Vestas Requirement Specification - Gearbox Repair

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Requirement Specification

Requirement Specification Gearbox Repair and Refurbishment

Abstract This Requirement Specification contains Specification contains requirements to procedures for repairing and refurbishing main gear units for Vestas wind turbines. It includes criteria for teardown, assessment, re-use, re-work, reassembly and testing, which any Service Provider for gearbox repairs ha s to comply with.

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Document Revision History rev.

release date

editor(s) pages changed description of changes

V00

02.03.2009

KERP

all

new document

All previous revisions become invalid with the release date of the latest document revision.

Table of Contents 1.

INTRODUCTION............................................ ..................... .............................................. ............................................... .................................. .......... 5

1.1

Purpose and Scope ............................... ................................................................... ........................................................................ ........................................................5 ....................5

1.2

Validity ............................... ................................................................... ........................................................................ ............................................................... .....................................7 ..........7

1.2.1

Level A Rema nufacturing ................................... ....................................................................... ........................................................................ ............................................7 ........7

1.2.2

Level B Refurbishments ............................... ................................................................... ........................................................................ ..................................................7 ..............7

1.2.3

Level C Repairs........................................... Repairs................................................................................ ......................................................................... .................................................7 .............7

1.3

References ................................ .................................................................... ........................................................................ ............................................................... ...............................8 ....8

1.4

Terms and Definitions............................ Definitions................................................................ ........................................................................ ........................................................8 ....................8

2.

TEARDOWN ............................................ ..................... .............................................. .............................................. ..................................... .............. 10

2.1

Incoming Inspection.......................................... Inspection.............................................................................. ........................................................................ ..........................................10 ......10

2.2

Teardown Procedures .................................. ...................................................................... ........................................................................ ................................................10 ............10

2.3

Cleaning and Storage of Parts Parts ................................. ..................................................................... ........................................................................ .....................................10 .10

2.4

Inspection of Components........................................ Components............................................................................ ........................................................................11 ....................................11

2.4.1

Gears, Pinions and shaf ts..................................................... ts......................................................................................... ............................................................11 ........................11

2.4.2

Rolling Element Bearings ................................... ....................................................................... ........................................................................ ..........................................12 ......12

2.4.3

Planet carrier ................................. ...................................................................... ......................................................................... ...........................................................12 .......................12

2.5

Inspection Report ................................. ..................................................................... ........................................................................ ......................................................12 ..................12

2.6

Root cause analysis................................................. analysis..................................................................................... ........................................................................14 ....................................14

3.

EVIEW BASED ON FAILURE MODES ............................................. DESIGN R EVIEW ...................... ....................................... ................ 16

3.1

Purpose .................................... ........................................................................ ........................................................................ ............................................................... .............................16 ..16

3.2

Vestas CIM-Process........................................... CIM-Process............................................................................... ........................................................................ ..........................................16 ......16

3.3

Engineering Change Management ................................. ...................................................................... ....................................................................16 ...............................16

4.

EPAIR MANUAL ............................................ R EPAIR ...................... ............................................. .............................................. .............................. ....... 17

5.

EQUIREMENTS TO THE SERVICE PROVIDER .............................................. R EQUIREMENTS ....................... ....................................... ................ 18

5.1

Facilities ................................... ....................................................................... ........................................................................ ............................................................... .............................18 ..18

5.1.1

Test facilities .................................. ....................................................................... ......................................................................... ...........................................................18 .......................18

5.1.2

Painting .................................... ........................................................................ ........................................................................ ............................................................... .............................18 ..18

5.1.3

Storage .................................... ........................................................................ ........................................................................ ............................................................... .............................18 ..18

5.1.4

Transportation................................................................................................................................19

5.2

Machines and tools ............................... ................................................................... ........................................................................ ......................................................19 ..................19

5.2.1

Machining equipment .................................. ...................................................................... ........................................................................ ................................................19 ............19

5.2.2

Measuring equipment .................................. ...................................................................... ........................................................................ ................................................19 ............19

5.2.3

Handling equipment .................................... ........................................................................ ........................................................................ ................................................19 ............19

5.2.4

Special tools.............................. tools.................................................................. ........................................................................ ............................................................... .............................19 ..19

5.3

Quality assurance ................................. ..................................................................... ........................................................................ ......................................................20 ..................20

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Document Revision History rev.

release date

editor(s) pages changed description of changes

V00

02.03.2009

KERP

all

new document

All previous revisions become invalid with the release date of the latest document revision.

Table of Contents 1.

INTRODUCTION............................................ ..................... .............................................. ............................................... .................................. .......... 5

1.1

Purpose and Scope ............................... ................................................................... ........................................................................ ........................................................5 ....................5

1.2

Validity ............................... ................................................................... ........................................................................ ............................................................... .....................................7 ..........7

1.2.1

Level A Rema nufacturing ................................... ....................................................................... ........................................................................ ............................................7 ........7

1.2.2

Level B Refurbishments ............................... ................................................................... ........................................................................ ..................................................7 ..............7

1.2.3

Level C Repairs........................................... Repairs................................................................................ ......................................................................... .................................................7 .............7

1.3

References ................................ .................................................................... ........................................................................ ............................................................... ...............................8 ....8

1.4

Terms and Definitions............................ Definitions................................................................ ........................................................................ ........................................................8 ....................8

2.

TEARDOWN ............................................ ..................... .............................................. .............................................. ..................................... .............. 10

2.1

Incoming Inspection.......................................... Inspection.............................................................................. ........................................................................ ..........................................10 ......10

2.2

Teardown Procedures .................................. ...................................................................... ........................................................................ ................................................10 ............10

2.3

Cleaning and Storage of Parts Parts ................................. ..................................................................... ........................................................................ .....................................10 .10

2.4

Inspection of Components........................................ Components............................................................................ ........................................................................11 ....................................11

2.4.1

Gears, Pinions and shaf ts..................................................... ts......................................................................................... ............................................................11 ........................11

2.4.2


2.4.3

Planet carrier ................................. ...................................................................... ......................................................................... ...........................................................12 .......................12

2.5

Inspection Report ................................. ..................................................................... ........................................................................ ......................................................12 ..................12

2.6

Root cause analysis................................................. analysis..................................................................................... ........................................................................14 ....................................14

3.

EVIEW BASED ON FAILURE MODES ............................................. DESIGN R EVIEW ...................... ....................................... ................ 16

3.1

Purpose .................................... ........................................................................ ........................................................................ ............................................................... .............................16 ..16

3.2

Vestas CIM-Process........................................... CIM-Process............................................................................... ........................................................................ ..........................................16 ......16

3.3

Engineering Change Management ................................. ...................................................................... ....................................................................16 ...............................16

4.

