dnvgl-se-420 certification of meteorological...

SERVICE SPECIFICATION

DNVGL-SE-0420 Edition December 2015

Certification of meteorological masts

DNV GL AS

The electronic pdf version of this document found through http://www.dnvgl.com is the officially binding version. The documents are available free of charge in PDF format.

FOREWORD
DNV GL service specifications contain procedural requirements for obtaining and retaining certificates andother conformity statements to the objects, personnel, organisations and/or operations in question.
© DNV GL AS December 2015

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. The use of thisdocument by others than DNV GL is at the user's sole risk. DNV GL does not accept any liability or responsibility for loss or damages resulting from any use ofthis document.

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Service specification, DNVGL-SE-0420 – Edition December 2015

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Contents
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Sec.1 Introduction.................................................................................................. 51.1 General...................................................................................................51.2 Objective................................................................................................61.3 Scope .....................................................................................................71.4 Application .............................................................................................71.5 Definitions..............................................................................................9

1.5.1 Terminology and definitions ............................................................91.5.2 Abbreviations and symbols............................................................11

1.6 References ..........................................................................................111.7 Procedural requirements......................................................................12

1.7.1 Customer - DNV GL interaction ......................................................121.7.2 Certification requirements, quality management...............................121.7.3 Documentation requirements.........................................................121.7.4 Standards, codes and additional requirements .................................131.7.5 Combination of standards .............................................................131.7.6 Surveillance requirements.............................................................14

Sec.2 Service Overview ........................................................................................ 152.1 Procedure and content of project certification .....................................15

2.1.1 Overview ....................................................................................152.1.2 Project certification phases............................................................152.1.3 Deliverables ................................................................................162.1.4 Certificate validity and maintenance ...............................................16

Sec.3 Service Description ..................................................................................... 183.1 Phase I: Design basis ...........................................................................18

3.1.1 General .....................................................................................183.1.2 Design basis met mast structure ....................................................183.1.3 Equipment and instrumentation .....................................................21

3.2 Phase II: Design...................................................................................223.2.1 General ....................................................................................223.2.2 Met mast structure.......................................................................223.2.3 Equipment and instrumentation .....................................................25

3.3 Phase III: Manufacturing .....................................................................283.3.1 Met mast structure ......................................................................283.3.2 Equipment and instrumentation ....................................................29

3.4 Phase IV: Transport and installation ....................................................293.4.1 General ......................................................................................293.4.2 Met mast structure transportation and installation surveillance...........293.4.3 Equipment and instrumentation installation surveillance ....................30

3.5 Phase V: Commissioning ......................................................................303.5.1 General .....................................................................................303.5.2 Equipment and instrumentation ....................................................30

3.6 Phase VI: In-service ............................................................................313.6.1 General ......................................................................................313.6.2 Met mast structure ......................................................................323.6.3 Equipment and instrumentation ....................................................33

App. A Annex project certificate ............................................................................. 34App. B Annex statement of compliance .................................................................. 35


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SECTION 1 INTRODUCTION
1.1 GeneralThis service specification (SE) specifies DNV GL’s services for certification of meteorological (met) masts. DNVGL-SE-0420 serves as a:

— guidance for developers/owners from concept to in-service of the met mast — guidance for different subcontractors such as designers and manufacturers— description to meet the state-of-the-art requirements for met masts— common communication platform for describing the scope and extent of activities performed for

certification of a met mast (met mast structure/equipment and instrumentation/both) — contractual basis for certification of a met mast.

The service specification is divided into the following main sections:

Sec.1 provides general information of the met mast covered in this service specification and general requirements regarding certification.

Sec.2 provides a service overview for the defined project phases and the deliverables of project certification as shown in Table 1-1.

Sec.3 describes the services in detail, where the verification activities associated with the various project phases and their certification are presented in more detail.

The following table provides an application oriented guidance to determine which section applies for the part of interest.

The DNV GL document scheme is organized according to a three-level document hierarchy, with these main features:

— Principles and procedures related to DNV GL’s certification and verification services are separated from technical requirements and are presented in DNV GL service specifications (SE). Service specifications present the scope and extent of DNV GL’s services

— Technical requirements are issued as self-contained DNV GL standards (ST). 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 GL’s services

— Associated product documents are issued as DNV GL recommended practices (RP). Recommended practices provide DNV GL’s interpretation of safe engineering practice for general use by industry.

Guidance note:The latest revision of all DNV GL documents may be found in the list of publications on the DNV GL website www.dnvgl.com.

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Table 1-1 Certification of met masts – document guidance references

PhasesMet Parts

mast Met mast structure Equipment and instrumentation

I design basis [3.1] [3.1.2] [3.1.3]

II design [3.2] [3.2.2] [3.2.3]

III manufacturing [3.3] [3.3.1] [3.3.2]

IV transport and installation [3.4] [3.4.2] [3.4.3]

V commissioning [3.5] [3.5.1] [3.5.2]

project certificate met mast structure project certificate equipment and instrumentation

project certificatemet mast

VI in-service [3.6] [3.6.2] [3.6.3]


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1.2 Objective
Certification of the met mast ensures that the met mast can be operated safely and cost efficiently, that risks are mitigated and that all technical, design and construction requirements are met. The DNV GL scheme described in this service specification is to detail and clarify the verification activities and facilitate achieving compliance with the state-of-the-art.

The service specification has been written with the aim to provide a flexible certification concept to address individual needs, ro reduce costs over the life-time and at the same time to not compromise the added value and quality.

Additional phases can be chosen to enhance the met mast functionality, reliability and value. Mandatory and optional certification phases in the DNV GL scheme are outlined in Figure 1-1.

Figure 1-1 Phases in DNV GL project certification

The main advantage of using the DNV GL scheme are:

— more guidance and descriptions to facilitate the application — all met mast relevant topics are addressed in one service specification — flexible concept to address and allow project specific needs— shorter update cycles of standards and recommended practices to meet the latest state-of-the-art.

Depending on the specific individual interests and agreed scope the benefits by applying this service specification can be among others:

— independent approval of the met mast to reduce the risk in developing and designing— building of trust in design and construction— confidence in technical integrity — reducing costs by early detection of non-conformities— confirmation of requirements as stated by project developers, investors, operators, manufacturers,

governmental and non-governmental organisations

VI In-Service

Statement of Compliance

V Commisioning


IV Installation


III Manufacturing


II Design


I Design Basis


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— Proof by an independent body to meet the international acknowledged state-of-the-art
— utilise certificates for authorisation by governmental institutions — proof to an investor or insurer that third party approval has been performed succesfully— secure better insurance rates— minimis financial project risks— mitigate risks to environment and people— avoid damages— ensure reliable measurements.

1.3 ScopeThe certification concept for met masts constitutes a robust means to provide, through independent verification, evidence to stakeholders (financiers, partners, utility companies, insurance companies, the public, governmental and non-governmental organisations) that a set of requirements laid down in standards are being met during design and construction, and maintained during operation of a met mast.

The service specification describes also how to maintain the project certificate by periodic maintenance during the service life of the met mast.

1.4 ApplicationThis service specification applies to met mast certification and related verification tasks during the design, construction, transportation, installation, commissioning and operation of met masts.

