Abstract

Both Hazard and operability study (HAZOP) and Layer of Protection Analysis (LOPA) are two recognised techniques (or ‘tools') in the Process safety toolkit. Application of these techniques however has historically been restricted to a limited range of operations within upstream. This paper will describe how these tools can, and have been, successfully applied in broader applications.

HAZOP was first applied in the heavy organic chemicals division of Imperial Chemical Industries in 1963. The technique was subsequently developed and matured over the following years. Today in the upstream industry HAZOP is typically applied to both existing process operations and new projects. LOPA generally follows after a HAZOP to perform a semi-quantitative assessment of the event likelihood. Application of these techniques however has historically been restricted to a limited number of operations within upstream. The objectives of the paper are to i) describe examples where HAZOP has been successfully applied to novel operations and activities ii) show how LOPA can be applied, not just for determination of Safety Integrity Level (SIL) but to hazards not associated with an instrumented function and iii) demonstrate that broader application of these tools can lead to and improved understanding of risk and, through effective risk reduction, create value for operating companies.

An overview of potential challenges associated with implementing this adapted approach towards HAZOP is described, but also possible solutions. Following this the links between HAZOP and LOPA, including the information flows from one study to another are re-capped. This includes highlighting the difference between safeguards and layers of protection and qualitative risk assessment (HAZOP) versus semi-quantitative (LOPA). Current triggers for applying LOPA are compared to other approaches that result in a broader perspective and applicability. The key here is to demonstrate that there are a number of additional hazards that may be identified through HAZOP study, but for which an instrumented function may not be provided. As a result these are currently not always taken forward for further, semi-quantitative assessment. This current approach therefore limits our understanding of the associated risk.

In summary, through the use of example scenarios, the paper reveals some of the limitations resulting from restricted application of HAZOP and LOPA. The intent is to raise awareness of how companies are applying these tools to analyse additional operations or activities and, as a result, reduce the frequency of high severity events. The key conclusion is that these existing tools i) with some effort can be readily applied to new / novel areas and ii) can help management understanding of risk and provide assurance that these risks are being adequately managed. In short to fully understand the Process Safety risks associated with our projects and operations we must look to broaden the application of both HAZOP and LOPA tools.

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