Safety Critical Systems Handbook - 1st Edition - ISBN: 9780080967813, 9780080967820

Safety Critical Systems Handbook

1st Edition

A Straight forward Guide to Functional Safety, IEC 61508 (2010 EDITION) and Related Standards, Including Process IEC 61511 and Machinery IEC 62061 and ISO 13849

Authors: David Smith Kenneth Simpson
Hardcover ISBN: 9780080967813
eBook ISBN: 9780080967820
Imprint: Butterworth-Heinemann
Published Date: 11th November 2010
Page Count: 288
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Safety Critical Systems Handbook: A Straightfoward Guide to Functional Safety, IEC 61508 (2010 Edition) and Related Standards, Including Process IEC 61511 and Machinery IEC 62061 AND ISO 13849, Third Edition, offers a practical guide to the functional safety standard IEC 61508. The book is organized into three parts. Part A discusses the concept of functional safety and the need to express targets by means of safety integrity levels. It places functional safety in context, along with risk assessment, likelihood of fatality, and the cost of conformance. It also explains the life-cycle approach, together with the basic outline of IEC 61508 (known as BS EN 61508 in the UK). Part B discusses functional safety standards for the process, oil, and gas industries; the machinery sector; and other industries such as rail, automotive, avionics, and medical electrical equipment. Part C presents case studies in the form of exercises and examples. These studies cover SIL targeting for a pressure let-down system, burner control system assessment, SIL targeting, a hypothetical proposal for a rail-train braking system, and hydroelectric dam and tidal gates.

Key Features

  • The only comprehensive guide to IEC 61508, updated to cover the 2010 amendments, that will ensure engineers are compliant with the latest process safety systems design and operation standards
  • Helps readers understand the process required to apply safety critical systems standards
  • Real-world approach helps users to interpret the standard, with case studies and best practice design examples throughout


Chemical, Process, Plant, Oil and Gas and related systems safety engineers

Table of Contents

A quick overview

The 2010 version of IEC 61508


Part A: The Concept of Safety Integrity 1

Chapter 1 The Meaning and Context of Safety Integrity Targets

1.1 Risk and the Need for Safety Targets

1.2 Quantitative and Qualitative Safety Targets

1.3 The Life-cycle Approach

1.4 Steps in the Assessment Process

1.5 Costs

1.6 The Seven Parts of IEC 61508

Chapter 2 Meeting IEC 61508 Part 1

2.1 Establishing Integrity Targets

2.2 ALARP (“As low as Reasonably Practicable

2.3 Functional Safety Management and Competence

IEC 61508 Part 1

Chapter 3 Meeting IEC 61508 Part 2

3.1 Organizing and Managing the Life-cycle

3.2 Requirements Involving the Specification

3.3 Requirements for Design and Development

3.4 Integration and Test (Referred to as Verification

3.5 Operations and Maintenance

3.6 Validation (Meaning Overall Acceptance Test and the Close Out-of Actions)

3.7 Safety Manuals

3.8 Modifications

3.9 Acquired Sub-systems

3.10 “Proven in Use” (Referred to as Route 2s in the Standard

3.11 ASICs and CPU Chips

3.12 Conformance Demonstration Template

IEC 61508 Part 2

Chapter 4 Meeting IEC 61508 Part 3

4.1 Organizing and Managing the Software Engineering

4.2 Requirements Involving the Specification

4.3 Requirements for Design and Development

4.4 Integration and Test (Referred to as Verification

4.5 Validation (Meaning Overall Acceptance Test and Close Out of Actions

4.6 Safety Manuals

4.7 Modifications

4.8 Alternative Techniques and Procedures

4.9 Data Driven Systems

4.10 Some Technical Comments

4.11 Conformance Demonstration Template

IEC 61508 Part 3

Chapter 5 Reliability Modeling Techniques

5.1 Failure Rate and Unavailability

5.2 Creating a Reliability Model

5.3 Taking Account of Auto-test

5.4 Human Factors

Chapter 6 Failure Rate and Mode Data

6.1 Data Accuracy

6.2 Sources of Data

6.3 Data Ranges and Confidence Levels

6.4 Conclusions

Now try the exercise and the example, which are Chapters 11 and 12.