EPAIR MANUAL ............................................ R EPAIR ...................... ............................................. .............................................. .............................. ....... 17

5.

EQUIREMENTS TO THE SERVICE PROVIDER .............................................. R EQUIREMENTS ....................... ....................................... ................ 18

5.1

Facilities ................................... ....................................................................... ........................................................................ ............................................................... .............................18 ..18

5.1.1

Test facilities .................................. ....................................................................... ......................................................................... ...........................................................18 .......................18

5.1.2

Painting .................................... ........................................................................ ........................................................................ ............................................................... .............................18 ..18

5.1.3

Storage .................................... ........................................................................ ........................................................................ ............................................................... .............................18 ..18

5.1.4

Transportation................................................................................................................................19

5.2

Machines and tools ............................... ................................................................... ........................................................................ ......................................................19 ..................19

5.2.1

Machining equipment .................................. ...................................................................... ........................................................................ ................................................19 ............19

5.2.2

Measuring equipment .................................. ...................................................................... ........................................................................ ................................................19 ............19

5.2.3

Handling equipment .................................... ........................................................................ ........................................................................ ................................................19 ............19

5.2.4

Special tools.............................. tools.................................................................. ........................................................................ ............................................................... .............................19 ..19

5.3

Quality assurance ................................. ..................................................................... ........................................................................ ......................................................20 ..................20

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5.3.1

Documentation, specifications and instructions ................................ ..................................................................... ...................................................20 ..............20

5.3.2

Technology transfer .................................... ........................................................................ ........................................................................ ................................................20 ............20

5.4

Personnel...................................................................... Personnel.................................. ........................................................................ ............................................................... .............................20 ..20

5.4.1

Training.........................................................................................................................................20

6.

R E-USE OF COMPONENTS ............................................ ..................... .............................................. .......................................... ................... 22

6.1

Acceptance Criteria for Re-use of Components....................................................................................22 Components....................................................................................22

6.2

Gears and Pinions ................................. ..................................................................... ........................................................................ ......................................................22 ..................22

6.2.1

Internal Gearing ................................... ....................................................................... ......................................................................... ......................................................22 .................22

6.2.2

External Gearing........................................................... Gearing................................................................................................ ..................................................................25 .............................25

6.3


6.4

Integrated Bearing Outer Rings ............................... ................................................................... ........................................................................ .....................................29 .29

6.5

Gear-Shaft Connections ............................... ................................................................... ........................................................................ ................................................30 ............30

6.6

Spline Connections............................................ Connections................................................................................ ........................................................................ ..........................................30 ......30

6.7

Planet Carrier and Planet Pins.................................. Pins...................................................................... ........................................................................ .....................................30 .30

6.7.1

Planet Carrier ................................. ...................................................................... ......................................................................... ...........................................................30 .......................30

6.7.2

Planet Pins ................................ .................................................................... ........................................................................ ............................................................... .............................31 ..31

6.8

Gearbox Housing .................................. ...................................................................... ........................................................................ ......................................................31 ..................31

6.9

Various Gearbox Components (not main components).......................................................... components).........................................................................33 ...............33

6.9.1

Pitch tube (centre post, energy tube, tube, centre pipe, stub shaft…) ................................ ............................................................33 ............................33

6.9.2

Shafts for torque supports ................................ .................................................................... ........................................................................ ...........................................34 .......34

6.9.3

Dowel pins and spring pins...................................................................................... pins...............................................................................................................34 .........................34

6.9.4

Piping including pipe fittings, spray nozzles, orifices, flow control valves, etc. .................................... .........................................34 .....34

6.9.5

Bolts and nuts ................................ ..................................................................... ......................................................................... ...........................................................34 .......................34

6.9.6

Elastomeric seals and flat gaskets ................................. ...................................................................... ....................................................................35 ...............................35

6.9.7

Hydraulic hoses .................................... ........................................................................ ......................................................................... ......................................................35 .................35

6.10

Gearbox Accessories ................................... ....................................................................... ........................................................................ ................................................35 ............35

6.10.1

Filter Blocks (Valve Blocks, Manifold Blocks) and Filter Bowls Bowls ................................... ...............................................................35 ............................35

6.10.2

Level Switch................................................ Switch.................................................................................... ........................................................................ ...............................................36 ...........36

6.10.3

Oil Heaters.................................................. Heaters...................................................................................... ........................................................................ ...............................................36 ...........36

6.10.4

Temperature Sensors .................................. ...................................................................... ........................................................................ ................................................36 ............36

6.10.5

Gear oil pumps ............................... ................................................................... ......................................................................... ............................................................37 .......................37

6.10.6

Pump couplings .................................... ........................................................................ ......................................................................... ......................................................37 .................37

7.

R E-WORKING OF COMPONENTS ........................................... ..................... ............................................. ................................... ............ 38

7.1

Acceptance Criteria for Re-working Components .................................... ......................................................................... .............................................38 ........38

7.2

Gears and Pinions ................................. ..................................................................... ........................................................................ ......................................................38 ..................38

7.2.1

Internal Gearing ................................... ....................................................................... ......................................................................... ......................................................39 .................39

7.2.2

External Gearing........................................................... Gearing................................................................................................ ..................................................................42 .............................42

7.3

Spline Connections............................................ Connections................................................................................ ........................................................................ ..........................................44 ......44

7.4


7.5

Integrated Bearing Outer Rings ............................... ................................................................... ........................................................................ .....................................46 .46

7.6

Gear-Shaft Connections ............................... ................................................................... ........................................................................ ................................................47 ............47

7.7

Planet Carrier and Planet Pins.................................. Pins...................................................................... ........................................................................ .....................................49 .49

7.7.1

Planet carrier hollow shaft (input shaf t):.................................................................. t):............................................................................................49 ..........................49

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7.7.2

Planet carrier bores for planet pins and carrier bearing(s):...................................................................50

7.7.3

Planet pins:....................................................................................................................................50

7.8

Housings .......................................................................................................................................51

7.8.1

Worn housing bores ........................................................................................................................51

7.8.2

Housing split lines...........................................................................................................................52

7.9

Gearbox Accessories .......................................................................................................................52

7.9.1

Filter Blocks ...................................................................................................................................53

7.10

Procedures for Qualifying Refurbishment Procedures ...........................................................................53

8.

SCRAPPING OF COMPONENTS ................................................................................. 54

8.1

Scrap Criteria .................................................................................................................................54

9.