The following parts of met masts (see Figure 1-2) are covered by the services described herein:

— met mast structure— equipment and instrumentation (E&I).

Figure 1-2 Definition of met mast parts (structure, E&I)

Met mast structure

Equipment and instrumentation (E&I)


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Each part of the met mast may be further subdivided into components for met mast structures and
equipment and instrumentation sections.

In this service specification, the terms “met mast structure” and “equipment and instrumentation (E&I)” are used for the following:

— Components of a met mast structure are:

— onshore

- foundation - tower

— offshore

- foundation- sub-structure including transition piece, work platform, boat landing and associated secondary

steelwork (e.g. railings, davit crane, gates, grillage etc.)- tower

— Components of Equipment and Instrumentation are:

— onshore

- meteorological instrumentation- data acquisition system (DAS)- electrical power supply (EPS)- communication system (Com)- aviation lights- instrumentation attachments: Parts supporting the equipment and instrumentation (e.g. booms,

junction boxes and all associated attachments to the structures)- all cables associated with the above

— offshore

- meteorological instrumentation- oceanographic instrumentation- data acquisition system (DAS)- electrical power supply (EPS)- communication system (Com)- aviation lights- aids to navigation (AtoN)- instrumentation attachments: Parts supporting the equipment and instrumentation (e.g. booms,

junction boxes, protective shelters and all associated attachments to the structures)- all cables associated with the above.


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Figure 1-3 Definition of offshore and onshore met mast structural components

This service specification is generally applicable for fixed met mast. However, these specifications are broadly applicable to the case of floating installations. In this case it is recommended to agree the scope of work for certification with DNV GL at an early stage.

1.5 Definitions

1.5.1 Terminology and definitions Table 1-2 Definitions of verbal forms

Verbal forms Definitionshall verbal form used to indicate requirements strictly to be followed in order to conform to the documentshould verbal form used to indicate that among several possibilities one is recommended as particularly suitable,

without mentioning or excluding others, or that a certain course of action is preferred but not necessarily required

may verbal form used to indicate a course of action permissible within the limits of the document


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Table 1-3 Definitions of terms

Term Definition

asset term used in the context of met mast projects to describe the project or object to be developed, manufactured and maintainedIn this service specification the term refers to the whole met mast system comprising “met mast structure” and “Equipment and Instrumentation”.

certification refers to third-party issue of a statement, based on a decision following review, that fulfilment of specified requirements has been demonstrated related to products, processes or systems (ISO 17000)

component a main sub-part of an asset In this service specification, the term refers to the tower and support structure of the met mast structure and elements of the E&I.

customer DNV GL’s contractual partner (applicant)

design brief supporting document for describing methodologies for design calculationsMostly issued by the designers.

foundation the part of the support structure for a meteorological mast that transfers the loads acting on the structure into the soil

instrumentation attachments

parts supporting the equipment and instrumentation (e.g. booms and uprights, junction boxes, protective shelters and all associated attachments to the structures)

optional services optional services are services which are not part of the scope which is required in order to obtain statement of compliance and project certificates.

outstanding issue the term outstanding issue is used to denote a deviation from standards and technical requirements specified in the certification agreement, and which needs to be completed for full compliance

part parts of the met mast are referring to either “met mast structure” or “equipment and instrumentation”

primary structure the primary structure consists of the load-bearing structure that transfers permanent loads, life loads and environmental loads, caused by gravity and environment and actions on the support structure, to the soilStructural parts the failure of which will have substantial consequences shall be classified as primary structure.

project certificate a document signed by DNV GL and affirming that, at the time of assessment, the part referred to in the certificate met the requirements stated in the normative documents

recommendation non-mandatory advice

secondary structure secondary structures are e.g. boat landings, access ladders, access platforms

special structure same as primary structureIn addition these parts are subject to particularly arduous conditions (e.g. stress condition that may increase the probability of brittle fracture, multi-axial stresses).

sub-structure term referring to the part of the support structure for a met mast which extends upwards from the soil and connects the foundation and the tower

support structure the support structure of a met mast is defined as the structure below of the tower structure and includes sub-structure and foundation of a met mast

tower the tower is the structure that holds the wind measurement equipment, the height of the tower corresponds usually to the hub height of a wind turbine

verification refers to the confirmation, through the provision of objective evidence, that specified requirements have been fulfilled (ISO 9000)


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1.5.2 Abbreviations and symbols
Abbreviations and symbols used in this service specification.

1.6 References This document makes reference to relevant international documents and DNV GL documents. Unless otherwise specified in the certification agreement or in this service specification, the latest valid revision of each referenced document applies.

Table 1-4 Abbreviations

Abbreviation In full

ALS accidental limit state

AtoN aids to navigation

Com communication system

DAS data acquisition system

E&I equipment and instrumentation

EPS electrical power supply

EPC engineering, procurement and construction

FEM finite element method

FAT factory acceptance test

FLS fatigue limit state

IEC international electrotechnical commission

ISO international organization for standardization

MEASNET international network for harmonised and recognised measurements in wind energy

met meteorological

O&M operation and maintenance

RP DNV GL recommended practices

SE DNV GL service specification

SLS serviceability limit state

ST DNV GL standards

ULS ultimate limit state

Table 1-5 DNV GL documents

Reference TitleDNVGL-ST-0126 Support structures for wind turbines (planned published 2016)DNVGL-ST-0437 Loads and site conditions wind for turbines (planned published 2016)DNVGL-RP-0416 Corrosion protection of offshore wind turbines (planned published 2016)DNVGL-RP-0005 Fatigue design of offshore steel structures

Table 1-6 IEC documents

Reference Title

IEC 61400-12-1 Wind Turbines – Part 12-1: Power performance measurements of electricity producing wind turbines

Table 1-7 ISO documents

Reference TitleISO 9000 Quality management systems – Fundamentals and vocabularyISO 9001 Quality management systems – Requirements ISO/IEC 17000 Conformity assessment – Vocabulary and general principlesISO/IEC 17025 General requirements for the competence of calibration and testing laboratories


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1.7 Procedural requirements

1.7.1 Customer - DNV GL interactionDNV GL provides third party verification and conformance testing of wind farm service projects, especially related to specific customer needs.

This document has a dual objective. It serves as a publicly available description of DNV GL’s certification services for met masts and it should be referred to as a contractual document in the certification agreement between the customer and DNV GL. The document specifies the obligations of the customer when his met mast shall be certified, as well as DNV GL’s service obligations to the customer.

The deliverables by DNV GL shall be agreed in detail between the customer and DNV GL as part of the contract. In general the DNV GL project certificate is issued when all of the required statements of compliance according to the project certification scheme have been issued and the final evaluation has been performed successfully. The deliverables are listed in [2.1.3].

Each certification phase for a component may be verified independently according to the DNV GL project certification scheme and shall be completed upon successful evaluation with the issue of a statement of compliance for the part under verification. Final timeframes of the verification and certification activities shall be discussed and agreed between the customer, DNV GL, and suppliers before commencement of the work.

The typical project certification applicant is the wind farm developer, owner or operator, although this could equally be an EPC contractor, responsible for supply and installation of a certified met mast structure. The splitting of the project certificate per part allows the involvement of part related contractors in the project set-up. This allows the involvement of additional resources from an applicant perspective.

