Hazard and Operability Study (HAZOP)

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.  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.

The objective of a HAZOP study is to examine the design to identify any hazards that could result in injury to persons, environmental pollution, damage to equipment or structures, or have a serious impact on operations.  These risks should be controlled and minimised by applying suitable physical or operational safeguards.

The HAZOP process is best understood if divided into the following steps:

  • Select the appropriate section of the plant (node)
  • Define the node’s design intent and process conditions
  • Apply the first/ next parameter
  • Apply the first/ next guide word, which when combined with the parameter will give the deviation
  • Determine (by brainstorming) all the potential causes of the deviation
  • Agree the credibility of each cause
  • Assess the consequences of each cause
  • Assess the protection provided against the causes and its consequences
  • Agree a recommendation for action or further consideration of the problem
  • Apply the next guide word (relevant to the selected parameter)
  • Apply the next parameter until they have all been considered
  • Move onto the next node of the system until the whole study has been examined