v

Contents

Preface .............................................................................................................xix

Acknowledgements .............................................................................................xxi

PART 1 Understanding Reliability Parameters and Costs ...................................1

Chapter 1: The History of Reliability and Safety Technology .....................................31.1 Failure Data ........................................................................................................... 31.2 Hazardous Failures ................................................................................................ 51.3 Reliability and Risk Prediction .............................................................................. 51.4 Achieving Reliability and Safety-Integrity ............................................................ 81.5 The RAMS Cycle .................................................................................................. 91.6 Contractual and Legal Pressures .......................................................................... 11

Chapter 2: Understanding Terms and Jargon .........................................................132.1 Defining Failure and Failure Modes .................................................................... 132.2 Failure Rate and Mean Time Between Failures ................................................... 15

2.2.1 The Observed Failure Rate ...............................................................................152.2.2 The Observed Mean Time Between Failures ...................................................162.2.3 The Observed Mean Time to Fail .....................................................................162.2.4 Mean Life .........................................................................................................17

2.3 Interrelationships of Terms .................................................................................. 172.3.1 Reliabilty and Failure Rate ...............................................................................172.3.2 Reliabilty and Failure Rate as an Approximation ............................................192.3.3 Reliabilty and MTBF .......................................................................................20

2.4 The Bathtub Distribution ..................................................................................... 202.5 Down Time and Repair Time ............................................................................... 212.6 Availability, Unavailability and Probability of Failure on Demand .................... 252.7 Hazard and Risk-Related Terms .......................................................................... 262.8 Choosing the Appropriate Parameter ................................................................... 26

Chapter 3: A Cost-Effective Approach to Quality, Reliability and Safety ..................293.1 Reliability and Optimum Cost ............................................................................. 293.2 Costs and Safety .................................................................................................. 33

3.2.1 The Need for Optimization ..............................................................................333.2.2 Costs and Savings Involved with Safety Engineering ......................................33

3.3 The Cost of Quality ............................................................................................. 34

PART 2 Interpreting Failure Rates....................................................................39

Chapter 4: Realistic Failure Rates and Prediction Confidence ..................................414.1 Data Accuracy ..................................................................................................... 414.2 Sources of Data .................................................................................................... 43

4.2.1 Electronic Failure Rates ...................................................................................444.2.2 Other General Data Collections .......................................................................464.2.3 Some Older Sources .........................................................................................48

4.3 Data Ranges ......................................................................................................... 484.3.1 Using the Ranges .............................................................................................50

4.4 Confidence Limits of Prediction .......................................................................... 524.5 Manufacturers’ Data ............................................................................................ 544.6 Overall Conclusions ............................................................................................. 55

Chapter 5: Interpreting Data and Demonstrating Reliability ...................................575.1 The Four Cases .................................................................................................... 575.2 Inference and Confidence Levels ......................................................................... 575.3 The Chi-Square Test ............................................................................................ 595.4 Understanding the Method in More Detail .......................................................... 625.5 Double-Sided Confidence Limits ........................................................................ 635.6 Reliability Demonstration .................................................................................... 635.7 Sequential Testing ................................................................................................ 685.8 Setting Up Demonstration Tests .......................................................................... 69Exercises ..................................................................................................................... 70

Chapter 6: Variable Failure Rates and Probability Plotting .....................................716.1 The Weibull Distribution ..................................................................................... 716.2 Using the Weibull Method ................................................................................... 73

6.2.1 Curve Fitting to Interpret Failure Data .............................................................736.2.2 Manual Plotting ................................................................................................756.2.3 Using the COMPARE Computer Tool .............................................................776.2.4 Significance of the Result ................................................................................796.2.5 Optimum Preventive Replacement ...................................................................81

6.3 More Complex Cases of the Weibull Distribution ............................................... 816.4 Continuous Processes .......................................................................................... 82Exercises ..................................................................................................................... 83

PART 3 Predicting Reliability and Risk .............................................................85

