Een praktische aanpak voor het voorspellen van majeure ongevallen in de procesindustrie op basis van de barriere status op scenario niveau

OCI Nitrogen aims to build up knowledge of (leading) indicators that provide insight in advance into the process safety performance of their ammonia production process. Two sub-studies have already been published in TtA. The first sub-study focused on ranking the most dangerous process units of the ammonia production process. In the second sub-study, the most important static equipment of the ammonia production process was mapped, which are related to mechanical failure mechanisms. This manuscript describes the third part of the research with the question of whether - based on the status of the barrier system – indicators can be derived that provide advance information about the development and likelihood of the major accident processes in the ammonia production process.

The accident processes are visualized as scenarios in bowties. This research focuses on the status of the preventive barriers on the left-hand side of the bowtie. Both the quality – expressed in reliability/availability and effectiveness - and the activation of the barrier system give an indication of the development of the accident scenarios and the likelihood of the central event. This likelihood is calculated as a loss of risk reduction compared to the original design. The calculations of this assessment result in indicators called "preventive barrier indicators". They provide an indication of the likelihood of the scenario. This likelihood is not an absolute value, but rather an indication of the change in the status quo which should initiate further action. This manuscript shows what this action must be and what the urgency of the action is.

In the presented concept, every technical change of the barrier system is used to determine the current development and likelihood of the scenario. If the quality parameters of the barriers are accommodated in an automated system, the preventive barrier indicator can be calculated and displayed in real time. This is different for non-technical changes: they will have to be entered and processed manually.