HAZOP
Hazard Identification within the process (and many other related) industries has been dominated for over 40 years by the HAZOP (Hazard & Operability) methodology which uses a structured, deviation-based approach to identify possible causes and potential consequences and assign or propose appropriate safeguards to eliminate or reduce the risk associated with the respective hazard scenario. The HAZOP technique is described in the international standard IEC 61882:2016 and is typically documented in a tabular form using either a generic worksheet e.g. Microsoft Excel spreadsheet or Word table or commercially available HAZOP (or PHA – Process Hazard Analysis) software.
Whilst the current recording style is relatively easy to interpret, it does not provide the immediate clarity of a bowtie diagram - particularly for those who were not present during the study and/or when reviewing/revalidating studies at regular intervals (typically 5 years for many international jurisdictions where Major Accident Hazard regulations mandate ongoing evaluation).
However, the major limitation of the most common worksheet format is often the inability to unambiguously match prevention safeguards to causes and mitigation safeguards to consequences which can lead to incomplete or inconsistent studies as the line of sight between cause (threat) and consequence is not clearly defined such that the safeguards can be properly identified and managed.