Chapter 7: Basic Reliability Prediction Theory .......................................................877.1 Why Predict RAMS? ........................................................................................... 877.2 Probability Theory ............................................................................................... 88

7.2.1 The Multiplication Rule ...................................................................................887.2.2 The Addition Rule ............................................................................................887.2.3 The Binomial Theorem ....................................................................................897.2.4 Bayes Theorem.................................................................................................90

7.3 Reliability of Series Systems ............................................................................... 917.4 Redundancy Rules ............................................................................................... 92

7.4.1 General Types of Redundant Configuration .....................................................927.4.2 Full Active Redundancy (Without Repair) .......................................................927.4.3 Partial Active Redundancy (Without Repair) ...................................................947.4.4 Conditional Active Redundancy ......................................................................957.4.5 Standby Redundancy ........................................................................................967.4.6 Load Sharing ....................................................................................................98

7.5 General Features of Redundancy ......................................................................... 987.5.1 Incremental Improvement ................................................................................987.5.2 Further Comparisons of Redundancy .............................................................1007.5.3 Redundancy and Cost .....................................................................................101

Exercises ................................................................................................................... 101

Chapter 8: Methods of Modeling .......................................................................1038.1 Block Diagrams and Repairable Systems .......................................................... 103

8.1.1 Reliability Block Diagrams ............................................................................1038.1.2 Repairable Systems (Revealed Failures) ........................................................1058.1.3 Repairable Systems (Unrevealed Failures) ....................................................1078.1.4 Systems With Cold Standby Units and Repair ...............................................1098.1.5 Modeling Repairable Systems with Both Revealed and Unrevealed Failures ...........................................................................1108.1.6 Conventions for Labeling ‘Dangerous’, ‘Safe’, Revealed and Unrevealed Failures ...........................................................................110

8.2 Common Cause (Dependent) Failure ................................................................ 1118.2.1 What is CCF? .................................................................................................1118.2.2 Types of CCF Model ......................................................................................1128.2.3 The BETAPLUS Model .................................................................................114

8.3 Fault Tree Analysis ............................................................................................ 1188.3.1 The Fault Tree ................................................................................................1188.3.2 Calculations ....................................................................................................1198.3.3 Cutsets ............................................................................................................1228.3.4 Computer Tools ..............................................................................................1228.3.5 Allowing for CCF ..........................................................................................1248.3.6 Fault Tree Analysis in Design ........................................................................1268.3.7 A Cautionary Note .........................................................................................126

8.4 Event Tree Diagrams ......................................................................................... 1268.4.1 Why Use Event Trees? ...................................................................................1268.4.2 The Event Tree Model ....................................................................................1278.4.3 Quantification .................................................................................................1298.4.4 Differences .....................................................................................................1308.4.5 Feedback Loops .............................................................................................131

Chapter 9: Quantifying the Reliability Models .....................................................1339.1 The Reliability Prediction Method .................................................................... 1339.2 Allowing for Diagnostic Intervals ..................................................................... 135

9.2.1 Establishing Diagnostic Coverage .................................................................1359.2.2 Modeling ........................................................................................................1359.2.3 Partial Stroke Testing .....................................................................................1379.2.4 Safe Failure Fraction ......................................................................................137

9.3 FMEA (Failure Mode and Effect Analysis) ...................................................... 1379.4 Human Factors ................................................................................................... 140

9.4.1 Background ....................................................................................................1409.4.2 Models ............................................................................................................1409.4.3 HEART (Human Error Assessment and Reduction Technique) ....................1419.4.4 THERP (Technique for Human Error Rate Prediction) .................................1439.4.5 TESEO (Empirical Technique to Estimate Operator Errors) .........................1439.4.6 Other Methods ................................................................................................1449.4.7 Human Error Rates .........................................................................................1449.4.8 Trends in Rigor of Assessment ......................................................................146

9.5 Simulation .......................................................................................................... 1479.5.1 The Technique ................................................................................................1479.5.2 Some Packages ...............................................................................................149