1.7.2 Certification requirements, quality managementIn general subsequent phases shall not be initiated before previous or dependent phases are completed and approved. For example, prior to verification of the manufacturing phase, the design basis phase and the Design phase shall both be completed and approved. Therefore the manufacturing of the components for the project shall not be started before the design is approved and surveillance is agreed. Alternative ways and the related risks shall be discussed and agreed with DNV GL in advance.

The customer shall provide evidence of a consistent quality management system covering all aspects of the development and operation of the met mast. In particular the customer shall show quality relevant procedures to DNV GL for his procedures and his suppliers, covering design, manufacturing, transportation, installation, inspection, operation and documentation processes. When a valid certificate for ISO 9001 of an accredited certification body is in place, the certification body may reduce this assessment to a plausibility check.

In general test reports delivered shall be prepared by accredited testing laboratories and meet the requirements of ISO IEC 17025 and relevant standards. For non-accredited test laboratories, DNV GL shall verify that the testing laboratories carry out their work according IEC/ISO 17025, as applicable.

1.7.3 Documentation requirementsThe documentation submitted for the certification process shall be complete and self-explanatory. The content shall meet the requirements of the applied standards. All relevant documentation shall be subject oriented and in a logical sequence to facilitate cross checking between documents (e.g. design basis, design, manufacturing, transport, installation, commissioning etc.). Each document shall be named explicitly by

Table 1-8 Other documents

Reference TitleEN 1997-2 Eurocode 7: Geotechnical design – Part 2: Ground investigation and testingEN 1993-3-1 Eurocode 3: Design of steel structures – Part 3-1: Towers and mastsEN 1993-1-9 Eurocode 3: Design of steel structures – Part 1-9: FatigueEN 50308 Wind Turbines – Protective measures – Requirements for design, operation and maintenance


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e.g. title, report no., page no., date and a revision description table. Furthermore the documents should be
signed officially at least by the author and/or the approver to identify responsibilities. Alternatively the documentation submitted shall bear unambiguous evidence of having been subject to designer’s and/or owner’s own quality management system.

The documentation, including standards and codes as well as other requirements and specifications, shall be prepared in the English language, unless otherwise agreed in writing between DNV GL and the customer.

All documentation for the verification shall be forwarded to DNV GL in electronic form, preferably as pdf-files. Other forms of documentation such as print-outs can be an alternative, if agreed.

Guidance note:The documents submitted should be on a logical work package basis per phase, see [2.1.2], and cover the requirements as stipulated in Sec.3 to facilitate the process.


1.7.4 Standards, codes and additional requirementsThe standards, codes and requirements which form the basis for the met mast project shall be listed and agreed in the so-called design basis document at a very early stage. For the site in question, relevant statutory requirements shall also be listed. Such requirements could be de-commissioning and safety related issues such as requirements for embarkation and rescue.

Other requirements relevant for the certification such as specific requirements of the owner shall be listed as well.

The standards, codes and additional requirements, which are applicable for the project and site in question, will be verified for compliance with the design prerequisites of the project and for completeness and adequate suitability and applicability. The verification of the choice of standards, codes and requirements shall be conducted early in the project phase in order to avoid fundamental discussions on this basic aspect of the design basis.

For dated standards and codes, only the edition cited applies. For undated references, the latest edition of the referenced document including any amendments applies. In case of deviations from this rule, it shall be agreed on an individual basis and in advance with DNV GL.

1.7.5 Combination of standardsDNV GL certification, according to internationally recognized standards, shall follow the principles described in this service specification. Wherever combinations of such standards and external criteria are used, the exact terms of reference and documents to be issued shall be agreed at the beginning of the project and shall be specified in detail in the design basis.

The application of standards other than those referenced here does not allow for a reduction of the targeted safety as described in this service specification in combination with the related technical standards. DNV GL reserves the right to ask for additional requirements to cover issues essential to the certification process and not covered by the standards in question.

It is not allowed to combine safety measures of different standard systems due to the possible differences in the underlying safety philosophies of the different standard systems.

In case standards are combined, caution shall be exercised and the choice of standards is subject to acceptance by DNV GL.

Guidance note:Within a particular standard, aspects such as requirements for partial safety factors for calculations of design loads and design resistance are generally mutually balanced to give an overall acceptable safety level. In another standard with the same overall acceptable safety level, the requirements for the safety factors may have been balanced differently. Picking requirements for load factors from one standard and material factors from another may therefore easily result in unpredictable, and possibly too low or too high, safety levels.



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1.7.6 Surveillance requirements
The customer, or other entity having legal responsibility for the premises where DNV GL personnel will work, shall inform DNV GL of any safety and/or health hazards related to the work and/or any safety measures required for the work, prior to starting the work, or if such information is not available at that time, during the performance of the work.

Whenever DNV GL undertakes to work on site, the customer shall provide all adequate safety measures to ensure a working environment that is safe and in accordance with all relevant legislation.

If at any time during the execution of work on site a DNV GL employee judges that the work situation is unsafe then work shall be suspended until such situation has been made safe.

For on- and offshore projects the transport and installation surveillance starts from loading at the manufacturers’ production sites and ends at the wind power plant site.

Guidance note:In offshore projects the transport surveillance may be combined with the marine warranty surveillance, if both activities are carried out by DNV GL or other acknowledged marine warranty surveyor and agreed at the beginning of the project. Caution should be taken as the scope of the transport surveyor and marine warranty surveyor differ significantly with respect to the certification purpose. Briefings and written approvals for consent between the parties with respect to availability and instructions of the marine warranty surveyor for the success of the transport surveillance are required.



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SECTION 2 SERVICE OVERVIEW
2.1 Procedure and content of project certification

2.1.1 OverviewProject certification of met masts in accordance with this service specification is carried out according to the DNV GL project certification scheme.

The project certificate for the onshore or offshore met masts comprises the project specific certification of the two parts of the met mast ensuring the verification of the boundary condition between the two parts.

A project certificate met mast consists of certification of the following parts with the respective statements of compliance and certification reports:

— met mast structure— equipment and instrumentation.

The DNV GL project certification scheme consists of six phases, see Figure 1-1. The phases refer to the project certification phases design basis, design, manufacturing, transport, installation, commissioning and maintenance of the certificate during the in-service phase.

Statements of compliances will be issued after successful completion of each phase. Statement of compliances can be split up for each component and issued on request.

Phases I – V are mandatory for obtaining the project certificate. The project certificate for a met mast will be issued after successful completion of all phases for all parts of the met mast.

In case of outstanding issues provisional statements of compliance and provisional project certificate may be issued on request, see [2.1.3].

The project certificate may be maintained throughout the in-service phase. For maintenance of the certificate throughout the in-service phase, reference is made to [2.1.4].

2.1.2 Project certification phasesThe project certification phases are specified below:

Each phase will be completed with the issue of a statement of compliance.

After completion of phases I through V for each part of the met mast and prior to the issue of the project certificate met mast, a final evaluation shall be performed. During the final evaluation DNV GL shall check all parts of the certification (certification reports and statements) for consistency and completeness with regard to the phases and parts described in this service specification. A DNV GL project certificate met mast will be issued after successful completion of the final evaluation. The certificate states compliance at the date of issue of the project certificate for a certain project with the standards specified and agreed in the design basis.

