DNV-OSS-901: Project Certification of Offshore Wind Farms

OFFSHORE SERVICE SPECIFICATION

The electronic p

DNV-OSS-901

Project Certification of Offshore Wind Farms

JUNE 2012

DET NORSKE VERITAS AS

df version of this document found through http://www.dnv.com is the officially binding version

FOREWORD

DET NORSKE VERITAS (DNV) is an autonomous and independent foundation with the objectives of safeguarding life,property and the environment, at sea and onshore. DNV undertakes classification, certification, and other verification andconsultancy services relating to quality of ships, offshore units and installations, and onshore industries worldwide, andcarries out research in relation to these functions.

DNV service documents consist of among others the following types of documents:— Service Specifications. Procedural requirements.— Standards. Technical requirements.— Recommended Practices. Guidance.

The Standards and Recommended Practices are offered within the following areas:A) Qualification, Quality and Safety MethodologyB) Materials TechnologyC) StructuresD) SystemsE) Special FacilitiesF) Pipelines and RisersG) Asset OperationH) Marine OperationsJ) Cleaner EnergyO) Subsea Systems

© Det Norske Veritas AS June 2012

Any comments may be sent by e-mail to [email protected]

This service document has been prepared based on available knowledge, technology and/or information at the time of issuance of this document, and is believed to reflect the best ofcontemporary technology. The use of this document by others than DNV is at the user's sole risk. DNV does not accept any liability or responsibility for loss or damages resulting fromany use of this document.

Offshore Service Specification DNV-OSS-901, June 2012Introduction –

GeneralThis document replaces the DNV document “DNV Project Certification Scheme, General Scope of Work forProject Certification of Offshore Wind Farms”, 2005-12-08.


Offshore Service Specification DNV-OSS-901, June 2012 Contents –

CONTENTS

Sec. 1 INTRODUCTION.............................................................................................................................. 7

A. General ........................................................................................................................................................................... 7A 100 Objectives ............................................................................................................................................................. 7A 200 Scope of application.............................................................................................................................................. 7A 300 Organization of the OSS ....................................................................................................................................... 7A 400 Hierarchy of DNV Offshore Publications............................................................................................................. 7

B. Definitions ...................................................................................................................................................................... 8B 100 General.................................................................................................................................................................. 8B 200 Verbal forms ......................................................................................................................................................... 8B 300 Terms .................................................................................................................................................................... 8B 400 Acronyms.............................................................................................................................................................. 9B 500 Symbols .............................................................................................................................................................. 10

C. References .................................................................................................................................................................... 10C 100 General................................................................................................................................................................ 10C 200 DNV documents ................................................................................................................................................. 10C 300 IEC documents.................................................................................................................................................... 11C 400 ISO documents.................................................................................................................................................... 11C 500 Other documents ................................................................................................................................................. 11

Sec. 2 SERVICE OVERVIEW .................................................................................................................. 12

A. General ......................................................................................................................................................................... 12A 100 Objective ............................................................................................................................................................. 12A 200 Selection of certification system......................................................................................................................... 12

B. DNV Project Certification.......................................................................................................................................... 12B 100 Certification phases............................................................................................................................................. 12B 200 Basis and procedure ............................................................................................................................................ 13B 300 Deliverables ........................................................................................................................................................ 13B 400 Validity and maintenance of certificate .............................................................................................................. 13

C. Certification to the IEC System................................................................................................................................. 15C 100 General................................................................................................................................................................ 15

D. Certification to National Approval Systems............................................................................................................. 16D 100 General on national requirements ....................................................................................................................... 16D 200 National requirements in relation to the DNV system........................................................................................ 16D 300 Danish Project Certification System................................................................................................................... 16D 400 Other national systems........................................................................................................................................ 16

E. Maintenance of Project Certificate............................................................................................................................ 16E 100 Period of validity ................................................................................................................................................ 16E 200 Maintenance of certificate................................................................................................................................... 16E 300 Recertification..................................................................................................................................................... 16

F. Accredited Project Certification................................................................................................................................ 17F 100 Accreditations ..................................................................................................................................................... 17

G. Client–DNV Interaction ............................................................................................................................................. 17G 100 Documentation requirements .............................................................................................................................. 17G 200 Deliverables and Schedule.................................................................................................................................. 17

H. Combination of Codes and Standards ...................................................................................................................... 18H 100 General................................................................................................................................................................ 18

Sec. 3 DETAILED SERVICE DESCRIPTION:WIND TURBINE AND SUPPORT STRUCTURE ...................................................................... 19

A. Introduction................................................................................................................................................................. 19A 100 Objective ............................................................................................................................................................. 19

B. Phase I: Verification of Design Basis......................................................................................................................... 19B 100 General................................................................................................................................................................ 19B 200 Site conditions..................................................................................................................................................... 20B 300 Codes, standards and requirements..................................................................................................................... 21B 400 Design criteria..................................................................................................................................................... 21B 500 Load-out, transport, installation and commissioning ......................................................................................... 21B 600 Operation and maintenance................................................................................................................................. 22

C. Phase II: Verification of Design................................................................................................................................. 22C 100 General................................................................................................................................................................ 22



C 200 Load and response............................................................................................................................................... 22C 300 Wind turbine type ............................................................................................................................................... 23C 400 Wind turbine ....................................................................................................................................................... 24C 500 Primary support structure.................................................................................................................................... 25C 600 Secondary structures ........................................................................................................................................... 26C 700 Tertiary structures ............................................................................................................................................... 26C 800 Other installations ............................................................................................................................................... 26C 900 Load-out, transportation, installation and commissioning plan.......................................................................... 26C 1000 Operation and maintenance plan......................................................................................................................... 27

D. Phase III: Manufacturing Survey.............................................................................................................................. 27D 100 General................................................................................................................................................................ 27D 200 Survey of wind turbine and components ............................................................................................................ 28D 300 Survey of support structure................................................................................................................................. 28

E. Phase IV: Installation Survey .................................................................................................................................... 29E 100 General................................................................................................................................................................ 29E 200 Installation survey............................................................................................................................................... 29E 300 Warranty survey.................................................................................................................................................. 30

F. Phase V: Commissioning Survey ............................................................................................................................... 31F 100 General................................................................................................................................................................ 31F 200 Commissioning survey ....................................................................................................................................... 31

G. Phase VI: In-service Surveys ..................................................................................................................................... 31G 100 General................................................................................................................................................................ 31G 200 Surveys................................................................................................................................................................ 31G 300 Wind turbine ....................................................................................................................................................... 32G 400 Submerged structures ......................................................................................................................................... 32G 500 Validation of certificate ...................................................................................................................................... 33

Sec. 4 DETAILED SERVICE DESCRIPTION:SUBSTATION TOPSIDE AND SUPPORT STRUCTURE......................................................... 34

A. Introduction................................................................................................................................................................. 34A 100 Objective ............................................................................................................................................................. 34

B. Phase I: Verification of Design Basis......................................................................................................................... 34B 100 General................................................................................................................................................................ 34B 200 Site conditions..................................................................................................................................................... 34B 300 Codes, standards and requirements..................................................................................................................... 34B 400 Design criteria..................................................................................................................................................... 35B 500 Load-out, transportation, installation and commissioning.................................................................................. 35B 600 Operation and maintenance................................................................................................................................. 35

C. Phase II: Verification of Design................................................................................................................................. 35C 100 General................................................................................................................................................................ 35C 200 Structural design and geotechnical design.......................................................................................................... 35C 300 Primary structures ............................................................................................................................................... 36C 400 Secondary structures ........................................................................................................................................... 37C 500 Tertiary structures ............................................................................................................................................... 37C 600 Electrical design.................................................................................................................................................. 37C 700 Fire and explosion protection design .................................................................................................................. 38C 800 Access and transfer design.................................................................................................................................. 38C 900 Emergency response design................................................................................................................................ 39C 1000 Load-out, transportation, installation and commissioning plan.......................................................................... 39C 1100 Operation and maintenance plan......................................................................................................................... 40

D. Phase III: Manufacturing Survey.............................................................................................................................. 40D 100 General................................................................................................................................................................ 40D 200 Topside structure................................................................................................................................................. 41D 300 Topside equipment.............................................................................................................................................. 41D 400 Support structure................................................................................................................................................. 41

E. Phase IV: Installation Survey .................................................................................................................................... 41E 100 General................................................................................................................................................................ 41E 200 Installation survey............................................................................................................................................... 41E 300 Warranty survey.................................................................................................................................................. 42

F. Phase V: Commissioning Survey ............................................................................................................................... 42F 100 General................................................................................................................................................................ 42F 200 Commissioning survey ....................................................................................................................................... 43

G. Phase VI: In-service Surveys ..................................................................................................................................... 43G 100 General................................................................................................................................................................ 43G 200 Surveys................................................................................................................................................................ 43G 300 Substation ........................................................................................................................................................... 43



G 400 Submerged structures.......................................................................................................................................... 44G 500 Validation of certificate ...................................................................................................................................... 44

App. A SAMPLE CERTIFICATION DOCUMENTS............................................................................... 45

A. Sample Statement of Compliance.............................................................................................................................. 45A 100 Sample statement of compliance ........................................................................................................................ 45

B. Sample Project Certificate ......................................................................................................................................... 46B 100 Sample project certificate ................................................................................................................................... 46


Offshore Service Specification DNV-OSS-901, June 2012 Sec.1 –

SECTION 1INTRODUCTION

A. General

A 100 Objectives

101 This Offshore Service Specification (OSS) specifies DNV’s service for project certification of offshorewind farms.

102 The document has a dual function in that it

— provides a common communication platform for describing the scope and extent of activities performedfor project certification of wind farms.

— forms a reference document for defining the scope of work in accordance with requirements by theapplicable certification system.

103 This OSS is an object-specific detailed service specification conforming to the philosophy defined inDNV-OSS-300 Risk-Based Verification, Sec.1E. The service specified in this OSS is in compliance with theIEC Project Certification System described in IEC 61400-22.

104 DNV’s project certification service includes certification to the DNV Project Certification System, basedon DNV standards, as well as certification to other certification systems, based on other standards.

105 The project certification concept for offshore wind farms constitutes a robust means to provide, throughindependent verification, evidence to stakeholders (financiers, partners, utility companies, insurancecompanies and the public) that a set of requirements laid down in standards are met during design andconstruction, and maintained during operation, of an offshore wind farm.

106 The OSS describes the activities which are necessary to be carried out to obtain a DNV ProjectCertificate and it describes how to maintain this certificate by periodical validation during the service life ofthe wind farm.

107 This document has a dual objective: It serves as a publicly available description of DNV’s projectcertification service for offshore wind farms and it will be referred to as a contractual document in the projectcertification contract between the client and DNV. The document specifies the obligations of the client whenhis wind farm is to become certified, as well as DNV’s service obligations to the client.

A 200 Scope of application

201 This OSS applies to project certification and related verification tasks during the design, construction andoperation of offshore wind farms.

202 The following two assets of offshore wind farms are covered by the service:

— Wind turbines and their support structures— Substations including topsides and support structures.

203 Each asset may be further subdivided into elements. In this OSS, the term element is used for thefollowing components:

— Wind turbines— Support structures for wind turbines— Substation topsides— Support structures for topsides.

A 300 Organization of the OSS

301 The OSS is divided into four main sections. Sec.1 provides general information about projectcertification of offshore wind farms. Sec.2 provides a general service overview. Sections 3 and 4 providedetailed descriptions of the service. Sec.3 contains details of the service concerned with the wind turbine andthe support structure. Sec.4 contains details of the service concerned with the substation.

A 400 Hierarchy of DNV Offshore Publications

401 DNV Offshore Publications are organized according to a three-level document hierarchy, with thesemain features:

— Principles and procedures related to DNV’s certification and verification services are separate fromtechnical requirements and are presented in DNV Offshore Service Specifications

— Technical requirements are issued as self-contained DNV Offshore Standards— Associated product documents are issued as DNV Recommended Practices.



402 The hierarchy in 401 is designed with these objectives:

— Offshore Service Specifications present the scope and extent of DNV’s services— Offshore Standards are issued as neutral technical standards to enable their use by national authorities, as

international codes and as company or project specifications without reference to DNV’s services— Recommended Practices provide DNV’s interpretation of safe engineering practice for general use by

industry.

Guidance note:The latest revision of all DNV documents may be found in the publications list on the DNV web site www.dnv.com.

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B. Definitions

B 100 General101 The definitions in the DNV standards “DNV-OS-J101 Design of Offshore Wind Turbine Structures” and“DNV-OS-J201 Offshore Substations for Wind Farms” apply for this OSS. Key definitions and specificdefinitions for this OSS are given in B300.

B 200 Verbal forms201 The terms will, can and may are used when describing DNV’s actions and activities, whereas the termsshall, should and may are used when referring to actions and activities by other parties than DNV.202 Shall: Indicates requirements strictly to be followed in order to conform to this OSS and from which nodeviation is permitted.203 Should: Indicates that among several possibilities, one is recommended as particularly suitable, withoutmentioning or excluding others, or that a certain course of action is preferred but not necessarily required. Otherpossibilities may be applied subject to agreement.204 Will: Indicates a mandatory action or activity to be undertaken by DNV (in contrast to the use of shallfor other parties).205 Can: Indicates an action or activity which DNV does not necessarily undertake unless specificallyrequired by the client (in contrast to the use of should for other parties). Can may also indicate an action oractivity which DNV wants to undertake even if not specifically required by the client.206 May: Verbal form used to indicate a course of action permissible within the limits of the OSS.

