studies originated in the 1960s at Imperial Chemical Industries (ICI) in the UK, as a systematic technique to identify potential hazards and operability issues in chemical processes by examining deviations from design intent using guide words (e.g., "no," "more," "less"). It gained widespread adoption in the 1970s following the 1974 Flixborough disaster, which highlighted the need for rigorous hazard analysis. In 1974, ICI offered the first formal training course, and the technique was publicized through papers and guides. By 1977, industry associations published guidance, and HAZOP became a standard tool in process safety management. It was later standardized in IEC 61882 (2001), and today it is widely applied beyond chemicals to various industries for risk identification.