The Safety Critical Systems Handbook : A Straightforward Guide to Functional Safety: IEC 61508 (2010 Edition), IEC 61511 (2015 Edition) and Related Guidance

332 Pages·2016·5.8 MB·English

by  Kenneth G. L., David J

The Safety Critical Systems
Handbook
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The Safety Critical Systems
Handbook
A Straightforward Guide To Functional Safety: IEC 61508
(2010 Edition), IEC 61511 (2016 Edition) & Related
Guidance
Including Machinery and other industrial sectors
FOURTH EDITION
Dr David J Smith
Kenneth GL Simpson
AMSTERDAM • BOSTON • HEIDELBERG • LONDON • NEW YORK • OXFORD
PARIS • SAN DIEGO • SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO
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Contents
A Quick Overview ............................................................................................ xv
The 2010 Version of IEC 61508...................................................................... xvii
The 2016 Version of IEC 61511....................................................................... xix
Acknowledgments ............................................................................................ xxi
PART A: THE CONCEPT OF SAFETY INTEGRITY........................................... 1
Chapter 1 The Meaning and Context of Safety Integrity Targets ........................... 3
1.1 Risk and the Need for Safety Targets.......................................................................... 3
1.2 Quantitative and Qualitative Safety Target ................................................................. 6
1.3 The Life-Cycle Approach ............................................................................................ 9
Section 7.1 of Part 1.....................................................................................................9
1.4 Steps in the Assessment Process ............................................................................... 13
Step 1. Establish Functional Safety Capability (i.e., Management)..........................13
Step 2. Establish a Risk Target ..................................................................................13
Step 3. Identify the Safety Related Function(s).........................................................13
Step 4. Establish SILs for the Safety-Related Elements ...........................................13
Step 5. Quantitative Assessment of the Safety-Related System ...............................14
Step 6. Qualitative Assessment Against the Target SILs ..........................................14
Step 7. Establish ALARP...........................................................................................14
1.5 Costs ........................................................................................................................... 15
1.5.1 Costs of Applying the Standard ...................................................................... 15
1.5.2 Savings from Implementing the Standard....................................................... 15
1.5.3 Penalty Costs from Not Implementing the Standard ...................................... 15
1.6 The Seven Parts of IEC 61508 .................................................................................. 16
1.7 HAZOP (Hazard and Operability Study) .................................................................. 19
1.7.1 Objectives of a HAZOP................................................................................... 20
1.7.2 HAZOP Study Team........................................................................................ 20
1.7.3 Typical Information Used in the HAZOP....................................................... 21
1.7.4 Typical HAZOP Worksheet Headings ............................................................ 22
1.7.5 Risk Ranking ................................................................................................... 23
1.7.6 Quantifying Risk.............................................................................................. 23
v
vi Contents
Chapter 2 Meeting IEC 61508 Part 1.............................................................. 25
2.1 Establishing Integrity Targets .................................................................................... 25
2.1.1 The Quantitative Approach ............................................................................. 25
2.1.2 Layer of Protection Analysis........................................................................... 34
2.1.3 The Risk Graph Approach............................................................................... 36
2.1.4 Safety Functions .............................................................................................. 38
2.1.5 “Not Safety-Related”....................................................................................... 39
2.1.6 SIL 4 ................................................................................................................ 39
2.1.7 Environment and Loss of Production.............................................................. 40
2.1.8 Malevolence and Misuse ................................................................................. 40
2.2 “As Low as Reasonably Practicable” ........................................................................ 40
2.3 Functional Safety Management and Competence..................................................... 44
2.3.1 Functional Safety Capability Assessment ....................................................... 44
2.3.2 Competency ..................................................................................................... 44
2.3.3 Independence of the Assessment..................................................................... 48
2.3.4 Hierarchy of Documents.................................................................................. 48
2.3.5 Conformance Demonstration Template........................................................... 49
IEC 61508 Part 1......................................................................................................... 49
2.4 Societal Risk .............................................................................................................. 50
2.4.1 Assess the Number of Potential Fatalities ...................................................... 50
2.4.2 It Is Now Necessary to Address the Maximum Tolerable Risk ..................... 50
2.4.3 The Propagation to Fatality ............................................................................. 51
2.4.4 Scenarios with Both Societal and Individual Implications............................. 52
2.5 Example Involving Both Individual and Societal Risk............................................. 52
2.5.1 Individual Risk Argument ............................................................................... 52
2.5.2 Societal Risk Argument................................................................................... 53
2.5.3 Conclusion ....................................................................................................... 55
Chapter 3 Meeting IEC 61508 Part 2.............................................................. 57
