This page provides outline information and links to information on HAZOP studies and their purpose.
The implementation Hazard and Operability Studies are completed at an early stage
in the design project to ensure that if the plant is operated away from the design
intent there are no unacceptable safety or the Operability consequences.
Hazops were initially 'invented' by ICI in the United Kingdom. Through the general
exchange of ideas and personnel, the system was then adopted by the petroleum industry,
which has a potential for major disasters. A number of industries now use
this system including the water industry , the nuclear industry, the food industry to note just a
The procedures used are most conveniently applied to the chemical industry but, with only minor
modifications can be applied to any industry.
A hazop study is generally completed by a team which includes the designers, safety representatives
and a number of members with expertise in a range of related fields. The team should also
include individuals who have knowledge of operating similar equipment and plant.
Information presented to for HAZOP Study
The design process generally includes a number of HAZOP studies (HAZOP 1, 2 3)
The first (HAZOP 1) study would be based on the design specification and the resulting process flow diagrams / block
The second (HAZOP 2) study would be based on the design specification and the more detailed Engineeering Flow Diagram
/ Mechanical Flow diagrams.
The later HAZOP studies would be based on actual Production and Operating document
The HAZOP study is based on the use of Primary and Secondary Keywords
Primary Keywords which focus attention upon a particular aspect of the design intent or an associated process condition or parameter.
Secondary Keywords which, when combined with a primary keyword, suggest possible deviations.
The Hazop study process involves applying in a systematic way all relevant keyword
combinations to the plant in question in an effort to uncover potential problems.
Each flow sheet is reviewed on a line by line, item by item basis.
The results are recorded systematically in tabular form. Relevent Headings for the
table are provided below:
On completion of the HAZOP review activity a detailed list of HAZOP table is produced and actions
are identified. The actions are completed and are circulated and accepted by the full team or the
actions are reviewed at a follow-up meeting.