9.6 Comparing Predictions with Targets .................................................................. 153Exercises ................................................................................................................... 153

Chapter 10: Risk Assessment (QRA) .................................................................15510.1 Frequency and Consequence ........................................................................... 15510.2 Perception of Risk, ALARP and Cost per Life Saved ..................................... 156

10.2.1 Maximum Tolerable Risk (Individual Risk) ...............................................15610.2.2 Maximum Tolerable Failure Rate ...............................................................15710.2.3 ALARP and Cost per Life Saved ...............................................................15910.2.4 Societal Risk ...............................................................................................16110.2.5 Production/Damage Loss ...........................................................................164

10.3 Hazard Identification ....................................................................................... 16410.3.1 HAzOP .......................................................................................................16510.3.2 HAzID .......................................................................................................16910.3.3 HAzAN (Consequence Analysis) ..............................................................169

10.4 Factors to Quantify .......................................................................................... 16910.4.1 Reliability ...................................................................................................17010.4.2 Lightning and Thunderstorms ....................................................................17010.4.3 Aircraft Impact ...........................................................................................17010.4.4 Earthquake ..................................................................................................17310.4.5 Meteorological Factors ...............................................................................17410.4.6 Other Consequences ...................................................................................174

PART 4 Achieving Reliability and Maintainability ...........................................177

Chapter 11: Design and Assurance Techniques ....................................................17911.1 Specifying and Allocating the Requirement .................................................... 17911.2 Stress Analysis ................................................................................................. 18111.3 Environmental Stress Protection ...................................................................... 18411.4 Failure Mechanisms ......................................................................................... 185

11.4.1 Types of Failure Mechanism ......................................................................18511.4.2 Failures in Semiconductor Components.....................................................18611.4.3 Discrete Components .................................................................................187

11.5 Complexity and Parts ....................................................................................... 18711.5.1 Reduction of Complexity ...........................................................................18711.5.2 Part Selection ..............................................................................................18811.5.3 Redundancy ................................................................................................188

11.6 Burn-In and Screening ..................................................................................... 18911.7 Maintenance Strategies .................................................................................... 190

Chapter 12: Design Review, Test and Reliability Growth ......................................19112.1 Review Techniques .......................................................................................... 19112.2 Categories of Testing ....................................................................................... 192

12.2.1 Environmental Testing ...............................................................................193

12.2.2 Marginal Testing ........................................................................................194

12.2.3 High-Reliability Testing ............................................................................19512.2.4 Testing for Packaging and Transport ...........................................................195

12.2.5 Multiparameter Testing ..............................................................................196

12.2.6 Step-Stress Testing .....................................................................................19712.3 Reliability Growth Modeling ........................................................................... 198

12.3.1 The CUSUM Technique ............................................................................198

12.3.2 Duane Plots ................................................................................................201Exercises .................................................................................................................202

Chapter 13: Field Data Collection and Feedback .................................................20513.1 Reasons for Data Collection ............................................................................ 20513.2 Information and Difficulties ............................................................................ 20513.3 Times to Failure ............................................................................................... 20713.4 Spreadsheets and Databases ............................................................................ 20813.5 Best Practice and Recommendations ............................................................... 21013.6 Analysis and Presentation of Results ............................................................... 21113.7 Manufacturers’ data ......................................................................................... 21213.8 Anecdotal Data ................................................................................................ 21313.9 Examples of Failure Report Forms .................................................................. 213

Chapter 14: Factors Influencing Down Time .......................................................21714.1 Key Design Areas ............................................................................................ 217

14.1.1 Access .........................................................................................................21714.1.2 Adjustment .................................................................................................21714.1.3 Built-In Test Equipment .............................................................................21814.1.4 Circuit Layout and Hardware Partitioning .................................................21814.1.5 Connections ................................................................................................21914.1.6 Displays and Indicators ..............................................................................22014.1.7 Handling, Human and Ergonomic Factors ...............................................22114.1.8 Identification .............................................................................................22214.1.9 Interchangeability .....................................................................................22214.1.10 Least Replaceable Assembly ....................................................................22314.1.11 Mounting ..................................................................................................22314.1.12 Component Part Selection ........................................................................22314.1.13 Redundancy ..............................................................................................22414.1.14 Safety ........................................................................................................22414.1.15 Software ...................................................................................................22414.1.16 Standardization .........................................................................................22514.1.17 Test Points ................................................................................................225