R E-ASSEMBLY AND ACCEPTANCE TEST ..................................................................... 55

9.1

Cannibalizing..................................................................................................................................55

9.2

Assembly Procedures ......................................................................................................................55

9.3

As-Built Documentation ...................................................................................................................56

9.3.1

Inspection......................................................................................................................................56

9.3.2

Traceability ....................................................................................................................................56

9.3.3

Deviations .....................................................................................................................................56

9.3.4

Identification..................................................................................................................................56

9.4

Acceptance Test .............................................................................................................................57

9.5

Painting and corrosion protection ......................................................................................................57

9.6

Transport and delivery requirements .................................................................................................58

APPENDIX A: GEARBOX DEFINITIONS

AND

ABBREVIATIONS ................................................... 59

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1.

INTRODUCTION

1.1

Purpose and Scope This Requirement Specification defines Vestas’ minimum requirements for repaired and refurbished main gearboxes. It covers 

procedures for teardown, cleaning and storage of parts



inspection procedures



acceptance criteria for re-use of parts



acceptance criteria for refurbishing parts



criteria for qualifying refurbishing procedures



criteria for allowing cannibalizing



procedures and criteria (CTQ) for acceptance test of repaired gearboxes



documentation, both for incoming inspection, teardown inspection and as-build documentation of the repaired gearbox



workshop requirements



skills and competences

The document is divided into the functional elements going into a gearbox. The service provider is responsible to break the requirements down into processes. A typical best practice process will look as follows:

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1.2

Validity This Requirement Specification is on a general level submitted from Vestas to the Service Provider and outline Vestas’ general requirements to the Service Provider in respect of repair and service of gearboxes. Based on the Requirement Specification the Service Provider will submit for Vestas’ review a final Repair Manual covering the gearboxes repaired by the S ervice Provider. Neither Vestas’ Requirement Specification nor Vestas’ review of the final Repair Manual from the Service Provider make Vestas partly or wholly liable for the repair and service of gearboxes. Thus, nothing in this Requirement Specification shall in any way exclude or limit the Service Provider’s sole liability for the warranty of the repaired gearbox and the performance of the repairs and service on gearboxes. The content of this Requirement Specification shall be considered as confidential and shall not be disclosed to any third party or be used for any other purpose without the prior written consent of Vestas. The Service Provider shall only disclose confidential information to those of their employees or representatives who are directly involved in the repair process. This Requirement Specification is applicable to each gearbox that has been operated in a WTG that is returned to a gearbox repair facility for any kind of defect or performance deviation, both under the OEM warranty and after the contractual warranty period. This Requirement Specification also applies to gearboxes which have not been in operation, but are returned to the Service Provider for other reasons, e.g. transport, handling or storage damages. This Requirement Specification is not applicable to gearbox repairs carried out in-situ. This Requirement Specification defines three different quality levels for repairing these gearboxes as further described below. If not agreed otherwise in specific cases, level B is the default for repairing gearboxes. The requirements in this Requirement Specification apply to level B u nless explicitly specified otherwise.

1.2.1 Level A Remanufacturing Level A describes remanufacturing procedures executed in a workshop for bringing the item into “as new” condition as originally delivered by the OEM. It includes any modifications and upgrades for remedying known weaknesses and performance shortcomings of the respective design. Level A-reconditioned items shall comply with all requirements of the TPS for the corresponding new item in all respects, including requirements for design lifetime.

1.2.2 Level B Refurbishments Level B refurbishments will fix a ll actual failures and excessive wear and tear, such that the condition corresponds to what can be expected from items of similar service history. The design lifetime of refurbished items shall be comparable to the design life of the new item minus by the service life it already had completed.

1.2.3 Level C Repairs Level C repairs intend to only fix actual failures and damages in the item, especially in conjunction with containment programs. Wherever possible, level C repairs shall be executed with the item installed in the WTG, alternatively in a workshop.

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1.3

References Norms and Standards [1]

DIN 332-2:1983

Centre holes 60 ° with thread for shaft ends for rotating electrical machines

[2]

DIN 3990:1987

Calculation of load capacity of cylindrical gears

[3]

ISO 1122-1:1998

Vocabulary of Gear Terms – Part 1: Definition Related to Geometry

[4]

ISO 6336:2006

Calculation of load capacity of spur and helical gears (all parts)

[5]

ISO 10825:1995

Gears – Wear and Damage to Gear Teeth – Terminology

[6]

ISO 15243:2004

Rolling Bearings – Damage and Failures – Terms, Characteristics and Causes

[7]

ISO 81400-4:2005

Wind Turbines – Part 4: Design and Specification of Gearboxes

Vestas Specifications [8]

QS 993651

Inspection of Ground Gears – Grinding Steps and Grinding Notches

[9]

QS 993659

Quality Specification – Failure Analysis Inspection of Gears and Bearings for Standstill Marks

Reference Documents [10] PA 1.4

Purchase Agreement between Vestas and the respective manufacturer (OEM)

Terms and Definitions Terms term

definition

B e a r in g r e - w o r k e r

A legal entity providing assessment, requalification, refurbishment and re-work of bearings or bearing elements

Cannibalizing

A procedure where components from several incoming items are mixed in one repaired item

Cl u s t e r ( o f i n d e n t s )

A group of two or more indents, where the distance between two individual indents is smaller than twice the diameter of the larger of the two indents

Flip

Turn a gear on its shaft so that the unloaded flank becomes the new load flank

G e n e r a l R e p a ir M a n u a l

A Manual drawing up the overall lines for repairing any gearbox type. See also chapter 4

M a i n co m p o n e n t

A component forming a vital part of the gearbox and for which special requirements apply, e.g. housings, shafts, bearings, planet carrier and planet pins

P it c h t u b e

A pipe going through the gearbox in which the energy is transferred to the hub

S e r v i ce p r o v i d e r

A legal entity repairing or refurbishing gearboxes for Vestas, which may be the OEM

Specific Repair Man ual

A manual specifying exactly how a specific gearbox type will be repaired or upgraded. See also chapter 4

Upgrade

In-situ or shop repair where a known weakness is remedied by installing a solution developed to address that weakness

W o r k i n s t r u ct i o n

Written instruction describing which procedures must be followed and which tools must be used when carrying ou t a specific work

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Abbreviations abbreviation

definition

CIM

Continuous Improvement Management at Vestas

CIR

Component Inspection Report

CRB

Cylindrical Roller Bearings

CTQ

Critical-to-quality feature

DRBFM

Design Review Based on Failure Mode

ECM

Engineering Change Management

FMEA

Failure Mode and Effect Analysis

ID

Inner diameter, bearing

IR

Inner ring, bearing

MPI

Magnetic Particle Inspection (or Magnaflux)

NCR

Non Conformity Report

NDT

Non Destructive Testing

OD

Outer diameter, bearing

OEM

Original Equipment Manufacturer, here used for the gearbox manufacturer

OR

Outer ring, bearing

PA

Purchase Agreement

QS

Quality Specification

RCA

Root Cause Analysis

SRB

Spherical Roller Bearing

TPS

Technical Purchase Specification

TRB

Tapered Roller Bearing

TS

Test Specification

WI

Work Instruction

WTG

Wind Turbine Generator

Symbols and Units symbol

unit

definition

C 0

N

Static load capacity, bearing

m n

mm

The normal module

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2.