B 300 Terms301 Asset: Term used in the context of offshore wind farm projects to describe the project or object to bedeveloped, manufactured and maintained. In this OSS the term refers either to “Wind Turbines with SupportStructures” or to “Offshore Substation”.302 Certification: Action by a certification body, providing written assurance that adequate confidence isprovided that the asset in question is demonstrably in conformity with a specific standard or other normativedocument. Certification is the final statement that all requirements of a standard or normative document havebeen satisfied or conformed to. 303 Client: DNV’s contractual partner. 304 Condition: The term Condition is used for a major Outstanding Issue which would signify a deviationfrom a major technical requirement, and which could seriously affect the intended operation of the wind farm.In case of a Condition, a Project Certificate will not be issued until the outstanding issue has been rectified. Inspecial cases, project certificates can be issued with very limited outstanding issues. See Sec.2 G205.305 Conformity Statement: IEC term for Statement of Compliance.306 Det Norske Veritas (DNV): An autonomous and independent foundation with the purpose ofsafeguarding life, property and the environment. The foundation operates through the limited company DetNorske Veritas AS, which is registered in Norway and operates through a worldwide network of offices.307 Element: A system or a component that forms part of an asset. In this OSS, the term refers to rotor–nacelleassembly (wind turbine excluding tower), support structure for wind turbine (tower, substructure and foundation),topside equipment, and support structure for substation (topside structure, substructure and foundation).308 Foundation: The part of the support structure for an offshore wind turbine or substation that transfers theloads acting on the structure into the seabed.309 Offshore Wind Farm Project: Term referring to the total number of wind turbines including supportstructures within a wind farm. A substation may be defined as an integral element of the Offshore Wind FarmProject or as a separate asset.



310 Optional: Optional services are services which are not part of the scope which is required in order toobtain statements of compliance and project certificates.

311 Other installations: Installations such as cables, secondary structures and other equipment. The cablescomprise cables between the substation and the wind turbines and between the substation and the main grid.

312 Outstanding Issue: The term Outstanding Issue is used to denote a deviation from standards andtechnical requirements specified in the contract, and which needs to be completed for full compliance.Outstanding issues will be noted on the Statement of Compliance issued, see Sec.2 G205.

313 Primary Structure: The primary structure consists of the load-bearing structure that transfers permanentloads and environmental loads, caused by gravity and environment and acting on the support structure, to theseabed.

314 Project Certificate: A document signed by DNV and affirming that, at the time of assessment, the assetreferred to on the certificate met the stated requirements.

315 Recommendation: Non-mandatory advice.

316 Secondary Structure: Secondary structures are boat landings, access ladders, access platforms and J-tubes, which shall be covered by a risk-based verification before a Statement of Compliance can be issued.Note that J-tubes on substations are defined as part of the primary structure.

317 Statement of Compliance: Term referring to a document signed by DNV and affirming that, at the timeof assessment, the defined certification phase, project phase or natural part of the project met the statedrequirements. In the IEC system, this document is referred to as a Conformity Statement.

318 Substation: Term referring to transformer platforms and converter platforms, with or withoutaccommodations. An offshore substation may be defined as an integral element of the offshore wind farmproject or as a separate asset for DNV Project Certification.

319 Substructure: Term referring to the part of the support structure for an offshore wind turbine whichextends upwards from the seabed and connects the foundation and the tower. The term is also used to designatethe part of the support structure for a substation which extends upwards from the seabed and connects thefoundation and the topside.

320 Support Structure: The support structure for an offshore wind turbine is defined as the structure belowthe yaw system of the wind turbine and includes the tower structure, the substructure and the foundation. Theterm is also used to designate the topside structure, substructure and foundation for an offshore substation.

321 Tertiary Structure: Structural items such as internal ladders and platforms, stairs, gratings and handrails.

322 Verification: Verification consists of evaluating and checking information to establish that an object inquestion meets a technical requirement or standard. Multiple verification activities are performed andsuccessfully completed to support the decision to issue a statement of compliance.

323 Wind Turbine: System which converts kinetic energy in the wind into electrical energy. For windturbines in an offshore wind farm project subject to DNV Project Certification, the wind turbine is limited tothe rotor and nacelle assembly and the electrical installations and secondary structures located inside the tower.

B 400 Acronyms

401 Acronyms as given in Table B1 are used in this service specification.

Table B1 Acronyms

Acronym In fullAC Alternating currentALS Accidental Limit StateBEK Bekendtgørelse (Executive order, in Danish)BOEMRE Bureau of Ocean Energy Management, Regulation and EnforcementBSH Bundesamt für Seeschifffart und HydrographieCVA Certified Verification AgentDANAK Den Danske Akkrediterings- og Metrologifond (The Danish Accreditation and Metrology Fund, in Danish)DC Direct currentDNV Det Norske VeritasFEM Finite Element MethodFLEX5 Computer program for simulation of wind turbine dynamicsFLS Fatigue Limit StateHAWC Horizontal axis wind turbine simulation codeIEC International Electrotechnical CommissionISO International Organization for Standardization



B 500 Symbols501 Symbols as given in Table B2 are used in this service specification.

C. References

C 100 General101 This document makes reference to relevant DNV Rules and Standards and to international codes andstandards. Unless otherwise specified in the certification agreement or in this OSS, the latest valid revision ofeach referenced document applies.

C 200 DNV documents201 DNV rules, standards and service descriptions of relevance for offshore wind farms are listed in Table C1.

NDT Non-destructive testingNVN Nederlandse Voor Norm (Dutch pre-norm, in Dutch)O&M Operation and MaintenanceOWF Offshore Wind FarmQA Quality AssuranceROV Remotely Operated VehicleSLS Serviceability Limit StateSoC Statement of ComplianceTR Technical ReportTS Technical SpecificationULS Ultimate Limit StateUS United StatesWT Wind Turbine

Table B2 SymbolsSymbol InterpretationCd Hydrodynamic drag coefficientCm Hydrodynamic inertia coefficient

Table C1 DNV documentsReference TitleDNV-DSS-904 Type Certification of Wind TurbinesDNV-OSS-300 Risk Based VerificationDNV-OS-B101 Metallic MaterialsDNV-OS-C101 Design of Offshore Steel Structures, General (LRFD Method)DNV-OS-C401 Fabrication and Testing of Offshore StructuresDNV-OS-C502 Offshore Concrete StructuresDNV-OS-H101 Marine Operations, General DNV-OS-J101 Design of Offshore Wind Turbine StructuresDNV-OS-J201 Offshore Substations for Wind FarmsDNV-OS-J301 Standard for Classification of Wind Turbine Installation UnitsStandard for Certification No. 2.22 Lifting Appliances

Rules for Planning and Execution of Marine Operations

Table B1 Acronyms (Continued)Acronym In full



C 300 IEC documents301 IEC documents of relevance for offshore wind farms are listed in Table C2.

C 400 ISO documents401 ISO documents of relevance for offshore wind farms are listed in Table C3.

C 500 Other documents501 Other documents of relevance for offshore wind farms are listed in Table C4.

Table C2 IEC documentsReference TitleIEC 61400-1 Wind Turbines – Part 1: Design requirementsIEC 61400-3 Wind Turbines – Part 3: Design requirements for offshore wind turbinesIEC 61400-22 Wind Turbines – Part 22: Conformity Testing and CertificationIEC 60364 Electrical installations for buildingsISO/IEC 17025 General requirements for the competence of calibration and testing laboratories

Table C3 ISO documentsReference TitleISO 9001 Quality management systems – requirements

Table C4 Other documentsReference TitleEurocode 7 Geotechnical design – Part 2: Ground investigation and testing



SECTION 2SERVICE OVERVIEW

A. General

A 100 Objective101 The objective of this section is to provide an overview of the activities performed for project certificationof offshore wind farms. Certification according to various certification systems are dealt with.

A 200 Selection of certification system201 The certification system to be applied for the certification shall be agreed in the contract between theclient and DNV. 202 Project certification of wind farms is carried out according to one of several project certification systems.The following project certification systems are available and recognized by DNV:

— DNV Project Certification System— IEC 61400-22 Project Certification System— Danish Project Certification System.

DNV also offers project certification of wind farms according to certification systems by BSH under Germanjurisdiction and as CVA according to US legislation, but not as an accredited service.

B. DNV Project Certification

B 100 Certification phases101 DNV Project Certification is a particular form of certification where the total scope of the involvedactivities is defined by DNV. For project certification of Offshore Wind Farms (OWF) this OSS defines thescope.102 The DNV Project Certification System consists of six modules, see Figure 1. The modules refer to fiveparticular phases during the design and construction and to one in-service phase.

Figure 1 The phases of a DNV Project Certification

103 Phases I and II cover the steps necessary to achieve final design verification. This verification includesa site-specific design approval of the integrated structural system consisting of wind turbine and supportstructure or substation topside and support structure. 104 Phases III through V involve all follow-up verification and on-site inspections during the implementationof the project.105 Phase VI involves follow-up verification and on-site inspections after the completion of the project andduring the in-service period.

III Manufacturing

IV Installation

I Design Basis

II Design

V Commissioning

VI In- Service

DN

V Project Certificate

Statement of Compliance





Maintenance

of Certificate



106 Each phase will be completed with the issue of a Statement of Compliance. After completion of PhasesI through V for the wind turbine and the support structure or for the substation, a DNV Project Certificate willbe issued. The certificate documents compliance with specified or agreed standards at the date of issue.

107 Statements of compliance may be issued with no or minor outstanding issues. An outstanding issue on astatement of compliance implies that the outstanding issue regarding compliance with specified or agreedstandards have not been rectified.

108 The project certificate may be issued with minor outstanding issues. An outstanding issue on a projectcertificate implies that the outstanding issue regarding compliance with specified or agreed standards have notbeen rectified. The project certificate may be validated throughout the in-service phase VI. For validationthroughout the in-service phase, reference is made to Sec.3G and Sec.4G.

109 On request, complementary services to DNV Project Certification may be performed and will then bedocumented separately. Such services may include precertification services, for example verification of projectplanning and permitting, and pre-design evaluation and warranty surveys.

110 The DNV Project Certification System is in compliance with the IEC Project Certification System asspecified in IEC 61400-22 Conformity Testing and Certification of Wind Turbines.

B 200 Basis and procedure

201 DNV-OS-J101 and DNV-OS-J201 in conjunction with their respective referenced DNV standards andrules provide the technical key requirements to be fulfilled for the assets subject to the project certification.

202 Wherever DNV-OS-J101 and DNV-OS-J201 refer to acceptance, agreement and qualification, this shallbe by DNV.

203 In essence project certification consists of a series of verification activities. The extent of these activitiesis defined in this OSS and the activities are organized in phases. Following a successful completion of a phase,DNV issues a Statement of Compliance (SoC).

204 The requirement for obtaining a DNV Project Certificate is that a SoC has been issued by DNV for eachof the five Phases I through V.

205 For each certification phase, the assets covered by the project certification can be subdivided intoelements as defined in Sec.1 A307. One SoC is issued for each individual element verified in the phase or onecommon SoC is issued for all elements verified in the phase. For example, for the Design Basis Phase separateSoCs can be issued for the elements “Wind Turbine” and “Support Structure” or one common SoC coveringboth the wind turbine and the support structure can be issued for the Design Basis phase.

206 Following the successful completion of a project certification of an offshore wind farm project, DNVissues project certificates for offshore wind farm assets, which are either the wind turbines with supportstructures or the substation topsides with support structures, or both, depending on the agreed scope of thecertification.

B 300 Deliverables

301 A DNV Project Certificate can be issued for an offshore wind farm asset as defined in this OSS. Possibleproject certificates are certificates for

— wind turbines and their support structures— substations including topside components and support structures.

B 400 Validity and maintenance of certificate

401 The DNV Project Certificate refers to statements of compliance issued for the completed phases of theproject certification. The project certificate is valid for one year after the date of first issuance.

402 When an in-service agreement for the wind farm is in place between DNV and the client, the validity ofthe project certificate is extended to the duration of the service agreement plus one year; however, five years isthe maximum period of validity.

403 Maintenance of the certificate is conditioned on:

— annual reporting by client covering the certified wind farm project and including information about

— installed turbines and additional installations as installed on the site— deviating operating experience— minor modifications

— reporting by client of planned major modifications without delay— the wind farm and the turbines and structures that it comprises are maintained at a standard complying with

the requirements of applicable codes and relevant manuals— periodical surveys by DNV. A statement of compliance that validates the certificate will be issued on the

basis of successful periodical in-service surveys.



