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Procedural risk analysis HAZOP and What If –

HAZOP is a tried and very effective method to analyze risks in a process. HAZOP is required by law in many countries worldwide, and in Israel HAZOP has become a legal requirement in the natural gas layout and an accepted practice throughout industry.

HAZOP is part of a family of procedural risk analysis approaches (PHA-Process Hazard Analysis) that are adjusted based on the type of process we wish to analyze.

Procedural risk analysis in general and HAZOP specifically are required as part of risk management from stationary sources in the aspect of hazardous substances incidents (existing condition). In addition, plants and planners can routinely implement procedural risk analysis, during planning, operation, regular operation and changes in the facility or a process.

Among the methods resembling HAZOP, we can note HAZID which is designed to examine the process’ layout and initial identification, even prior to the detailed planning, of the expected risks in the process. The FMECA which focuses on analysis of irregular operation manners such as stopping activity in emergency, ESD, initial operation and delivery of a hazardous process to maintenance and receiving it back to production etc. and finally, the What-If as well which constitutes a “mini” HAZOP designed to examine changes in the process.

HAZOP is suitable for a production process, however in reality can include any activity that involves hazardous substances and/or extreme working conditions such as pressure and temperature. In addition, HAZOP or any of its accompanying methods is suitable for any of the stages in a plant’s life:

  • Initial planning
  • Detailed planning
  • Commissioning
  • Routine operation
  • Recovery from faults
  • Dismantling and deactivation

HAZOP – Hazard and Operability study

Following is a short description of each method:

A known and common method for procedural risk analysis in the industry. The characteristics of the method – a structured, thorough methodology that requires brainstorming by a team of experts with knowledge of the process – turn it into a convenient and especially appropriate tool for a methodical analysis of processes, to identify risks and operational implications.

A HAZOP analysis is appropriate in different variations, both to existing processes and planned processes, and it is applicable in various stages in the life of a facility or process.

What – If

What if is a method based on HAZOP which is very similar to it, but less structured than it.

This method is usually used in cases where a full HAZOP is inappropriate or “too big” in relation to the goal of the analysis. Mainly for risk assessment for changes in an existing process that do not significantly impact the risk.


Hazard Identification is also a method based on HAZOP, where the risk identification was adjusted to the initial stages of the project to identify principal risks, detecting issues that may arise from placing equipment and distances between functions and structures, identifying safety issues, identifying the processes requiring a full HAZOP etc.


Failure Modes & Criticality Analysis (FMECA) is designed to analyze risks in non-routine processes. The method, designed to analyze different operation manners in a process, is especially effective in the following cases:

  • Examining risks on the emergency shutdown sequence and routine shutdown of a hazardous process.
  • Analysing accompanying equipment to the process and especially machines such as turbines, steam boilers, extruders etc.
  • Switching between different modes of operation: such as changing fuel type in a torch, equipment operation sequence, process start-up sequence.


Hazmat places two instructors at the organization’s disposal. The lead instructor (leader, facilitator) along with the team that the organization tasks with the subject, instructs the brainstorming and raises several theoretical scenarios for discussion. Processes that have been identified as relevant are analysed in depth: the risk is examined and considered, the existing protection systems are checked, their level of effectiveness is examined and the residual risk is tested and in places where there is an unacceptable residual risk, additional protective measures are suggested and examined.

The HAZOP is done in accordance with international standard IEC 61882:2016.

Procedural instrumentation is checked to SIL reliability level in accordance with international standard IEC61511.

The instruction is escorted by an additional instructor from Hazmat, the role of whom is to document the discussion in a designated software, ensuring that all failure manners are reviewed and that each scenario is fully analysed. At the end of discussions a report is produced.

Below is an example in Hebrew and English from the software.

The experts

All of our HAZOP instructors completed a HAZOP instructors training course and have a rich experience in all types of processes in the chemical industry.