TEARDOWN

2.1

Incoming Inspection All gearboxes returned to a Service Provider for level A, B or C repair shall be subjected to an incoming inspection, which shall document the condition of the gearbox at the time of arrival. Damages from dismounting, handling, transport and improper storage shall be noted in the inspection report and documented by photos.

2.2

Teardown Procedures The Service Provider shall prepare a Teardown Manual, which shall assure that gearboxes are disassembled and the individual components are handled in a safely manner. Vestas shall be offered the opportunity to review the Teardown Manual. As a minimum the Teardown Manual shall contain: 

proper disassembly procedures



necessary disassembly tools



marking procedures for gearbox components



cleaning and storage procedures



inspection procedures



procedures for reporting and documentation

Gearboxes returned for level A or level B repairs shall be completely disassembled, and all elements shall be inspected as described below. Level C will typically only include a partial disassembly and thorough visual inspection of the remainder of the gearbox. No failed parts or fragments thereof, which could contribute to the root cause analysis (RCA), shall be discarded prior to inspection. In connection with the RCA these parts shall be made available to the examiner. During the disassembly and inspection the components shall be uniquely marked in order to ensure full traceability. Special attention should be paid to the marking of bearings, for which it shall be possible also to determine how the inner rings and outer rings were mounted in the gearbox.

2.3

Cleaning and Storage of Parts After disassembly and marking of the gearbox parts, these shall be properly cleaned and free from dust, dirt, oil, sediments and metal debris in order to perform a thorough inspection and correct assessment of the components. Failed components shall preferably be cleaned by hand and not by using a component washer. Non failed components which obviously can not be re-used or re-worked need not be cleaned. Components which need to be stored for shorter or longer periods shall be properly protected against the environment. As a minimum the components shall always be given a proper corrosion protection regardless how short the storage period may be. Housing components shall preferably be stored in a way that prevents dust and dirt to accumulate on the internal surfaces. The store shall be dry and with a controlled climate ensuring low humidity (below 60% relative humidity) and constant temperature. Outside storage of gearboxes or gearbox components is not acceptable, regardless these be protected against the weather.

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Failed components shall be stored for at least 8 weeks after the inspection report, as described in section 2.4, has been forwarded to Vestas.

2.4

Inspection of Components The gearbox components covered by this document shall be subjected to a thorough inspection in order to determine or confirm the failure mode(s) and evaluate the consequential damages to the gearbox. In the same connection it shall be determined which components are candidates for re-use or re-work and which components have to be scrapped. This clause specifies the minimum requirements to the inspection of gears, pinions, shafts, bearings, housings and planet carriers.

2.4.1 Gears, Pinions and shafts When a Service Provider receives a gearbox it is essential that all components are inspected thoroughly in order to assure the quality of the repaired gearbox. Special attention shall be paid to the gears and pinions, which are naturally exposed to debris damages. As a result thereof all gear teeth shall be inspected for: 

tooth rupture



partial tooth fracture and cracks



pitting or spalling



scuffing and scoring



micropitting



wear



indentations



standstill marks



corrosion



any other deviation from the expected condition after the respective service history

Shafts and pinions shall further be inspected for 

any damage, scores, or fretting corrosion on bearing journals



any damage, scores, or fretting corrosion on possible gear journals



geometrical accuracy of possible gear journals (applicable for re-usable a nd re-workable components only)



plastic deformation or cracks in connection with keyways



any other deviation from th e expected condition after the respective service history

Gears shall further be inspected for 

any damage, scores, or fretting corrosion in the bore



geometrical accuracy of bore (applicable for re-usable and re-workable components only)



plastic deformation or cracks in connection with keyways



any other deviation from the expected condition after the respective service history

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2.4.2 Rolling Element Bearings A high amount of gearbox failures are related to bearing failures which underlines the importance of having the bearings properly inspected in order to address any upcoming issue at an early stage. Especially in cases where no other failure has been found in the gearbox, it is essential to have the normally inaccessible raceways inspected in order to have a failure confirmed. All bearings shall be inspected for: 

cracks



pitting or spalling



wear



micropitting



indentations



corrosion and fretting corrosion on raceways



smearing



overheating



fretting corrosion in bores and outer diameters

2.4.3 Planet carrier Like the housings, some planet carriers are also exposed to the environment and are also likely to get handling or transport damages. Planet carriers shall be inspected for:

2.5



handling and transportation damages



axial and circumferential score marks in the hollow shaft



corrosion and fretting corrosion on functional surfa ces



wear in bores from rotating bearing outer rings



wear on bearing journals from rotating bearing inner rings



overheating

Inspection Report The Service Provider shall prepare an inspection report for each gearbox he receives for repair. The report shall be pre-approved by the local Vestas Quality Technician after which the report shall be forwarded to the relevant department(s) in Vestas. The inspection report shall be in English and build up in a structured way and shall at least contain the following information, which is relevant for the RCA and for statistical purpose: (a) Document information: The inspection report shall give the necessary information to identify the Service Provider and the gearbox which the report covers. As a minimum the following shall be given in the header which shall be visible on all pages of the report: 

Name / logo of the Service Provider



Report number, which shall reflect the gearbox serial number

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

Report revision



Report date



Gearbox make and type



Gearbox serial number

Furthermore, the document shall provide information about who attended the inspection and who prepared the report. This information need not be printed on each page of the report. (b) Wind turbine data: This data shall contain information about the turbine, its location and the operational data. 

Site name



Country





Turbine type



Turbine no.





Operating hours, generator 1, generator 2



Production kWh



Gearbox installation date



Gearbox replacement date



Failure detection date

Commissioning date

(c) Gearbox data: This data shall contain relevant information about the returned gearbox. 