Table B1 Phases of DNV Project Certification and associated activities for wind turbine and support structure; references are to subsection numbers in Sec.3.PHASES ELEMENTS

Rotor–nacelle assembly(wind turbine exclusive of tower)

Support structure(tower, substructure and foundation)

I. Design Basis B 200 Site conditionsB 300 Codes, standards and requirements B 300 Codes, standards and requirementsB 400 Design criteria B 400 Design criteria B 500 Transport, installation and commissioning

B 600 Operations and maintenance

B 500 Transport, installation and commissioning B 600 Operation and maintenance

II. Design C 200 Load and responseC 300 Wind turbine type C 400 Wind turbineC 900 Load-out, transportation, installation and commissioning planC 1000 Operation and maintenance plan

C 500 Primary support structureC 600 Secondary structuresC 700 Tertiary structuresC 800 Other installationsC 900 Load-out, transportation, installation and commissioning planC 1000 Operation and maintenance plan

III. Manufacturing D 200 Survey of wind turbine and components D 300 Survey of support structure IV. Transport and Installation

E 200 Installation survey E 200 Installation survey

V. Commissioning F 200 Commissioning survey F 200 Commissioning surveyVI. In-Service G 200 Surveys

G 300 Wind turbineG 500 Validation of certificate

G 200 SurveysG 400 Submerged structures G 500 Validation of certificate

Table B2 Phases of Project Certification and associated activities for substation topside and support structure; references are to subsection numbers in Sec.4.PHASES ELEMENTS

Substation topside(topside structure, fire and safety, topside

equipment, escape routes)(optional: helideck, crane, electrical components, ventilation system, etc.)

Substation support structure(substructure and foundation)

I. Design Basis B 200 Site conditionsB 300 Codes, standards and requirements B 300 Codes, standards and requirementsB 400 Design criteria B 400 Design criteriaB 500 Load-out, transportation, installation and commissioningB 600 Operation and maintenance

B 500 Load-out, transportation, installation and commissioningB 600 Operation and maintenance

II. Design C 200 Structural design C 200 Structural design and geotechnical designC 300 Primary structuresC 400 Secondary structuresC 500 Tertiary structuresC 600 Electrical design*C 700 Fire and explosion protection designC 800 Access and transfer designC 900 Emergency response designC 1000 Load-out, transportation, installation and commissioning planC 1100 Operation and maintenance plan

C 300 Primary structuresC 400 Secondary structuresC 500 Tertiary structuresC 1000 Load-out, transportation, installation and commissioning planC 1100 Operation and maintenance plan

III. Manufacturing D 200 Topside structureD 300 Topside equipment

D 400 Support structure

IV. Transport and Installation

E 200 Installation survey E 200 Installation survey

V. Commissioning F 200 Commissioning survey F 200 Commissioning surveyVI. In-Service G 200 Surveys

G 300 TopsideG 500 Validation of certificate

G 200 SurveysG 300 Support structure above waterG 400 Submerged structures G 500 Validation of certificate

* Electrical design is currently optional as it is not covered by DNV-OS-J201, 2009.



404 The verification activities associated with the various elements and certification phases covered byTables B1 and B2 are presented in more detail in Sections 3 and 4.405 Warranty surveys are not part of the project certification scope, but can be carried out as an optionaladditional service.

C. Certification to the IEC System

C 100 General101 Wind farm projects can be certified to the IEC system, which is specified in IEC61400-22 ConformityTesting and Certification of Wind Turbines and which refers to requirements in IEC61400-1 and IEC61400-3.102 DNV offers certification of wind farm projects to the IEC system. The DNV certification according tothe IEC system and according to the DNV system defined in Subsection B are mutually compliant. The extentof the verification activities necessary to lead to the issue of a certificate according to the IEC system aredefined in IEC 61400-22. 103 With a view to certification according to the IEC system, the objective of this OSS is to detail and clarifythe verification activities within the IEC system and to fill gaps in the governing IEC standards, in particularwith respect to representation of the structural capacity in design.104 DNV-OS-J101 and DNV-OS-J201 can be used as guidance and serve as DNV’s interpretation of therequirements of IEC 61400-22, IEC 61400-1 and IEC61400-3 for offshore wind farms.105 The IEC system covers a number of certification phases. A conformity statement is issued at thecompletion of the verification activities for each certification phase within the IEC system. The conformitystatement is analogous to the statement of compliance issued at the completion of a certification phase withinthe DNV system. 106 Mandatory and optional certification phases in the IEC system are outlined in Figure 2, in which thecertification phases according to the DNV system are included for comparison. The DNV system complies withthe IEC system with the main difference that some DNV phases comprise multiple IEC phases. The number ofconformity statements issued when the IEC system is followed for the certification will therefore be larger thanthe number of statements of compliance issued when the DNV system is followed. Another difference betweenthe two systems consists of slightly differently formulated requirements in a few cases where the IECrequirements are relatively openly formulated and where the corresponding DNV requirements have beensubject to a reformulation for clarity. However, as the IEC system and the DNV system are mutually compliant,the IEC system is fulfilled when the DNV system is followed for the certification, and vice versa.

Figure 2 IEC certification phases (blue) in comparison with DNV Project Certification phases (green)

Site Conditions Assessement

Design Basis Evaluation

Integrated Load Analysis

Support Structure Design Evaluation

Support Structure Manuf . Surveillance

Commissioning Surveillance

Transportation & Install . Surveillance

Final Evaluation

Project Characteristics Measurements

Project Certificate

Wind Turbine / RNA Manuf. Surveillance

Wind Turbine / RNA Design Evaluation

Other Installations Manuf . Surveillance

Other Installations Design Evaluation

Operations & Maintenance Surveillance

Type Certificate

Design Basis

DesignInstal-lation

Comm

is-sioning

Manufac-turing

In-service

OptionalMandatory

Project Certificate



D. Certification to National Approval Systems

D 100 General on national requirements

101 Wind farms can be certified to national approval systems for offshore wind farms. DNV offerscertification to such national approval systems.

102 For certification to national approval systems for offshore wind farms, the pertinent national rules andregulations form the requirements for the DNV certification. These requirements need to be fulfilled in orderto allow a project certificate to be issued for an offshore wind farm.

103 DNV-OS-J101 and DNV-OS-J201 can be used as guidance and serve as DNV’s interpretation of therequirements of the national rules and requirements in question.

D 200 National requirements in relation to the DNV system

201 National approval systems may impose requirements which come in addition to the requirements of theDNV system. The DNV system may also contain requirements which come in addition to the nationalrequirements.

202 For DNV’s approval and for DNV to issue statements of compliance in connection with certification tonational approval systems, all requirements set forth in the DNV system need to be fulfilled.

Guidance note:This policy is in force on the grounds that DNV needs to verify that requirements for safety level are met before DNVcan issue statements of compliance.


D 300 Danish Project Certification System

301 Project certification is according to the Danish Energy Agency Executive Order No. 651, 2008-06-26.

D 400 Other national systems

401 National systems and standards are in place for Germany and the United States. These standards includerequirements which come in addition to those set forth by IEC and they require appropriate national bodies forthe final approval.

402 Germany: Bundesamt für Seeschifffart und Hydrographie (BSH) Standard Konstruktive Ausführungvon Offshore-Windenergieanlagen. BSH-Nr. 7005, June 12, 2007.

403 United States: BOEMRE. Federal Register 30 CFR Parts 250, 285 and 290 Renewable Energy andAlternative Uses of Existing Facilities on the Outer Continental Shelf; Final Rule.

E. Maintenance of Project Certificate

E 100 Period of validity

101 The validity period of a project certificate for a wind farm is one year from the date of first issuance.

102 When an in-service agreement for the wind farm is in place between DNV and the client, the validityperiod of the project certificate is extended to the duration of the service agreement plus one year; however,five years is the maximum period of validity.

E 200 Maintenance of certificate

201 Maintenance of the project certificate is conditioned on periodical surveys by DNV.

202 A statement of compliance that validates the certificate will be issued on the basis of successfulperiodical in-service surveys.

E 300 Recertification

301 DNV may require recertification if additional requirements for maintenance of the project certificate areset by national authorities or by the applicable design code or standard during the validity period of thecertificate.

302 Major revision to a referenced standard as well other new industry learning during the validity period fora project certificate will be evaluated by DNV. If such a revision is judged to have implications for the integrityand safety of the certified wind farm, the wind farm will have to be modified and/or re-evaluated in order toretain its project certificate. Transition periods and guidance for implementation of new revisions will beestablished by DNV for each individual case.



F. Accredited Project Certification

F 100 Accreditations101 DNV is accredited for project certification of wind farms according to systems as specified in 102.102 DNV is accredited for project certification of wind farms according to the following systems:

— DNV Project Certification System according to DNV-OSS-901, 2012— Offshore and Onshore Wind Turbine Parks according to Danish Energy Agency Executive Order No. 651,

2008-06-26 Executive Order on the Technical Certification Scheme for the Design, Manufacture,Installation, Maintenance and Service of Wind Turbines

— Offshore and onshore Wind Turbine Parks according to IEC 61400-22 Wind turbines – Part 22: Conformitytesting and certification, Section 9.

103 The accreditation is granted by DANAK and is limited to DNV Denmark (Det Norske Veritas, DanmarkA/S).

G. Client–DNV Interaction

G 100 Documentation requirements101 The documentation packages pertaining to each task listed in Tables A1 and A2 and provided to DNVby the client shall be complete and self-explanatory.102 The documentation shall be provided to DNV in a logical sequence to facilitate cross checking betweendocuments.103 The documentation, including codes and standards as well as other requirements and specifications, shallbe prepared in the English language, unless otherwise agreed in writing between DNV and the client.104 All documentation for verification shall be forwarded to DNV in electronic form. DNV may requiredrawings to be forwarded in hard copy form. 105 DNV assumes that the verification of each documentation package consists of one initial documentreview and one follow-up review after changes have been implemented to comply with DNV comments. Nomajor changes of methods and other provisions between the first time review and the follow-up review areaccounted for in this review set-up.

G 200 Deliverables and Schedule201 The deliverables by DNV must be agreed in detail between the client and DNV as part of the contract.In general the DNV Project Certificate is issued when all of the required statements of compliance accordingto the DNV Project Certification System have been issued. 202 Each certification phase for a considered element can be verified independently according to the DNVProject Certification System and will be completed with the issue of a statement of compliance for that element.However, successful completion of preceding phases whose completion is a prerequisite for the phase inquestion is required. For example, prior to verification of the Manufacturing phase for the tower and thesubstructure, the Design Basis phase and the Design phase for these elements must both be completed andverified.203 During the verification of documentation DNV provides the following deliverables:

— DNV review letters and verification comments will be issued during the review process to state progressof reviews including any red flags and forecast to completion. These review letters will be issued inelectronic form and delivered by e-mail to the client.

— DNV Technical Report(s) will be issued to document DNV’s verification work. These reports will bedelivered in a hard copy (paper) as well as electronically as a pdf-file.

204 For surveys during manufacturing, transportation, installation and commissioning as well as in service,DNV will report critical findings immediately after the survey to the client. DNV will issue survey reports tothe client and the frequency of these shall be agreed with the client (for example daily, weekly or monthly).The report will describe the extent of the survey including findings, nonconformities and possiblerecommendations. The report will be issued in electronic form and sent by e-mail to the client.205 Final DNV Design Verification Reports and Letters and corresponding Statements of Compliance willbe issued to the client upon completion of the project tasks. The documentation will be delivered in a hard copy(paper) as well as electronically as a pdf-file.In the event that a full compliance is not obtained for all issues, the deliverables will depend on the characterof the lack of compliance. Three deliverable options are available:

— No outstanding issues. A Statement of Compliance with an accompanying DNV Technical Report will be



issued. In the case of certification to the IEC system, an IEC conformity statement will be issued.— A few outstanding less critical issues. A Statement of Compliance will be issued with the outstanding issues

listed in the Statement of Compliance. Specific description of the outstanding issues will be given in theaccompanying DNV Technical Report. As outstanding issues become closed, updated Statements ofCompliance can be issued.

— Major outstanding issues, referred to as conditions. A Statement of Compliance will not be issued. DNVwill deliver the DNV Technical Report that would normally accompany the Statement of Compliance forthe relevant elements or phases. The DNV Technical Report will pinpoint the outstanding issues whoserectification is required before a Statement of Compliance can be issued.

206 After completion of Phases I through V for the wind turbine and the support structure, or alternativelyfor the substation topside and the support structure, the DNV Project Certificate will be issued. The ProjectCertificate will be delivered in a hard copy (paper) as well as electronically as a pdf-file.207 An updated DNV Project Certificate will be issued on the basis of successful periodical in-servicesurveys. The updated DNV Project Certificate will be delivered in a hard copy (paper) and electronically as apdf-file.208 DNV will make an effort to comply with the overall time schedule of the certification and verificationactivities. Final timeframes shall be discussed and agreed between the client, DNV, consultants and suppliersbefore commencement of the work.

Guidance note:In planning the certification schedule it may be assumed that the turn-around time for review comments is in the orderof 10 to 15 working days when the documentation is delivered according to the agreed time schedule. A typicalduration of DNV’s independent analysis and structural strength analysis is 20 to 25 working days.


H. Combination of Codes and Standards

H 100 General101 DNV certification to internationally recognized standards replacing or supplementing DNV-OS-J101and DNV-OS-J201 shall follow the principles described in this OSS. Wherever combinations of such standardsand external criteria are used, the exact terms of reference and documents to be issued shall be agreed at thebeginning of the project and shall be specified in detail in the design basis.102 The application of standards other than DNV standards does not allow for a reduction of the target safetyas described in the safety philosophy sections of DNV-OS-J101 and DNV-OS-J201. DNV reserves the right tocall for additional requirements to cover issues essential to the certification process and not covered by thestandards in question.103 It is strongly recommended not to combine standards from different standard systems due to the possibledifferences in the underlying safety philosophies of the different standard systems. In case standards arecombined, caution must be exercised and the choice of standards is subject to acceptance by DNV, even if thestandards belong to the same standard system.

