I’ve been teaching our FSE100 course now for nearly 10 years and it always amazes me that when teaching the course, the number of times I find that end users in the class are not really measuring the performance of their SIS.  In most cases, they are doing some measurements but not thoroughly and documenting the results is patchy and inconsistent.  Quite a few are using SAP to store the information, but it often requires manual intervention to input the data, especially from Proof Testing.  Here too, this doesn’t get done in a timely fashion.

It was partly for this reason that some of the changes to IEC61511, in the 2016 edition, focused on measuring performance.  After all, IEC61511 is a performance-based standard that requires end users to “periodically” measure performance and now why a Functional Safety Assessment (FSA4) is required to be specifically undertaken to measure performance.  Therefore, if we don’t do this, then how do we know that our SIS is achieving its target performance, as defined in the SRS?

Setting up the Key Performance Indicators (KPIs) to measure performance isn’t difficult to do and there are different ways of doing this (the use of Leading and Lagging Indicators is one method).  Many of these can be taken from the SRS itself.  For example, performing proof testing per the SRS is one.  If the SRS specifies a proof test interval of 12 months and is only performed every 18 months, then this will have a detrimental effect on the integrity of the SIFs (i.e. if the SIF was designed to be SIL 2 it could soon degrade to a SIL 1). Not analyzing any trips to root cause and/or investigating near misses are also other KPIs that should be recorded.  Near misses such as relief valves being triggered is an indication that all is not well and should be recorded and investigated and the number of occurrences reduced.  The number of Functional Safety Assessments and Functional Safety Audits being performed should also be recorded since these will help identify any non-conformances.  These are just some examples of KPIs that will give an indication of how well functional safety is being performed and followed.

Accidents, such as the Texas City Isomerization Explosion, in 2005, was the result of management not following up on incidents and audit reports that highlighted serious deficiencies, to ensure the proper resolution of these problems.  There have been other incidents since then that have also occurred due to poor implementation of Functional Safety.  By undertaking regular performance checks, potential serious problems could be identified and corrected before becoming major issues.  The IEC61511 committee has recognized that end users are not following through on the Operations and Maintenance (O&M) requirements properly, which is why the requirements have been strengthened.  If end users don’t follow through on the O&M requirements it may lead to future consequences.

Check out some of our webinars on the subject of Leading and Lagging Indicators and Operations and Maintenance requirements or look out for our training course on O&M, as well as the upcoming webinar on this topic.  Always remember, if you think safety’s expensive then try an accident!

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Tagged as:     Steve Gandy     SRS     SIS     Proof Test     IEC61511     FSE 100     CFSE  

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