The verification activities associated with the various certification phases and for the different met mast parts are presented in more detail in Sec.3.

Phase I: Design basis covers the site conditions and the basis for design. Phase II: Design covers the steps necessary to achieve final design verification. This verification includes

a site-specific design approval of the integrated structural system consisting of tower and support structure. And a design approval of E&I.

Phase III: Manufacturing covers the surveillance during manufacturing of the project related parts (met mast structure and E&I).

Phase IV: Transport and installation covers the surveillance during transport and installation of the project related parts.

Phase V: Commissioning involves all follow-up verification and on-site inspections during the implementation of the met mast.

Phase VI: In-service involves follow-up verification and periodic on-site inspections after start of operation and during the subsequent in-service period.


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2.1.3 Deliverables
A DNV GL project certificate may be issued for an onshore or offshore met mast or its individual met mast parts as defined in this service specification (see [2.1]).

A project certificate for met mast contains the following:

— project certificate met mast structure— project certificate equipment and instrumentation— final certification report.

Each project certificate is supported by at least the following:

— statement of compliance design basis— statement of compliance design— statement of compliance manufacturing— statement of compliance transport and installation— statement of compliance commissioning— final certification report.

For the maintenance of the project certificate a statement of compliance in-service shall be issued.

Each statement of compliance is supported by a subject related certification report.

The project certificate met mast can be obtained based on the two related project certificates or by fulfilling the mandatory phases for the two parts as described in this service specification.

For surveillance during manufacturing, transportation, installation and commissioning as well as in-service, DNV GL shall report critical findings to the customer immediately after the surveillance. DNV GL shall issue surveillance reports to the customer and the frequency of these shall be agreed with the customer (for example daily, weekly or monthly). The reports shall describe the extent of the surveillance including findings, non-conformities and possible recommendations. The reports will be issued in electronic form and sent by e-mail to the customer.

In the event that full compliance is not obtained during the project certification, the deliverables will depend on the nature of the lack of compliance. Three deliverable outcomes are available depending on the lack of compliance and are described in the following:

— No outstanding issue. Statements of compliance with the accompanying DNV GL certification reports will be issued. A DNV GL project certificate will be issued based on the statements of compliance for the met mast part verified.

— Non-safety critical outstanding issues. One or more provisional statement(s) of compliance will be issued with the outstanding issue(s) listed in the statement(s) of compliance. A provisional project certificate can be issued on request, which points out the outstanding issues. The outstanding issues listed on the statement(s) of compliance shall be repeated in the project certificate. Specific description of the outstanding issues will be given in the accompanying DNV GL certification reports. As outstanding issues become closed, an updated statement of compliance and finally a project certificate with no outstanding issues can be issued.

— Safety critical outstanding issues. (A) Statement(s) of compliance and the project certificate will not be issued. DNV GL shall deliver the DNV GL certification report(s) that would normally accompany the statement of compliance for the relevant phase. The DNV GL certification report(s) shall list the outstanding issues whose rectification is required before (a) statement(s) of compliance can be issued.

2.1.4 Certificate validity and maintenanceThe DNV GL project certificate refers to statements of compliance issued for the completed phases of the project certification.

The validity of the project certificate is limited to the design life-time of the installation stated in the project certificate.


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Maintenance of the project certificate is conditional on periodic in-service verification by DNV GL and
requires the following informations/actions:

— annual reporting by the customer covering the certified met mast project and including information about:

— met mast structure and E&I as installed at the site— abnormal or deviant operating experience or operating failures as well as minor modifications.

— reporting by the customer of planned major modifications without delay and in sufficient time to allow for evaluation by DNV GL before implementation and to enable updating of the design phase and others, if relevant

— the met mast and the parts of the met mast of which it is comprised are maintained to a standard complying with the requirements of applicable codes and relevant manuals

— periodic inspections by DNV GL or other acknowledged in-service inspectors during the validity period of the certificate to check that the met mast corresponds with the certified design.

The project certificate shall be confirmed one year after the date of first issuance by a statement of compliance in-service. When a periodic in-service agreement for the met mast is in place between DNV GL and the customer, the interval of confirmation of the project certificate is set to the duration of the service agreement plus one year; however, five years is the maximum period of confirmation.

Following a successful completion of an in-service verification, a statement of compliance in-service that validates the project certificate will be issued.

Re-certification may be necessary, if additional requirements for maintenance of the project certificate are set by national authorities or by the applicable design code or standard during the validity period of the certificate.

Safety relevant incidents shall be reported to DNV GL without delay. DNV GL shall evaluate the incidents. In case of a serious defect of the met mast, DNV GL shall suspend the certificate until elimination of the cause. The certificate shall be reaffirmed after successful verification of the rectifying measure.

Provisional statements or provisional certificates have a maximum validity of one year. During this period the customer shall document the closing of the outstanding issues and these shall be evaluated by DNV GL.

Guidance note:In-service is optional according to this service specification. However, it becomes mandatory if the maintenance of the project certificate is chosen. It is strongly recommended to maintain the certificate from issuing date over the life-time. Resuming the certificate maintenance of a suspended or invalid project certificate may be difficult or even impossible.



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SECTION 3 SERVICE DESCRIPTION
3.1 Phase I: Design basis

3.1.1 General 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 for design are properly established and documented and that this design basis is sufficient for a safe design of the met mast.

DNV GL’s verification activities are based on DNVGL-ST-0437 for loads, DNVGL-ST-0126 for structure and IEC 61400-12-1 for E&I.

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

a) site conditionsb) standards, codes and requirements, see [1.7.4] c) design criteriad) procurement, fabrication, E&I testing, transport, installation and commissioning requirementse) operation and maintenance requirements.

DNV GL shall verify the design basis for compliance with DNV GL’s standards and other standards and codes identified in the design basis.

Once the verification of the design basis has been successfully completed, DNV GL will issue a statement of compliance for Phase I: Design Basis for the verified met mast asset.

3.1.2 Design basis met mast structure3.1.2.1 Site conditionsIntegral part of the design basis are the site design conditions which denote all external influences acting on the met mast’s primary and secondary structures and instrumentation attachments from outside.

The following site design conditions shall be documented:

— wind conditions— geotechnical conditions— earthquake conditions— other environmental conditions (e.g. ice, high temperatures, lightning).

Additionally for offshore sites:

— marine conditions, and weather windows and weather downtime.

Additionally for onshore sites:

— terrain and topographical conditions.

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

As the purpose for the met mast is to collect wind (and wave) measurements site-specific measurements might not be available. Instead the wind and wave conditions can be based on data from nearby sites and hindcasts.

The geotechnical site investigation and laboratory testing are assumed to have been carried out by companies with relevant experience of similar work. The quality of the soil investigation and the test results shall fulfil the requirements given in EN 1997-2.


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Not necessarily all parts of ISO/IEC 17025 may apply to the geotechnical field and laboratory work. In all
cases, a description of all test procedures and relevant standards shall be presented.

DNV GL shall verify that relevant reports properly document the site conditions.

