View source for Hazard and Operability Study

== Introduction ==

A Hazard and Operability Study (HAZOP) is a structured and systematic examination of a complex planned or existing process or operation in order to identify and evaluate problems that may represent risks to personnel or equipment. The intention of performing a HAZOP is to review the design to pick up design and engineering issues that may otherwise not have been found. The technique is based on breaking the overall complex design of the process into a number of simpler sections called 'nodes' which are then individually reviewed.

[[Image:Detail-46629.jpg|thumb|center|A group of professionals discussing over a table with blueprints and safety equipment.|class=only_on_mobile]]
[[Image:Detail-46630.jpg|thumb|center|A group of professionals discussing over a table with blueprints and safety equipment.|class=only_on_desktop]]

== History ==

The HAZOP technique was initially developed to analyze chemical process systems, but has later been extended to other types of systems and also to complex operations and to software systems. A HAZOP is a qualitative technique based on guide-words and is carried out by a multi-disciplinary team (HAZOP team) during a set of meetings. The HAZOP technique was first described at the [[Imperial Chemical Industries|ICI]] in 1974 by Trevor Kletz.

== Methodology ==

The HAZOP methodology can be broken down into a series of steps: preparation, selection of nodes, and the actual HAZOP study which consists of the following steps: examination of the design intent, identification of deviations, assessment of consequences, estimation of risk, suggestion of remedial measures, and finally, recording of results.

=== Preparation ===

The first step in the HAZOP methodology is preparation. This involves the selection of the team, the preparation of the HAZOP study procedure, and the collection of information. The HAZOP team should be multidisciplinary, including process, mechanical, and instrument engineers, as well as operations and maintenance personnel. The team leader should be a person experienced in HAZOP studies.

=== Selection of Nodes ===

The next step is the selection of nodes. A node is a part of the process where a hazard could occur. The selection of nodes is a critical step in the HAZOP methodology. The nodes are typically selected based on the complexity of the process, the potential for hazards, and the availability of information.

=== HAZOP Study ===

The actual HAZOP study involves the examination of the design intent, the identification of deviations, the assessment of consequences, the estimation of risk, the suggestion of remedial measures, and the recording of results. The HAZOP study is a systematic way to identify potential hazards and operability problems.

==== Examination of Design Intent ====

The first step in the HAZOP study is the examination of the design intent. This involves a detailed review of the process design, including the process flow diagrams, piping and instrumentation diagrams, and process descriptions.

==== Identification of Deviations ====

The next step is the identification of deviations. A deviation is a departure from the design intent. The HAZOP methodology uses a set of guide words to help identify potential deviations. These guide words include: no, more, less, as well as, part of, reverse, and other than.

==== Assessment of Consequences ====

Once the deviations have been identified, the next step is the assessment of consequences. This involves determining the potential effects of each deviation. The consequences could include equipment damage, injury to personnel, environmental damage, or loss of production.

==== Estimation of Risk ====

The next step is the estimation of risk. This involves determining the likelihood of each consequence occurring and the severity of the potential effects. The risk is typically estimated using a risk matrix.

==== Suggestion of Remedial Measures ====

Once the risks have been estimated, the next step is the suggestion of remedial measures. These could include changes to the design, changes to the operating procedures, or the addition of safety systems.

==== Recording of Results ====

The final step in the HAZOP study is the recording of results. This involves documenting the findings of the HAZOP study in a report. The report should include a summary of the findings, recommendations for remedial measures, and a plan for follow-up actions.

== Applications ==

HAZOP is most commonly used in the chemical and process industries, but it can also be applied to other industries where there is a potential for hazards, such as the nuclear, aerospace, and pharmaceutical industries. In addition to its use in design, HAZOP is also used in operations and maintenance, and in the investigation of incidents.

== Limitations ==

While HAZOP is a powerful tool for identifying potential hazards and operability problems, it does have some limitations. These include the time and resources required to conduct a HAZOP study, the need for a multidisciplinary team, and the subjective nature of the risk assessment process. In addition, HAZOP is a qualitative technique and does not provide a quantitative measure of risk.

== See Also ==

* [[Failure mode and effects analysis]]
* [[Fault tree analysis]]
* [[Risk assessment]]
* [[Process safety management]]

[[Category:Safety engineering]]
[[Category:Chemical engineering]]
[[Category:Risk management]]