Guidance note:Within a particular standard, aspects such as requirements for partial safety factors for calculation of design load anddesign resistance are normally mutually balanced to give an overall acceptable safety level. In another standard withthe same overall acceptable safety level, the requirements for the safety factors may have been balanced differently.Picking requirements for load factor from one standard and material factor from another can therefore easily result inunpredictable, and possibly too low, safety levels.




SECTION 3DETAILED SERVICE DESCRIPTION:

WIND TURBINE AND SUPPORT STRUCTURE

A. Introduction

A 100 Objective

101 This section provides the details of DNV’s verification activities for each of the phases of the DNVProject Certification System for the asset that consists of the wind turbines and their support structures.

B. Phase I: Verification of Design Basis

B 100 General

101 The purpose of the verification of the Design Basis is to evaluate if the site conditions and the basis fordesign including general specifications, criteria, parameters, design approach and other assumptions relevantfor design are properly established and documented and that this design basis is sufficient for a safe design andimplementation of the project.

102 Unless otherwise agreed, the verification activities are to DNV’s offshore standard DNV-OS-J101,which is in compliance with the IEC system.

103 A Design Basis shall be provided to DNV. This design basis shall include documentation of thefollowing:

a) site conditions

b) codes, standards and requirements

c) design criteria

d) transport, installation and commissioning requirements

e) operation and maintenance requirements

f) wind turbine type.

The Design Basis identifies the basic assumptions, specification, methods and requirements for the projectdesign. In the case of the project being implemented as a multi-contract project, the design of elements, suchas the wind turbine and the support structure, may be carried out by different parties. In such cases the DesignBasis forms an essential tool with a view to ensuring, documenting and verifying the safety of the total systemand consistency between the different project parts. It is strongly recommended that the Design Basis isdeveloped as an integrated document to be applied for all parts. If the development of the Design Basis isdivided between suppliers of parts of the project, the design basis for each part shall contain all information ofrelevance for the design of that part.

In the case of multi-contracting, the design basis may comprise three parts that together form the Design Basisfor the project:

1) Site conditions and general requirements relating to (a) through (e)

2) Wind turbine specific requirements relating to (b) through (f), including definition of design load cases anddesign wind parameters, load factors and turbine design methodology

3) Structure-specific requirements relating to (b) through (e), including interpretation of geotechnical andenvironmental (metocean) data for design, specification of design methodology including principles,procedure, materials and requirements for Installation and Commissioning and for Operation andMaintenance

Typically DNV carries out the work for Part A for the project owner, Part B for the wind turbine supplier andPart C for the support structure contractor.

The wind turbine type certificate is not needed in the Design Basis phase, but in the Design phase, for whichreason the client’s obligations and DNV’s services related to the wind turbine type are given in Subsection 3Bfor the Design phase.

104 DNV will verify the Design Basis for compliance with DNV-OS-J101 and other codes and standards,identified in the Design Basis. Following a successful completion of the verification of the design basis, DNVwill issue a statement of compliance.



B 200 Site conditions

201 DNV will evaluate the establishment of site conditions detailed in DNV-OS-J101, IEC 61400-1 and IEC61400-3 based on reported data and/or applicable standards or methods valid for the site.

The following site conditions shall be addressed and will be subject to verification:

— wind conditions— wave conditions— weather windows— soil conditions— earthquake conditions— other environmental conditions— electrical power network conditions.

202 For measured data DNV will assess principles and methods for:

— data acquisition— statistical methods applied— establishment of design parameters.

203 The metocean conditions provided may be derived from site-specific measurements supported byhindcasts. Site-specific measurements shall when possible be correlated with data from a nearby location forwhich long term measurements exist. The monitoring period for the site-specific measurements shall besufficient to obtain reliable data for design.

The site-specific measurements shall be carried out and documented as required in DNV-OS-J101 unless aconservative approach is adopted. Such an approach may utilize the uniform conditions at sea together withhindcast models.Independent analysis for selected parameters may be carried out by DNV, based on the environmental andgeotechnical data provided. 204 Measurements of the site conditions shall either be carried out by a testing laboratory accredited to ISO/IEC 17025 or shall be subject to approval by DNV on the basis of an evaluation of the quality and reliabilityof the measurements. Such an evaluation will cover the following issues:

— test and calibration methods— equipment— measurement traceability— assurance of the quality of test and calibration results— reporting of the results.

The geotechnical site investigation and laboratory testing are assumed to be carried out by companies withrelevant experience from similar work. The quality of the soil investigation and the test results shall fulfil therequirements given in Eurocode 7 Part 2.All parts of ISO/IEC 17025 may not necessarily apply to the geotechnical field and laboratory work. In allcases, a description of all test procedures and relevant standards shall be presented.205 DNV will verify that relevant reports properly document the site conditions.

206 DNV will assess the interpretation of the site conditions and the identification of the design parametersdescribing the site conditions to be used for design of the wind turbine, support structure and other installations.Design parameters representing the following conditions shall be included:

— wind climate— wave climate— correlation between relevant parameters such as wind, waves and current— current— water level— ice— water depth— seabed topography— geotechnical data— other site conditions, such as seismicity, lightning, salinity, temperature, spray ice, marine growth, air

density, traffic, disposed matters, pipelines and cables— electrical network conditions.

207 The verification of the geotechnical design basis will focus on:

— extent, quality and relevance of the soil investigations— derivation of soil parameters from the soil investigations.



The geotechnical design basis may, in addition to site-specific soil data, include derived soil profiles andrecommendations regarding calculation methods.

208 DNV will review the electrical power network conditions to be used as the basis for the offshore windfarm project. If the electrical power network conditions for the site differ from the normal electrical powernetwork conditions specified in IEC 61400-3, such conditions, applicable at the wind turbine terminal, shall bedocumented and stated.

B 300 Codes, standards and requirements

301 The codes and standards which form the basis for the wind farm project shall be listed in the design basis.For the site in question, relevant statutory requirements shall also be listed. Such requirements could be safetyrelated issues such as requirements for embarkation, rescue and decommissioning.

302 Other requirements relevant for the project certification such as requirements for the grid connection andother specific requirements from the owner and the grid operator shall be listed.

303 The codes, standards and additional requirements if applicable for the project and site in question will beverified for compliance with the design prerequisites of the project and for completeness and adequatesuitability and applicability. The verification of the selected codes, standards and requirements will beconducted early in the project phase in order to avoid fundamental discussions on this basic aspect of the designbasis.

B 400 Design criteria

401 The design of the integrated structure that comprise the wind turbine and its support structure shall bebased on the specific site conditions as well as the methods and principles as given in DNV-OS-J101.

402 DNV will require and assess all relevant overall design aspects and parameters to be applied in thecalculations regarding the wind and wave conditions, loads, load combinations, partial safety factors appliedfor loads and materials, water depth and tide, scour protection design, corrosion allowance, marine growth andother issues of relevance.

403 DNV will require and assess information needed to determine the resulting conditions due to wakes fromneighbouring wind turbines. This information shall comprise a detailed site layout, a description of thecalculation method to be applied as well as an analysis of wake effects for all wind turbine positions in theactual wind farm layout.

404 Furthermore, DNV will require and assess a description of the main design methodology, including themethod of load calculation, and structural and geotechnical design methodologies. This is important in orderto obtain early agreements regarding methodologies and to avoid discussions about overall principles andmethods late in the project.

405 DNV will verify the principles used to establish load combinations for the SLS, the ULS, the FLS and ifrelevant the ALS for compliance with DNV-OS-J101.

406 The verification of the Design Basis for load calculations will focus on:

— design values for wind conditions and other environmental conditions— design values for sea states, wave heights, crest elevations, directional scatter, fetch, sea level— design values for combination of wind and wave conditions. In particular also misalignments between

wind, wave and currents.— design values for water levels and seabed levels— applied wave theory and models for hydrodynamic loads— design values for soil stiffness, soil strength and soil damping— load combinations and soil properties for assessment of cyclic degradation of soil strength— selection of wave theory and hydrodynamic parameters such as the drag coefficient Cd and the inertia

coefficient Cm— methods and principles used for prediction of extreme design loads and fatigue design loads, and methods

and principles for response analyses— partial safety factors — load combinations (Design Load Cases)— duration of simulation as well as number of simulations — load factors and load reduction factors— design lifetime of components, systems and structures.

407 If the design of, for example, the support structure will be partly based on model tests, DNV will evaluatethe test program.

B 500 Load-out, transport, installation and commissioning

501 The design basis shall state assumptions, specifications and requirements for structural design againstloads occurring during load-out, transportation, installation and commissioning, such as environmental loads,lifting loads, and local loads from temporary supports. The design basis shall also state assumptions,



specifications and requirements for the load-out, transportation, installation and commissioning programmesthemselves. Commissioning of the wind turbine and the tower is usually properly documented through therequired type certification. Commissioning requirements for the substructure and the foundation are usuallyvery limited.

502 Assumptions, specifications and requirements may include:

— codes and standards— specifications and tolerances— limiting environmental conditions — methods and loads of relevance for load-out, transport and installation— requirements for load-out, transportation, installation and commissioning manuals— quality assurance systems for the installation contractors.

The assumptions, specifications and requirements are expected to depend on owner’s requirements as well ason the actual contractual arrangements for the offshore wind farm project.

503 When the wind turbine has been type certified by DNV, only assumptions, specifications andrequirements not verified as part of the type certification shall be stated.

504 DNV will verify assumptions, specification and requirements stated in the design basis.

B 600 Operation and maintenance

601 The design basis shall state assumptions, specifications and requirements for structural design againstloads occurring during operation and maintenance. The design basis shall also state assumptions, specificationsand requirements for the operation and maintenance programmes.

Assumptions, specifications and requirements may include:

— inspection scope and frequency— target lifetime of components, systems and structures— requirements for service and maintenance manuals— requirements for condition monitoring systems.

For the type approved wind turbine, most of these assumptions, specifications and requirements are covered bymanuals approved in the type approval process.

602 When the wind turbine has been type certified by DNV, only assumptions, specifications andrequirements not verified as part of the type certification shall be stated.


C. Phase II: Verification of Design

C 100 General

101 DNV will verify the final design for compliance with DNV-OS-J101 and other codes and standardsidentified in the Design Basis. Details of the verification activities in this phase are given in 200 through 800.

102 Once the verification of the final design has been successfully completed, DNV will issue a Statementof Compliance for Phase II of the project certification.

C 200 Load and response

201 The loads and responses will be verified based on documentation review and independent analyses forcompliance with the approved Design Basis and DNV-OS-J101. The design report for load and response shallas a minimum document the following:

— The wind turbine together with its support structure shall be analysed for the relevant load cases. The waveand wind loads should preferably be combined and applied to the calculation model to enable simulationin the time domain. The expected foundation stiffness variations due to soil and structural properties as wellas water depth variations shall be considered in the calculations.

— The wake effects from neighbouring wind turbines shall be taken into account using the method describedin the approved Design Basis.

— The load cases shall be selected such that load cases are included that represent situations with lowaerodynamic damping. Such cases may include misaligned wind and wave directions, yaw error due to gridloss or malfunction of the control system.

— The loads and responses in the design reports shall be presented in a form that allows for design checks andverification.

— As part of the documentation the calculated time histories shall be supplied to DNV in a readable format.



Guidance note:To allow for design checks for both fatigue loads and ultimate loads, the design reports should present the fundamentalload and responses for all design load cases in a suitable form, for example in terms of cross-sectional forces andmoments at the blade root, in the rotor shaft, in the tower top and bottom, at tower–substructure interfaces, and atmudline. Loads and responses should be presented in terms of the basic statistics (mean, standard deviation) as wellas in terms of extreme loads and fatigue equivalent loads wherever appropriate.Wherever the extreme loads are arrived at by statistical load extrapolation, they should be documented by statisticsand plots that allow review of the appropriateness of the method applied and the accuracy of the extrapolation.


202 In order to verify the site-specific loads for the turbines in question DNV may perform an independentanalysis of the loads and responses.Such an independent analysis will be carried out based on a full dynamic load modelling of the integratedsystem consisting of wind turbine and support structure, including soil modelling and using an aeroelasticcomputer program such as Flex5, HAWC2 or the equivalent.

Critical load cases and load combinations will be analysed by DNV in order to verify loads.

C 300 Wind turbine type301 DNV will require that the wind turbine for the project has a type certificate. The type certificate shall bevalid on the date of issue of the Statement of Compliance for the Design phase. The certification system appliedfor the wind turbine type certificate shall be stated in the Design Basis. In lieu of a type certificate, DNV willaccept a rotor–nacelle assembly certificate provided all relevant measurements and type tests have beenexecuted, such as load measurements and blade tests.302 The type certificate shall preferably be issued by DNV. However, type certificates issued by othercertifying bodies may be accepted by DNV based on agreement made in an early stage of the project. In suchcases DNV will not be responsible for the type certification work carried out by the other certifying body.303 The following type certification systems are available and are recognized by DNV:

— IEC 61400-22 Type Certification System— IEC WT 01 Type Certification System— Danish Type Certification Scheme— Dutch Type Approval Scheme— Special Level Type Certification System.

