HazOp is a systematic technique for reviewing a process design to understand the hazards present and identify appropriate control measures.
HazOp uses the experience and expertise of a multi-disciplinary team, working under the guidance of an experienced HazOp facilitator (chair) who is an expert in the application of the technique.
The team will be made up of professionals with different backgrounds, such as operations, engineering and chemistry, to ensure that there is a wide spread of knowledge within the room.
A HazOp scribe may also be appointed to record the discussion.
The HazOp approach should be agreed in advance of the meeting and recorded in a “Terms of Reference” (ToR) or similar document. The ToR describes the scope of the study, the method to be used and the team that will attend.
During the meeting, the process being studied is split into sections, called “nodes”. A series of guidewords are then applied to each node.
A guideword is a deviation from the design intent - for example “high temperature”. In this case, the team will record all the causes of high temperature they can think of, and the consequences of high temperature.
If the consequences are hazardous, or cause operability problems, the team will then write down the control measures which are in place for preventing high temperature from occurring.
This process is repeated until each of the guidewords have been applied to all of the nodes.
=Method s approach is to carry out a basic risk assessment for each HazOp scenario, by using an appropriate process safety risk matrix. The purpose of this assessment is to help the team to decide if the current control measures are controlling the risk adequately.
Finally, further actions are recorded where necessary. Actions could be to make changes to the design to improve safety or operability (for example putting additional control measures in place), or if some aspects are unclear, to find out more information so the scenario can be understood in more detail.
Following HazOp, the high-severity scenarios are referred on for further study using LOPA. (typically those which could cause a fatal accident or another incident of equivalent severity).
This information can then be used to establish which hazard scenarios need to be analysed in more detail – typically by way of a Layer of Protection Analysis (LOPA).
Whilst Hazard & Risk Assessment using HazOp is part of the “Process Safety Lifecycle”, it is also the first stage of the Functional Safety Lifecycle (as defined by the functional safety standard, IEC 61511). This means that in order to comply, the HazOp studies must be verified (i.e. checked), assessed and linked to the later functional safety lifecycle stages.
=Method s experience is that planning for functional safety before the HazOp starts makes it far easier for the whole project to comply with functional safety standards. The HazOp should be viewed not as an end in itself, but part of a broader approach, which is reflected in the way the HazOp is executed and documented.
=Method can provide expert HazOp facilitators and scribes, who will use our tools and templates to deliver a HazOp that is effective, efficient and (as far as is possible) enjoyable. Our approach ensures that the functional safety lifecycle tasks which follow the HazOp (i.e. verification, allocation of safety functions to protection layers and the functional safety assessment) are fully supported by the HazOp approach.
If you wish to develop your own expertise in this area, =Method has a variety of training courses, such as our IChemE approved Hazard Study Leaders Course. Following training, we can also offer mentoring to new HazOp facilitators as they grow into the role.
If you have any enquiries about our Process Safety Consultancy services please call us on +44 (0)1462 713313 or contact us online.[Other Consultancy Services]
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