New Techniques of Reliability and their Application to Offshore Wind Farms

1. New Techniques of Reliability and their Application to Offshore Wind Farms European Offshore Wind 2009, Stockholm Technology and Innovation Offshore Wind Turbine Reliability 16th September 2009

2. Introduction - Michael Starling Background • Chartered Mechanical Engineer, started work in 1979, worked for BMT since 1990 • worked in Renewable Energy since 2004 • specialise in engineering and risk • applied to transport, energy and the built environment Current/recent projects • construction, transportation and installation system for concrete offshore wind turbine foundations (with Gifford) • reliability, maintainability and survivability guide for the European Marine Energy Centre in Orkney • navigation impact assessment of a tidal fence across the Severn

3. Introduction - BMT British Ship Research Association NMI Ltd British Maritime Technology Ltd established 1985 (now BMT Group Ltd)

4. Reliability – Some major projects • Air to Air Refuelling Tanker Aircraft

5. Reliability – Some major projects • Channel Tunnel Trains

6. Reliability – Some major projects • Ro Ro Ferries

7. Reliability – Some major projects • Offshore and Subsea Oil & Gas

8. Reliability – Personal contact with my work • Aircraft Fuel Pumps – Airport Baggage Handling – Airport Trains – Metros - Escalators

9. Reliability – A current project • Pulse Tidal Generator

10. Who achieves high reliability?

11. Aircraft achieve high reliability • An A330 will typically achieve greater than 98.5% operational availability • and they guaranteed it from day 1

12. How do they achieve high reliability?

13. Fundamental economic driver • A complete common purpose between safety, reliability, performance and profitability

14. International standards driven • Everything is specification, certification and approvals led

15. Technical drivers • Complete hierarchy of specification and certification from the smallest component to the whole aircraft and from an individual maintainer to the operator • Approvals are technical, organisational and individual • There is international commonality and transferability

16. Functional drivers • Aircraft design based on equipment functionality and integrity • and on appropriate redundancy

17. Appropriate redundancy • Redundancy “enhances high integrity” • It does not “compensate for low integrity”

18. What process do they follow?

19. Formal processes of assurance • Defining what the equipment, operation or service has to do • Designing, operating and maintaining it to do it • Finding some assurance that it will “work and keep on working”

20. Summary • Aircraft Achieve High Reliability By • Reliable Design • demonstrated by • Reliability Assurance • based on • Integrity, Functionality, Appropriate Redundancy and Comprehensive Testing • mandated by • Specification, Certification and Approval • and controlled through life by • Monitoring and Modification

21. Three topics for rest of this paper • Design for reliability • Maintain for reliability • Success-based reliability

22. Design for Reliability

23. How reliable does a device have to be? • Common measure of reliability is Mean Time Between Failure (MTBF) • Common belief that a 10 year MTBF means that the equipment will last about 10 years • That is a 10 year life not a 10 year MTBF • After 10 years running approximately 63% of “10 year” MTBF equipment will have failed • For 1% failed the MTBF needs to be approximately 1,000 years • Some MTBFs • Offshore Wind Turbine, 1 month • Domestic Boiler, 5 years – Double Glazing, 10 years

24. Does redundancy help? • Typical solution to poor reliability is redundancy • Works well for repairable systems • Works badly for non repairable systems • It works better for non-repairable systems when the equipment is reliable • It is often better to spend money on increasing integrity rather than fitting redundancy

25. Design for reliability - conclusion • Design for high integrity • Backup with redundancy only if easy to repair

26. Maintain for Reliability

27. What type of maintenance can I do? • Preventive Maintenance • The routine activities to prevent failure, i.e. the servicing • Typically done to a planned schedule based on time or usage • Ideal is to do when no wind resource available Corrective Maintenance • The activities required to respond to failure, i.e. the repairs • Typically done to a reactive schedule • Ideal is to avoid • Predictive Maintenance • The activities required to respond to an indicator of future failure, i.e. maintenance triggered by some measurement of condition • Ideal is to be able to defer predictive maintenance to times when preventive maintenance takes place

28. Classical “Bathtub” • Wear-out • Degradation • Initial Success • Steady • Early Life Failure What type of maintenance should I do? • Depends on the nature of the failure

29. Classical “Bathtub” • Bit worse • Made better • Wear-out • Bit better • Degradation • Initial Success • Bit better • No difference • Steady • Made worse • Early Life Failure Effect of time scheduled maintenance

30. Classical “Bathtub” • Bit worse 4% • Made better 2% • Wear-out 5% • Bit better • Degradation 7% • Initial Success • Bit better • No difference 14% • Steady 68% • Made worse • Early Life Failure Example using of aircraft data

31. Maintain for reliability - conclusion • Define maintenance based on understanding the types of failure

32. Success-based reliability

33. A bit of history • These success-based techniques grew out of failure • failure of reliability techniques to lead to change • failure of techniques to improve reliability • failure of techniques to be value for money Led to questioning the fundamental reliability techniques • techniques are focussed on failure • should they be focussed on success?

34. Focus on success • For many years those of us in reliability have concentrated on understanding and eliminating failure. • why things fails, when they fail, where they fail and how to stop them failing are questions that are examined in great detail. • However in doing so we may have overlooked the equal importance of understanding and creating success. • why things work, when they work, where they work and how to make them work are equally, or perhaps more important, questions.

35. How to achieve success? – via assurance • to define what the equipment, operation or service has to do • to design it and operate it to do it • find some evidence that it will work and keep on working. • identify and eliminate threats to success.

36. Assurance via developing a reliability case • Part Technical Process • that aims to provide the “Evidence of Success” and • identify and eliminate the “Risk of Failure” • and produce a “Reasoned Argument” supporting expected performance • Part Management Process • that aims to provide “Scrutiny” that the evidence and argument is valid

37. Assessing the quality of the evidence • Proof? Evidence? Faith?

38. Producing a reasoned argument • The reasoned argument leads to • a claim of expected reliability performance • an assessment of the level of risk associated with the claim There is an obligation to use all evidence, the supporting and the opposing

39. Typical Management Process – providing scrutiny

40. This philosophy is not new • Rene Descartes • 1596 - 1650 • Knowledge should be based on • “Proof and evidence rather than just faith” • and • “Nothing should be accepted unless subject to scrutiny”

41. And finally • Some advice on how to achieve high reliability • Specify the reliability you want • and specify it in terms meaningful to your business • Design to achieve it • but beware the false promise of redundancy • Build up a Reliability Case • and expose it to scrutiny (and don’t always believe your experts!) • Maintain for reliability • base your maintenance on understanding failure

42. Discussion Michael Starling BMT Fleet Technology www.fleetech.com mstarling@fleetech.com +44(0)780 3925110

43. Typical Technical Process – building up evidence