Chapter 7 Demonstrating and Certifying Conformance

7.1 Demonstrating Conformance

7.2 The Current Framework for Certification

7.3 Self Certification (Including Some Independent Assessment

7.4 Preparing for Assessment

7.5 Summary

Part B: Specific Industry Sectors

Chapter 8 Second-tier Documents e Process, Oil and Gas Industries

8.1 IEC International Standard 61511: Functional Safety - Safety Instrumented Systems for the Process Industry Sector

8.2 Institution of Gas Engineers and Managers IGEM/SR/15: Programmable Equipment in Safety-related Applications e 5th Edition 2010

8.3 Guide to the Application of IEC 61511 to Safety Instrumented Systems in the UK Process Industries

8.4 ANSI/ISA-84.00.01 (2004) e Functional Safety, Instrumented Systems for the Process Sector

8.5 Recommended Guidelines for the Application of IEC 61508 and IEC 61511 in the Petroleum Activities on the Norwegian Continental Shelf OLF-070

Chapter 9 Machinery Sector

9.1 EN ISO 14121

9.2 EN ISO 13849

9.3 BS EN 62061

Chapter 10 Other Industry Sectors

10.1 Rail

10.2 UK MOD Documents

10.3 Earth Moving Machinery

10.4 C Coding Standard (MISRA e Motor Industries Research Association) e Development Guidelines for Vehicle Based Programmable Systems

10.5 Automotive

10.6 IEC International Standard 61513: Nuclear Power Plants - Instrumentation and Control for Systems Important to Safety - General Requirements for Systems

10.7 Avionics

10.8 Medical e IEC 60601 Medical Electrical Equipment, General Requirements for Basic Safety and Essential Performance

10.9 Stage and Theatrical Equipment

10.10 Electrical Power Drives

10.11 Documents which are now Withdrawn

Part C: Case Studies in the Form of Exercises and Examples

Chapter 11 Pressure Control System (Exercise)

11.1 The Unprotected System

11.2 Protection System

11.3 Assumptions

11.4 Reliability Block Diagram

11.5 Failure Rate Data

11.6 Quantifying the Model

11.7 Proposed Design and Maintenance Modifications

11.8 Modeling Common Cause Failure (Pressure Transmitters)

11.9 Quantifying the Revised Model

11.10 ALARP

11.11 Architectural Constraints

Chapter 12 Burner Control Assessment (Example)

Executive Summary & Recommendations

12.1 Objectives

12.2 Integrity Requirements

12.3 Assumptions

12.4 Results

12.5 Failure Rate Data

12.6 References

Annex I Fault tree details

Chapter 13 SIL targeting e some practical examples

13.1 A Problem Involving EUC/SRS Independence

13.2 A hand-held Alarm Intercom, Involving Human error in the Mitigation

13.3 Maximum Tolerable Failure Rate Involving Alternative Propagations to Fatality

13.4 Hot/cold Water Mixer Integrity

13.5 Scenario Involving High Temperature Gas to a Vessel

13.6 Example using the LOPA Technique

Chapter 14 Hypothetical Rail Train Braking System (Example)

14.1 The Systems

14.2 The SIL Targets

14.3 Assumptions

14.4 Failure Rate Data

14.5 Reliability Models

Chapter 15 Rotorcraft Accidents and Risk Assessment

15.1 Helicopter Incidents

15.2 Floatation Equipment Risk Assessment

Chapter 16 Hydro-electric Dam and Tidal Gates

16.1 Flood-gate Control System

16.2 Spurious opening of either of two tidal lock gates involving a trapped vessel

Appendix 1 Functional Safety Management

Appendix 2 Assessment Schedule (Checklist)

Appendix 3 Betaplus CCF Model, Scoring Criteria

Appendix 4 Assessing Safe Failure Fraction and Diagnostic Coverage

Appendix 5 Answers to Examples

Appendix 6 References

Appendix 7 Quality and Safety Plan

Appendix 8 Some Terms and Jargon of IEC 61508



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© Butterworth-Heinemann 2011
11th November 2010
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About the Author

David Smith

Dr David J Smith is the Proprietor of Technis Consultancy. He has written numerous books on Reliability and Safety over the last 35 years. His FARADIP database has become widely used, and his other software packages are also used throughout the profession. His PhD thesis was on the subject of reliability prediction and common cause failure. He contributed to the first drafting of IEC 61508 and chairs the IGEM panel which produces SR/15 (the gas industry safety related guidance). David is past President of the Safety and Reliability Society.

Affiliations and Expertise

Independent Consultant, Technis, Tonbridge, UK

Kenneth Simpson

Kenneth G. L. Simpson is Managing Director of Engineering Safety Consultants Ltd and has been associated with safety related systems design and also with their assessment for over 40 years. He is a member of both the IEC61508 and IEC61511 drafting committees and the IGEM (SR15) panel, which writes the gas industry guidance. Following a career in aerospace, Ken has spent over 35 years in the control and safety system industry, has written a number of papers on the topic and gives frequent lectures.

Affiliations and Expertise

Independent Consultant, ESC, UK

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