Reference is made to DNV-DSS-904 for details about these systems. The Special Level Type CertificationSystem is not aimed to be used for offshore wind farm projects.304 DNV will verify that a valid type certificate is in place for the wind turbine. In addition, the followingconditions, requirements and specifications shall be presented to DNV and will be verified by DNV:

— External conditions assumed for the wind turbine design including the grid conditions— Requirements for transport and installation— Requirements for operation and maintenance — Specification for the interfaces between wind turbine and support structure, e.g. tower–substructure

geometry, stiffness of support structure, and stiffness of soil support.

305 A methodology for how to handle deviations from the type certificate, such as reinforcement of theblades, reinforcement of the tower top and yaw system, and modification of the electrical systems, shall beoutlined.

Guidance note:Major deviations from the wind turbine design covered by the type certificate may require an update of the typecertificate; see DNV-DSS-904.


306 The wind turbine specification shall uniquely define the wind turbine type. If the wind turbine has beentype certified by DNV, the wind turbine specification may be limited to a reference to the type certificate andspecifications of possible deviations from the certified wind turbine type, such as a site-specific tower oradditional corrosion protection.

307 For the independent load analysis of the integrated wind turbine and support structure, DNV shall begiven permission to use specifications and wind turbine models from the DNV wind turbine type certification.The control system applied shall be the same as for the type certified wind turbine.

308 If the wind turbine has been type certified by a certification body other than DNV and this body isrecognized by DNV, DNV will require documentation of the wind turbine type, necessary for evaluation andindependent calculation of the loads and response of the integrated wind turbine and support structure, andDNV will verify this documentation.



Guidance note:Documentation of the wind turbine type for evaluation and independent calculation of the loads and response of theintegrated wind turbine and support structure may include turbine specifications and a FLEX or a HAWC model ofthe wind turbine and the load conditions and loads, which form the basis for the type certificate, such that DNV canassess the adequacy of the model before performing an independent load analysis of the wind turbine and the site-specific support structure.


C 400 Wind turbine

401 DNV will verify that the wind turbine design is in compliance with the verified design basis and theverified load and response documentation. The type certificate for the wind turbine will be evaluated withrespect to the site specific loads and the requirements in the design basis.

402 DNV will review the wind turbine type certificate conditions and limitations as compared to the actualsite conditions. The action taken by designers with respect to these conditions shall be stated in the designdocumentation. This comparison will in addition to covering metocean conditions include other relevantconditions such as:

— temperature— humidity— solar radiation— rain, hail, snow and ice— chemically active substances— mechanically active particles— salinity — electrical conditions— lightning— earthquake.

Due account shall be taken of the generally more aggressive environment offshore than on land. Environmentalconditions other than wind and marine conditions can affect the integrity and safety of the offshore wind turbineby thermal, photochemical, corrosive, mechanical, electrical and other physical actions.

Moreover, combinations of the climatic parameters given may increase their effects. Hence, the documentationfor utilization ratios used will be subject to special considerations.

In particular, electrical components like generator, converter, transformer, switch gear and enclosures shall bedesigned for the appropriate site conditions. The corrosion protection systems shall be able to withstand thesite-specific marine environment.

403 DNV will review the submitted design report of the site-specific loads with respect to the loads assumedfor the type certificate. The objective is to verify that the loads do not exceed the verified capacity. Anyincreases in load level as well as any changes in vibration modes and natural frequencies shall be stated in theDesign Report and will be evaluated.

The evaluation of the site-specific loads shall consider the relevance and validity of load measurements,functional testing and component tests such as blade test. Furthermore, the evaluation shall also identifycomponents that will require reinforcement or modifications.

404 Design documentation shall be provided for new, modified or reinforced components and systems, suchas corrosion protection systems, which are not fully covered by the type certificate for the wind turbine. Thedocumentation shall be prepared according to the Design Basis and, if relevant, according to the requirementsfor the type certification system applied.

405 DNV will verify that the wind turbine electrical system including the wind turbine terminals meets therequirements in the approved Design Basis in the following respects:

— The design of the electrical system shall ensure minimal hazards to people as well as minimal potentialdamage to the wind turbine and external electrical system during operation and maintenance of the windturbine under all normal and extreme conditions.

— The electrical system, including all electrical equipment and components, shall comply with the relevantIEC standards. Specifically, the design of a wind turbine electrical system shall comply with therequirements of IEC 60364.

— The design of the electrical system shall take into account the fluctuating nature of the power generationfrom wind turbines.

— Provisions shall be made to ensure adequate protection of all electrical components and systems against theeffects of corrosion and humidity.

The electrical system is usually covered by the type certificate for the turbine.

406 If the type certificate is issued by a certifying body other than DNV and this body is recognized by DNV,



DNV may accept this body’s site-specific wind turbine design verification for the project certification. DNV’sacceptance will be based on an evaluation on a case-by-case basis.

C 500 Primary support structure

501 The support structure comprises the tower, the substructure connecting the tower to the foundation andthe foundation, which transfers the loads into the seabed. Distinction is made between primary, secondary andtertiary structures for the support structure. Primary structures transfer permanent loads and environmentalloads, acting on the support structure, to the seabed, whereas secondary structures covered by the DNV scopecomprise boat landings, access ladders, main structural elements in external access platforms, and J-tubes. Theprimary support structure forms the subject of this subsection. Secondary structures attached to the primarysupport structure are covered in 600. Tertiary structures are addressed in 700.

502 DNV will verify that the design of the support structure is in compliance with the Design Basis. Theverification of the structural design will include design review and independent design analyses if deemednecessary.

503 The design evaluation will be carried out to an extent sufficient to enable DNV to state that the supportstructure complies with the approved Design Basis and the offshore standard DNV-OS-J101. In cases wherethe Design Basis or DNV-OS-J101 is insufficient, reference to a recognized standard or design method can bemade by the designer provided this is accepted by DNV. However, the client shall document that the resultingsafety level complies with the intended level in DNV-OS-J101.

504 The following verification activities are conducted:

— review of detailed design calculation reports, design drawings and manufacturing specifications fordetailed structural design of the offshore support structure

— relevant independent analyses of loads and structural strength, see 200.

505 The verification may include independent analyses of the support structure using appropriate methods,such as FEM analyses, and covers:

— structural strength (stress levels, buckling and joint check)— soil stiffness and soil capacity— fatigue life.

506 If the design includes highly utilized structural connections, such as grouted connections of steelstructures and tubular joints, detailed independent FEM calculations of the connections may have to be carriedout by DNV. If relevant, DNV will tailor an independent scope of work for this activity.

507 Environmental loads from wind, waves and current, acting on the support structure, shall be based on aload analysis of the integrated system of wind turbine and support structure, and documentation in a formsuitable for verification shall be submitted to DNV. The verification may include an independent analysisaccording to 200.

508 The verification of the structural design will focus on:

— review of design calculations for the ULS, the SLS, the FLS and, if relevant, the ALS — review of design implementation of manufacturing and installation requirements, however only with

respect to the structural integrity of the final installed (permanent) support structure— evaluation of proposed corrosion protection system(s) against design premises with a view to required

design life, standards and codes, and maintenance— review of design drawings and manufacturing specifications with respect to requirements in codes,

standards and with respect to assumptions in calculations regarding dimensions, materials, tolerances andtesting.

509 The verification of the geotechnical design will focus on:

— evaluation of calculation methods, stability and failure modes— review of geotechnical design calculations for the ULS, the FLS, the SLS and, if relevant, the ALS— review of design documentation regarding seabed preparation, tolerances and scour protection — the expected stiffness and damping of the support structure will be checked against assumptions made in

calculations of wind turbine loads.

510 The following design documentation shall be submitted for verification of the final structural andgeotechnical design:

— design documentation for the structural and geotechnical design calculations, for the ULS, the SLS, theFLS and the ALS. The documentation should include description of the assumptions made for thecalculations, for example regarding manufacturing and installation methods.

— design report containing design calculations for the corrosion protection system(s)— design report for the driveability study (if applicable)



— design drawings including General Note Drawing(s)— design documentation regarding scour and scour protection design.

C 600 Secondary structures

601 The secondary structures covered in the project certification consist of boat landings, access ladders,main structural elements in external access platforms, and J-tubes.

602 The verification of the structural design of secondary structures in the support structure will be verifiedwith focus on:

— design methodology— materials— corrosion protection system(s) with respect to issues such as design life and maintenance as required in

codes and standards— design drawings and manufacturing specifications with respect to requirements in codes and standards.

603 The secondary structures to be covered by the project certification shall as a minimum comprise thosesecondary structures that have an influence on the structural integrity of the primary structure, for example interms of welds, load distributions, stiffness and corrosion. Only secondary structures with no influence on theprimary structure may be excluded from the project certification. The specific secondary structures to becovered by the project certification shall be specified and agreed with the client.

C 700 Tertiary structures

701 Tertiary structures comprise all structures and structural components not covered by any primary orsecondary structures. Examples include internal ladders and platforms, stairs, kick plates, gratings andhandrails. For tertiary structures, DNV’s focus will be on verification of personnel safety issues.

C 800 Other installations

801 Installations other than primary and secondary structures comprise installations such as cables andelectrical installations.

802 Every time verification of cable design is included as part of the verification of design, a separate scopeof work for this verification shall be specified.

803 The design of electrical systems to be covered by the design verification comprises electrical design notcovered by the wind turbine type certification, i.e. it comprises electrical systems beyond the wind turbineterminals. The design will be verified for compliance with the appropriate standards focusing on the safety ofthe installations as defined in the approved Design Basis. The verification will be carried out on a spot-checkbasis and will cover the documentation in the form of diagrams, specifications and calculations of distributionsystem. Design documentation of the following items shall be submitted for review by DNV, if relevant:

— cabling— semiconductor devices— switchboards— transformers— converters— other equipment.

C 900 Load-out, transportation, installation and commissioning plan

901 The load-out, transportation, installation and commissioning processes for the support structure andother installations will be reviewed by DNV for compliance with the agreed requirements stated in theapproved Design Basis.

902 The following verification activities will be conducted by DNV in order to verify compliance of theinstallation procedures with the approved Design Basis:

— review of installation requirements (load-out, sea transportation, offshore lifting and stabbing)— review of structural design subjected to installation loads.

The overall DNV aim is to verify that the final structure in-place has not been exposed to unforeseen loadingduring load-out, transportation, installation and commissioning.

903 For the wind turbine, DNV will require preparation of an installation manual, which as a minimum shallconsist of the installation procedures and the emergency procedures specified by the wind turbinemanufacturer. The manual should also include contingency procedures. The manual may be based on theinstallation manual for the type-certified wind turbine, duly updated with a view to the offshore application.

904 DNV will review the installation manual for the wind turbine and verify its compliance with the windturbine’s type certification system and the approved Design Basis. The review and verification will cover thefollowing:



— installation procedures— commissioning procedures including check lists describing function test of protection system, initial

energization of the electrical system, testing after installation to confirm proper, safe and functionaloperation of all devices, controls and apparatus safe start-up

— procedures for safe shutdown; safe emergency shutdown— environmental conditions, e.g. required weather window— interface points, e.g. connection to foundation and to the electrical system— quality control, measurements and inspections— personnel safety.

The final site-specific wind turbine manual will be reviewed during the installation phase.

905 Installation manuals will normally not be ready at the design stage. The installation manuals for thesupport structure will be reviewed in the installation phase.

C 1000 Operation and maintenance plan

1001 For the wind turbine, DNV will require preparation of a user’s manual and a service and maintenancemanual, which as a minimum shall consist of the service and maintenance requirements and emergencyprocedures specified by the wind turbine manufacturer. The manuals shall also provide for unscheduledmaintenance. The manuals may be based on the user’s manual and the service and maintenance manual for thetype-certified wind turbine, duly updated with a view to the offshore application.

1002 DNV will review the user’s manual and the service and maintenance manual for the wind turbine andwill verify that these manuals are in compliance with the wind turbine’s type certification system and theapproved Design Basis. The review and verification will cover the following:

— scheduled maintenance actions including inspection intervals and routine actions— condition monitoring systems— safety related operational procedures or maintenance activities— quality recording and record keeping processes.

1003 For the support structure and other installations, DNV will require that relevant input to the inspectionand maintenance plan shall be prepared. The input to the inspection plan and the maintenance manual shall beseen as a help to the O&M organization that normally will be established later. Examples of issues to be coveredare inspections and checks of scour protection system and corrosion protection system, assumed service vessel,and inspections for fatigue cracks if relevant.

1004 It is strongly recommended that the designer during his design work prepares a report that states allassumptions made in design and that this report is used as input to the development of the operation andmaintenance plan.

D. Phase III: Manufacturing Survey

D 100 General

101 DNV will conduct manufacturing surveys in order to verify compliance between the approved designand the product. The surveys will be conducted at the manufacturer’s premises for production of maincomponents as well as in the wind turbine assembly shop and will involve:

— evaluation of production — evaluation of client’s quality system— product related quality audits— surveillance of contractor’s quality assurance activities — periodical surveys.