DNV GL shall assess the interpretation of the site conditions and the identification of the design parameters describing the site conditions to be used for design of the met mast. Design parameters representing the following conditions shall be included:

— wind climate— ice— geotechnical data— other site conditions, such as seismicity, lightning, temperature.

Additionally for offshore sites:

— wave climate— correlation between relevant parameters such as wind, waves and current— ocean current— water level— water depth— seabed topography— other site conditions, such as salinity, spray ice, marine growth, air density, traffic, disposed matters,

pipelines and cables.

Additionally for onshore sites

— terrain topography and complexity.

The verification of the geotechnical design basis shall focus on:

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

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

3.1.2.2 Load and safety considerations The met mast (both for onshore and for offshore) shall be designed for the environmental load combinations given in DNVGL-ST-0437. Only the relevant load cases shall be taken into account, as not all load cases apply to a met mast.

The met mast structure shall be designed to the same level of safety as the wind turbine support structure. The safety philosophy described in DNVGL-ST-0126 and DNVGL-ST-0437 is thus governing. This means that the safety factors and load factors given in DNVGL-ST-0126 and DNVGL-ST-0437 shall be applied.

3.1.2.3 Design criteriaThe design basis shall specify the principal input for the design process, in order to ensure that the final structure can be presumed to withstand the loads expected within the design lifetime.

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

Furthermore, the design basis has to identify all hazards that may jeopardize the safety or reliability of the structure, and translate them into specific dimensional or other design constraints which shall be fulfilled by the final design.

A general description of the met mast and its characteristics shall be given.


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The design basis shall include a catalogue of requirements for the specific met mast planned. Those are in
particular:

— external design parameters— design load cases and load case combination for ULS, FLS, SLS and ALS if relevant— load factors and load reduction factors— partial safety factors applied on loads and materials— description of simulations— methods for extreme and fatigue design loads/response analysis— target lifetime of coating and corrosion protection systems;— interface between tower and sub-structure— assumptions for coupled analysis— consideration of ship impact, if relevant.

If the design is partly based on model tests, DNV GL shall evaluate the test program.

Damping shall be considered with the following parameters of contribution to damping:

— soil damping (due to internal friction)— soil radiation damping (due to pressure wave radiation)— wave damping— viscous damping— aerodynamic damping— structural damping— slosher dampers, tuned mass dampers etc.

3.1.2.4 Manufacturing, transport, installation and commissioningThe design basis shall state assumptions, specifications and requirements for the structural design against loads occurring during manufacturing, 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 manufacturing, load-out, transportation, installation and commissioning programmes themselves. Commissioning requirements for the substructure and the foundation are usually very limited.

The conditions prevailing at the installation site analysed and the rules and premises to be applied for the design shall be documented. This includes the following aspects:

— 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 management systems for the installation contractors— description of the service vessel.

The assumptions, specifications and requirements are expected to depend on owner’s requirements as well as on the actual contractual arrangements for the met mast.

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

3.1.2.5 Operation and maintenanceThe design basis shall state assumptions, specifications and requirements for the structural design against loads occurring during operation and maintenance. The design basis shall also state assumptions, specifications and requirements for the operation and maintenance programs. Assumptions, specifications and requirements may include:

— inspection scope and frequency


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

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

3.1.3 Equipment and instrumentationThe specifications and design basis concerning the instrumentation and related power supply systems, will be reviewed and assessed against the recommendations in IEC 61400-12-1, Ed.1, as well as customer specifications, and typical industry practice.

DNV GL shall issue a statement of compliance relating to the design basis of E&I.

3.1.3.1 Design criteriaThe design basis for the E&I systems shall be based on the specific site conditions, the consenting requirements and the particular measurements planned. The E&I criteria shall be verified with emphasis on the following points:

— definition of wind and other meteorological measurement requirements, including accuracy requirements

— definition of required height coverage for wind and other meteorological properties— definition of required vertical sampling/resolution for wind and other meteorological properties— identification of instrument mounting orientation(s)— definition of oceanographic measurement requirements (if applicable)— data quality as the paramount goal— data availability— data storage redundancy— data transfer and communication— aviation lighting and aids to navigation (AtoN) requirements.

3.1.3.2 Manufacturing, transport, installation and commissioning Design basis assumptions, specifications and requirements for manufacturing, factory acceptance testing, transportation, installation and commissioning may include, but are not necessarily limited to:

— supplier and manufacturer requirements and quality management systems— E&I requirements for transportation, installation (incl. loading and unloading) and commissioning

manuals — limiting environmental conditions (e.g. limiting wind speeds for working at height)— requirements and quality management systems for installation contractors.

DNV GL shall verify assumptions, specification and requirements stated in the design basis.

3.1.3.3 Operation and maintenanceThe design basis shall state assumptions, specifications and requirements including, but not necessarily limited to:

— target lifetime of components, systems and structures— O&M strategy for change out of sensors, periodic maintenance and unscheduled maintenance response

for critical and non-critical systems.— requirements for service and maintenance manuals— requirements for condition monitoring signals or systems.

DNV GL shall verify assumptions, specification and requirements stated in the design basis.


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3.2 Phase II: Design
3.2.1 General DNV GL shall verify the final design for compliance with DNVGL-ST-0126 and IEC 61400-12-1 and other standards and codes identified in the design basis. Details of the verification activities in this phase are given in the following sub-sections.

3.2.2 Met mast structure3.2.2.1 GeneralThe verification of the design of the met mast structure shall be based on loads, capacities, design methods and principles specified in the approved design basis and in relevant DNV GL standards, e.g. DNVGL-ST-0126. For areas where the approved design basis or the DNV GL standards do not apply, reference to a recognized standard or design method may be accepted by DNV GL.

The structural design verification shall include:

— loads and load combinations— geotechnical design — tower— primary structure of the met mast— secondary structure of the met mast— transportation, installation, operation and maintenance— grout design, if applicable— connections.

The following design reports and drawings shall be submitted to DNV GL for verification of the final structural and geotechnical design of the support structure:

— design documentation for the structural and geotechnical design calculations for ULS, SLS, FLS and ALS— design calculation shall cover transportation and installation as well as operational conditions— assumptions made for the calculations, for example regarding manufacturing and installation methods— design report(s) containing design calculations for corrosion protection system(s)— design report for the driveability study (if applicable)— design drawings— design documentation regarding scour and scour protection design.

3.2.2.2 Structural design loadsThe loads on the met mast structure may comprise the following loads:

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

Additionally for an offshore met mast:

— environmental loads from waves and ocean current— impact loads on boat landings— accidental loads from ship collisions.

The principles used to establish load combinations for SLS, ULS, FLS and ALS shall be reviewed for compliance with DNVGL-ST-0126. The load combinations for the met mast structure shall be reviewed with a focus on:

— selection of load combinations


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

For dynamically sensitive offshore met masts both the wind and waves contribute to the tower and sub-structure loading, if necessary, the customer has to determine the loading by a fully coupled analysis.

3.2.2.3 Geotechnical designReference is given to DNVGL-ST-0126 for geotechnical design of foundations and guidance for prediction of scour and means to prevent scour. The purpose of a soil investigation is to provide a range of strength and deformation parameters with sufficient accuracy. Additionally the investigations shall supply information to evaluate deterioration from dynamic loads in sufficient detail. The investigations should be focused on the actual phase of the project with respect to extent, details and accuracy.