14.2 Maintenance Strategies and Handbooks .......................................................... 22514.2.1 Organization of Maintenance Resources ....................................................22614.2.2 Maintenance Procedures ............................................................................22714.2.3 Tools and Test Equipment ..........................................................................22814.2.4 Personnel Considerations ...........................................................................22914.2.5 Maintenance Manuals ................................................................................23014.2.6 Spares Provisioning ....................................................................................23214.2.7 Logistics .....................................................................................................23814.2.8 The User and the Designer .........................................................................23814.2.9 Computer Aids to Maintenance ..................................................................239

Chapter 15: Predicting and Demonstrating Repair Times .....................................24115.1 Prediction Methods .......................................................................................... 241

15.1.1 US Military Handbook 472 – Procedure 3 .................................................24215.1.2 Checklist – Mil 472 – Procedure 3 .............................................................24315.1.3 Using a Weighted Sample ..........................................................................250

15.2 Demonstration Plans ........................................................................................ 25015.2.1 Demonstration Risks ..................................................................................25015.2.2 US Military Standard 471A (1973) ............................................................25215.2.3 Data Collection ...........................................................................................254

Chapter 16: Quantified Reliability Centered Maintenance ....................................25516.1 What is QRCM? .............................................................................................. 25516.2 The QRCM Decision Process .......................................................................... 25616.3 Optimum Replacement (Discard) .................................................................... 256

16.4 Optimum Spares .............................................................................................. 25916.5 Optimum Proof Test ........................................................................................ 26016.6 Condition Monitoring ...................................................................................... 262

Chapter 17: Systematic Failures, Especially Software ..........................................26317.1 Programable Devices ....................................................................................... 26317.2 Software-related Failures ................................................................................. 26517.3 Software Failure Modeling .............................................................................. 26717.4 Software Quality Assurance (Life Cycle Activities) ....................................... 268

17.4.1 Organization of Software QA ....................................................................26917.4.2 Documentation Controls ............................................................................26917.4.3 Programming (Coding) Standards ..............................................................27217.4.4 Fault-Tolerant Design Features ..................................................................27317.4.5 Reviews ......................................................................................................27417.4.6 Integration and Test ....................................................................................274

17.5 Modern/Formal Methods ................................................................................. 27517.5.1 Requirements Specification and Design .....................................................27617.5.2 Static Analysis ............................................................................................27717.5.3 Test Beds ....................................................................................................279

17.6 Software Checklists ......................................................................................... 27917.6.1 Organization of Software QA .....................................................................27917.6.2 Documentation Controls ............................................................................28017.6.3 Programming Standards .............................................................................28017.6.4 Design Features ..........................................................................................28117.6.5 Code Inspections and Walkthroughs ..........................................................28217.6.6 Integration and Test ....................................................................................282

PART 5 Legal, Management and Safety Considerations .................................285

Chapter 18: Project Management and Competence .............................................28718.1 Setting Objectives and Making Specifications ................................................ 28718.2 Planning, Feasibility and Allocation ............................................................... 28818.3 Program Activities ........................................................................................... 28918.4 Responsibilities and Competence .................................................................... 29118.5 Functional Safety Capability ........................................................................... 29418.6 Standards and Guidance Documents ............................................................... 295

Chapter 19: Contract Clauses and Their Pitfalls ..................................................29719.1 Essential Areas................................................................................................. 297

19.1.1 Definitions ..................................................................................................29819.1.2 Environment ...............................................................................................29919.1.3 Maintenance Support ..................................................................................29919.1.4 Demonstration and Prediction ....................................................................30019.1.5 Liability ......................................................................................................301

