Reliability, maintainability and risk practical methods for engineers; [including reliability centred maintenance and safety-related systems]

365 Pages·2005·2.26 MB·English

RELIABILITY, MAINTAINABILITY AND RISK
Also by the same author
Reliability Engineering,Pitman,1972
Maintainability Engineering,Pitman,1973 (with A. H. Babb)
Statistics Workshop,Technis,1974,1991
Achieving Quality Software,Chapman & Hall,1995
Quality Procedures for Hardware and Software,Elsevier,1990 (with J. S. Edge)
Functional Safety:A Straightforward Guide to IEC 61508,2nd Edition,Butterworth-Heinemann,
2004,ISBN 0 7506 6269 7 (with K. G. L. Simpson)
Reliability, Maintainability
and Risk
Practical methods for engineers
Seventh Edition
Dr David J Smith
BSc,PhD,CEng,FIEE,FIQA,HonFSaRS,MIGasE
AMSTERDAM (cid:2)BOSTON (cid:2)HEIDELBERG (cid:2)LONDON (cid:2)NEW YORK (cid:2)OXFORD
PARIS (cid:2)SAN DIEGO (cid:2)SAN FRANCISCO (cid:2)SINGAPORE (cid:2)SYDNEY (cid:2)TOKYO
Elsevier Butterworth-Heinemann
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First published by Macmillan Education Ltd 1981
Second edition 1985
Third edition 1988
Fourth edition published by Butterworth-Heinemann Ltd 1993
Reprinted 1994, 1996
Fifth edition 1997
Reprinted with revisions 1999
Sixth edition 2001
Reprinted 2002, 2003 (twice)
Seventh edition 2005
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Contents
Preface xi
Acknowledgements xiii
Part One Understanding Reliability Parameters and Costs 1
1 The history of reliability and safety technology 3
1.1 Failure data 3
1.2 Hazardous failures 4
1.3 Reliability and risk prediction 5
1.4 Achieving reliability and safety-integrity 7
1.5 The RAMS-cycle 8
1.6 Contractual pressures 10
2 Understanding terms and jargon 11
2.1 Defining failure and failure modes 11
2.2 Failure Rate and Mean Time Between Failures 12
2.3 Interrelationships of terms 15
2.4 The Bathtub Distribution 17
2.5 Down Time and Repair Time 18
2.6 Availability,Unavailability and Probability of Failure on Demand 21
2.7 Hazard and risk-related terms 21
2.8 Choosing the appropriate parameter 22
Exercises 23
3 A cost-effective approach to quality,reliability and safety 24
3.1 Reliability and cost 24
3.2 Costs and safety 27
3.3 The cost of quality 30
Part Two Interpreting Failure Rates 35
4 Realistic failure rates and prediction confidence 37
4.1 Data accuracy 37
4.2 Sources of data 39
4.3 Data ranges 43
4.4 Confidence limits of prediction 46
4.5 Overall conclusions 49
vi Contents
5 Interpreting data and demonstrating reliability 50
5.1 The four cases 50
5.2 Inference and confidence levels 50
5.3 The Chi-square Test 51
5.4 Double-sided confidence limits 53
5.5 Summarizing the Chi-square Test 54
5.6 Reliability demonstration 54
5.7 Sequential testing 57
5.8 Setting up demonstration tests 59
Exercises 60
6 Variable failure rates and probability plotting 61
6.1 The Weibull Distribution 61
6.2 Using the Weibull Method 63
6.3 More complex cases of the Weibull Distribution 69
6.4 Continuous processes 70
Exercises 71
Part Three Predicting Reliability and Risk 73
7 Basic reliability prediction theory 75
7.1 Why predict RAMS? 75
7.2 Probability theory 75
7.3 Reliability of series systems 78
7.4 Redundancy rules 79
7.5 General features of redundancy 85
Exercises 88
8 Methods of modelling 89
8.1 Block Diagrams and Repairable Systems 89
8.2 Common cause (dependent) failure 96
8.3 Fault Tree Analysis 101
8.4 Event Tree Diagrams 109
9 Quantifying the reliability models 113
9.1 The reliability prediction method 113
9.2 Allowing for diagnostic intervals 114
9.3 FMEA (Failure Mode and Effect Analysis) 116
9.4 Human factors 118
9.5 Simulation 123
9.6 Comparing predictions with targets 128
Exercises 129
10 Risk assessment (QRA) 130
10.1 Frequency and consequence 130