The scope of the periodical surveys is detailed in 200 and 300.

102 The client shall assure that DNV gets access to the relevant construction, manufacturing and assemblysites.

103 The extent of the inspections and the number of surveys to be carried out for project certification will beevaluated by DNV for each specific project and will depend on DNV’s experience with the manufacturer. Theaim is to complete the survey of at least 10% of the wind turbines and components with a minimum of threesurveys at each manufacturer. In case the manufacturer does not hold a valid ISO 9001 certificate, the numberof surveys to be completed by DNV may be increased.

104 The surveys will be based on relevant standards together with design documentation previouslysubmitted to DNV as input for the design verification, such as documentation of:

— critical items



— test programs — approved details.

If the type certificate is issued by another certifying body, the relevant documentation shall be agreed on a case-by-case basis.105 Each survey is to be completed at the manufacturing premises and the following documentation shall bemade available to DNV for the survey:

— general arrangement drawings and specifications— manufacturing drawings, specifications and instructions— inspection check sheets, NDT reports, and measurements reports.

106 Each survey will be documented in a detailed survey report including photo documentation wheneverdeemed necessary.Once the surveys have been satisfactorily completed, DNV will issue a Statement of Compliance for Phase IIIof the project certification.

D 200 Survey of wind turbine and components201 The type certification of the wind turbine is based on design verification, manufacturing evaluation,evaluation of quality control, testing and measurements. The evaluation of quality control mainly relies on thepresence of a certified quality management system (ISO 9001). The DNV Project Certification will in additionto this, and in accordance with IEC 61400-22 requirements, include inspection and audit activities in order toverify that the manufacturing of wind turbines, support structures and foundations for the specific project arecarried out according to the approved design and with the intended quality.202 The wind turbine survey will be completed in the wind turbine manufacturing assembly workshop. Thesurvey will be carried out on a random basis and will be focused on:

— compliance with quality plan requirements— visual inspection of units under assembly — visual inspection of assembled wind turbines— visual inspection of electrical installation— documentation review (components certificates, production worksheets and final documentation).

203 The blade survey will be completed at the blades manufacturing shop. The survey will be carried out ona random basis and will be focused on:

— compliance with quality plan requirements— visual inspection of on-going jobs— visual inspection of finished blades before shipping— documentation review.

204 A survey will be carried out of the main wind turbine components, such as gear box, electrical generator,hub, and machine frame. The main components are in most cases manufactured as serial products without aspecific destination, stored at the manufacturer premises and later on assigned to a particular project. Themanufacturing survey can in such cases not be focused on the visual inspection of the components. Themanufacturing survey will be carried out on a random basis and will be based on a documentation review at themanufacturer’s premises, covering the following elements:

— compliance with quality plan requirements — visual inspection of on-going jobs in order to check compliance with documented manufacturing

procedures— test documentation review— final documentation review.

D 300 Survey of support structure301 The support structure for the wind turbine consists of the following components:

— tower— substructure— foundation.

Separate surveys of these components will be carried out as outlined in 302 through 306.302 A tower section manufacturing survey will be carried out: The survey will be completed at themanufacturer’s shop and will be focused, random basis, on:

— compliance with quality plan requirements — welding procedures specification



— welders qualification— construction drawings versus reviewed drawings— visual inspection of on-going jobs.— witnessing of non-destructive testing— visual inspection of finished sections before shipping— documentation review.

303 Surveys of monopiles and jacket structures will be completed at the manufacturer’s shop or in thefabrication yard and will be focused, random basis, on:

— compliance with quality plan requirements — welding procedures specification— welders qualification— construction drawings versus reviewed drawings— visual inspection of on-going jobs— corrosion protection systems— witnessing of non-destructive testing— visual inspection of finished monopiles before shipping— documentation review.

304 Surveys of concrete structures and foundations will be completed at the fabrication shop or on theconstruction site and will be focused, random basis, on:

— construction and shop drawings for compliance with design drawings and specifications— survey of measuring and testing equipment— compliance to the specifications, standards and procedures— formwork, reinforcing steel, embedment prior to concrete casting— preparations for casting, use of correct materials, construction joints, grouting of ducts, curing conditions etc.— corrosion protection systems— repair work— documentation review.

305 For other types of support structures, such as floating structures and suction buckets, a detailedmanufacturing survey program will be tailor made for each specific project.

306 Agreed surveys of secondary structures will be completed at the fabrication yard or at the manufacturer’spremises. The survey will be carried out on a random basis and will be focused on:

— compliance with quality plan requirements — welding procedures specification— welders qualification— construction drawings versus reviewed drawings— visual inspection of on-going jobs.— witnessing of non-destructive testing.— visual inspection of finished structures before shipment— documentation review.

E. Phase IV: Installation Survey

E 100 General

101 Load-out, transport and installation offshore are crucial temporary phases in an offshore wind farmproject. DNV will perform an Installation Survey as part of the project certification process. The InstallationSurvey can be complemented by an optional marine warranty survey in order to minimize the risks involvedwith these temporary phases.

102 The Installation Survey will be followed up by a detailed survey report. This survey report will includephoto documentation whenever deemed necessary.

Once the Installation survey has been satisfactorily completed, DNV will issue a Statement of Compliance forPhase IV of the project certification.

E 200 Installation survey201 Prior to the installation of the first support structure in the wind farm, load-out manuals and installationmanuals shall be issued for DNV review.The installation survey is divided in two parts:

— load-out survey, will be completed at the barge loading pier



— offshore survey, will be completed on the site.

202 Load-out survey: A DNV surveyor will be present during load-out of the first wind turbine supportstructure. The surveyor will focus on the following:

— survey of welding of sea-fastening to structure— survey of installation and testing of grouting system, if relevant— survey of lifting, skidding operations during load-out.

203 Offshore survey: The surveyor will perform the tasks deemed necessary to verify compliance with theverification basis, verified design, drawings, specifications and procedures as far as safety is concerned. Thesurveyor will ascertain that non-conformances and deviations from the verified design, drawings andprocedures are identified, recorded and acted upon.

204 The extent of the survey activities will be dependent on the contractor’s efforts, abilities and willingnessto live up to the intentions of his own quality system and the contract specifications.

205 During the survey, the surveyor will focus on the following (if applicable):

— survey of structure for damage prior to cutting of sea-fastening— witnessing of upending and lifting operations— survey grouting operations and sample taking.

206 When welding is performed, the following will be subject to inspection:

— survey of preparation for welding including correct use of materials, fit up, weather protection— survey of welding performance including adherence to welding procedures, preheating, tack welding,

welding, post weld heat treatment, weld repairs— survey of NDT activities including performance of NDT, evaluation of results and of the extent of the NDT.

207 For bolted connections the focus during the survey will be on:

— survey of fit-up— bolt pretensioning.

208 The DNV project certification surveyor will be present during the first installation and during one otherinstallation randomly chosen among the remaining wind turbine support structures within the wind farm.However, the final number of installations to be attended by the DNV project certification surveyor may belarger depending on the project details and the number and types of wind turbines.

209 When DNV performs a marine warranty survey, the DNV surveyor for project certification will only bepresent during the first load-out and installation. The remaining surveys will be covered by the marine warrantysurveyor.

210 The final as-built documentation shall be issued for DNV review. The review will focus on items such as

— pile driving records— 28 days grout strength— general deviations from approved design

in order to verify that the design is still sufficient.

E 300 Warranty survey

301 Warranty surveys are optional and include on-site surveys.

Guidance note:

Warranty surveys typically include:

- marine verification

- survey of load-out and transportation of support structure, wind turbine and substation, the latter including anytopside modules

- survey of installation of support structure, wind turbine and substation, the latter including any topside modules.Surveys of piling operations are based on a limited number of pile installations, which are considered sufficient toensure that the piling operations are carried out in accordance with approved procedures.

For details about warranty surveys, reference is made to DNV-OS-H101.




F. Phase V: Commissioning Survey

F 100 General

101 This subsection provides details of DNV’s verification activities for the commissioning of the windturbines and their support structures.

102 DNV will perform a commissioning survey as part of the project certification with the purpose to verifythat the wind turbines erected on site are commissioned according to the requirements of the manufacturer andin compliance with relevant documentation provided in the design phase.

103 DNV will attend the commissioning of at least two wind turbines; however, the final number of windturbine commissionings to be attended may be larger depending on the project details and the number and typesof wind turbines.

104 The following documentation shall be made available to the DNV surveyors prior to the commencementof the surveys:

— commissioning procedures— commissioning checklist.

105 The commissioning survey will be followed up by a detailed survey report. The survey report willinclude photo documentation whenever deemed necessary.

Once the commissioning survey has been satisfactorily completed, DNV will issue a Statement of Compliancefor Phase V of the project certification.

F 200 Commissioning survey

201 The wind turbine commissioning shall be carried out in accordance with the submitted proceduresreviewed and approved by DNV in advance of the commissioning.

During commissioning, main systems and equipment shall be checked for compliance with approveddocumentation and commissioning procedures.

The relevant systems shall be functionally tested, as practicable as possible in accordance with approvedprocedures, to confirm proper, safe and functional operation of all devices, controls and apparatus safe start-up.

The following procedures are to be witnessed by DNV or tested in presence of the attending surveyor:

— starting and stopping routines of the wind turbine in automatic and manual mode— checking of the control system settings — function test of protection system — safe shutdown— safe emergency shutdown— safe shutdown from overspeed or a representative simulation of such shutdown— running test of wind turbine.

G. Phase VI: In-service Surveys

G 100 General

101 The In-Service phase implies an activity, by which the wind turbine, the support structure and otherinstallations such as J-tubes and cables are surveyed regularly during their entire operational life. DNV willconduct periodical in-service surveys in order to validate the project certificate and to verify that the requiredstandard is observed and maintained.

102 Prior to DNV’s initiation of surveys, a Maintenance, Repair and Inspection Program shall be developedand submitted to DNV for approval. The program shall serve as a reference for parties involved in maintenanceand repair carried out on the wind farm. The Maintenance, Repair and Inspection Program shall be updated asrequired based on findings and deviations. Any update of the program shall be subject to DNV approval.

G 200 Surveys

201 DNV will tailor a detailed scope of work for the periodical in-service surveys. The scope of work willinclude a detailed project-specific plan that identifies the DNV survey activities required, the survey intervals,the number of wind turbines to be surveyed and the reporting requirements. The interval between surveys willdepend on the wind turbine type and on the knowledge built up during the previous phases of the certificationprocess. The first survey after completion of the wind farm project will usually take place after one year. Thescope will include assessment of the status regarding any outstanding issues from the previous survey. DNV-OS-J101 provides some guidance regarding inspection plans and number of wind turbines to be inspected in asurvey.

202 The DNV report will highlight any findings or deviations reported during the periodical survey. Major



findings and deviations will be reported to the client in terms of recommendations. 203 A DNV survey will be carried out to provide evidence as to whether the surveyed installation or partsthereof continues to comply with the approved design. Prior to the survey the status of outstanding items aswell as information about all revisions made to the maintenance system within the last year shall be submittedto DNV.204 As a part of the survey, records of maintenance and repairs carried out since the previous survey will bereviewed and verified against the program. The company responsible for the maintenance and repairs will besubject to audits in order to verify the documentation for work carried out. The review will include:

— follow-up of outstanding issues from the previous survey and status regarding recommendations— review of revised procedures— review of maintenance documentation— review of maintenance history in the file or registration in the computer— preparation of the offshore program, based on findings from the onshore part and systems.

205 The surveys conducted offshore may in general include:

— verification that installed components are in compliance with type certification requirements— verification that repair and maintenance according to approved program and manufacturer’s

recommendations are conducted— general survey and test of selected systems and components— subsea inspections of structures and cables.

206 Components recommended for consideration in surveys of the wind turbine, support structures andcables are given in 300 and 400.

G 300 Wind turbine301 DNV will periodically carry out surveys of a number of wind turbines and those parts of their supportstructures that are located above water, thereby to verify compliance with the approved design. The surveyswill comprise relevant systems of the wind turbine installations such as:

— rotor including blades and hub assembly— mechanical transmission including gear boxes— nacelle structure and connections— generators, converters and transformers— control and protection systems — electrical systems— lifting appliance— personnel safety installations.

302 The survey of the systems listed in 301 will focus on the following items:

— fatigue cracks— dents and deformation(s)— bolt pretension— status on outstanding points from previous surveys— settings and parameters used by the control system— cooling media for transformer and generator if applicable— lubrication where applicable— test of the control and protection system (witness tests carried out by the operator)— condition monitoring system— additional surveys identified based on findings and deviations, e.g. witnessing of tests and inspections in

order to distinguish between random and systematic failures.

G 400 Submerged structures 401 The support structure below water will be subject to periodical surveys in order to verify compliance withapproved design. The subsea inspections will be initiated by the owner or assigned contractors, and they willbe performed by an ROV and/or by divers in accordance with the approved Maintenance, Repair and InspectionProgram. 402 The subsea inspection will as a part of the survey be supervised by a DNV surveyor in order to monitorthe condition of:

— support structure below water including foundation— access platforms— J-tubes— ladders— fenders



— corrosion protection systems — marine growth— cracks and deformations— scour protection— dents — bolt pretension— status of outstanding issues from previous surveys.

