Tech Tuesday: Quantitative LOPA with FT/ET

Joe Belland

Howdy, folks. As Jeremy has mentioned, this past Friday, April 4th, we hosted a webinar to demonstrate Isograph’s FaultTree+ tool. One of the topics we discussed was how you can use the Fault Tree and Event Tree features of the tool to perform a quantitative Layer Of Protection Analysis (LOPA). This post will serve as a little summary of that meeting, for anyone who was unable to attend.

The first stage of a LOPA might be done externally to a quantitative tool like Fault Tree. The first thing you’d want to do is identify hazards, determine an acceptable risk level for those hazards, and ask what you’re doing to mitigate them. This might have more in common with a Hazop study. Once you’ve identified your hazards and protection layers against those hazards, the next thing you might want to do is quantify it. How often will the hazard occur? How effectively will our layers of protection mitigate the risk of the hazards? Can we objectively rank these risks? This sounds like a job for Fault Tree and Event Tree analysis.

A Fault Tree can very easily be used to quantify a hazard. In fact, that’s the primary usage of the method. By coupling it with an Event Tree, we can find out how well that hazard is mitigated by protection systems. If you’re not familiar with it, Event Tree analysis is related to Fault Tree analysis. It uses a similar quantitative calculation. The difference is that, while Fault Trees examine the failure leading to a hazard, Event Trees examine the consequences following the hazard. Sometimes, when coupled together, they’re called “bowtie events”.

Yeah, it's cool. Bow ties are cool.

Continue reading Tech Tuesday: Quantitative LOPA with FT/ET

Performing a LOPA using FaultTree+

Jeremy Hynek

On Friday April 4th at 9am PST to learn more about applications of our FaultTree+ software. During this demonstration we will introduce our fault tree analysis software FaultTree+ and as an added bonus we will be discussing how to tie a fault tree to an event tree and perform a LOPA study. Layer of Protection Analysis, or LOPA, is a study developed to identify risk. By performing a LOPA on a system you can create a method for identify the actions available to mitigate the potential consequences of a particular risk. To do this we will start with likelihood of a particular hazard occurring, analyze the system using quantitative methods, and identify the mitigation measures against the hazards that have been identified.

Once the mitigating actions have been identified the probability of those hazards occurring can be reduced by implementing safeguards that bring the hazard into an acceptable level. An event tree is an excellent way to determine the consequences of successful, or the failure of, safeguards.

Basically, a LOPA is performed to identify the weakest points of a system and evaluate the safeguards in place to mitigate the consequences of that hazard.

To join this webinar: Register Here