News & Events.
exida Presented and Exhibited at ADIPEC 2015
November 23, 2015
Greg Chantler, exida senior safety consultant presented and exhibited at ADIPEC 2015, which was held November 7-10, 2015 in Abu Dhabi, UAE. The presentation was titled “Getting Realistic Failure Rate Data for SIS Verification.”
Presentation Title: Getting Realistic Failure Rate Data for SIS Verification
Realistic Failure Data is important for good safety function design in a performance based system like IEC 61511. Failure data comes from two types of analysis – estimation and prediction. Reputable sources of estimated failure data include OREDA and DOW as that data has been vetted and reviewed by experts. Estimation techniques however require aggregation of many different applications and devices to achieve statistically significant data volumes. Predictive techniques use a combination of design strength analysis and/or testing to predict failure rates. The results from these different methods may vary. Which method is correct? Which method is best?
This paper explains the failure data analysis methods, there limitations, and compares results from several reputable sources. Differences are explained. The data comparisons show how limits can be established to validate any set of failure data. Potentially unrealistic data can be flagged for a more detailed analysis. By using this data integrity checking method, the integrity of safety instrumented function designs can be maintained.