Gearbox type



Serial number



Version, 1 or 2 generator



Ratio:



Oil type:



Latest oil change:



Date of first delivery:



Date of return:



Disassembly date:

(d) Reason for replacement: This is a short description of the reason for replacing the gearbox. The information is taken from either the CIR initiating the gearbox replacement or from the NCR as applicable and shall contain at least the following: 

A list of confirmed failures reported in the CIR (or non conformities in case of NCR)



A list of suspected failures reported in the CIR (or non conformities in case of NCR)



Other relevant observations reported in the CIR, e.g. oil level, oil sump temperature, bearing temperatures

(e) Service history: Where information about on site interventions to the gearbox is available to the Service Provider, this information shall be reported, regardless the relevance for the failure that caused the gearbox to be replaced. For each intervention the fo llowing shall be reported: 

Reason for intervention



Date of intervention



Repair description



Generator hours, generator 1, generator 2



Production, kWh

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(f) Findings: The report shall give exact information about the failures found during inspection and the consequences thereof. Failures and consequential damages shall be documented by good quality colour photos, which shall be integrated in the inspection report. Designations and abbreviations for shafts, gears, bearings, etc., used in the report shall comply with Appendix A of this document. The minimum information to be reported is: 

Primary failure (failure causing the gearbox replacement)



Secondary failures



Consequential damages



Other findings, e.g. pitting, micropitting, corrosion, polishing, fretting corrosion, wear, etc.

(g) Parts list: Each inspection report shall contain a summary in shape of a parts list. This parts list shall include all main components and provide, as a minimum, the following details for each of th ese components, where applicable:

2.6



Part name



Part marking (unique identification)



Bearing type and manufacturing code



Findings (in short)



Decision, re-use, re-work, scrap or upgrade

Root cause analysis All observations from the disassembly and subsequent inspection of the components must be properly evaluated and it must be decided whether the observations shall lead to further examinations in connection with a root cause analysis. The Service Provider shall prepare a complete list for each gearbox type covering all disassembled gearboxes of that type and their failures. The list must be updated on a bi-weekly basis and forwarded to the person in Vestas Technology R&D responsible for that gearbox type. The list shall be made in spreadsheet format and contain at least the following information: 

Gearbox type



Gearbox serial number



Turbine number



Reason for return (suspected failure a ccording CIR)



Main failure(s) found during inspection



Secondary failures found during inspection



Components, which will be subjected to further examinations



Which labs/experts will carry out above examinations



Report number for examinations already carried out and reported to the Service Provider

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

Failure statistics for the different failure modes

Examination of failed components shall be carried out by experts agreed between the Service Provider and Vestas Technology R&D. The experts must report their findings directly to the Service Provider, who shall forward the report to the Vestas Technology R&D without further delay. Vestas shall be offered the opportunity to comment on the report and require further examinations, when necessary. In general all failures to gears, shafts and bearings must be subjected to further analysis by an expert, with the following exceptions: 

Cases where the failure mode is known and a proper upgrade solution has been developed



Cases where it is obvious that the failure is consequential



When the failed component is too damaged for proper RCA

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3.

DESIGN R EVIEW BASED ON FAILURE MODES

3.1

Purpose The DRBFM shall secure that findings of the inspected gearboxes are properly evaluated, and that all learning get fed back into the design to continuously improve the performance of the inspected gearbox type, as well as into similar designs and the general design practices. The design review shall address all observations, not just the failure that had caused the gearbox replacement. Typical observations not causing gearbox replacement but which shall call for design review are: 

Pitting, scuffing and polishing



Micropitting in general, but in particular if located near the tooth root or in connection with end contact lines



Abnormal gear contact pattern



Creeping bearing outer or inner rings



Leakages from labyrinth seals, split lines, bearing covers or other bolt connections



Fretting corrosion in gear to shaft connections and in bolt connections



Key and keyway deformations



Cracks

The design review is a joint activity between Vestas, the OEM, and the Service Provider. The design review will be held in terms, and will typically cover results of several gearbox inspections in order to understand the variation of the observation.

3.2

Vestas CIM-Process The results of the design review may in following cases initiate the Vestas CIM-Process:

3.3



failures, or early indications, with a potential relevance for other gearboxes in the fleet



batch related quality problems



repeating failure modes

Engineering Change Management For gearboxes which still are in serial production, the design review may initiate engineering change requests which will be treated in the ECM-system agreed between Vestas and the gearbox manufacturer in the relevant Purchase Agreement.

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4.

EPAIR MANUAL R EPAIR The service provider shall prepare a ‘General Repair Manual’ which shall comply with the criteria in this document. Furthermore, the service provider shall prepare a set of ‘Gearbox Specific Repair Manuals’ – one for each gearbox type as shown in Figure 4.1. 4.1. The ‘General Repair Manual’ shall outline how to assess the different components in any gearbox send to the service provider, which repair method will be used and under which conditions the different repair methods apply The ‘Gearbox Specific Repair Manual’ shall describe in details how the specific gearbox type is repaired, which upgrades have been agreed, etc. The ‘Gearbox Specific Repair Manual’ shall also have a chapter describing the different failures found in the gearbox and how these failures are addressed when repaired – both as shop repair and as in-situ repair if applicable. I.e. the manual shall at any time describe ‘the life’ of the specific gearbox type. For traceability reasons the ‘Gearbox Specific Repair Manuals’ shall state when the agreed repair solutions have been implemented in service (date) as well as in serial production (date and the first serial number(s) if applicable. Also changes to the tooth corrections shall be traceable in these manuals. Either the General or the Specific Repair Manual shall give information about the gearbox renaming process in order to determine from the serial number which repairs or upgrades any gearbox has had. Both the ‘General Repair Manual’ and the ‘Gearbox Specific Repair Manual’ shall be agreed between the service provider and Vestas Wind Systems A/S, Technology R&D, Drive Train. The manuals shall at least be written in English and all photos shall be in colour.

Figure 4.1: Creation process for repair manua ls

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5.

EQUIREMENTS TO THE SERVICE PROVIDER R EQUIREMENTS This clause defines the minimum requirement to the Service Provider. It includes requirements to the Service Provider’s facilities, machines, tools, quality assurance and his personnel.

5.1

Facilities The environment within the workshop must be clean and tidy. Precautions must be taken to assure clean air conditions. The temperature in machining, assembly and storage areas shall be held at constant temperature and the air humidity in same areas shall be below 60 % relative humidity. In the measurement area, the temperature shall be held at 20±2

°C

and the relative humidity shall be less than 60 %. In machining, assembly and

measurement areas, proper temperature compensation shall be made when applicable (temperature ≠ 20 °C).

5.1.1 Test facilities The test facilities shall at least have the following qualities: 

Be sufficient for carrying out a full load test and obtain measurements on both vibrations and noise.



Shall include equipment for pre-filtering the test lubricant to a cleanliness of -/14/11 according ISO 4406:1999.



Shall include equipment to flush the gearboxes and also document the oil cleanliness on a continuous basis (APC equipment)



A proper data acquisition system for continuous logging of oil cleanliness together with all required temperatures and pressures.

5.1.2 Painting The Service Provider shall have access to the necessary facilities to paint the gearboxes after reassembly and test.

5.1.3 Storage When storing gearboxes (waiting for disassembly or already reassembled gearboxes) the following shall be complied with: 

The gearboxes shall be kept indoors in dry facilities to protect against corrosion.



