HAZOP method, deviation analysis

The Hazard and Operability analysis (HAZOP) was developed by Imperial Chemical Industry in 1963. At first, it was established for chemical industries, in order to evaluate risks related to the possible deviations of a project.

HAZOP is a systematic and structured method mainly used during the first deign produce. It is also regularly updated during the operating stage of the plant. The main theory assumes that deviations forms are triggered by the operating design and bring about risky events. This method enables to analyze possible deviations of a plant, their causes and consequences in order to mitigate risks. The plant’s operating parameters (pressure, temperature…) are associated with “guide words” (more, less, no for instance) so that risks can be revealed and quantified. As a consequence, the plant is reviewed in a safer, more reliable and more efficient way. The strength is founded on the multidisciplinary team “brainstorming” at each step of this structured hazard analysis.

Part of a project’s risk management, this method also optimizes resources and brings about financial benefits to the plant’s owner (and operator). It highlights which control and safety systems are really needed to the plant. The quickest HAZOP’s recommendations are applied in the design process, the most are the benefits. Nowadays many companies use this method to enhance their project management. It is particularly well suited to systems that employ material and energy flows.

History

HAZOP was initially thought for reviewing a new phenol plant design. The Heavy Organic Chemicals Division of the Imperial Chemical Industry (British and international company) conceived this method in 1963. At the beginning, it was based on a “critical examination” studying the alternatives of a system. Later, the method’s focus was altered in order to study system’s deviations after producing the first detailed design of the plant. The "operability studies" method was created.

In 1977, ICI published a guide of this method. It was officially named HAZOP. Since that date, the deviation analysis process has been applied in many projects from various types of company. Discussions and research have highlighted its usefulness in project management, but they have also unveiled some limits.