
remote events
3.2
accidental design situation
design situation involving exceptional conditions of the structure or its exposure
EXAMPLE Impact, fire, explosion, local failure or loss of intended differential pressure (e.g. buoyancy).
3.3
action
external load applied to the structure (direct action) or an imposed deformation or acceleration (indirect action)
EXAMPLE An imposed deformation can be caused by fabrication tolerances, settlement, temperature change or
moisture variation.
NOTE An earthquake typically generates imposed accelerations.
[ISO 19900:2002]
3.4
action combination
design values of different actions considered simultaneously in design checks of the structure for a specific
limit state
3.5
action effect
effect of actions on structural components
EXAMPLE Internal forces, moments, stresses, strains, rigid body motions or elastic deformations.
[ISO 19900:2002]
3.6
air gap
clearance between the highest water surface that occurs during the extreme environmental conditions and the
lowest exposed part not designed to withstand wave impingement
[ISO 19900:2002]
3.7
basic variable
one of a specified set of variables representing physical quantities which characterize actions, environmental
influences, geometrical quantities, or material properties, including soil properties
[ISO 19900:2002]
3.8
characteristic value
value of a basic variable, an action or a strength model having a prescribed probablilty of not being violated by
unfavorable values
NOTE 1 In the case of actions and related properties, the characteristic value normally relates to a reference period.
NOTE 2 Adapted from ISO 19900:2002, definition 2.7.
ISO 19904-1:2006(E)
3.9
design criteria
quantitative formulations that describe the conditions to be fulfilled for each limit state
[ISO 19900:2002]
3.10
design format
mathematical description for checks to verify non-exceedance of a limit state
NOTE In this part of ISO 19904, both partial factor and working stress design (WSD) formats are permitted.
3.11
design service life
assumed period for which a structure or a structural component is to be used for its intended purpose with
anticipated maintenance, but without substantial repair being necessary
NOTE Adapted from ISO 19900:2002, definition 2.12.
3.12
design situation
set of physical conditions during a certain reference period for which the design demonstrates that relevant
limit states are not exceeded
NOTE Adapted from ISO 19900:2002, definition 2.13.
3.13
design value
value of a basic variable, action or strength model derived from a representative value for use in a design
verification procedure
NOTE 1 For a ULS design check in accordance with the partial factor design format, a design value for a strength
variable or model is found by dividing the representative value of strength by a partial resistance factor, while for an action
variable it is found by multiplying the representative value of the action effect by a partial action factor.
NOTE 2 For an FLS, SLS or ALS design check in accordance with the partial factor design format, all partial factors are
equal to unity so that, in these cases, a design value is equal to the representative value.
NOTE 3 For any design check in accordance with the working stress design format, all partial factors are equal to unity
so that, in these cases, a design value is equal to the representative value. Appropriate global safety or utilization factors
are applied in design checks.
NOTE 4 In the case of actions and related properties, the value can relate to a reference period.
NOTE 5 Adapted from ISO 19900:2002, definition 2.14.
3.14
dynamic action
action that induces acceleration of a structure or a structural component of a magnitude sufficient to require
specific consideration
[ISO 19901-7:2005]
3.15
dynamic positioning
DP
stationkeeping technique consisting primarily of a system of on-board thrusters, which generate appropriate
thrust vectors to counter the mean and slowly varying induced actions
4 © ISO 2006 – All rights reserved

ISO 19904-1:2006(E)
3.16
exposure level
classification system used to define the requirements for a structure based on consideration of life-safety and
of environmental and economic consequences of failure
[ISO 19900:2002]
3.17
failure
insufficient strength or inadequate serviceability of a structure or structural component, or, in a structural
check, a condition in which a structure or component thereof does not fulfil its limit state requirement
3.18
fit-for-purpose, adjective
fitness-for-purpose, noun
meeting the intent of a standard although not meeting specific provisions of that standard in local areas, such
that failure in these areas cannot cause unacceptable risk to life-safety or the environment
NOTE Adapted from ISO 19900:2002, definition 2.16.
3.19
floating structure
structure where the full weight is supported by buoyancy
[ISO 19900:2002]
NOTE The full weight includes lightship weight, mooring system pre-tension, riser pre-tension and operating weight.
3.20
freeboard
distance measured vertically downwards between the top of the hull and the mean water surface at a given
draught
3.21
green water
overtopping of deck by water causing slamming and pressure actions to structures on deck
3.22
limit state
state beyond which the structure no longer fulfils the relevant design criteria
[ISO 19900:2002]
3.23
mobile offshore drilling unit
MODU
structure capable of engaging in drilling and well intervention operations for exploration or exploitation of
subsea petroleum resources
[ISO 19901-7:2005]
3.24
mobile offshore unit
MOU
structure intended to be relocated to perform a particular function
[ISO 19900:2002]
ISO 19904-1:2006(E)
3.25
monohull
floating structure consisting of a single, continuous, buoyant hull, and having a geometry similar to that of
ocean-going ships, barges, etc.
3.26
nominal value
value of a basic variable, action or strength model determined on a non-statistical basis, typically from
acquired experience or physical conditions
EXAMPLE Value published in a recognized code or standard.
NOTE Adapted from ISO 19900:2002, definition 2.22.
3.27
owner
representative of the company or companies which own a development, who can be the operator on behalf of
co-licensees
[ISO 19901-7:2005]
3.28
platform
complete assembly including structure, topsides and, where applicable, foundations and stationkeeping
system
NOTE Adapted from ISO 19900
...