Congratulations! You’ve completed the Analysis and Realization phases of the Safety Lifecycle, and are about to begin the Operation phase, but what’s next? Well obviously you need to do proof testing, but is there anything else? You may be familiar with the figure below:
The functional safety standards require that you record any demands and failures that occur during normal operation, as well as the results of all your proof testing. Furthermore, you are expected to periodically compare your actual performance with your assumed performance. In other words, do demands occur as frequently as you expected? More frequent means that the risk is higher than you had estimated; less frequent means the actual risk seems to be lower than you expected. Similarly does the equipment reliability match your assumptions? Are the field failure rates lower or higher than assumed? If they are higher you obviously do not achieve the safety integrity you needed to achieve, if failure rates are lower than you could argue that for future projects you could justify the use of lower failure rates and therefore, for example, extend proof test intervals.
So how can you record all this information you need?
exida has just released a new product called SILStat™, which allows you to record functional safety related statistics. This goes beyond the performance of your SIF, as it includes the performance of layers of protection that you have defined as part of your hazard and risk evaluation and SIL Selection. You can also include performance metrics for non-SIF and non-IPL equipment, record associated maintenance actions, etc.
SILStat™ also allows you to record demands and identify which protection layer caught the demand and which failed (if any). There is a built- in proof test generator, based on the exida Safety Equipment Reliability Handbook (SERH) database, which will allow you to define your proof tests stepwise with pass/fail criteria for each step. Then when you go out in the field you can record the results for each step. SILStat™ will then automatically determine if your proof test was successful or failed by evaluating the factual data recorded.
SILStat™ consists of three main pieces:
- SILStat™ Server: Where all information is recorded
- SILStat™ Workstation: A PC based program that allows configuration of the site, the devices, locations/addresses of the devices, proof tests, etc.;
- SILStat™ Recorder: A handheld device that you can take out into the field and use to record proof test, maintenance activities, etc