HAZOP Analysis.

What is HAZOP analysis? The advantages and disadvantages. The HAZOP matrix. Example HAZOP analysis. 


HAZARD and operational study HAZOP, is a highly structured approach to hazard identification. The process requires highly detailed process information, which forms the input into a review of a process, the output from the HAZOP analysis will be a table of potential deviations, potential hazards associated with these deviations and recommended actions to address. The potential hazards identified will be related to deviations which could arise due to shortcomings in the design or operation of the process under review. These deviations could result in hazards and consequently harm to individuals, the business or the environment. The HAZOP analysis seeks to ensure appropriate actions are taken to prevent harm arising in the first instance.


Advantages and disadvantages of HAZOP Analysis.

The major advantage associated with performing a HAZOP analysis is the fact that the resultant analysis will be very highly structured, comprehensive and detailed. In addition the HAZOP analysis requires input from a range of disciplines resulting in a more balanced analysis. This team approach required from HAZOP encourages multiple viewpoints and ensures a broad range of potential concerns can input into the analysis. The process itself is relatively easy to understand and is not highly technical, therefore does not require extensive training for team members inputting into the analysis. HAZOP outputs a clearly documented analysis, identifying the hazards, the potential failures, the potential causes of failure and the recommended actions to address.

Disadvantages of HAZOP are that the analysis only focusses on single failure conditions rather than on combinations of possible events leading to resultant failure. In reality, process failure often results from multiple failed inputs, however HAZOP does not capture these scenarios. The HAZOP process can be time consuming, can become overly detailed and complex and often requires some form of expert facilitation. Also HAZOP relies on “guide words” to progress the analysis, potential failures cannot always be linked to “guide words” and therefore run the risk of being missed by the HAZOP analysis.


HAZOP Analysis Matrix.

A hazard matrix is essentially similar to the matrix applied in a failure mode effects analysis, without the inclusion of probability, severity and detectability. Normal headings applied in the HAZOP matrix are i) the process parameter under analysis ii) the potential hazard iii) the potential failures associated with the hazard iv) potential cause or causes of the failure v) the detail(s) of the causes of failure and vi) any recommended action to address.


Performing a HAZOP Analysis.

HAZOP Analysis

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To perform a HAZOP Analysis, start by creating a full description of the process for which you wish to complete the analysis. Then proceed to systematically question the entire process from start to finish. This questioning process, needs to include any related process which interacts with the process under review, also, needs to include inputs into and outputs from the process. The objective is to identify how any deviations from the design intent or deviations from the intended mode of operation could arise. The greater the intensity of questioning, the greater opportunity for potential hazard identification, which will ultimately result in a more comprehensive analysis.

As a simple example consider a sterilization process. The key operating parameter may be the sterilization temperature. If the temperature is too low, then product will not be sterilized appropriately. This may result in dangerous product reaching the end customer. If the sterilization temperature is too high, then product may be over heated and the process will be shut down, resulting in financial loss of the manufacturer. The cause of the incorrect temperature could be related to non-performance of routine calibration. The solution could be to detail a calibration procedure, with frequent re-calibration checks.

We can use a Process HAZOP Analysis to review the sterilization process, consider the impact of a temperature failure and via analysis determine the cause of failure (identified as calibration in the above) and recommended actions to address.

The “Process operating parameter” – Sterilization temperature specification

The “Potential hazard” – Temperature too low or temperature too high.

The “Potential failure associated with the hazard”
– Temperature to low, product will not be sterilized, risk to end users.
– Temperature to high, product overheated, process shutdown, financial loss of business.

The “Potential cause” – Calibration in-sufficient.

The “Details of the cause” – Calibration program not in place and no calibrations performed on a consistent basis.

The “Recommended actions to address” – Define, document, release and implement a calibration procedure. Train staff. Define calibration frequency schedule for the sterilization temperature process. Monitor calibration results.


The above is normally documented in the form of a process HAZOP Analysis table. It is important to revisit the process analysis on a systematic basis. Whenever there are any changes to products, processes, suppliers, etc., the HAZOP analysis should be reviewed. During on-going operations there will be continuous performance feedback both from internal processes and from end user experiences. These are invaluable sources of information which can feed into and add to the accuracy and relevance of the HAZOP process.


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Quality Improvement Techniques

Quality Management Tools and Techniques …

        • Continuous improvement utilizing Analytical Techniques.
        • Brainstorming
        • 5 why’s analysis
        • Process Flow Diagrams/Flowcharts/Process Mapping
        • Check sheets /Check Lists
        • Run charts
        • Histograms
        • Scatter Diagrams/Scatter Plot
        • Cause and Effect/Fishbone/Ishikawa Diagrams
        • Identifying sources & causes of variation
        • Control/Shewart Charts/DPU Charts
        • Cpk and Ppk Analysis
        • Pareto Analysis
        • Bottleneck Analysis
        • Benchmarking
        • FMEA
        • FTA
        • HAZOP
        • SIPOC
        • Etc. Etc.
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