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Hazard and Operability Studies: The Basics

By Kurina Baksh
Published: October 25, 2016
Key Takeaways

HAZOP studies seek to identify hazards so that they can be resolved.

Source: SergeBertasius/

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 so that their associated risks to personnel or equipment can be evaluated and prevented. HAZOP studies are conducted via the use of structured and systematic examinations based on guide-words. A multi-disciplinary team or a HAZOP team carries out a HAZOP study.

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, thus, 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—what is known today as a HAZOP Study. HAZOP studies, then, were initially developed to analyze chemical process systems. However, it is now used to analyze many other types of systems, including software systems and complex operations.

When Should a HAZOP Study Be Performed?

HAZOP studies can be performed at the following stages:

  • Early in the design phase/initial concept phase when drawings are available; the HAZOP study can thus influence or enhance the design/concept
  • During the construction and installation phases; this ensures that recommendations and mitigation measures are 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: process HAZOP, procedure HAZOP, human HAZOP and software HAZOP.

  1. Process HAZOP: Assesses plants and process systems
  2. Procedure HAZOP: Reviews procedures and operational sequences.
  3. Human HAZOP: Focuses on human errors opposed to technical failures
  4. Software HAZOP: Identifies possible errors in the development of software

The HAZOP Team

A multi-displinary team or a HAZOP team carries out a HAZOP study. Team members include but are not limited to:

  • Team Leader: A HAZOP team leader is responsible for defining the purpose of the HAZOP study, selecting the HAZOP team members, planning and preparing the study, and chairing HAZOP meetings. The ideal HAZOP team leader should have to affiliations with the process or operations being analyzed.
  • HAZOP Secretary: The duties of the HAZOP secretary include preparing HAZOP worksheets, recording discussions during HAZOP meetings, and preparing the HAZOP reports.
  • HAZOP Team Members: A previously mentioned, the HAZOP team is a multi-disciplinary team. Thus, the members of the team will vary from study to study with regards to their areas of expertise. For example, for a HAZOP study being conducted for a process plant, team members may comprise a project engineer, a commissioning manager, a process engineer, an instrument or electrical engineer, a safety engineer, a maintenance engineer, and an operating team leader. Furthermore, each member of the HAZOP team is required to contribute significantly sharing his or her ideas and knowledge, as well as to be critical in a positive and constructive manner.

The HAZOP Procedure

The overall procedural steps in a HAZOP study are:

Step 1: The Company’s Safety Team Meet
Step 2: Identification of the Project for the HAZOP Study
Step 3: Identification of the Lead Process Engineer
Step 4: Selection of an Independent HAZOP Team Leader
Step 5: Defining the Purpose and Scope of the HAZOP Study
Step 6: Selection of the HAZOP Team and Defining their Roles and Responsibilities
Step 7: Host a Pre-HAZOP Meeting with the Lead Process Engineer and HAZOP Study Leader. At this meeting: (a) Identify and Obtain Required Information; (b) Plan the Study Sequence; and (c) Plan the Schedule
Step 8: Inform everyone concerned
Step 9: Conduct the HAZOP Study and Document the Results
Step 10: Prepare and Submit the HAZOP Study Report
Step 11: Take the necessary actions specified in the report
Step 12: Host a Close-Out Meeting and Sign-Off on the HAZOP Study

Reviewing HAZOP Studies

The review of HAZOP studies are done via review meetings. The purpose of review meetings are therefore, to monitor the completions of agreed actions that were recorded. Actions are noted and classified as “Action is complete,” “Action is in progress,” or “Action is incomplete.” Additionally, a review meeting must involve the entire HAZOP team.

The Benefits of HAZOP Studies

Conducting HAZOP studies can be very beneficial to companies. Some of these benefits include:

  • Improvements to the systems and operations
  • Reduce risk to personnel and equipment
  • More efficient operations
  • Increased productivity
  • Improvements to procedures; allows for procedures to be done in a logical order
  • Increases awareness among all parties concerned
  • Facilitates team building

The Pitfalls of HAZOP Studies

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