19.2 Other Areas ...................................................................................................... 30219.2.1 Reliability and Maintainability Program ....................................................30219.2.2 Reliability and Maintainability Analysis ....................................................30219.2.3 Storage ........................................................................................................30219.2.4 Design Standards ........................................................................................30319.2.5 Safety-Related Equipment ..........................................................................303

19.3 Pitfalls .............................................................................................................. 30419.3.1 Definitions ..................................................................................................30419.3.2 Repair Time ................................................................................................30419.3.3 Statistical Risks ..........................................................................................30419.3.4 Quoted Specifications .................................................................................30419.3.5 Environment ...............................................................................................30519.3.6 Liability ......................................................................................................30519.3.7 In Summary ................................................................................................305

19.4 Penalties ........................................................................................................... 30519.4.1 Apportionment of Costs During Guarantee ...............................................30519.4.2 Payment According to Down Time ............................................................30719.4.3 In Summary ................................................................................................307

19.5 Subcontracted Reliability Assessments ........................................................... 308Examples .................................................................................................................. 308

Chapter 20: Product Liability and Safety Legislation ...........................................31120.1 The General Situation ...................................................................................... 311

20.1.1 Contract Law ..............................................................................................31120.1.2 Common Law .............................................................................................31220.1.3 Statute Law .................................................................................................31220.1.4 In Summary ................................................................................................313

20.2 Strict Liability .................................................................................................. 31320.2.1 Concept .......................................................................................................31320.2.2 Defects ........................................................................................................313

20.3 The Consumer Protection Act 1987 ................................................................ 31420.3.1 Background ................................................................................................31420.3.2 Provisions of the Act ..................................................................................314

20.4 Health and Safety at Work Act 1974 ............................................................... 31520.4.1 Scope ..........................................................................................................31520.4.2 Duties .........................................................................................................31520.4.3 Concessions ................................................................................................31520.4.4 Responsibilities ..........................................................................................31520.4.5 European Community Legislation..............................................................31620.4.6 Management of Health and Safety at Work Regulations 1992 ..................316

20.5 Insurance and Product Recall .......................................................................... 31620.5.1 The Effect of Product Liability Trends ......................................................31620.5.2 Some Critical Areas ...................................................................................316

20.5.3 Areas of Cover ............................................................................................31720.5.4 Product Recall ............................................................................................317

Chapter 21: Major Incident Legislation ..............................................................31921.1 History of Major Incidents............................................................................... 31921.2 Development of Major Incident Legislation .................................................... 32021.3 CIMAH Safety Reports ................................................................................... 32221.4 Offshore Safety Cases ...................................................................................... 32421.5 Problem Areas ................................................................................................. 32721.6 The COMAH Directive (1999 and 2005 Amendment) ................................... 32821.7 Rail ................................................................................................................... 32821.8 Corporate Manslaughter and Corporate Homicide .......................................... 329

Chapter 22: Integrity of Safety-Related Systems .................................................33122.1 Safety-Related or Safety-Critical? ................................................................... 33122.2 Safety-Integrity Levels (SILs) ......................................................................... 332

22.2.1 Targets ........................................................................................................33222.2.2 Assessing Equipment Against the Targets .................................................336

22.3 Programable Electronic Systems (PESs) ......................................................... 33822.4 Current Guidance ............................................................................................. 338

22.4.1 IEC International Standard 61508 (2010): Functional safety of electrical/electronic/programmable electronic safety-related systems: 7 parts ................................................................. ...339

22.4.2 IEC International Standard 61511: Functional safety – Safety instrumented systems for the process industry sector ............................. ...339

22.4.3 Institution of Gas Engineers and Managers IGEM/SR/15: programmable equipment in safety-related applications – 5th edition ... ...339

22.4.4 European Standard EN 50126: Railway applications – The specification and demonstration of dependability, reliability, maintainability and safety (RAMS) ....... .. ...... ...339

