Reliability, Maintainability and Risk (eBook)

Cover 1
Contents 6
Preface 12
Acknowledgements 14
Part One: Understanding Reliability Parameters and Costs 16
Chapter 1. The history of reliability and safety technology 18
1.1 Failure data 18
1.2 Hazardous failures 19
1.3 Reliability and risk prediction 20
1.4 Achieving reliability and safety-integrity 21
1.5 The RAMS-cycle 22
1.6 Contractual pressures 24
Chapter 2. Understanding terms and jargon 26
2.1 Defining failure and failure modes 26
2.2 Failure Rate and Mean Time Between Failures 27
2.3 Interrelationships of terms 29
2.4 The Bathtub Distribution 31
2.5 Down Time and Repair Time 32
2.6 Availability 35
2.7 Hazard and risk-related terms 35
2.8 Choosing the appropriate parameter 36
Chapter 3. A cost-effective approach to quality, reliability and safety 38
3.1 The cost of quality 38
3.2 Reliability and cost 41
3.3 Costs and safety 44
Part Two: Interpreting Failure Rates 48
Chapter 4. Realistic failure rates and prediction confidence 50
4.1 Data accuracy 50
4.2 Sources of data 52
4.3 Data ranges 56
4.4 Confidence limits of prediction 59
4.5 Overall conclusions 61
Chapter 5. Interpreting data and demonstrating reliability 62
5.1 The four cases 62
5.2 Inference and confidence levels 62
5.3 The Chi-square Test 64
5.4 Double-sided confidence limits 65
5.5 Summarizing the Chi-square Test 66
5.6 Reliability demonstration 67
5.7 Sequential testing 71
5.8 Setting up demonstration tests 72
Exercises 72
Chapter 6. Variable failure rates and probability plotting 73
6.1 The Weibull Distribution 73
6.2 Using the Weibull Method 75
6.3 More complex cases of the Weibull Distribution 82
6.4 Continuous processes 83
Exercises 84
Part Three: Predicting Reliability and Risk 86
Chapter 7. Essential reliability theory 88
7.1 Why predict RAMS? 88
7.2 Probability theory 88
7.3 Reliability of series systems 91
7.4 Redundancy rules 92
7.5 General features of redundancy 98
Exercises 101
Chapter 8. Methods of modelling 102
8.1 Block Diagram and Markov Analysis 102
8.2 Common cause (dependent) failure 113
8.3 Fault Tree Analysis 118
8.4 Event Tree Diagrams 125
Chapter 9. Quantifying the reliability models 129
9.1 The reliability prediction method 129
9.2 Allowing for diagnostic intervals 130
9.3 FMEA (Failure Mode and Effect Analysis) 132
9.4 Human factors 133
9.5 Simulation 138
9.6 Comparing predictions with targets 141
Exercises 142
Chapter 10. Risk assessment (QRA) 143
10.1 Frequency and consequence 143
10.2 Perception of risk and ALARP 144
10.3 Hazard identification 145
10.4 Factors to quantify 150
Part Four: Achieving Reliability and Maintainability 156
Chapter 11. Design and assurance techniques 158
11.1 Specifying and allocating the requirement 158
11.2 Stress analysis 160
11.3 Environmental stress protection 163
11.4 Failure mechanisms 163
11.5 Complexity and parts 165
11.6 Burn-in and screening 168
11.7 Maintenance strategies 169
Chapter 12. Design review and test 170
12.1 Review techniques 170
12.2 Categories of testing 171
12.3 Reliability growth modelling 175
Exercises 178
Chapter 13. Field data collection and feedback 179
13.1 Reasons for data collection 179
13.2 Information and difficulties 179
13.3 Times to failure 180
13.4 Spreadsheets and databases 181
13.5 Best practice and recommendations 183
13.6 Analysis and presentation of results 184
13.7 Examples of failure report forms 185
Chapter 14. Factors influencing down time 188
14.1 Key design areas 188
14.2 Maintenance strategies and handbooks 195
Chapter 15. Predicting and demonstrating repair times 208
15.1 Prediction methods 208
15.2 Demonstration plans 216
Chapter 16. Quantified reliability centred maintenance 220
16.1 What is QRCM? 220
16.2 The QRCM decision process 221
16.3 Optimum replacement (discard) 222
16.4 Optimum spares 225
16.5 Optimum proof-test 225
16.6 Condition monitoring 226
Chapter 17. Software quality/reliability 228
17.1 Programmable devices 228
17.2 Software failures 229
17.3 Software failure modelling 230
17.4 Software quality assurance 232
17.5 Modern/formal methods 238
17.6 Software checklists 241
Part Five: Legal, Management and Safety Considerations 246
Chapter 18. Project management 248
18.1 Setting objectives and specifications 248
18.2 Planning, feasibility and allocation 249
18.3 Programme activities 249
18.4 Responsibilities 252
18.5 Standards and guidance documents 252
Chapter 19. Contract clauses and their pitfalls 253
19.1 Essential areas 253
19.2 Other areas 256
19.3 Pitfalls 257
19.4 Penalties 259
19.5 Subcontracted reliability assessments 261
19.6 Example 262
Chapter 20. Product liability and safety legislation 263
20.1 The general situation 263
20.2 Strict liability 264
20.3 The Consumer Protection Act 1987 265
20.4 Health and Safety at Work Act 1974 266
20.5 Insurance and product recall 267
Chapter 21. Major incident legislation 269
21.1 History of major incidents 269
21.2 Development of major incident legislation 270
21.3 CIMAH safety reports 271
21.4 Offshore safety cases 274
21.5 Problem areas 276
21.6 The COMAH directive (1999) 277
Chapter 22. Integrity of safety-related systems 278
22.1 Safety-related or safety-critical? 278
22.2 Safety-integrity levels (SILs) 279
22.3 Programmable electronic systems (PESs) 281
22.4 Current guidance 283
22.5 Accreditation and conformity of assessment 287
Chapter 23. A case study: The Datamet Project 288
23.1 Introduction 288
23.2 The DATAMET Concept 288
23.3 Formation of the project group 292
23.4 Reliability requirements 293
23.5 First design review 294
23.6 Design and development 296
23.7 Syndicate study 297
23.8 Hints 297
Appendices 298
Appendix 1. Glossary 298
Appendix 2. Percentage points of the Chi-square distribution 307
Appendix 3. Microelectronics failure rates 311
Appendix 4. General failure rates 313
Appendix 5. Failure mode percentages 320
Appendix 6. Human error rates 323
Appendix 7. Fatality rates 325
Appendix 8. Answers to exercises 327
Appendix 9. Bibliography 332
Appendix 10. Scoring criteria for BETAPLUS common cause model 335
Appendix 11. Example of HAZOP 342
Appendix 12. HAZID checklist 345
Index 348