The Flow Method: An improved Hazard and Operability Study methodology

Abstract The traditional Hazard and Operability Study (HAZOP) is a well‐established methodology in the chemical industry for hazard identification and risk analysis, also known as Process Hazard Analysis (PHA). However, its deviation‐based approach can lead to inefficiencies, fragmented reviews, and increased team fatigue. The Process Flow Failure Modes Analysis (PFFM) was introduced as an efficient alternative, evaluating risk based on the natural process flow, and recognizing that each piece of equipment has knowable failure modes. However, PFFM's limitations include the intensive preparation and the qualitative nature of the evaluation, leaving potential for missed risks. Layer of Protection Analysis (LOPA), a more quantitative method, typically relies on HAZOP results, which increases team resource usage. This paper introduces the “Flow Method,” an evolved and optimized blend of HAZOP, PFFM, and LOPA. By integrating additional tools, the Flow Method enhances the overall PHA process, resulting in streamlined, and consistent studies with unparalleled thoroughness. With over 200 studies conducted across 25 production sites and terminals, Nutrien has now adopted the Flow Method for all PHA studies. This paper presents comparative data from multiple studies and locations, demonstrating the Flow Method's effectiveness and its potential to revolutionize process safety analysis in the chemical industry.