In connection with long term storage (more than 1 month) the store shall be dry and with a controlled climate ensuring low humidity (below 60% relative humidity) and constant temperature. Outside storage of gearboxes is not acceptable, regardless these be protected against the weather.



The store shall provide a clean environment.



The size of the store shall be adequate to ensure safe handling and storage of the gearboxes.

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The Service provider shall also have adequate storage facilities to store components from disassembled gearboxes as well as new components intended as replacements for failed components. Please refer to section 2.3 for 2.3 for details.

5.1.4 Transportation 

Transportation inside the workshop must be carried out in consideration of both safeties as well as machines, tools and other parts.



5.2

During transportation the gearboxes shall be protected against shock loads.

Machines and tools Processing machines and tools for handling and measuring shall in general be in a state so that they do not damage any parts. Tools must be stores in a proper way to avoid damages and wear. When relevant they shall be identifiable.

5.2.1 Machining equipment 

The Service provider shall as a minimum have access to machining and measuring all main components (except bearings) of the gearbox. Sub-suppliers are acceptable provided they comply with requirements of this clause and provided they are approved by Vestas on beforehand.



Gear grinding machines shall be profile grinding machines (index grinding is not accepted by Vestas).



The machines shall be able to produce and reproduces components of the same quality and accuracy as originally specified for the components

5.2.2 Measuring equipment 

The measuring equipment shall mea sure with SI-units (metric system)



There shall be a clear description of which tools are within a calibration routine

5.2.3 Handling equipment 

Handling equipment for both lifting and carrying components must be in a good state, and be dimensioned for the load for which it will be exposed.



There shall be equipment to control the handling of the housings in order to avoid shocks, e.g. assembly benches.



There shall be a clear description of which handling equipment need to be controlled ac-cording to local regulations.

5.2.4 Special tools 

Where necessary special tools shall be available, e.g. to mount bearings in bores or on shafts. Likewise special tools shall be available for disassembly of the gearboxes.

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5.3

Quality assurance The Service Provider shall be part of or have its own third part approved quality system – such as ISO 9000. There shall be a clear description telling who is responsible within the different area s of the work-shop. Vestas must always approve any workshops repairing Vestas gear units. If there are any changing’s that can affect the requirements for form, fit, function, performance and/or durability Vestas shall always be notified. When talking component level drawings, that do not impact the design record for the gearbox, notification will not be required.

5.3.1 Documentation, specifications and instructions 

There must be a valid and updated quality manual for the workshop.



There must be adequate working instructions. Adequate means on a process level.



It must be documented who is trained to do the different jobs needed for the workshop

5.3.2 Technology transfer When the workshop, repairing the gearbox, is not part of the main factory, or when outsourcing, it must be ensured that: 

The latest updates of instructions and drawings are always available.



The technology transfer (failure reports, test documentation, etc.) between the manufacturing factory and the work shop is described.



If gearboxes are repaired by a Service Provider with no direct relation to the OEM, then inspection reports must be send to both the relevant Vestas department and to the OEM.

5.4

Personnel There must be a description of requirements for the training of all personnel (incoming inspection, fitters, test personnel, painters, outgoing inspection, etc.). Furthermore, there must be a described training period and documentation, who has carried out the training.

5.4.1 Training 

The fitters must be qualified in all processes necessary to repair the gea rbox type.



When the repair is not done at the main factory, there must be fitters present with detailed knowledge about all the processes, which are to be carried out in the work shop, for each type of gearbox that is to be repaired.



There must be fitters present who are trained to evaluate tooth and bearing damages, and decide whether they can be reused, reworked or shall be scrapped.



Fitters who are evaluating vibrations, noise, temperature and oil cleanliness, must be trained to do so according to the Vestas requirements (TPS, TS and QS).



The Service Provider shall at least have one person who is qualified to evaluate parts which are failed and if necessary arrange a closer investigation and form an opinion about the possible root cause and work out an inspection report.

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

The Service Provider shall have the necessary technical personnel (engineers/gearbox designers) to develop repairs and upgrade solutions when necessary.

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6.

R E-USE OF COMPONENTS

6.1

Acceptance Criteria for Re-use of Components Components with usual traces of wear and tear, corresponding to the age of the original gearbox, may be reused without refurbishment, even if they deviate from the specifications for the corresponding new item. This is acceptable as long as the functionality of the gearbox within the specified design lifetime and expected service life is not compromised. The acceptance limits shall in critical cases be supported by a risk assessment to prove that the deviating components meet the design lifetime requirements, and that expected service life of the gearbox is still achievable.

6.2

Gears and Pinions For the gear damage and failures described below ISO 10825:1995 ‘Wear and Damage to Gear Teeth – Terminology’ refers. It must be noted that not all possible damages can be described nor a combination thereof. For the same reason it is of utmost importance that the assessment is made by well trained and experienced personnel in order to take a qualified decision in the ‘grey zone’ cases. Unless otherwise stated the re-worked component shall remain within the specifications for th e original component. Re-used components need not be subjected to NDT.

6.2.1 Internal Gearing Re-use of internal gearing are applicable for gears where the load flanks are in such good condition that the gears are fit for further use without any kind of re-work. Furthermore, internal gears are often designed so that they can be flipped (with or without mechanical processing) so that the unloaded flanks become the new load flanks. (a) Re-use component as is When both flanks are still in good connection the following surface defects are acceptable in the described extent and the component can be re-used without further re-work: 

The gear shows only normal wear (abrasive or adhesive) and light scuffing which can be removed or smoothened by a 3M sponge (Figure 6.4).



Moderate scratching which can be removed or smoothened by 3M sponge (Figure 6.3 and Figure 6.4).



Chemical corrosion of superficial character which can be removed by 3M sponge (Figure 6.7 ).



Micropitting lines of maximum 3 mm in width when in connection with end contact lines (Figure 6.6 ). This type of micropitting shall initiate a design review in order to develop more appropriate tooth corrections. See 3.1.



Micropitting on maximum 2% of the flank, when located minimum 0.4mn above the root transition and provided the micropitting is ‘equally distributed’ across the tooth width, i.e. not caused by misalignment or incorrect helix correction. Micropitting closer to the tooth root than 0.4mn is not acceptable.

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

The flanks have only a limited number of indents which must be smaller than 1 mm in diameter and where grinding lines are still visible. Maximum 10 such indents are acceptable on each tooth flank (Figure 6.10).



Stand still corrosion of severity class 1 and 2 as per QS993659.R0. Discolouration should be removed by 3M sponge (Figure 6.1 and Figure 6.8).



Fretting corrosion of mild character on the gear side faces which does not affect the bolt connection or sealing abilities of the component and which can be removed by 3M sponge or fine grain sand paper.