22.4.5 UK Defence Standard 00-56 (Issue 3.0): Safety Management Requirements for Defence Systems ....................... ...340

22.4.6 RTCA DO-178B/(EUROCAE ED-12B): Software Considerations in Airborne Systems and Equipment Certification ...................................... .. 340

22.4.7 Documents Related to Machinery ..............................................................34022.4.8 Other Industry Sectors ................................................................................34122.4.9 Technis Guidelines, Q124, 2010: Demonstration of product/system

compliance with IEC 61508 .................................................................... .. 34122.5 Framework for Certification ............................................................................ 341

22.5.1 Self-Certification ..........................................................................................34222.5.2 Third-Party Assessment ...............................................................................34222.5.3 Use of a Certifying Body .............................................................................342

Chapter 23: A Case Study: The Datamet Project ................................................34323.1 Introduction ..................................................................................................... 34323.2 The Datamet Concept ...................................................................................... 34323.3 The Contract .................................................................................................... 34623.4 Detailed Design ............................................................................................... 34723.5 Syndicate Study ............................................................................................... 34823.6 Hints ................................................................................................................. 348

Chapter 24: A Case Study: Gas Detection System ...............................................34924.1 Safety-Integrity Target ................................................................................... 34924.2 Random Hardware Failures ........................................................................... 35024.3 ALARP .......................................................................................................... 35224.4 Architectures .................................................................................................. 35224.5 Life-Cycle Activities ..................................................................................... 35324.6 Functional Safety Capability ......................................................................... 353

Chapter 25: A Case Study: Pressure Control System ...........................................35525.1 The Unprotected System................................................................................ 35525.2 Protection System .......................................................................................... 35625.3 Assumptions .................................................................................................. 35725.4 Reliability Block Diagram ............................................................................. 35725.5 Failure Rate Data ........................................................................................... 35825.6 Quantifying the Model ................................................................................... 35825.7 Proposed Design and Maintenance Modifications ........................................ 35925.8 Modeling Common Cause Failure (Pressure Transmitters) .......................... 35925.9 Quantifying the Revised Model ..................................................................... 36025.10 ALARP .......................................................................................................... 36125.11 Architectural Constraints ............................................................................... 361

Appendix 1: Glossary .......................................................................................363A1.1 Terms Related to Failure ................................................................................ 363

A1.1.1 Failure ......................................................................................................363A1.1.2 Failure Mode ...........................................................................................363A1.1.3 Failure Mechanism ..................................................................................363A1.1.4 Failure Rate .............................................................................................364A1.1.5 Mean Time Between Failures and Mean Time to Fail ............................364A1.1.6 Common Cause Failure ...........................................................................364A1.1.7 Common Mode Failure ...........................................................................364

A1.2 Reliability Terms ............................................................................................ 364A1.2.1 Reliability ................................................................................................364A1.2.2 Redundancy .............................................................................................364A1.2.3 Diversity ..................................................................................................365A1.2.4 Failure Mode and Effect Analysis ...........................................................365A1.2.5 Fault Tree Analysis .................................................................................365

A1.2.6 Cause Consequence Analysis (Event Trees) ...........................................365A1.2.7 Reliability Growth ...................................................................................365A1.2.8 Reliability Centered Maintenance ...........................................................365

A1.3 Maintainability Terms .................................................................................... 365A1.3.1 Maintainability ........................................................................................365A1.3.2 Mean Time to Repair (MTTR) ................................................................365A1.3.3 Repair Rate ..............................................................................................366A1.3.4 Repair Time .............................................................................................366A1.3.5 Down Time .............................................................................................366A1.3.6 Corrective Maintenance .........................................................................366A1.3.7 Preventive Maintenance .........................................................................366A1.3.8 Least Replaceable Assembly (LRA) ......................................................366A1.3.9 Second-Line Maintenance .....................................................................366