G 500 Validation of certificate501 When an in-service agreement for the wind farm is in place between DNV and the client, the validityperiod of the project certificate is extended to the duration of the service agreement plus one year; however,five years is the maximum period of validity. Following a successful completion of an in-service survey, astatement of compliance that validates the project certificate will be issued.



SECTION 4DETAILED SERVICE DESCRIPTION:

SUBSTATION TOPSIDE AND SUPPORT STRUCTURE

A. Introduction

A 100 Objective

101 This section provides the details of DNV’s verification activities for each of the phases of the DNVProject Certification System for the asset that consists of the Offshore Substations. The following types ofsubstations and their support structures are covered:

— high voltage AC (transformer) platforms— high voltage DC (converter) platforms— associated accommodation platforms or integrated accommodations.

102 Wherever the service for offshore substations are identical to the service for wind turbines and theirsupport structures, reference is made to the service descriptions in the relevant parts of Sec.3.

B. Phase I: Verification of Design Basis

B 100 General

101 The purpose of the design basis verification is to evaluate if the site conditions and the basis for design,including general specifications, criteria, parameters, design approach and other assumptions relevant fordesign, are properly established and documented and that this design basis is sufficient for a safe design of thesubstation.

102 Unless otherwise agreed, the verification activities are to DNV’s offshore standard DNV-OS-J201.

103 A design basis shall be provided to DNV that includes documentation of the following:

a) site conditions

b) codes, standards and requirements

c) design criteria

d) transport, installation and commissioning requirements

e) operation and maintenance requirements.

104 DNV will verify the Design Basis for compliance with DNV-OS-J201 and other codes and standardsidentified in the Design Basis. Following a successful completion of the verification of the design basis, DNVwill issue a statement of compliance.

B 200 Site conditions

201 DNV will evaluate the establishment of site conditions detailed in DNV-OS-J101 and DNV-OS-J201based on reported data and/or applicable standards or methods valid for the site.

202 Sec.3 B200 specifies which site conditions shall be addressed in the design basis and provides detailsabout DNV’s services for verification of the site conditions.

203 In addition to verification of the external site conditions addressed in Sec.3 B200, the operatingconditions for components and equipment operated in an “air-conditioned” environment shall be addressed andwill be subject to verification.

B 300 Codes, standards and requirements

301 The codes and standards which form the basis for the substation shall be listed in the design basis. Forthe site in question, relevant statutory requirements shall also be listed. Such requirements could be safetyrelated issues such as requirements for embarkation, rescue and decommissioning.

302 Other requirements relevant for the project certification such as requirements for the grid connection aswell as specific requirements from the owner and the grid operator may be listed.

303 The codes and standards applicable for the substation and the site in question will be verified forcompliance with the design prerequisites of the wind farm project and for suitability, applicability andcompleteness. The verification of the selected codes, standards and requirements will be conducted early in theproject phase in order to avoid fundamental discussions regarding this basic aspect of the design basis.



B 400 Design criteria401 The design of the integrated structure that comprises the substation shall be based on the specific siteconditions as well as the methods and principles given in DNV-OS-J201. 402 Design criteria shall be specified in accordance with DNV-OS-J201. This applies to the differentengineering disciplines including:

— structural design— electrical design*— fire and explosion protection design— access and transfer design— emergency response design.

* Currently optional as electrical design is not covered by DNV-OS-J201, 2009. A specific scope must beagreed.403 The documentation for the individual engineering disciplines shall include the following:

— safety philosophy— main design methodology— design aspects and design parameters.

404 For verification of the Design Basis, DNV will adhere to the specifications given in Sec.3 B400 asapplicable.

B 500 Load-out, transportation, installation and commissioning501 The design basis shall state assumptions, specifications and requirements for structural design againstloads occurring during load-out, transportation, installation and commissioning, such as environmental loads,lifting loads, and local loads from temporary supports. The design basis shall also state assumptions,specifications and requirements for the load-out, transportation, installation and commissioning programmesthemselves. 502 Assumptions, specifications and requirements may include, but are not necessarily limited to:

— codes and standards— specifications and tolerances— limiting environmental conditions — methods and loads of relevance for transport and installation— requirements for load-out, transportation, installation and commissioning manuals— quality assurance system.


B 600 Operation and maintenance601 The design basis shall state assumptions, specifications and requirements for structural design againstloads occurring during operation and maintenance. The design basis shall also state assumptions, specificationsand requirements for the operation and maintenance programmes themselves. 602 Assumptions, specifications and requirements to be stated include, but are not necessarily limited to:

— inspection scope and frequency— target lifetime of components, systems and structures— requirements for service and maintenance manuals— requirements for condition monitoring systems.


C. Phase II: Verification of Design

C 100 General101 DNV will verify the final design for compliance with DNV-OS-J201 and other codes and standardsidentified in the Design Basis. Details of the verification activities in this phase are given in 200 through 1000.102 Once the verification of the final design has been successfully completed, DNV will issue a Statementof Compliance for Phase II of the project certification.

C 200 Structural design and geotechnical design201 The verification of the design of the substation topside and the support structure will be based on loads,capacities, design methods and principles specified in the approved design basis and in relevant DNV



standards, e.g. DNV-OS-J201, DNV-OS-J101, DNV-OS-C101 and DNV-OS-C502. For areas where theapproved design basis or the DNV offshore standards do not apply, reference to a recognized standard or designmethod may be acceptable by DNV.

The structural design verification will include:

— loads and load combinations— geotechnical design— design of primary structure— design of secondary structures— topside arrangement— load-out, transportation, installation, operation and maintenance.

202 The following design reports and drawings shall be submitted to DNV for verification of the finalstructural and geotechnical design of the substation topside and the support structure:

— design documentation for the structural and geotechnical design calculations for the ULS, the SLS, the FLSand the ALS

— assumptions made for the calculations, for example regarding manufacturing and installation methods— design report containing design calculations for corrosion protection system(s)— design report for the driveability study (if applicable)— design drawings including general note drawing(s)— design documentation regarding scour and scour protection design.

203 The loads on the substation topside and the support structure may comprise the following loads and loadcombinations:

— dead weight of structures and appurtenances— dead weight and variable loads from equipment— live loads— environmental loads, for example from wind, waves and ice— accidental loads, for example from ship collisions and dropped objects.

The principles used to establish load combinations for the SLS, the ULS, the FLS and the ALS will be reviewedfor compliance with the relevant DNV standards. The load combinations for the substation topside and thesupport structure will be reviewed with focus on:

— selection of load combinations— selection of load factors and load reduction factors— calculation results.

204 The verification of the geotechnical design for the substation will focus on:

— evaluation of calculation methods, stability and failure modes— review of geotechnical design calculations for the ULS, the SLS and the ALS— review of design documentation regarding seabed preparation, tolerances and scour protection— the expected stiffness and damping of the support structure will be checked.

C 300 Primary structures

301 The verification of the structural design of the primary structures in topside and support structure willfocus on:

— design methodology, safety level, materials— review of design calculations for the ULS, the SLS, the FLS and the ALS— eigenfrequency and vortex shedding analyses— manufacturing and installation methods, with respect to the structural integrity of the final installed

(permanent) structure— corrosion protection system(s) with respect to issues such as design life and maintenance as required in

codes and standards— design drawings and manufacturing specifications with respect to requirements in codes and standards as

well as assumptions in calculations with respect to issues such as dimensions, materials, tolerances, andtesting.

302 The design verification of the primary structures, including attachments for secondary structures, willinclude independent analyses and covers:

— review of loads— structural strength (stress levels, buckling and joint checks)— fatigue life.



303 If the design includes highly utilized structural connections (e.g. grouted connections of steel structuresand tubular joints), extra detailed independent finite element calculations of the connections will have to becarried out by DNV. Such analysis will be described in an independent scope of work.

C 400 Secondary structures401 The verification of the structural design of secondary structures in the topside and the support structurewill be verified with focus on:

— design methodology— materials— corrosion protection system(s) with respect to issues such as design life and maintenance as required in

codes and standards— design drawings and manufacturing specifications with respect to requirements in codes and standards.

402 The secondary structures to be covered by the project certification shall as a minimum comprise thosesecondary structures that have an influence on the structural integrity of the primary structure, for example interms of welds, load distributions, stiffness and corrosion. Only secondary structures with no influence on theprimary structure may be excluded from the project certification. The specific secondary structures to becovered by the project certification shall be specified and agreed with the client.

C 500 Tertiary structures501 Tertiary structures comprise all structures and structural components not covered by any primary orsecondary structures. Examples include internal ladders and platforms, stairs, kick plates, gratings andhandrails. For tertiary structures, DNV’s focus will be on verification of personnel safety issues.

C 600 Electrical design601 Verification of electrical design is currently optional. A specific scope must be agreed.602 When verification of electrical design is to be included, the electrical design will be verified forcompliance with the appropriate standards specified in the design basis. The focus of the verification will beon the safety of the installations as defined in the approved design basis. The verification will be carried out byspot checks of the documentation in the form of diagrams, specifications and calculations of distributionsystem.603 The electrical design review will include:

— main system design and component loading (main transformer, switchgear, cables and, if applicable,semiconductor converter)

— arrangement of components, with regard to safety— system earthing— cabling— emergency power system.

604 The following documentation for the electrical system shall be submitted for verification:

— functional design specification— single line diagrams including identification of components— data sheets for electrical equipment— system earthing and bonding principles.

605 The following documentation for cabling shall be submitted for verification:

— cable selection philosophy— cable routing sketch— cable sizing and specifications, including fire properties and certificate reference— cable schedules.

606 Specific studies for which documentation shall be made available include:

— short circuit study— discrimination study— load calculations on emergency power systems.

607 The verification activities will include review of the following:

— high-voltage / power equipment safety— control and protection systems— main component (main transformer, converter, switchgear) utilization and protection— emergency generation capabilities— heating/ventilation/air conditioning, also as corrosion protection measure.



608 The power and communication cables will be reviewed with regard to

— selection of low smoke, low fume types suitable in offshore environments— cable loading— cable routing.

609 Optionally, the electrical performance of the substation connected to wind farm and grid can be reviewedby analysing:

— wind farm electrical layout— active and reactive power flows— influence on existing electrical power grid (harmonics, flickers, lines overload, compensation)— critical details.

C 700 Fire and explosion protection design

701 Verification of the fire and explosion protection design will be based on applicable standards, i.e. DNV-OS-J201 and country-specific shelf-state regulations.

702 The following documentation shall be submitted to DNV for verification as applicable:

— fire protection philosophy and specification— fire zone layout— general arrangement of all rooms showing fire insulation and draught stops— fire integrity of walls and decks; insulation material specification and position; deck and surface coverings

material specification and positions— penetrations of cables and pipes through fire walls, details of fire dampers— ventilation system layout including dimensions and penetrations of ducts through fire divisions— fire pumps, fire mains, hydrants and hoses, deluge, sprinkler and spray systems, and other active fire

protection systems— fixed fire detection and alarm systems in accommodation spaces, machinery spaces, and product storage

spaces; specification and location of detectors, equipment alarms and call points; wiring diagrams.

703 The documentation submitted to DNV for verification shall in addition address the following topics:

— nature and risks of potential fires and explosions— quantities of fluids, flammable and combustible materials handled, processed and stored on the substation— manning philosophy and human factors.

704 In the context of fires and explosions, the results of the evaluation process and the decisions taken withrespect to the need for, and role of, any risk reduction measures (the “fire and explosion strategy”) will bereviewed for verification.

Guidance note:Complex substations are likely to require detailed studies to address hazardous fire and explosion events. Simplesubstations may rely on application of recognized codes and standards. The fire and explosion strategy shoulddescribe the role and functional requirements for each of the systems used to manage possible hazardous events onthe substation.


705 As for functional requirements, the following will be reviewed for verification:

— purpose and duty of a particular system— integrity, reliability and availability of the system— survivability of the system and dependency on other systems.

706 For substations featuring an accommodation module, specific verifications to assure compliance withapplicable regulations will be carried out.

C 800 Access and transfer design

801 Verification of the access and transfer design will be based on applicable standards, e.g. DNV-OS-J201,and country-specific shelf-state regulations.

802 The following documentation shall be submitted for verification:

— boat landing documentation— helicopter deck documentation (if applicable)— helicopter winching area documentation (if applicable)— details of area and deck-to-deck access.

803 The design of the boat fender system will be verified as part of the structural design review.



804 Verification of the design of the helicopter deck is optional. A specific scope must be agreed.

805 Deck layout and fire fighting measures will be checked for compliance with applicable regulations.

806 Layout of stairs and ladders will be verified as part of the emergency response design.

C 900 Emergency response design

901 Verification of the emergency response design will be based on applicable standards as specified in thedesign basis, e.g. DNV-OS-J201 and country-specific shelf-state regulations.


— safety philosophy and design principles— platform arrangement— orientation, fire and safety plans.

The documentation submitted to DNV for verification shall in addition address the following topics:

— environmental conditions— distance to the nearest installation, to shore and to coastal facilities— number and distribution of personnel— effect of time of day on emergency response— immediate effects of an incident on the installation and people— development of heat and smoke in the event of fire— capacity for treatment at available medical facilities.

