HazId studies are used to assess, in a semi-quantitative way (risk matrix), the major risks related to a site. For application of HazId method on a single plant please refer to Plant Safety, for the specific field of downstream plants please refer to Refinery safety.
HazId are usually developed during the following phases:
- the verification, required by Management of Change system, that a proposed modification of a site will not impact the “no-increase of risk” policy. For further details please refer to Plant Safety.
- the feasibility phase of a new project to help the customer assessing the safety (and the costs related). Please refer to Engineering Assistance.
- the screening phase of a site safety assessment to identify the units to be investigated with HazOp analysis (this is an alternative approach to DOW index or derivative).
- the screening phase of a whole-site domino effect risk analysis to identify major sources of accidents when a complete site safety review is not requested by the customer.
Sometimes, Eidos also uses a hybrid approach where the identification of the top-event is done using the “HazId” approach but the following risk quantification is based on a full quantitative approach (fault trees – event trees – consequences calculation): no unpleasant surprises in later stages!