(b) Flipping component The following criteria shall be applied for 

Case carburised, nitrided and through hardened gears where regrinding of the teeth is not possible but where the gear (with or without machining) can be flipped so that the unloaded flanks become the new load flanks. Special attention must be paid to ensure that the new load flank comply with the minimum required hardening depth as per the original gear design standard (ISO 6336/DIN 3990).

Under the following conditions the component can be flipped without applying re-work to the flanks. Minor manual rework to the original load flanks is acceptable: 

The new load flanks comply with the criteria for re-use (alternatively after manually re-worked)



Moderate wear (abrasive or adhesive) is acceptable on the original load flanks



Micropitting (covering up to 100%) is acceptable on the original load flanks



Indents in the original load flanks smaller than 10 mm diameter and in limited number per flank are acceptable when located completely within a distance of 0.8m n from the pitch line. Outside 0.8m n from the pitch line, indents smaller than 5 mm diameter are acceptable. The sum of the diameters of the indents (including clusters) must not exceed 10% of the active tooth width.



Group of indents forming a cluster of less than 1mn diameter in the original load flanks. Only one such cluster per flank is allowed



Chemical corrosion of superficial character which can be removed by 3M sponge is acceptable



Stand still corrosion of severity class 1 or 2 as per QS993659.R0 is acceptable. Discolouration should be removed by 3M sponge



Fretting corrosion on the gear side faces which can be removed by 3M sponge, fine grain sand paper or by regrinding and which, after re-work, does not affect the bolt connection or the sealing abilities of the component is acceptable

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Figure 6.1 Minor stand still corrosion

Figure 6.2 Good condition

Figure 6.3 Moderate scratching from particles trapped in the mesh

Figure 6.4 Mild sliding wear/normal wear

Figure 6.5 Normal wear (mild polishing with grinding lines still visible)

Figure 6.6 End contact with micropitting

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6.2.2 External Gearing External gearing can be divided into pinions and gears. Gears can often be designed in such a way that flipping of the gear is possible whilst flipping of pinions is rarely practised. The cost of the repair shall determine whether a gear shall be flipped or reworked. If flipping for instance always involves regrinding of new load flank in order to apply correct micro geometry or because the gear has to be ground after mounting on the shaft, then it would often be cheaper to reground the original load flanks and rework of the component should thus be chosen. Likewise, if the fit between gear and shaft is so strong that remounting the gear in order to flip it, will damage the shaft journal and gear bore so that a new or reworked shaft or gear is needed. Also in this case the repair resulting in the lowest cost shall be chosen. (a) Re-use of pinions and gears as is When both flanks are still in good connection the following surface defects are acceptable in the described extent and the component can be re-used without further re-work: 

Mild sliding wear which can be removed or smoothed by 3M sponge (Figure 6.4).



Light scoring which can be removed or smoothed by 3M sponge



Micropitting lines of maximum 3 mm in width when in connection with end contact lines (Figure 6.6)



Micropitting on maximum 2% of the flank, when located minimum 0.4mn above the root transition and provided the micropitting is ‘equally distributed’ across the tooth width, i.e. not caused by misalignment or incorrect helix correction.



Mild chemical corrosion which can be removed by 3M sponge (Figure 6.7 ).



Stand still corrosion (caused by fretting) of severity class 1 and 2 (acc. to QS993659.rev.0) which can be removed/smoothened by 3M sponge (Figure 6.1 and Figure 6.8).



The tooth flanks show only a limited number of indents between 0.5 mm and 1 mm diameter where grinding lines are still visible. Maximum 10 indents per flank are allowed. (Figure 6.10)

(b) Re-use of gears by flipping For gears where regrinding is not possible but where the gears, with or without machining, can be flipped, the following criteria apply: 

The micro geometry of the new load flanks shall be equal or compatible to the micro geometry of the original load flanks. Where the micro geometry of the original load flank is unknown it shall be measured.



The new load flanks shall comply with the criteria for re-use as specified in 6.2.2 (a) or criteria for manual re-work as specified in 7.2.2 (b).



Moderate adhesive or abrasive wear on the original load flanks is acceptable.



Micropitting (covering up to 100% of the active tooth width) on the original load flank s is acceptable.



Indents smaller than 5 mm diameter in the original load flanks and in limited number per flank. The sum of the diameters of the indents (including clusters) must not exceed 10% of the active tooth width in any tooth contact line.



Group of indents forming a cluster of less than 1mn diameter in the original load flanks. Only one such cluster per flank is allowed

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

Chemical corrosion of superficial character which can be removed by 3M sponge is acceptable



Stand still corrosion of severity class 1 or 2 as per QS993659.R0 is acceptable. Discolouration should be removed by 3M sponge

Figure 6.7 Mild corrosion

Figure 6.8 Stand still corrosion (fretting corrosion)

Figure 6.9 Indents

Figure 6.10 Small soft indentations

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6.3

Rolling Element Bearings In cases where bearings are in such a good condition that mechanical processing is not required in order to restore or improve the performance and life of the bearings, re-use of these bearings can be considered. When reusing bearings without mechanical processing two options are available: 1.

Re-use without disassembly and inspection of an y bearing elements

2.

Re-use after disassembly and/or inspection of one or more of the bearing elements

A conscientious assessment of the bearing shall be carried out before it can be determined whether the condition of the bearing qualifies for re-use. This assessment shall be carried out by skilled and experienced personnel and the Service Provider must be able to demonstrate that the personnel have the qualifications and experience needed. Furthermore, re-use of bearings can be divided into two categories: Category 1: The gearbox has in its lifetime not suffered from any damage, where metal debris has been distributed to the oil sump and there is no suspicion of failure of the gearbox internals. The repair involves only partly or no disassembly of the gearbox, e.g. replacement of a failed housing, replacement of a failed torque plate or if the gearbox has been taken down for a shop upgrade. In this category all bearings can be re-used according option 1 above provided 

The gears do not show a ny signs of debris having circulated in th e oil



No metal debris is retained on magnets in the oil sump, oil channels or bearing covers



No metal debris is retained on th e chip detector



There are no signs of overheating, e.g. burned paint or significant discolouration



Bearings being checked by a bearing analyzer or equivalent during load testing of the gearbox

In cases where sub surface failures of specific bearings on specific locations are known or suspected, these bearings shall always be exchanged regardless the gearbox has not yet suffered from such failure(s). Planets with integrated raceways need only be discarded in case sub surface failures of these raceways are known or suspected. Category 2: The gearbox has in its lifetime suffered from damage, where metal debris has been distributed to the oil sump or there is a suspicion/indication of failure of the gearbox internals. In this category the following bearings are acceptable candidates for re-use according option 2 above: 

