Hazard Identification: Planning for Success

Article by Phil Eames CEng FIChemE

My name is Phil Eames and I’m a chemical engineer with 36 years of experience in the process industries in a variety of engineering and management roles. I have a long-held interest in process safety and have practised as a process safety consultant for the last ten years, attaining Professional Process Safety Engineer status in 2015.

The introductory article in this series identified increasing the effectiveness of process hazards identification as an important challenge in process safety management. This second article suggests some ways to address this challenge, with a focus on hazard and operability study (HAZOP).

As an experienced HAZOP facilitator I’m often approached to lead studies in many sectors of the process industries. Invariably the offer comes in the form: “Can you come and lead a 2-day (or 5-day, or 3-week etc) HAZOP study for us?” The duration is nearly always specified and, in my experience, appears to be based more on project timescales or the availability of personnel rather than on the time required to carry out a comprehensive study. In today’s fast-moving, competitive world, this is understandable but, given the value we place in hazard identification at the heart of process safety management (to manage hazards we have to first understand them), it may suggest that we could be at risk of compromising the effectiveness of the technique and missing opportunities to make our processes safer and more resilient.

A recent study of the 100 largest loss incidents in the onshore oil, gas and petrochemical sectors between 1996 and 20151 supports this possibility. It showed that almost 60% of non-mechanical integrity failure incidents involved weaknesses in hazard identification, as shown in Figure 1, principally due to:

  • inadequate quality of hazard identification;
  • limited attention given to HAZOP of safety-critical activities and transient operations; or
  • failure to identify safety-critical devices.
The 100 largest losses 1996–2015, non mechanical integrity failure incidents (57 of 100), secondary management system failures

We cannot quantify the effectiveness of hazard identification studies at the time they are performed, but we can give ourselves the best chance of being able to execute rigorous (thorough and creative) studies. Here are some ways you can help this:

  • Select the most appropriate method of hazard identification, which may not always be HAZOP. Consult an experienced HAZOP leader when deciding if HAZOP is the best tool and, if it is, consider using the hazard identification (HAZID) technique before HAZOP; it is quicker and will give you an indication of potential major accident scenarios (which are generally more difficult and expensive to prevent or mitigate) much earlier.
  • Use an experienced HAZOP leader to estimate how much time you will need. You can do this as soon as you know the number of P&IDs there are likely to be, and this will enable you to plan the right amount of time into the project schedule. A better time estimate can be made if the number of study nodes is identified; this can be approximated using the process flow diagram (PFD) and so can be done well before detailed P&IDs are developed.
  • Think carefully about which style of HAZOP will be used (continuous, sequential or a mixture) and which operating modes will be studied (normal operation, startup and shutdown, abnormal modes of operation). Both of these factors will have a significant bearing on the time required. Remember that most incidents happen outside of normal operations, so aim to include other modes if you want to get the most out of the study.
  • Appoint a HAZOP leader as early as you can to enable them to play an active role in the planning and preparation process, particularly in planning time requirements, selecting the team and establishing requirements for process safety information to support the study. Develop terms of reference for the study and conduct a readiness review before starting the HAZOP sessions; it is important that the goals of the study are clear and that the team can work efficiently right from the start.
  • Select an experienced independent HAZOP leader with a strong track record, good references and strong facilitation skills (you’ll get some idea of their facilitation skills when you talk with them, as well as from the references). Effective HAZOP is about maximising the use of the knowledge, experience and creativity of the team.
  • Support the HAZOP leader through the preparation process and then through the study itself. Take an active interest in the progress and outcomes of the study, and show your appreciation of the team’s efforts, especially through longer studies.

Effective hazard identification will improve our understanding of the process, make it safer and make it more resilient to disturbances, but it requires adequate time, a team with the right mix of knowledge and experience, good supporting information, and a skilled facilitator. Getting all that to come together at the right time requires good planning.

In the next article we will explore the concept of the “basis of safety” and how it can be documented and maintained. In the meantime, I hope you can use some of the ideas presented here to plan for greater effectiveness in future hazard identification studies and, through that, make your new and existing plants safer and more resilient.


1. Jarvis and Goddard, "An Analysis of Common Causes of Major Losses in the Onshore Oil, Gas and Petrochemical Industries", Loss Prevention Bulletin 255, June 2017.

IChemE’s HAZOP Leadership & Management course provides a more detailed exploration of this topic, including HAZOP planning, preparation and facilitation skills.

Article by Phil Eames CEng FIChemE

An IChemE Fellow and an independent consultant. Eames has worked on process safety in most sectors of the process industries including oil and gas, petrochemicals, pharmaceuticals, power generation and water. He is also a trainer for IChemE, delivering a range of courses including the HAZOP Leadership and Management course

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