HAZOP: a risk analysis method - Presentation and background

The HAZOP method is a formalized, systemic and semi-empirical tool that has been used and developed over the last forty years to analyze the potential risks associated with the operation of an industrial facility.

Invented in 1965 in Great Britain by ICI (Imperial Chemical Industries), it was conceived as a technique and aimed particularly at the detailed engineering phase of new chemical or petrochemical installations. It was a departure from the practices of construction codes and schematic safety reviews employed by engineering companies at the time, all of which were based on the analysis of past events. Its originality lay in its a priori approach to the hazards and malfunctions of a plant, through the systematic study of deviations in the parameters governing the process under analysis.

This technique was developed outside the confines of ICI, within the chemical and petrochemical industry, after the catastrophic explosion in 1974 of a 40-ton cloud of cyclohexane at Flixborough in Great Britain, which killed 28 people and injured 89 others. From a simple technique, the HAZOP method has become a practice for the identification of hazards and operability problems, adopted by many "at-risk" industries, in particular the oil industry, characterized by hazards similar to those of the chemical or petrochemical industry, but also in industries where the hazards are of a different nature, such as those encountered in the nuclear, food and transport sectors.

The HAZOP method is divided into three parts:

• this first article [SE 4 030] is devoted to definitions, objectives and fields of application;

• the second, [SE 4 031] presents the principle;

• the third, [SE 4 032] , is devoted to implementing and illustrating this method.

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