3.1 Organizing and Managing the Life Cycle................................................................. 57
Sections 7.1 of the Standard: Table ‘1’......................................................................57
3.2 Requirements Involving the Specification................................................................. 59
Section 7.2 of the Standard: Table B1 (avoidance) ...................................................59
3.3 Requirements for Design and Development.............................................................. 60
Section 7.4 of the Standard: Table B2 (avoidance) ...................................................60
3.3.1 Features of the Design..................................................................................... 60
Sections 7.4.1e7.4.11 excluding 7.4.4 and 7.4.5 ......................................................60
3.3.2 Architectures (i.e., SFF) .................................................................................. 63
Section 7.4.4 Tables ‘2’ and ‘3’ .................................................................................63
3.3.3 Random Hardware Failures ............................................................................. 66
Section 7.4.5 ...............................................................................................................66
3.4 Integration and Test (Referred to as Verification)..................................................... 66
Section 7.5 and 7.9 of the Standard Table B3 (avoidance) .......................................66
Contents vii
3.5 Operations and Maintenance ..................................................................................... 67
Section 7.6 Table B4 (avoidance) ..............................................................................67
3.6 Validation (Meaning Overall Acceptance Test and the Close Out of Actions) ....... 67
Section 7.3 and 7.7: Table B5 ....................................................................................67
3.7 Safety Manuals........................................................................................................... 68
Section 7.4.9.3e7 and App D ....................................................................................68
3.8 Modifications.............................................................................................................. 68
Section 7.8 ..................................................................................................................68
3.9 Acquired Subsystems................................................................................................. 68
3.10 “Proven in Use” (Referred to as Route 2s in the Standard)...................................... 69
3.11 ASICs and CPU Chips............................................................................................... 70
(a) Digital ASICs and User Programmable ICs.........................................................70
Section 7.4.6.7 and Annex F of the Standard ............................................................70
(b) Digital ICs with On-Chip Redundancy (up to SIL 3) .........................................70
Annex E of the Standard ............................................................................................70
3.12 Conformance Demonstration Template ..................................................................... 71
IEC 61508 Part 2 .......................................................................................................... 71
Chapter 4 Meeting IEC 61508 Part 3.............................................................. 79
4.1 Organizing and Managing the Software Engineering............................................... 79
4.1.1 Section 7.1 and Annex G of the Standard Table “1” ..................................... 79
4.2 Requirements Involving the Specification................................................................. 83
4.2.1 Section 7.2 of the Standard: Table A1............................................................ 83
4.3 Requirements for Design and Development.............................................................. 83
4.3.1 Features of the Design and Architecture......................................................... 83
4.3.2 Detailed Design and Coding ........................................................................... 84
4.3.3 Programming Language and Support Tools.................................................... 84
4.4 Integration and Test (Referred to as Verification)..................................................... 85
4.4.1 Software Module Testing and Integration....................................................... 85
4.4.2 Overall Integration Testing.............................................................................. 85
4.5 Validation (Meaning Overall Acceptance Test and Close Out of Actions).............. 86
Paragraphs 7.3, 7.7, 7.9, Table A7 .............................................................................86
4.6 Safety Manuals........................................................................................................... 86
(Annex D) ...................................................................................................................86
4.7 Modifications.............................................................................................................. 87
Paragraph 7.6, 7.8, Table A8 and B9.........................................................................87
4.8 Alternative Techniques and Procedures..................................................................... 87
4.9 Data-Driven Systems ................................................................................................. 88
4.9.1 Limited Variability Configuration, Limited Application Configurability ...... 88
4.9.2 Limited Variability Configuration, Full Application Configurability............. 88
4.9.3 Limited Variability Programming, Limited Application Configurability....... 89
4.9.4 Limited Variability Programming, Full Application Configurability............. 89
viii Contents
4.10 Some Technical Comments ....................................................................................... 89
4.10.1 Static Analysis............................................................................................... 89
4.10.2 Use of “Formal” Methods............................................................................. 90
4.10.3 PLCs (Programmable Logic Controllers) and their Languages................... 90
4.10.4 Software Reuse.............................................................................................. 91
4.10.5 Software Metrics ........................................................................................... 92
4.11 Conformance Demonstration Template ..................................................................... 92
IEC 61508 Part 3........................................................................................................... 92
Chapter 5 Reliability Modeling Techniques ...................................................... 101
5.1 Failure Rate and Unavailability ............................................................................... 101
