Author: Jake Bumpus, Process Safety Engineer at Chris Mee Group


What are HAZOP studies?

A Hazard & Operability study is a technique for identifying process safety hazards. It was originally developed in the 1960s by the UK chemical company ICI. Since then, it has continued to be developed and is now one of the most widely used hazard identification techniques used across many industries including Pharmaceuticals, Chemicals, Oil & Gas and Nuclear. They are also frequently used in Dairy, Distilling, and Wastewater Treatment.

As the name suggests, as well as being a technique for identifying hazards (i.e. aspects of a system with the potential to cause harm), it can also be used to tease out potential operational issues that may arise.

How is a HAZOP study carried out?

It is a structured approach which breaks down complex systems into discrete chunks (usually referred to as ‘nodes’). A team of people meet to apply a set of guidewords in combination with system parameters to each node, in order to seek deviations from the design intention.

For example, if considering a node concerning a solvent storage vessel, the team might consider the parameter ‘pressure’ with the guide word ‘high’. They would then look to see what could cause the solvent vessel tank to become over-pressurised, what the consequence of this may be, and what control measures have been or could be implemented to prevent this deviation occurring.

A HAZOP team generally has a chairperson/study leader to guide the discussions, a secretary/scribe to formally record the discussions, as well as number of team members such as engineers, managers, operators, safety representatives and other specialists.

What can a HAZOP study be used for?

As a technique, HAZOPs are extremely flexible and can therefore be tailored to be used to identify hazards and operability issues in a wide range of processes and industries, as well as for processes at different stages of their life cycle:

  • New-build design stage
  • Installation and commissioning
  • Modifications to existing facilities
  • Start-up and shutdowns
  • Prior to decommissioning and demolition

What are the advantages of carrying out a HAZOP study?

The key advantage of carrying out a HAZOP study is that it is a structured and systematic approach to hazard identification. It is recognised across many industries as being best practise, if carried out by competent persons and supported by good quality information.

As they are a team-based activity, they allow different stakeholders to interact and discuss the process, and the HAZOP study is often the first place where they have the opportunity to do this in detail, face-to-face.

Although very structured, it can also be a creative process, allowing hazards to be identified which would have otherwise not been thought about.

Common pitfalls

There a number of common pitfalls associated with HAZOP studies, which require the advice of experienced and competent HAZOP chairs and team members to avoid:

  • Ensuring that the documents which underpin the study are of good quality and have the necessary level of information. If too much information is missing or incorrect, then the HAZOP cannot be effective.
  • Carrying out the HAZOP at the right stage of the design/modification project – too early and not enough information is available for a good quality HAZOP, too late and there will not be enough time to easily implement recommendations for improvement.
  • Selection of the HAZOP team – the competence of the team members is important for a good quality HAZOP, as well as the size of the study team. If too small, hazards might be missed due to a lack of expertise; if too large, the HAZOP may become excessively long and costly.

What HAZOP services can the Chris Mee Group provide?

CMSE Consultancy Process Safety consultants can carry out the overall HAZOP process for our clients.

  • We can deliver process safety experts to attend the HAZOP meetings
  • We can provide a chair and/or scribe for the HAZOP meetings
  • We can provide a detailed systematic process and associated procedures and documentation/checklists, etc.
  • We provide a high degree of practicality and quality to the hazard identification, risk assessment and control process.
  • We always apply the ALARP principle in identifying the appropriate control measures and design changes
  • During our HAZOP process we look closely at the full life cycle covering construction phase, validation phase, commissioning phase, operational phase, maintenance activities, foreseeable demolition situations, etc.

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