The verification of the geotechnical design for the met mast shall focus on:

— evaluation of calculation methods, stability and failure modes— review of geotechnical design calculations for ULS, SLS and ALS— review of design documentation regarding soil preparation, tolerances and scour protection— soil stiffness and soil capacity.

3.2.2.4 Primary structureThe verification of the primary structural design of the met mast shall focus on:

— design methodology, safety level and materials— review of design calculations for ULS, SLS, FLS and ALS— Eigen frequency and vortex shedding analyses— manufacturing and installation methods, with respect to the structural integrity of the(permanently)

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

in DNVGL-RP-0416.— instrumentation attachment points (to tower)— lightning protection— 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 and testing.

Fatigue design documents shall be based on DNVGL-ST-0126 or other recognised standards such as EN 1993-1-9. A combination of standards with regard to design fatigue factors and S/N-curves is not acceptable.

The following verification activities are conducted:

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

— relevant independent analyses of loads and structural strength.

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

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

The primary structure for the met mast tower will be analysed for wind loads, ice accretion if relevant, and interaction of wind measurement equipment and mast structure. The dynamic loading of the complete system of mast and foundation due to wave induced loads in the mast and foundation structure will be analysed.

If the design includes highly utilized structural connections (e.g. grouted connections of steel structures and


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tubular joints), detailed independent finite element calculations of the connections shall have to be carried
out by DNV GL. Such analysis will be described in an independent scope of work.

3.2.2.5 Secondary structureThe secondary structures to be covered by the certification shall as a minimum comprise those secondary structures that have an influence on the structural integrity of the primary structure, for example in terms of welds, load distributions, stiffness and corrosion. Only secondary structures with no influence on the primary structure may be excluded from the scope of the certification. These specific secondary structures to be covered by the certification shall be specified and agreed with the client.

The secondary structure for the tower comprises for example platforms, ladders, instrumentation attachments and hand rails.

The secondary structures for the support structure comprises access ladders, main structural elements in external access platforms and boat landings, if relevant.

The secondary structure will be checked for structural and personnel safety according to DNVGL-ST-0126 and EN50308.

The verification of the structural design of secondary structures in the support structure shall be verified with focus on:

— design methodology and safety level— materials— review of design calculations for ULS, SLS and ALS— 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— verification of the met mast structures and the integration of the equipment and instrumentation with

the structure.

3.2.2.6 Manufacturing, transport, installation and commissioning planVerification of manufacturing, transportation and installation (incl. loading and unloading, such as lifting loads) shall be based on DNVGL-ST-0126 and national regulations. Commissioning processes are normally based on the clients requirements.

The overall DNV GL aim is to verify that the final structure in-situ has not been exposed to unforeseen loading during manufacturing, transportation, installation and commissioning. Exposure to fatigue loading during transportation may be of relevance.

The following documentation shall be submitted for verification:

— description of concepts and procedures— method statements for transfer operations (i.e. loading and unloading, float-out, lift-off and mating)— installation and commissioning manual including emergency procedures.

The documentation shall be evaluated and verified for compliance with the approved design basis and the design documentation including:

— manufacturing and goods handling processes— review of transportation and installation requirements (goods loading, load out, sea transportation,

lifting and installation)— essential installation procedures— essential commissioning procedures.

Normally the different manuals will not all be finalised at the design stage. However, at least the design influencing assumptions shall be documented by the respective manuals, at the design phase. The final site-specific manuals will be reviewed during the transport, installation and commissioning phase. However, the relevant temporary situations shall be considered in the design phase.


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3.2.2.7 In-service plan for met mast structure
DNV GL requires that relevant input to the inspection and maintenance plans shall be prepared. The input to the inspection plan and the maintenance manual shall be seen as a help to the operations and maintenance organization that normally will be established later. Examples of issues to be covered are inspections and checks of the scour protection system and the corrosion protection system, assumed service vessel(s), and inspections for fatigue cracks if relevant.

Verification of the operation and maintenance programme shall be based on DNVGL-ST-0126.


— description of risk based inspection and maintenance programmes, covering inspection, scheduled maintenance and unscheduled maintenance

— service and maintenance manual for key components.

The documentation shall be evaluated and verified for compliance with the approved design basis and the design documentation regarding 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 management.

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

The above mentioned documentation may not be finalised during the design phase and the verification of this documentation will therefore be covered in the Installation phase. However, at least the design influencing assumptions shall be documented, at the design phase.

3.2.3 Equipment and instrumentation3.2.3.1 Instrumentation attachments Equipment and instrumentation attachments shall be verified with a focus on minimising the effects of the mast and attachments on wind speed and other measurements. This shall be achieved with reference to IEC standard 61400-12-1 (where applicable) and good industry practice and shall include consideration of:

— orientation of booms, mounting of sensors— boom lengths, diameters of booms and uprights— height of sensors above booms or mast top, distance to neighbouring components— structural mast components— attached components e.g. avionics warning lights, AtoN, neighbouring sensors, bird radar etc.— lightning protection systems e.g. lightning finials— guy wires of mast or boom structure— junction boxes and bracketry— sufficient distance from platforms, and other structures— mast porosity to account for maximal centre-line wind speed deficit.

Further focus shall be on the design of instrument mountings to facilitate the planned approach to offshore installation, the design for minimal maintenance and the design of instrument mountings for sensor service and exchange, including a review of:

— working platforms— retractable or hinged booms— resting platforms


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— climbing aids and fall arrest systems
— hatch and gate design.

3.2.3.2 Equipment and instrumentation system designThe verification will focus on the review of the following elements compared to the design basis, typical industry practice, the appropriate customer specifications and the instrumentation manufacturer specifications:

— the proposed suite of sensors based on appropriateness and classification of the measurement equipment, reliability, maintenance requirements, and measurement accuracy. This includes the selection of non-wind meteorological and oceanographic sensors (e.g. pressure, humidity, wave radar, etc.)

— the sensor configuration with respect to industry standards to ensure the met mast collects sufficient, accurate and appropriate data. The review will consider sensor heights and sensor vertical spacing for all measurement equipment

— the required redundancy of wind sensors per measurement height to allow for (a) wind data reconstruction in case of a failure and (b) to account for wind direction sector dependent flow distortions, induced by the mast structure on the wind sensors (e.g. on cups and vanes)

— the data logging, communications and power supply equipment will be reviewed and assessed for reliability, redundancy and general ability of the proposed equipment to yield a reliable stream of the required data from the proposed sensor suite. This shall include assessment of the capability to achieve the required data availability (if specified)

— the design of all avionics beacons and aids to navigation (AtoN) (where applicable) shall be reviewed against specifications, consenting requirements and design basis. This review shall include consideration of:

— adequacy of power supply(s) including any power supply redundancy or independence from other systems and any switch-over mechanisms as required

— redundancy of avionics beacons, AtoN devices and associated detectors, sensors and controllers as required

— condition status monitoring, including fault signals and voltage or current monitoring.

3.2.3.3 Manufacturing, transport, installation and commissioning planThe overall DNV GL aim is to verify that the manufacturing, transport, installation and commissioning plans for the equipment and instrumentation are:

— to minimise the risk of harm to personnel— adequate to ensure the proper and reliable functioning of the final system— to minimise the risk of damage to the components.