10.2 Perception of risk and ALARP 130
10.3 Hazard identification 132
10.4 Factors to quantify 137
Contents vii
Part Four Achieving Reliability and Maintainability 143
11 Design and assurance techniques 145
11.1 Specifying and allocating the requirement 145
11.2 Stress analysis 147
11.3 Environmental stress protection 150
11.4 Failure mechanisms 150
11.5 Complexity and parts 153
11.6 Burn-in and screening 155
11.7 Maintenance strategies 156
12 Design review and test 157
12.1 Review techniques 157
12.2 Categories of testing 158
12.3 Reliability growth modelling 163
Exercises 166
13 Field data collection and feedback 167
13.1 Reasons for data collection 167
13.2 Information and difficulties 167
13.3 Times to failure 168
13.4 Spreadsheets and databases 169
13.5 Best practice and recommendations 171
13.6 Analysis and presentation of results 172
13.7 Examples of failure report forms 173
14 Factors influencing down time 176
14.1 Key design areas 176
14.2 Maintenance strategies and handbooks 183
15 Predicting and demonstrating repair times 196
15.1 Prediction methods 196
15.2 Demonstration plans 204
16 Quantified reliability centred maintenance 208
16.1 What is QRCM? 208
16.2 The QRCM decision process 209
16.3 Optimum replacement (discard) 210
16.4 Optimum spares 212
16.5 Optimum proof test 212
16.6 Condition monitoring 214
17 Systematic failures,especially software 215
17.1 Programmable devices 215
17.2 Software-related failures 217
17.3 Software failure modelling 218
17.4 Software quality assurance 219
17.5 Modern/formal methods 225
17.6 Software checklists 228
viii Contents
Part Five Legal,Management and Safety Considerations 233
18 Project management 235
18.1 Setting objectives and specifications 235
18.2 Planning,feasibility and allocation 236
18.3 Programme activities 236
18.4 Responsibilities 238
18.5 Functional safety capability 239
18.6 Standards and guidance documents 240
19 Contract clauses and their pitfalls 241
19.1 Essential areas 241
19.2 Other areas 244
19.3 Pitfalls 246
19.4 Penalties 247
19.5 Subcontracted reliability assessments 249
19.6 Examples 250
20 Product liability and safety legislation 251
20.1 The general situation 251
20.2 Strict liability 252
20.3 The Consumer Protection Act 1987 253
20.4 Health and Safety at Work Act 1974 253
20.5 Insurance and product recall 255
21 Major incident legislation 257
21.1 History of major incidents 257
21.2 Development of major incident legislation 258
21.3 CIMAH safety reports 259
21.4 Offshore safety cases 262
21.5 Problem areas 263
21.6 The COMAH directive (1999) 264
21.7 Rail 265
22 Integrity of safety-related systems 266
22.1 Safety-related or safety-critical? 266
22.2 Safety-integrity levels (SILs) 267
22.3 Programmable electronic systems (PESs) 270
22.4 Current guidance 272
22.5 Framework for certification 274
23 A case study:The Datamet Project 276
23.1 Introduction 276
23.2 The DATAMET concept 276
23.3 The contract 279
23.4 Detailed design 280
23.5 Syndicate study 280
23.6 Hints 280
Contents ix
24 A case study:Gas Detection System 282
24.1 Safety-integrity target 282
24.2 Random hardware failures 283
24.3 ALARP 285
24.4 Architectures 285
24.5 Life-cycle activities 285
24.6 Functional safety capability 285
Appendix 1 Glossary 286
Appendix 2 Percentage points of the Chi-square distribution 294
Appendix 3 Microelectronics failure rates 298
Appendix 4 General failure rates 300
Appendix 5 Failure mode percentages 307
Appendix 6 Human error rates 310
Appendix 7 Fatality rates 312
Appendix 8 Answers to exercises 314
Appendix 9 Bibliography 320
Appendix 10 Scoring criteria for BETAPLUS common cause model 323
Appendix 11 Example of HAZOP 330
Appendix 12 HAZID checklist 334
Appendix 13 Markov analysis of redundant systems 337
Index 343