HAZOP is a structured hazard identification tool using a multi-disciplined team.  It has become accepted as the main technique for the identification of process hazards in the design and operation of a facility.  Other identification techniques by discipline review or compliance with checklists are limited by their reliance on previous experience and constrained by their narrow approach. 

HAZOP is based on brainstorming and has important advantages over other techniques.The method is equally applicable to major green-field developments, brown-field projects, small plant modifications or operating procedures. 

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The concept is to break the plant into small sections and then to identify hazards by examining each section and using a series of parameter and guide word filters to structure the brainstorming process.