Main bearing(s) integrated in the gearbox



Planet carrier bearings



Low speed and intermediate shaft bearings with IR ID larger than 250 mm



Planet bearings with IR ID larger than 250 mm



Planet bearing outer rings integrated in the planet gears

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Re-use of any of the above bearings in Cate gory 2 will be acceptable provided compliance with the f ollowing: 



Proper Work Instructions shall be prepared. The WI shall include at least the following procedures: o

Dismounting of bearings from shafts and housings

o

Disassembly and cleaning of bearings

o

Inspection and assessment of bearings

o

Marking of reusable bearings

o

Re-assembly and corrosion protection of bearings

The bearing is less than 10 years old determined from the type code. This does, however, not apply to the following bearings



o

Main bearings integrated in the gearbox

o

Planet carrier bearings

o

Planet bearing outer rings integrated in the planet gears

Bearing elements shall be removed from shaft seat and housing bore without being overheated or in other way physically damaged. Use of direct heating with open fire is not acceptable. Inductive heating or preheated dismounting tools shall be applied wherever possible to remove inner rings from shafts.



No use of excessive disassembly force going through raceways. A maximum equivalent radial load of 50% of C0 will be acceptable. For bearings which can not be dismounted without applying a disassembly force through one or more raceways, the Service Provider shall specify the maximum axial force that can be applied to the different bearings under dismounting without damaging the raceways. These values shall be listed in the Repair Manual for the specific gearbox type



Bearings shall be disassembled (separated) for inspection and assessment in as far it is possible without damaging the bearing components. Where necessary special tools shall be developed for removal of e.g. circlips in NCF bearings



Bearing elements shall be properly cleaned for oil, residuals, Loctite, mounting paste etc. before inspection



Assessment of bearings shall be based o n inspection of o

The IR when this can be separated from the bearing without damaging the cage, e.g. NJ, NU, QJ and NCF type bearings

o

The OR and partly inspection of rollers when only the OR can be separated from the bearing without damaging the cage, e.g. N and TRB type bearings.

o

The OR and partly inspection of the rollers when neither the IR nor the OR can be separated from the bearing, e.g. SRB



Where bearing IRs can not be fully inspected the assessment shall be based on the accessible parts. Special focus must in any case be given to the load zones and the rollers. Where possible the inaccessible raceway(s) shall be inspected by use of borescope



Bearings where neither of the raceways nor the rolling elements can be inspected, e.g. deep groove ball bearings, shall not be re-used

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

Bearing elements show no signs of material break out (spalling, flaking, pitting, micropitting) or cracks



Bearing elements show no signs of local h eating



No presence of score marks on roller end faces or ring flanges

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Bearing elements show no assembly/disassembly damages

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Very limited number of small debris dents

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Only superficial/light circumferential scratches

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Only superficial false brinelling (stand still marks) of visual character only and which is not perceptible by a well pointed pencil

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Superficial fretting corrosion on IR ID, OR OD and side faces which does not affect the performance/lifetime of the bearing. Fretting corrosion shall be removed and size and finish of the cleaned surfaces has to meet the original requirements

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Bearing elements show no chemical corrosion

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The specific bearing type and size on that specific location (e.g. NCF 18/600 rotor end planet carrier bearing) has not shown any signs of sub surface failure or generic defects



There shall be no mixing of rolling elements, rings or spacers from different bearings

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Bearings which are fully or partly coated show only normal wear of the coating

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Re-used bearings shall be permanently marked (e.g. engraving, etching or laser) next to the type code on the OR in order to recognize re-used bearings. The code shall be different from the code used to identify reworked bearings.

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Bearings shall be properly cleaned in order to remove debris, sediments and oil residues from all bearing elements

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Proper corrosion protection shall be applied after cleaning a nd inspection to ensure proper shelf life



The Service Provider shall make an assessment report documenting the condition of the re-used bearing

In case the Service Provider chooses to have the final assessment made by a Bearing Re-worker specialized in assessing and re-working of rolling bearings (e.g. SKF Industrial Services Centre or FAG Industrial Services) then this Bearing Re-worker and his requirements for re-use of bearings shall be agreed on beforehand between the Service Provider the Bearing Re-worker and Vestas Technology R&D. The Bearing Re-worker shall issue a detailed bearing analysis report for each assessed bearing returned for re-use.

6.4

Integrated Bearing Outer Rings Bearings raceways integrated in planet gears can be re-use according to the requirements below: 

Moderate circumferential scratches on the raceways ar e acceptable



Moderate polishing is acceptable

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Indents from hard particles are acceptable when smaller than 0.5 mm diameter. No indications of micro cracks around the indents.

Doc. No.

Rev No.:

0002-6759

V00

Title:

class:

Page:


II

30 (60)


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Indents from soft particles are acceptable when smaller than 2 mm diameter and in a limited number. No indication of micro cracks. Indents shall be polished by v ery fine sand paper.

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6.5

Superficial false brinelling is acceptable when it can not be detected by a sharp pointed pencil

Gear-Shaft Connections In cases where the surfaces for gear-shaft connections are in such a condition that the functionality of these surfaces are still intact, the shaft and the gear can be re-used without re-work provided the following conditions are complied with: 

The component shall be cleaned and free from oil, sediments and other foreign matter before inspection



There shall be no suspicion of shaft failures initiated by the fit or originating from the fit, e.g. from keyway root or crossing notches such as a circlip groove crossing a keyway. If suspicion of cracks a proper NDT must be carried out

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Shaft and bore diameters for interference fits shall meet the original requirements for size, fit and finish

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Keyways shall meet the original requirements for size, fit, form and finish. Fitting of oversize keys in worn keyways is not permitted

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Circlip grooves shall meet the original requirements for size and form

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Only superficial chemical corrosion or fretting corrosion is present in a limited amount which does not disturb the functionality of the surface or reduce the strength of the fit. Any kind of corrosion shall be removed before re-use of the component. The component shall meet the original requirements for size, fit and finish

6.6

Spline Connections Male and female splines can be re-used provided the condition of the spline components comply with the following requirements:

6.7

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The spline components (male or female) show only moderate wear on the load flanks

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The spline teeth show only fretting corrosion of moderate character

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The load flanks ha ve limited to moderate micropitting

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There are no presence of pitting, spalling or other material break-out

Planet Carrier and Planet Pins The following clause specifies the requirements for the functional surfaces for re-use of planet carriers and planet pins.

6.7.1 Planet Carrier For the functional surfaces of the planet carrier, such as the hollow shaft, bearing journals and bores for the planet pins, the following requirements are applicable: 

The component shall be properly cleaned before inspection. Special care must be taken in cleaning oil bores for which washing of the component is considered inadequate.

Vestas Requirement Specification - Gearbox Repair

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