SIL Certification vs Prior Use: Why ‘Certified’ Devices Can Make You Less Safe

In this webinar-style discussion, the speakers challenge the common belief that safety instrumented functions require SIL-certified field devices, arguing that ripping out existing brownfield instruments for “SIL stickers” can increase cost and even reduce safety. They emphasize that IEC 61511 and IEC 61508 focus on managing actual SIS performance over time through closed-loop feedback using maintenance and operations data (tests, failures, bypasses, demands) to compare assumed vs real performance and drive modifications. Certification assesses devices against IEC 61508 (not IEC 61511), excludes process interfaces and harsh service conditions, and may rely on optimistic assumptions (including what gets labeled “systematic”), so certified failure rates can be “too good to be true” without service modifiers. They present prior use as a practical, user-documented approach supported by data collection, approved vendor lists, and statistically valid operating history, with war stories showing how certified replacements failed in real service and how poor “as found” reporting can hide true failure rates. 00:00 SIL Sticker Myth 01:25 Brownfield vs Greenfield 02:32 Logic Solver Reality Check 05:45 SIL Certified vs Prior Use 07:24 Why Certification Isn’t in Standards 09:19 Prior Use Pays Off 12:24 Closed Loop Safety Data 17:43 Device Selection Decision Tree 24:33 Failure Rate Feedback Loop 26:00 Harsher Than Factory Conditions 27:31 Certified Data Assumptions 28:42 Systematic vs Random Failures 30:15 Diagnostics Too Good 30:59 Need Service Modifiers 32:07 Prior Use Beats Certified 34:55 Valve Pass Fail Logic 36:52 Gaming Valve Failure Rates 39:41 Prior Use Burden Myth 41:36 War Stories New Tech 44:45 How Much Data Needed 46:32 Q&A Tools and FSA4 49:50 Reporting Failures Honestly