903 The verification of the emergency response design will include an assessment of the proposed emergencyresponse measures, comprising an analysis of performance of the measures and a judgment of their adequacy.Platform layout and safety systems will be evaluated with regard to hazard identification and safety for humans,the environment and the asset considering:

— alarms and communications— shutdown— escape routes and muster areas— evacuation, rescue and recovery.

904 For the assessment of the selection of emergency response equipment, the following issues will beconsidered:

— location— type— number— capacity— accessibility and survivability under emergency conditions— reliability and/or availability— maintenance, usability and training requirements.

905 Changes on the installation or changes of the external situation that may affect the emergency responseprocedures will also be part of the assessment. Such changes in particular include:

— potential emergency scenarios— emergency response equipment— emergency response organization— emergency response procedures— staff experience— research results and new knowledge— changes in statutory legislation.

C 1000 Load-out, transportation, installation and commissioning plan

1001 Verification of the load-out, transportation, installation and commissioning programmes will be basedon applicable standards, e.g. DNV “Rules for Planning and Execution of Marine Operations”.


— description of concept and procedures— method statement for load transfer operations (i.e. load-out, float-out, lift-off and mating)— installation and commissioning manual including emergency procedures.

1003 The documentation will be evaluated and verified for compliance with the approved design basisincluding:



— review of installation requirements (load-out, sea transportation, offshore lifting and installation)— essential installation procedures— essential commissioning procedures— procedures for safe shutdown— personnel safety.

In most cases, the above documentation will not be available during the design phase and the verification ofthis documentation will therefore be covered in the installation phase. However, the relevant temporarysituations shall be considered in the design phase.

C 1100 Operation and maintenance plan1101 DNV will require that relevant input to the inspection and maintenance plan shall be prepared. The inputto the inspection plan and the maintenance manual shall be seen as a help to the O&M organization thatnormally will be established later. Examples of issues to be covered are inspections and checks of scourprotection system and corrosion protection system, assumed service vessel, and inspections for fatigue cracksif relevant.1102 Verification of the operation and maintenance programme will be based on applicable standards andindustry best practice.1103 The following documentation shall be submitted for verification:

— description of risk based inspection and maintenance programme, covering inspection, scheduledmaintenance and unscheduled maintenance

— service and maintenance manual for key components.

1104 The documentation will be evaluated and verified for compliance with the approved design basisregarding scope and intervals of the following:

— operational monitoring and condition monitoring— safety related inspection and maintenance— scheduled maintenance— unscheduled maintenance provisions— record keeping and quality control.

In most cases, the above documentation will not be available during the design phase and the verification ofthis documentation will therefore be covered in the installation phase.

D. Phase III: Manufacturing Survey

D 100 General101 The aim of the manufacturing survey is to check the compliance with the applicable rules and standards,verify compliance with approved drawings and check that the substation is being built with the intendedquality.The manufacturing survey will be conducted at the fabrication yard and will include:

— manufacturing evaluation— evaluation of client’s quality system— product related quality audits— surveillance of contractor’s quality activities — periodical surveys.

The scope of the periodical surveys is detailed in 200 through 400.102 The extent of the inspections and the number of surveys to be carried out for project certification will beevaluated by DNV for each specific project. In case the manufacturer does not hold a valid ISO 9001Certificate, the number of surveys to be completed by DNV may be increased. The minimum number ofsurveys is detailed in 200 through 400.103 The surveys will be based on relevant standards, such as DNV-OS-J201 and DNV-OS-C401, and ondesign documentation previously submitted to DNV as input for the design verifications, such asdocumentation of:

— critical items— test programs — approved details.

104 The surveys will be completed at the fabrication yard or the manufacturer’s premises and the followingdocumentation shall be made available to the DNV surveyors:



— general arrangement drawings and specifications— manufacturing drawings, specifications and instructions.

105 Each survey will be followed by a detailed survey report including photo documentation wheneverdeemed necessary.

106 Once all surveys have been successfully completed, DNV will issue a Statement of Compliance forPhase III of the project certification.

D 200 Topside structure201 Five to ten surveys at the manufacturer workshop or shipyard are considered as the minimum number ofsurveys to be completed by DNV. The surveys will be focused on:

— compliance with quality plan requirements — welding procedures specification— welders’ qualification— construction drawings versus reviewed drawings— visual inspection of on-going jobs.— witnessing of non-destructive testing— visual inspection of finished sections before shipping— documentation review.

D 300 Topside equipment301 Electrical equipment is not part of the project certification and manufacturing surveys of such topsideequipment are not necessary for certification of the substation.

For other topside equipment, the following documentation – in addition to the documentation specified in 104– shall be submitted to DNV for the verification of the manufacturing activities:

— fire-fighting, life-saving and escape-route general drawings.— layout and arrangement of the topside equipment and systems.

302 Three surveys at the topside assembly workshop or shipyard are considered as the minimum number ofsurveys to be completed by DNV. Two additional surveys may be necessary for testing purposes. Surveys willbe focused on:

— fire insulation— fire-fighting appliances— fire detection— escape routes— life-saving arrangement and equipment— electrical systems with voltage up to 440V.

D 400 Support structure

401 The surveys will be completed in accordance with specifications given in relevant parts of Sec.3 D300.

402 Five to ten surveys are considered as the minimum number of surveys to be completed by DNV, but aspecific agreement shall be established in each case. For support structure concepts and manufacturers thatDNV is familiar with, this minimum number of surveys may apply. For other types of support structures, suchas concrete structures and floating units, and for manufacturers that DNV is unfamiliar with, the number ofsurveys will be agreed for each project on a case-by-case basis.

E. Phase IV: Installation Survey

E 100 General

101 Load-out, transport and installation offshore are crucial phases in an offshore wind farm project. DNVperforms an installation survey as part of the project certification process. The installation survey can becomplemented by an optional marine warranty survey in order to minimize the risks involved with thesephases. 102 The installation survey will be followed up by a detailed survey report including photo documentationwhenever deemed necessary

103 Once the installation survey has been satisfactorily completed, DNV will issue a Statement ofCompliance for Phase IV of the project certification.

E 200 Installation survey

201 Prior to the installation of the substation and its support structure, load-out and installation manuals shall



be issued for DNV review.

The installation survey is divided in two parts:

— load-out survey, will be completed at the barge loading pier — offshore survey, will be completed on the site.

202 Load-out survey: A DNV surveyor will witness load-out of the substation and its support structure.

The surveyor will focus on the following:

— survey of welding of sea-fastening to structure— survey of installation and testing of grouting system— survey of lifting, skidding operations during load-out.

203 Offshore survey: The surveyors will perform the tasks deemed necessary to verify compliance with thedesign basis, verified design, drawings, specifications and procedures as far as safety is concerned. Thesurveyor will ascertain that non-conformances and deviations from the verified design, drawings andprocedures are identified, recorded and acted upon.

204 The extent of the survey activities will be dependent on the contractor’s efforts, abilities and willingnessto live up to the intentions of his own QA program and the contract specifications.

205 During the survey, the surveyor will focus on the following (if applicable):

— survey of structure for damage prior to cutting of sea-fastening— witnessing of upending, lifting operations— survey grouting operations and sample taking.

206 When welding is performed, the following will be subject to inspection:

— survey of preparation for welding including correct use of materials, fit up, weather protection, etc.— survey of welding performance including adherence to welding procedures, preheating, tack welding,

welding, post weld heat treatment, weld repairs etc.— survey of NDT activities including performance of NDT, evaluation of results and the extent of NDT.

207 For bolted connections the focus will be on:

— survey of fit-up— bolt pretensioning.

208 The DNV project certification surveyor will be present during the installation of the substation and itssupport structure.

209 Even when DNV performs a marine warranty survey, the DNV surveyor for project certification will bepresent during the load-out and installation.

E 300 Warranty survey

301 Warranty surveys are optional and include on-site surveys. Guidance note:Warranty surveys typically include:

- marine verification- survey of load-out and transportation of support structure and topside modules- survey of installation of support structure and any topside modules. For details about warranty surveys, reference is made to DNV-OS-H101.


F. Phase V: Commissioning Survey

F 100 General

101 DNV will perform a commissioning survey as part of the project certification with the purpose to verifythat the substation installed on site is commissioned according to the requirements of the manufacturer and incompliance with relevant documentation provided in the design phase.

102 The commissioning survey will be followed up by a detailed survey report. The survey report willinclude photo documentation whenever deemed necessary.

Once the commissioning survey has been satisfactorily completed, DNV will issue a Statement of Compliancefor Phase V of the project certification.



F 200 Commissioning survey201 Commissioning of the topside equipment shall be in accordance with the submitted procedures reviewedand approved by DNV in advance of the commissioning.Most of the commissioning and testing review will be performed at the manufacturer workshop or in the yard,see Sec.4 D201. To the extent that this review is supplemented by a commissioning survey duringcommissioning, main systems and equipment will be checked for compliance with approved documentationand commissioning procedures. The relevant systems shall be functionally tested in presence of DNV’sattending surveyor, to the extent practicable and in accordance with approved procedures, to confirm proper,safe and functional operation of all devices, controls and apparatus safe start-up.When a commissioning survey is carried out, the following items will be witnessed by DNV or shall be testedin the presence of the attending surveyor:

— checking of the control system settings — function test of protection system — safe shutdown— running tests of relevant systems— review of remedial work on structure and equipment.

G. Phase VI: In-service Surveys

G 100 General101 The In-Service phase implies an activity, by which the substation, support structure, J-tubes and cablesare surveyed regularly during their entire operational life. DNV conducts periodical in-service surveys in orderto validate the project certificate and to verify that the required standard is observed and maintained.102 Prior to DNV’s initiation of surveys, a Maintenance, Repair and Inspection Program shall be developedand submitted to DNV for approval. The program shall serve as a reference for parties involved in maintenanceand repair carried out on the wind farm. The Maintenance, Repair and Inspection Program shall be updated asrequired based on findings and deviations. Any update of the program shall be subject to DNV approval.

G 200 Surveys201 DNV will tailor a detailed scope of work for the periodical in-service surveys. The scope of work willinclude a detailed project specific plan that identifies the DNV survey activities required, the survey intervals,as well reporting requirements. The plan will also include assessment of the status regarding any outstandingissues from the previous survey.202 The DNV reports will highlight any findings or deviations reported during the periodical survey. Majorfindings and deviations will be reported to the client in terms of recommendations. 203 The DNV periodical survey will be carried out to provide evidence as to whether the surveyedinstallation or parts thereof continue to comply with the approved design. Prior to the survey the status ofoutstanding items as well as information on all revisions made to the maintenance system within the last yearshall be submitted to DNV.204 As a part of the periodical survey records of maintenance and repairs carried out will be reviewed andverified against the program on a spot check basis. The company responsible for the maintenance and repairswill be subject to audits in order to verify the documentation for work carried out. The review will include:

— follow-up of outstanding issues from the previous survey and status regarding recommendations— review of revised procedures— review of maintenance documentation— review of maintenance history in the file or registration in the computer— preparation of the offshore program, based on findings from the onshore part and systems.

205 The surveys conducted offshore may in general include:

— verification that repair and maintenance according to approved program and manufacturer’srecommendations are conducted

— general survey and test of selected systems and components— subsea inspections of structures and cables.

206 Components recommended for consideration in in-service surveys of the substation and its supportstructures, equipment and cables are given in 300 and 400.

G 300 Substation 301 DNV will periodically survey the substation and the part of its support structure above water in order toverify compliance with approved design. The survey comprises spot checks of:



— general survey of the topside and support structures— fire-fighting equipment and systems by visual inspection and test— life-saving appliances by visual inspection and test— selected systems and components by general inspection and test— additional surveys identified based on findings and deviations, e.g. witnessing of tests and inspections in

order to distinguish between random and systematic failures.

G 400 Submerged structures401 The support structure below water will be subject to periodical surveys in order to verify compliance withapproved design. The subsea inspections will be initiated by the owner or assigned contractors, and they willbe performed by an ROV and/or by divers in accordance with the approved Maintenance, Repair and InspectionProgram. 402 The subsea inspection will, as a part of the survey, be witnessed on a spot check basis by a DNV surveyorin order to monitor the condition of the following structural components;

— support structure below water including foundation— access platforms— J-tubes— ladders— fenders— corrosion protection systems

with a view to the following issues:

— marine growth— cracks and deformations— scour protection— dents — bolt pretension— status regarding outstanding issues from previous surveys.

G 500 Validation of certificate501 When an in-service agreement for the wind farm is in place between DNV and the client, the validityperiod of the project certificate is extended to the duration of the service agreement plus one year; however,five years is the maximum period of validity. Following a successful completion of an in-service survey, astatement of compliance that validates the project certificate will be issued.


Offshore Service Specification DNV-OSS-901, June 2012 App.A –

APPENDIX A SAMPLE CERTIFICATION DOCUMENTS

A. Sample Statement of Compliance

A 100 Sample statement of compliance

101 A sample statement of compliance is presented in Figure 1.

Figure 1 Sample statement of compliance


Offshore Service Specification DNV-OSS-901, June 2012 App.A –

B. Sample Project Certificate

B 100 Sample project certificate101 A sample project certificate is presented in Figure 2.

Figure 2 Sample project certificate


DNV-OSS-901: Project Certification of Offshore Wind Farms

Documents

Transcript of DNV-OSS-901: Project Certification of Offshore Wind Farms