— quality, safety and environmental certificates (as appropriate) for manufacturing, transport, installation and commissioning contractors and sub-contractors

— factory acceptance test (FAT) procedures.

E&I installation method statements, including:

— approach to site access (onshore or offshore)— scheduling— emergency procedures.— commissioning test procedures.

The documentation shall be evaluated and verified for compliance with the approved design basis including:

— manufacturing and goods handling processes— factory acceptance test (FAT) procedures, such as:


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— any particular hazards that should be observed during the tests
— what tests shall be undertaken and are these sufficient to demonstrate proper functioning of all systems

— how these shall be performed

— what results are expected.

— Review of transportation and installation requirements (goods loading, load-out, sea transportation, offshore lifting and installation as appropriate).

— Commissioning test procedures, including:

— any particular hazards that should be observed during the tests— what tests shall be undertaken and are these sufficient to demonstrate proper functioning of all

systems

— how these tests shall be performed— what results are expected.

— procedures for safe shutdown

— personnel safety.

3.2.3.4 In-service planNormally the O&M manuals will not be finalised at the design stage. However, the design influencing assumptions shall be documented at this phase. These inputs to the operations and maintenance plans and manuals shall cover the approach to all in-service works, including, but not limited to:

— data collection, processing and storage— periodic sensor change-out programmes

— other scheduled maintenance, inspections and cleaning works— remote monitoring

— fault finding and corrective works.


— description of maintenance programmes, covering inspection, scheduled maintenance and unscheduled maintenance

— service and maintenance manuals for key components— description of data collection and storage plans.

The documentation shall be evaluated and verified for compliance with the approved design basis and best practice for the following:

— operational and condition monitoring— data management

— safety-related inspection and maintenance— scheduled maintenance

— unscheduled maintenance provisions— record keeping and quality management.

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

The above mentioned documentation may not be finalised during the design phase and the verification of this documentation will therefore be covered in the installation phase. However, at least the design influencing assumptions shall be documented, at the design phase.


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3.3 Phase III: Manufacturing
3.3.1 Met mast structure The aim of the manufacturing surveillance is to check compliance with the applicable rules and standards, verify compliance with approved drawings and check that the met mast structure is being built to the intended quality.

The manufacturing surveillance shall be conducted at the fabrication yard and shall include:

— evaluation of manufacturing

— evaluation of quality system, if an ISO 9001 certificate is not available

— product related quality audits

— surveillance of contractor’s quality management activities

— periodical surveillances.

Manufacturing surveillance consists of one initial audit and inspection with further two inspections performed at mid, and end of production at each manufacturer. The surveillance activities comprise both on-site inspections and document review.

The purpose of the (initial) audit is to check the qualification (ability to perform the production of relevant components according to the assumed quality and to document this ability) of the manufacturing company prior to commencement of production and to check the documentation forming the basis for production.

Guidance note:The (initial) audit may be omitted, if a workshop approval for the production purpose is available.


The surveillance of the primary structures shall be completed at the manufacturers’ shops or in the fabrication yard and will be focused, on a random basis, on:

— compliance with quality plan requirements

— incoming goods inspection

— welding procedures specification

— welder qualifications

— construction drawings versus reviewed drawings

— visual inspection of on-going jobs

— corrosion protection systems

— witnessing of non-destructive testing

— visual inspection of finished structures before shipping

— documentation review.

The agreed surveillance of the secondary structures shall be completed at the fabrication shop(s) or at the manufacturers’ premises. The surveillance shall be carried out on a random basis and shall be focused on:

— compliance with quality plan requirements

— welding procedures specification and welding procedures qualification

— welder qualifications

— 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.


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3.3.2 Equipment and instrumentation
Agreed surveillance of equipment and instrumentation procurement and assembly shall be completed at the fabrication/assembly shop or at the manufacturers’ premises. The surveillance will be carried out on a random basis and shall be focused on:

— review of documentation: calibration tests for the anemometers, pressure, temperature and relative humidity sensors according to IEC 61400-12-1 and performed by a testing labarotory accredited according to ISO 17025 and MEASNET approved.

— witnessing of manufacturing/assembly process for the electrical and data logging systems— witnessing and validation of the factory acceptance tests for the:

— instrumentation— power supply / electrical systems— data logging systems— communication systems— safety systems (e.g. avionic warning lights, AtoN, etc.).

3.4 Phase IV: Transport and installation

3.4.1 GeneralTransportation and installation is a crucial temporary phase in a met mast project. DNV GL shall perform transportation and installation surveillance as part of the project certification process.

The transportation and installation surveillance shall be followed up by a detailed surveillance report. This surveillance report will include photo documentation whenever deemed necessary. Permissions required by suppliers shall be provided to DNV GL by the developer or contractor.

Prior to the transportation of the support structure and the met mast to the location, method statements for transportation and installation manuals including loading and unloading shall be issued for DNV GL review.

3.4.2 Met mast structure transportation and installation surveillanceReview of installation and transport methods, scale model tests and calculations, however, only with respect to the structural integrity of the (permanently) installed substructure.

During load out of the met mast support structure the DNV GL surveyor will focus on the following:

— review of relevant method statements for compliance with design requirements— visual survey for possible damages relevant for the installed structure— survey of ballasting the concrete caisson with respect to the relevant method statements.

Offshore survey will focus on:

— review of relevant method statements for compliance with design requirements— survey of structure for damages relevant for the permanently installed structure— witnessing of upending, lifting operations— surveyor shall ascertain that non-conformities/deviations from the verified design, drawings and

procedures are identified, recorded and acted upon— survey of gravel bed preparation— survey of ballasting caisson on to the seabed with respect toto the relevant method statements with

relevance for the installed structure.

The installation survey may be complemented by a warranty survey (optional) in order to minimize the risks involved with this phase.


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3.4.3 Equipment and instrumentation installation surveillance
A DNV GL surveyor shall be present during installation of the E&I. The surveyor shall focus on the following:

— review of the installation plan documentation with a focus on the handling of the equipment and instrumentation to avoid damage

— fastening of boom arms/sensors during offshore installation— orientation, height and inclination of the structure to conform with design and identification of any

offsets.

The final as-built documentation shall be issued for DNV GL review. The review shall focus on items such as the following in order to verify that the design is still sufficient:

— survey results for location, orientation and instrument heights— inclination of instrument mountings (e.g. verticality of uprights to which anemometers are attached)— any general deviations from the approved design.

The installation survey can be complemented by a warranty survey (optional) in order to minimize the risks involved with this phase.

3.5 Phase V: Commissioning

3.5.1 General DNV GL shall perform a commissioning surveillance as part of the met mast certification with the purpose to verify that the met mast (structure and E&I) installed on site are commissioned according to the requirements of the manufacturer and in compliance with relevant documentation provided in the design phase.

DNV GL shall attend the commissioning of the met mast and witness the commissioning tests. The following documentation shall be made available to the DNV GL surveyors prior to the commencement of the surveillance:

— general commissioning procedures and scheduled timeline— commissioning checklist.