5.2 Creating a Reliability Model ................................................................................... 101
5.2.1 Block Diagram Analysis................................................................................ 102
5.2.2 Common Cause Failure (CCF)...................................................................... 110
5.2.3 Fault Tree Analysis........................................................................................ 115
5.3 Taking Account of Auto Test .................................................................................. 116
5.4 Human Factors ......................................................................................................... 119
5.4.1 Addressing Human Factors ........................................................................... 119
5.4.2 Human Error Rates ........................................................................................ 121
5.4.3 A Rigorous Approach.................................................................................... 123
Chapter 6 Failure Rate and Mode Data.......................................................... 125
6.1 Data Accuracy.......................................................................................................... 125
6.2 Sources of Data ........................................................................................................ 127
6.2.1 Electronic Failure Rates ................................................................................ 128
6.2.2 Other General Data Collections .................................................................... 128
6.2.3 Some Older Sources ...................................................................................... 129
6.2.4 Manufacturer’s Data ...................................................................................... 130
6.2.5 Anecdotal Data .............................................................................................. 130
6.3 Data Ranges and Confidence Levels ....................................................................... 130
6.4 Conclusions .............................................................................................................. 132
Chapter 7 Demonstrating and Certifying Conformance ..................................... 135
7.1 Demonstrating Conformance ................................................................................... 135
7.2 The Current Framework for Certification................................................................ 135
7.3 Self-Certification (Including Some Independent Assessment) ............................... 137
7.3.1 Showing Functional Safety Capability (FSM) as Part of
the Quality Management System .................................................................. 137
7.3.2 Application of IEC 61508 to Projects/Products............................................ 137
7.3.3 Rigor of Assessment...................................................................................... 138
7.3.4 Independence ................................................................................................. 138
Contents ix
7.4 Preparing for Assessment ........................................................................................ 138
7.5 Summary .................................................................................................................. 140
PART B: SPECIFIC INDUSTRY SECTORS .................................................... 143
Chapter 8 Second Tier DocumentsdProcess, Oil and Gas Industries ................. 145
8.1 IEC International Standard 61511: Functional SafetydSafety
Instrumented Systems for the Process Industry Sector (Second Edition
to be Published in 2016) .......................................................................................... 145
8.1.1 Organizing and Managing the Life Cycle..................................................... 147
8.1.2 Requirements Involving the Specification .................................................... 148
8.1.3 Requirements for Design and Development ................................................. 149
8.1.4 Integration and Test (Referred to as Verification) ........................................ 152
8.1.5 Validation (Meaning Overall Acceptance Test and Close
Out of Actions) .............................................................................................. 152
8.1.6 Modifications ................................................................................................. 152
8.1.7 Installation and Commissioning.................................................................... 153
8.1.8 Operations and Maintenance ......................................................................... 153
8.1.9 Conformance Demonstration Template......................................................... 153
8.1.10 Prior Use ........................................................................................................ 162
8.2 Institution of Gas Engineers and Managers IGEM/SR/15: Programmable
Equipment in Safety-Related Applicationsd5th Edition 2010.............................. 165
8.3 Guide to the Application of IEC 61511 to Safety Instrumented Systems
in the UK Process Industries ................................................................................... 165
8.4 ANSI/ISA-84.00.01 (2004)dFunctional Safety, Instrumented Systems
for the Process Sector .............................................................................................. 166
8.5 Recommended Guidelines for the Application of IEC 61508 and IEC
61511 in the Petroleum Activities on the Norwegian Continental
Shelf OLF-070dRev 2, 2004.................................................................................. 166
8.6 Energy Institute: Guidance on Safety Integrity Level (SIL) Determination,
Expected to be Published 2016 ............................................................................... 168
Chapter 9 Machinery Sector .......................................................................... 169
9.1 EN ISO 12100:2010................................................................................................. 169
9.2 EN ISO 13849.......................................................................................................... 171
The Assessment ........................................................................................................174
9.2.1 Systematic Failures........................................................................................ 175
9.3 BS EN 62061 ........................................................................................................... 176
9.3.1 Targets............................................................................................................ 176
9.3.2 Design ............................................................................................................ 177
9.3.3 Template Assessment Checklist for BS EN 62061 ...................................... 178
9.4 BS EN ISO 13850: 2015 Safety of MachinerydEmergency
StopdPrinciples for Design .................................................................................... 186