Author: Jake Bumpus, Process Safety Engineer at Chris Mee Group
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.
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.
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:
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.
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:
CMSE Consultancy Process Safety consultants can carry out the overall HAZOP process for our clients.
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