Hazard and Operability Studies: The Basics

By Kurina Baksh
Last updated: March 14, 2024
Key Takeaways

HAZOP studies identify process deviations and hazards in complex systems and procedures.

What Is a HAZOP Study?

A Hazard and Operability (HAZOP) study is a qualitative technique used to identify hazards in a planned or existing process. This allows control measures to be implemented to mitigate the risks to personnel, equipment, the facility, and the natural environment.


HAZOP studies are conducted using structured and systematic examinations based on a set of guide-words.

These studies are carried out by a multidisciplinary HAZOP team, consisting of four or more specialists from different fields of expertise.


The History of HAZOP Studies

In 1963 the Heavy Organic Chemicals Division of Imperial Chemical Industries (ICI) was designing a plant for the production of phenol and acetone from cumene. The production manager had recently spent a year in ICI’s Central Work Study Department and decided to see if critical examination could be applied to the design of the phenol plant in order to bring to light any deficiencies in the design.

This critical examination forms the basis of what we know today as HAZOP studies.

While HAZOP was initially developed to analyze chemical process systems, it is now used to identify process deviations and hazards in other types of complex system, ranging from software systems to nuclear plant operations.

When Should a HAZOP Study Be Performed?

HAZOP studies are typically performed at the following stages:

  • Early in the design phase, when drawings, blueprints, and procedures have not yet been finalized. The HAZOP study can note areas of concern in the design and modify them before the facility is built and the processes established.
  • During the construction and installation phases, ensuring that recommendations and mitigation measures are being implemented.
  • During commissioning to identify modifications that needs to be implemented to reduce risks to personnel and equipment, as well as to identify operability issues.
  • During operation to make sure that plant and emergency operating procedures are reviewed and updated on a regular basis, as required by regulations and standards.

Types of HAZOP Studies

The four types of HAZOP studies that are conducted are:

  1. Process HAZOP, which assesses plants and process systems
  2. Procedure HAZOP, which reviews procedures and operational sequences
  3. Human HAZOP, which focuses on human errors
  4. Software HAZOP, which identifies possible errors in the development of software

Who Is Part of the HAZOP Team?

HAZOP studies are carried out by a multidsciplinary team, which will include (but not be limited to) the following members.

HAZOP Team Leader

The HAZOP team leader’s responsibilities include:

  • Defining the purpose of the HAZOP study
  • Selecting the members of the HAZOP team
  • Planning and preparing the study
  • Chairing HAZOP meetings

Ideally, the team leader should have an affiliation with the process or operation that is being analyzed.

Hazop Secretary

The duties of the HAZOP secretary include:

  • Preparing HAZOP worksheets
  • Recording discussions that take place during HAZOP meetings
  • Preparing the HAZOP report

Other HAZOP Team Members

The makeup of the HAZOP team will vary from study to study.

A HAZOP study of a process plant, for example, is likely to require a team consisting of:

  • A project engineer
  • A commissioning manager
  • A process engineer
  • An instruments or electrical engineer
  • A safety engineer
  • A maintenance engineer

Each member of the HAZOP team is required to make significant contributions to the study, sharing their ideas and expertise.


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The HAZOP Procedure

The overall procedural steps in a HAZOP study are:

  1. Hold a Safety Team Meet
  2. Identify the project for the HAZOP study
  3. Appoint the Lead Process Engineer
  4. Appoint an independent HAZOP Team Leader
  5. Define the purpose and scope of the HAZOP study
  6. Select the HAZOP team and define their roles and responsibilities
  7. Host a pre-HAZOP meeting with the Lead Process Engineer and HAZOP Study Leader to:
    1. Identify and obtain required information
    2. Plan the study sequence
    3. Plan the schedule
  8. Inform everyone concerned
  9. Conduct the HAZOP study and document the results
  10. Prepare and submit the HAZOP study report
  11. Take the necessary actions specified in the report
  12. Host a close-out meeting and sign-off on the HAZOP study
  13. Hold a review meeting involving the entire HAZOP team

The purpose of the HAZOP review meeting is to monitor the completion of agreed-upon actions from the HAZOP study. Actions are noted and classified as being “complete,” “in progress,” or “incomplete.”

The Benefits of HAZOP Studies

The benefits of conducting a HAZOP study include:

  • Improvements to the systems, operations, and procedures
  • Reduced risk to personnel and equipment
  • More efficient operations
  • Increased productivity

The Pitfalls of HAZOP Studies

HAZOP studies can be time consuming, costly, and problems may arise when selecting team members.

It can also be argued that HAZOP studies focus too much on solutions rather than identify hazards and evaluating their risks.

Despite this, HAZOP studies are being used across industries and have been to be quite successful.

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Written by Kurina Baksh

Kurina Baksh

Kurina Baksh is a Health, Safety and Environment Professional from Trinidad and Tobago. As a recent graduate in the field, she is trained to analyze and advise on a wide range of issues related to her area of expertise. Currently, she is an independent consultant who develops public outreach and education programmes for an international clientele. She strongly believes that increasing public outreach and education can promote hazard awareness and ultimately save lives.

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