Layers Of Protection Analysis

With the LOPA plug-in module added to the BowTieXP software, it is now possible to perform the semi-quantitative risk analysis called LOPA, on your bowtie. The results can be shown directly on the BowTie diagram or in one of the LOPA reports.

Bowtie - based Layers Of Protection Analysis

Layers of Protection Analysis (LOPA) is a semi-quantitative risk analysis in which the frequency of a negative event is calculated according to the risk reduction by the independent protection layers (IPLs). In bowtie-based LOPA, you calculate the frequency of a consequence, given the threats and IPLs in play. The LOPA plug-in allows you to fill in the initial frequencies of the threats and the probability of failure on demand (PFD) for the barriers. You can also add target frequencies for the consequences and the top event. The software then automatically calculates the relevant numbers, like the consequence frequency, and displays them on the bowtie if required.

How to use lopa plugin?

The plug-in is very easy to use. When you double click on a Threat, Barrier, Consequence or the Hazard/Top-event, you will see an additional tab on top of the edit screen called ‘Lopa’. You can use this tab to fill in the relevant parameters. The software will perform the calculations and indicate whether the Target Frequencies are met or not. If you adjust the parameters, the software will automatically update the calculations.

The LOPA can be done in a more traditional way with just a left sided bowtie, or using the full bowtie to extend the method itself. There are also reports available for both the more traditional LOPA and the bowtie-based LOPA.