The commissioning survey shall be followed up by a detailed survey report. The survey report will include photo documentation whenever deemed necessary. Permissions required by suppliers shall be provided to DNV GL by the developer or contractor.

3.5.2 Equipment and instrumentation The commissioning survey comprises witnessing of the commissioning tests once installation has been completed. Surveys will be performed in order to review the as-built systems and assess their compliance against the designs as well as with recommendations in IEC 61400-12-1, customer specifications, and industry practice.

This work will also include a review of the following documentation (if not already performed in the previous phases) for adequacy and completeness:

— as-built documentations including a list of all instruments installed with serial numbers and locations— factory acceptance tests for the E&I subcomponents— data logger operation plan (internal program)— communication system operation plan— calibration certificates for the sensors— O&M manual.

One crucial point is to confirm all E&I subcomponents are operating together seamlessly as a single unit. For an offshore met mast, this is sometimes confirmed during a quay-side (onshore) test campaign, with further confirmation sought as part of the offshore commissioning. It may therefore be the case that two witnessing visits are scheduled for offshore met mast commissioning.


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In particular, validation of the following points is considered crucial for the met mast:
— sensor layout with a focus on anemometers and supporting booms— height and orientation of the instruments and mounting booms— verticality of the anemometer supports as per IEC 61400-12-1 recommendations— appropriateness of the measurement readings for all sensors— correct logging, processing and remote communication of the data— time synchronisation in case several data loggers are used— remote communication with the E&I system for status check— operation of alarms: safety (fire, intrusion), measurement, power levels, fault signals, etc.— connection of instruments to the correct data logging channels— correct operation of safety systems, such as avionic beacons, AtoN or fire suppression systems

(including response to fault states where applicable).

3.6 Phase VI: In-service

3.6.1 GeneralThe in-service phase implies an activity by which the met mast components (structure and E&I) are surveyed regularly during their entire operational life. DNV GL or other acknowledged in-service inspectors shall conduct periodic in-service surveillance. The in-service surveillance results shall be evaluated to verify that the required standards are observed and maintained. The in-service phase serves to confirm the validity of the met mast certificate over the life-time.

Prior to the initiation of surveillance, a maintenance, repair and inspection programme shall be developed and submitted to DNV GL for approval. The programme shall serve as a reference for parties involved in maintenance and repair carried out at the met mast(s). The maintenance, repair and inspection programme shall be updated as required based on findings and deviations. Any update of the programme shall be subject to DNV GL approval.

In general the operation and maintenance plan required during the design phase, see [3.2.3.4] shall be taken into consideration.

The scope of work shall include a detailed project-specific plan that identifies the surveillance activities required, the surveillance intervals and the reporting requirements. The surveillance intervals will depend on the knowledge built up during the previous phases of the certification process. The first surveillance after commissioning will usually take place after one year. The scope will include assessment of the status regarding any outstanding issues from the previous surveillance. DNVGL-ST-0126 provides guidance regarding in-service inspection and maintenance of met masts to be inspected during periodic surveillance.

The surveillance reports shall highlight any findings or deviations reported during the periodic in-service surveillance. Major findings and deviations shall be reported to the customer in terms of recommendations.

The DNV GL periodic in-service phase shall be carried out to provide evidence as to whether the surveyed installation or parts thereof continue to comply with the approved design. Prior to the surveillance the status of outstanding issues as well as information on all revisions made to the maintenance procedure within the latest year shall be submitted to DNV GL.

As a part of the periodic surveillance, records of maintenance and repairs carried out since the previous surveillance shall be reviewed and verified against the program. The company responsible for the maintenance and repairs shall be subject to audits in order to verify the documentation for work carried out. The review shall include:

— follow-up of outstanding issues from the previous surveillance and status regarding recommendations— review of revised procedures— review of maintenance documentation— review of maintenance history in the file or any digital registration.


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The surveillance conducted offshore may in general include:
— preparation of the offshore program, based on findings from the onshore part and systems, if applicable— verification that installed components are in compliance with certification requirements— verification that repair and maintenance according to approved programme and manufacturer’s

recommendations were conducted— general surveillance and test of selected systems and components— subsea inspections of structure and scour protection.

Components recommended for consideration during in-service surveillance of the met mast are given in the following sub-sections.

3.6.2 Met mast structure 3.6.2.1 Support structure above water linePeriodic surveillances of the met mast tower and the part of the sub-structure that are located above water surface are required in order to verify compliance with the approved design. The surveillance shall comprise relevant structures such as:

— primary and secondary structures— access platforms— ladders— corrosion protection systems— personnel safety installations.

The surveillance of the systems listed above shall focus on the following items:

— fatigue cracks— dents and deformation(s)— bolt pre-tension— status of outstanding points from previous surveillance— additional surveillance identified based on findings and deviations, e.g. witnessing of tests and

inspections in order to distinguish between random and systematic failures.

3.6.2.2 Submerged support structureThe support structure below the water surface shall be subject to periodic surveillance in order to verify compliance with approved design. The subsea inspections shall be initiated by the owner, operator or assigned contractors, and they shall be performed by a remotely operated vehicle and/or by divers in accordance with the approved maintenance, repair and inspection programme. A DNV GL expert or other acknowledged in-service inspectors shall witness these inspections.

The subsea inspection shall, as a part of the surveillance, be witnessed on a spot check basis by a DNV GL or other acknowledged in-service surveyor in order to monitor the condition of the following structural components:

— support structure below the water surface including foundation— access platforms— ladders— fenders— corrosion protection systems.

This inspection shall be carried out with a view to the following issues:

— marine growth— cracks and deformations— scour protection— dents


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— bolt pretension
— status regarding outstanding issues from previous surveillance.

Before the inspection starts the structure shall be cleaned if the marine growth limits that have been assumed in the load calculations are exceeded or are likely to be exceeded. Inspection intervals of the submerged parts should not exceed 5 years. It is recommended to make more frequent inspections during the first five years, or if the design limits are likely to be exceeded.

3.6.3 Equipment and instrumentation The in-service certification process of the E&I will commence with the review of the following documentation:

— logs of instrumentation changes— logs of electrical system and safety devices maintenance.

A quality check of the data sets will be performed in order to check the following points:

— adequacy and completeness of the data acquired— monthly data availability— realistic measurement and system health signals without signs of short or long-term degradation.

The equipment and instrumentation shall be subject to surveillance in order to verify compliance with approved design. This site visit shall focus on the issue revealed by the review of documentation and the data quality check performed. It will primarily validate that the in-service E&I is maintained to operate as per the approved design, IEC 61400-12-1 standard and best industry practise.


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APPENDIX A ANNEX PROJECT CERTIFICATE

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APPENDIX B ANNEX STATEMENT OF COMPLIANCE

DNV GL AS

SAF

DNV GLDriven by our purpose of safeguarding life, property and the environment, DNV GL enables organizations to advance the safety and sustainability of their business. We provide classification and technical assurance along with software and independent expert advisory services to the maritime, oil and gas, and energy industries. We also provide certification services to customers across a wide range of industries. Operating in more than 100 countries, our 16 000 professionals are dedicated to helping our customers make the world safer, smarter and greener.

ER, SMARTER, GREENER

dnvgl-se-420 certification of meteorological...

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