A1.4 Terms Associated with Software .................................................................... 366A1.4.1 Software .................................................................................................366A1.4.2 Programable Device ...............................................................................367A1.4.3 High-Level Language.............................................................................367A1.4.4 Assembler ..............................................................................................367A1.4.5 Compiler ................................................................................................367A1.4.6 Diagnostic Software ...............................................................................367A1.4.7 Simulation ..............................................................................................367A1.4.8 Emulation ...............................................................................................367A1.4.9 Load Test ................................................................................................367A1.4.10 Functional Test .......................................................................................368A1.4.11 Software Error ........................................................................................368A1.4.12 Bit Error Rate .........................................................................................368A1.4.13 Automatic Test Equipment (ATE)..........................................................368A1.4.14 Data Corruption .....................................................................................368

A1.5 Terms Related to Safety .................................................................................. 368A1.5.1 Hazard ....................................................................................................368A1.5.2 Major Hazard .........................................................................................368A1.5.3 Hazard Analysis .....................................................................................368A1.5.4 HAzOP ..................................................................................................368A1.5.5 LOPA .....................................................................................................369A1.5.6 Risk ........................................................................................................369A1.5.7 Consequence Analysis ...........................................................................369A1.5.8 Safe Failure Fraction ..............................................................................369A1.5.9 Safety-Integrity ......................................................................................369A1.5.10 Safety-Integrity level..............................................................................369

A1.6 General Terms ................................................................................................. 369A1.6.1 Availability (Steady State) .....................................................................369A1.6.2 Unavailability (PFD) ..............................................................................369A1.6.3 Burn-In ...................................................................................................370

A1.6.4 Confidence Interval ................................................................................370A1.6.5 Consumer’s Risk ....................................................................................370A1.6.6 Derating ..................................................................................................370A1.6.7 Ergonomics ............................................................................................370A1.6.8 Mean ......................................................................................................370A1.6.9 Median ...................................................................................................370A1.6.10 PFD ........................................................................................................370A1.6.11 Producer’s Risk ......................................................................................370A1.6.12 Quality ....................................................................................................371A1.6.13 Random ..................................................................................................371A1.6.14 FRACAS ................................................................................................371A1.6.15 RAMS ....................................................................................................371

Appendix 2: Percentage Points of theChi-Square Distribution ...............................373

Appendix 3: Microelectronics Failure Rates.........................................................381

Appendix 4: General Failure Rates ....................................................................383

Appendix 5: Failure Mode Percentages ...............................................................391

Appendix 6: Human Error Probabilities ..............................................................395

Appendix 7: Fatality Rates................................................................................399

Appendix 8: Answers to Exercises ......................................................................401Chapter 2 .................................................................................................................. 401Chapter 5 .................................................................................................................. 401Chapter 6 .................................................................................................................. 402Chapter 7 .................................................................................................................. 402Chapter 9 .................................................................................................................. 403

Notes .....................................................................................................................404Chapter 12 ................................................................................................................ 405Chapter 25 ................................................................................................................ 406

25.2: Protection System ......................................................................................40625.4: Reliability Block Diagram .........................................................................40625.6: Quantifying the Model ...............................................................................40625.7 Revised diagrams: ......................................................................................40725.10 ALARP ......................................................................................................40925.11 Architectural Constraints ...........................................................................409

Appendix 9: Bibliography ..................................................................................411

Appendix 10: Scoring Criteria for BETAPLUS Common Cause Model ...................413A10.1 Checklist and Scoring for Equipment Containing

Programable Electronics ................................................................................413

A10.2 Checklist and Scoring for Non-Programable Equipment ............................. 415For Programable Electronics .................................................................................... 417For Sensors and Actuators ........................................................................................ 417

Appendix 11: Example of HAZOP .....................................................................419A11.1 Equipment Details ........................................................................................ 419A11.2 HAzOP Worksheets ..................................................................................... 419A11.3 Potential Consequences ................................................................................ 419

Worksheet ............................................................................................................421

Appendix 12: HAZID Checklist .........................................................................423

Appendix 13: Markov Analysis of Redundant Systems .........................................427

Index ..............................................................................................................433