- The document discusses a thesis defense for a universal interface for off-the-shelf safety instrumentation and controls. - It analyzes requirements from different industries like process, nuclear, and defense and finds compatibility at the component level according to IEC 61508 standards. - Examples are given of how individual components like transmitters and digital valve controllers that are certified to IEC 61508 can meet requirements across industries, lowering risks and costs compared to industry-specific solutions.

1. THESIS DEFENSE:
A UNIVERSAL
INTERFACE FOR OFF-
THE-SHELF SAFETY
INSTRUMENTATION
AND CONTROLS
Andrew Nack

2. Outline
• Introduction
• Multi-Industry Survey
• Compare and Contrast
• Universal Interface
• Conclusion

3. Introduction
• High risk industries require reliable and
correct safety systems
• Safety system reliability and correctness
must be provable
• Typical manufacturers may not achieve
the required levels of reliability and
correctness, or just can’t prove it

4. Introduction
• Each high risk industry has its own set of
laws, requirements, and guidelines
• Standardization could benefit
manufacturers and industries
• IEC 61508 is intended to be a non-industry
specific functional safety standard

5. Introduction
IEC 61508 (Non-industry specific)
• Part 1- general requirements
• Part 2- system and hardware requirements
• Part 3- software requirements
• Part 4- definitions and abbreviations
• Part 5- examples of determination of SILs
• Part 6- guidelines for Parts 2 and 3
• Part 7- overview of techniques and measures

6. Introduction
IEC 61508 (Non-industry specific)
• Safety Integrity Levels: 1, 2, 3, or 4
• Sample Implementation:

7. Introduction
SIL
Classification Design IntegrityInterface

8. Multi-Industry Survey
• Process Industry
• Commercial Nuclear Power Generation
• United States Department of Defense

9. Multi-Industry Survey
• Process Industry Includes:
• Chemicals
• Oil Refineries
• Oil and Gas Production
• Pulp and Paper
• Non-nuclear Power Production

10. Multi-Industry Survey
• Process Industry
• Relatively low level of regulation
• Early adoption of IEC 61508
• Large customer base for manufacturers
• SIL 4 applications are unlikely

11. Multi-Industry Survey
Commercial Nuclear Power Generation
• International Atomic Energy Agency (IAEA)
• IEEE Standards
• United States
• Asian Pacific Countries
• IEC Standards
• European Union

12. Multi-Industry Survey
Commercial Nuclear Power Generation
• Relatively high regulation
• Currently only limited adoption and utilization of IEC
61508
• Struggling with the incorporation of digital equipment
into safety systems
• Small customer base for manufacturers, and therefore,
has the greatest potential to benefit from IEC 61508

13. Multi-Industry Survey
United States Department of Defense
Includes: Army, Navy, and Airforce
• Wide variety of applications and requirements
• No broad adoption of IEC 61508
• A potentially large customer base for
manufacturer

14. Compare and Contrast
Categories for comparison:
• Classification of systems and components
• Defending against random failures
• Preventing systematic faults
• Suitability evaluations of “off-the-shelf”
equipment

15. Compare and Contrast
Classification of systems and components
• Deterministic vs Probabilistic
• Probability accounts for variability of risk
• Qualitative vs Quantitative
• Levels of Rigor
• Standardizes efforts to establish design integrity
• Each industry is different but all could map to
the SILs

16. Compare and Contrast
Defending against random hardware failures
• Single failure criterion vs probabilistic
reliability analysis
• Different at the system level but
compatible at the component level

17. Compare and Contrast
Preventing systematic faults
• Lifecycle processes and designing
techniques
• Built-in safety features
• Design analysis and verification & validation
• Hazard analysis

18. Compare and Contrast
Preventing systematic faults
• Common cause failure prevention
• Diversity and defense in-depth (D3) vs
general guidance
• Environmental qualification
• Some applications exceed typical qualification
levels

19. Compare and Contrast
Suitability evaluations of “off-the-shelf”
equipment
• Functional suitability
• Review design processes
• Operating history

20. Compare and Contrast
Category
Significance of
Differences at the
System Level
Significance of
Differences at the
Component Level
Classification Schemes
 Probabilistic vs Deterministic
 Level of Rigor
High
High
Low
Low
Defense against Random Hardware
Failures
High Low
Preventing Systematic Faults
 Lifecycle Processes
 Built-in Design Safety Features
 Design Analysis, Verification, and
Validation
 Hazard Analysis
 Common Cause Failure Prevention
 Environmental Qualification
Low
Low
Low
Low
High
High
Low
Low
Low
Low
Low
High
Suitability Evaluations of “Off-the-Shelf”
Equipment
Low Low

21. Universal Interface
• IEC 61508 is a non-industry specific,
technical requirements interface
• Compatibility of technical requirements at
the component level
• Third-party certification is a positive
indicator

22. Universal Interface
Example: Moore Industries STZ Transmitter
• SIL 3 Capable
• Defense against random failures
• Preventing systematic faults
• Lifecycle processes and designing techniques
• Built-in safety features
• Design analysis and verification & validation
• Hazard analysis
• Common cause failure prevention
• Environmental qualification (may require extra effort)

23. Universal Interface
Example: Fisher Controls DVC6200 SIS Digital
Valve Controller
• SIL 3 Capable
• Defense against random failures
• Preventing systematic faults
• Lifecycle processes and designing techniques
• Built-in safety features
• Design analysis and verification & validation
• Hazard analysis
• Common cause failure prevention
• Environmental qualification (may require extra effort)

24. Conclusion
• A universal interface at the component
level is feasible and beneficial
• IEC 61508 should be that interface
• Third-party certification removes
significant risk to industries

25. Questions