Process Hazard Review (PHR)

Process Hazard Review (PHR) is a systematic and consistent approach of handling process design and development for safer operations and maintenance. It comprises the hazardous events but where the HAZOP is a line by line approach, the PHR operates at the higher system-by-system level using hazardous event guidewords similar to HAZID approach. The risks involved in the proposed development shall be addressed to have the adequate administrative control and mitigating factors under the methods of risk management.


  1. To identify and understand the associated hazards and HSE risks.
  2. To assess the environmental effects
  3. To identify the critical equipment list which is potential to hazard.
  4. To ensure compliance with international codes of practices, regulations, procedures followed in proposed design.
  5. To facilitate effective, economic, efficient and safe operations


The rigorous review of each and every systems / plants to operate at a higher level than a HAZOP, applying the learnings observed during the site operation to previous version of PHA or HAZOP. P&ID is not required for the PHR study, a flow scheme / Process flow diagram is enough as an approach of this study.

Typically the study has a technique of developing what has already document through the observations in the site operation and adding the learnings from site operation, this includes the learning from the incidents or updation / changes made in the upstream or downstream of the original studies.

The process review and documenting procedures during the workshop will involve the operation representative of organization, process engineer involved in that particular scope, PHR scribe, technical authority & maintenance engineer.

Review & Assessment

PHR is applicable for all new and existing facilities wherever required. The risk ranking will be incorporated based on the event and its scenario which will address the following elements:

  • The hazards of the process.
  • Conditioning factors for existing systems / equipment.
  • Previous incidents which likely had a potential for catastrophic consequences.
  • Engineering and operation controls pertaining to the hazards and their interrelationships such as appropriate application of detection methodologies to provide early warning of releases.
  • Consequences of failure of engineering and administrative control
  • A qualitative evaluation of a range of the possible safety and health effects of the failure of controls on facility employees.
  • Process controls pressure relief event scenarios
  • Vent and Blow down discharge systems
  • Utility systems
  • Maintenance requirements and equipment.