332 / 975
The reader might conclude that the standards today require competent and independent review groups because
system designers don’t trust product designers or other application designers and therefore we would rather be
safe than sorry.
6. Summary
In summary:
§
Best in Class companies link safety to their success and invest in programs and systems to reduce
their risk
§
Engineers have attempted to reduce risk by minimizing the potential for common cause failures
§
Common cause failures can occur in products (hardware or software) or the implementation of the
application
§
The industry has conceived best practices (i.e. FSMS) to minimize the impact of human error
§
Human factors can’t be ignored in the design, particularly in the application design
§
Enforcement of these best practices via formal FSMS has proven to be a way to reduce the risk
introduced by engineers…it’s vital!
7. References
[1] IEC 61508 Functional safety of electrical/electronic/programmable electronic safety-related systems
International Standard 2010
[2] Integrating Control and Safety: Where to draw the line.
Robin McCrea-Steele, TÜV FSExpert, Invensys-Premier Consulting Services
[3] Common Cause and Common Sense, Designing Failure Out of Your SIS
Angela E. Summers, Ph.D. and Glenn Raney, Oct 2000
[4] Integrated but separate, Advances in integrated and safety control,
Roger Prew, ABB , June 2009
[5] IEC 61511 Functional safety - Safety instrumented systems for the process industry sector International
Standard 2003
[6] Providing Independent Layers of Protection with Integrated Safety Systems
Luis M. Duran, ABB and Ron Johnson Dow Chemical, Oct 2009
[7] Out of control: Why control systems go wrong and how to prevent failure
HSE Books ISBN 0-7176-2192-8