There is an analogy in Process Safety, that there are several layers of protection before a risk will be realised and an incident may occur. This is often likened to an onion – the LOPA onion 🧅
Our process safety team have found a multitude of uses for the LOPA methodology, because of how useful it can be at quantifying risk, and identifying gaps.
Some example of these include:
⚙️The traditional “Layers of Protection Analysis” where a safety trip is known and the LOPA tool is used to assess the reliability required of this trip (new or existing). Having a sound LOPA is required as part of the functional safety lifecycle, as it helps define the safety requirement specification for a SIF.
⚙️A “Gap Analysis” method, where there may be no safety trip, or it may be a simple BPCS trip, and the LOPA is used to identify if there is a risk gap present and how big it is.
⚙️ALARP demonstration, where the LOPA tool can be used to quantify the existing risk, to demonstrate whether risks are ALARP. Additional versions can be developed to show the impact of adding new layers of protection, for use in cost benefit analysis.
⚙️For input to studies such as Occupied Buildings Risk Assessment, where a multitude of complex scenarios may all contribute to one hazardous event, and the LOPA tool can be used to group these together for clear recording.
No two companies present a LOPA in the same way, and many can be confusingly laid out and only interpretable by the author. In our opinion, this is no good as the final output must be understandable by any competent engineer looking to understand the risk being assessed.
A good LOPA will therefore be clearly laid out, with all the information required presented in the one document. We also include a cover report – no matter what the study being carried out, which will include factors such as sensitivity analysis, and any recommendations on how to close those gaps – or add more layers to the onion!
How do you use LOPA? Contact Process Safety Displine Lead Owen Llanwarne to find out more.
