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HAZOP Checklist To Prevent Hazards And Disasters

Learn about the history of HAZOP, what it is, and how to perform one with the help of an example. Identify hazards and deviations within any type of processing plant. Perform your study with Lumiform’s free HAZOP template.

What Is the HAZOP Process?

The HAZOP (Hazard and Operability Study) process is intended to identify potential hazards and functional faults in existing or planned plant systems. The analysis method is primarily used to investigate complex operational hazards and functions in chemical processing plants, but also in nuclear, water, sewage, and wastewater treatment plants. This process is carried out by a team of interdisciplinary experts consisting of engineers, chemists, facility managers, and safety officers to identify process risks, process hazards, and design flaws.

HAZOP is a risk analysis procedure which ISO 14971 recommends in addition to the FMEA, FTA and PHA. The IEC 61882 standard describes this procedure in more detail. In order to make a hazard and operability study easier, various checklists can be employed to cover all areas of the analysis.

History of HAZOP in a Nutshell

Like many safety organizations and procedures, HAZOP originated as a direct result of a tragedy. In 1973, a chemical explosion occurred at a chemical plant in Flixbourough, England, killing 28 employees and injuring another 36. This incident was later termed the Flixbourough disaster and would lead to the development of HAZOP. A British company, Imperial Chemical Industries, studied the common denominator in other chemical plant failures and discovered the need for plant oversight by safety officers and on-site managers. From their research, the hazard and operability study was invented. Since then, it has aided many plants in preventing disasters and the subsequent loss of life.

This article deals with:

1. How the HAZOP process is used for risk assessment

2. Example of a HAZOP analysis in action

3. A tool for optimizing the HAZOP process

Potential hazards at a chemical processing plant

How to Use HAZOP as an Instrument of Risk Analysis?

The HAZOP process is based on the assumption that hazards arise because the design and operating elements may deviate from their original purpose. The HAZOP team discusses possible deviations and develops various scenarios in which the system or process could fail. These are clarified in tests with the aid of checklists. After analyzing the data obtained, the team can propose recommendations for safety precautions and improvements to reduce the risk of identified hazards and operational failures.

A HAZOP form primarily examines the following three parts of a plant function:

1. Construction

Assess the ability of the design to perform its intended task and identify its weak points, e.g. the composition of a chemical batch reactor.

2. Physical Environment

Assess the environment in which the system or design is operated to ensure that it is ideal, e.g. is there enough space for the batch chemical reactor to operate as intended ?

3. Procedure

Evaluate technical controls such as automation, the sequence of steps, human interactions, e.g. the steps to produce the target chemical concentration.

How to Write a HAZOP Analysis With an Example?

HAZOPs usually deal in heavily technical information, but the audit should still be written in a manner that is clear and intelligible to all who read it, especially since hazards and operability studies are written by an interdisciplinary team. It’s not helpful nor will it inhibit accidents in the workplace if not all members of the team understand the preventive measures associated with the risks.

The following section will show examples of the failures that eventually lead up to the Flixbourough disaster to show how the HAZOP analysis can prevent such an accident from occurring in the first place.

NOTE: A potential hazard such as an explosion can have hundreds or even thousands of causes that would normally be listed in an analysis. For the purposes of this example, we’ll be focusing on the leading cause that resulted in the explosion in Flixbourough.

Below is the process hazards analysis example:

1. Audit

General Information

Name of the Inspector
John Smith

Date of the Inspection

2. Hazards and Operability Analysis

Deviation Forecast

The target function was not fulfilled
Yes  No  N/A

The target function was only incompletely fulfilled
Yes No  N/A

Root Cause Analysis

What is the cause of the deviating result?

A potential cause of a hazardous event is a leak from the reactor circuit.

Assessing the Impact

What are the potential impacts of the current scenario?

The potential impacts of a major reactor circuit leak:

  • A cloud formation of highly flammable hydrocarbon
  • Nearby heat source can cause ignition of hydrocarbon cloud
  • Contact of hydrocarbon cloud with heat source can cause a fuel-air explosion
  • Explosion can cause loss of life, injuries, and property damage



  • Circuit leak


  • Process alarms
  • Standard operating procedure (SOP)
  • Pressure safety valves

Guide Word

  • Low
  • High
  • Early


  • Low refers to a decrease in original or standard levels (refres to temperature, flow, concentration, pressure)
  • High refers to an increase in original or standard levels (refers to temperature, flow, concentration, pressure)
  • Early is an event that takes place sooner than expected (refers to early detection)


  • The objective is to reduce the risk of explosion via a circuit leak.

Possible Cuases

  • Corrosion
  • Faulty seals
  • Improper repair
  • Inspection failures

It is my recommendation that we install a warning system to alert personnel to any sudden or undetectable leaks. The pressure gauge, valves, and Caprolactum output should be measured at six-hour intervals throughout the day.


  • Delayed production of Caprolactum
  • Low production of Caprolactum
  • Explosion
  • Death
  • Injuries
  • Property damage

Add a photo of the identified danger or opportunity of development

Full name and signature of the HAZOP team leader:
John Smith

HAZOP study performed on potential chemical hazards

Use a Digital Technology for the HAZOP Form

Lumiform is a powerful inspection app. It is used to streamline HAZOP data collection and reporting. With the mobile app, any type of quality and safety inspection can be easily performed via tablet or smartphone – online or offline. With the desktop software, inspection lists are created immediately where data collected on-site is stored for later evaluation at your own convenience. This significantly reduces the risk of quality losses, work accidents, documentation errors, and damage to company reputation.

Lumiform makes it easier to meet the requirements for process documentation by using the mobile app to record data via smartphone or tablet. The system guides the user intuitively through all documentation processes. Clean, transparent documentation helps to avoid process risks, process hazards and design errors. The easiest way to do this is with a digital solution such as Lumiform. Other advantages that help to implement the HAZOP process are:

  • The flexible form construction kit helps to convert any individual paper list into a digital checklist within minutes.
  • All audit results are bundled in a report and can be sent to stakeholders..
  • Generate real-time data via internal processes. This makes quality and safety measurable and allows processes to be continuously optimized based on data.
  • Get an overview of everything that’s going on-site.
  • Depending on the application, tests are carried out about 30%-50%.

To help you get started, we have created a free PAAG form that you can download and adapt to your needs.

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