The HAZOP (Hazard and Operability Study) process is a global standard in risk management, and it was actually developed because of a deadly chemical explosion in the 1970s. Today, you’ll find HAZOP used across diverse industries like chemical manufacturing, water treatment, and even nuclear power, helping prevent harmful incidents.
Since HAZOP is a systematic methodology that involves careful analysis, this guide will walk you through its key steps, along with an example report that you can follow. By breaking down complex systems and exploring possible deviations, implementing HAZOP allows you to uncover less obvious risks and boost safety for your organization.
What is the HAZOP process?
The purpose of HAZOP (Hazard and Operability Study) process to identify potential hazards and functional faults in existing or planned plant systems. The analysis method is primarily for investigating complex operational hazards and functions in chemical processing plants, but also in nuclear, water, sewage, and wastewater treatment plants.
A team of interdisciplinary experts consisting of engineers, chemists, facility managers, and safety officers carries out the process, identify risks, 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, you can employ various checklists 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.
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. Here are the steps for conducting a HAZOP:
1. Define the scope and objectives
The first step is to decide on the scope and objectives. You’ll identify the process or system to analyze, whether it’s a piece of equipment or a whole production line. You can then set clear goals such as:
- Identifying potential hazards (e.g. at least 10 potential process hazards that could lead to equipment failures, injuries, or environmental incidents)
- Improving safety protocols (e.g. review and update 5 key safety procedures)
- Optimizing operational efficiency (e.g. reduce unplanned equipment downtime by 25%)
Once the objectives are clear, it’s time to assemble a multidisciplinary team. This team should include individuals with diverse expertise, such as process engineers, operators, safety professionals, and maintenance personnel. A trained facilitator would lead the discussions to maintain focus and ensure productive outcomes, while someone else documents the findings.
2. Prepare and gather information
Next, collect important documents like:
- Piping and Instrumentation Diagrams (P&IDs)
- Process flow diagrams (PFDs)
- Standard operating procedures (SOPs)
- Historical risk assessments
These documents give you a detailed understanding of the system’s design, operation, and potential failure points. You can then divide the system into manageable sections or nodes, such as individual equipment or specific piping sections. This allows the team to focus on one area at a time for a systematic review.
3. Identify hazards and deviations
In general, a HAZOP form examines the following three parts of a plant function:
- 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.
- Physical environment: Assess the environment of the system or design to ensure that it is ideal, e.g. is there enough space for the batch chemical reactor to operate as intended ?
- Procedure: Evaluate technical controls such as automation, the sequence of steps, human interactions, e.g. the steps to produce the target chemical concentration.
The HAZOP team discusses possible deviations and develops various scenarios in which the system or process could fail. It involves using predefined “guide words” like “No,” “More,” “Less,” “As Well As,” or “Reverse.” These words prompt you to think about what could go wrong in each part of the process. For example, “No flow” might suggest a potential blockage, while “More pressure” could indicate a risk of equipment failure.
Once you’ve identified deviations, the team then explores their potential causes, consequences, and existing safeguards. This helps uncover gaps in the current system. For example, a valve failure might lead to overpressure, which could result in a rupture unless safety measures like relief valves are in place.
4. Recommend actions
After analyzing the data obtained, the team can propose recommendations for safety precautions and improvements. These might be:
- Design changes
- Additional safety controls
- Updated maintenance procedures
- Enhanced training for personnel.
If you’ve identified a risk of equipment overheating, a solution might involve installing temperature sensors with automatic shutoff features. Each recommendation should be practical and cost-effective.
Document all of these findings and recommendations in detail so there’s a comprehensive record of the HAZOP study. This also acts as evidence of due diligence for regulatory compliance.
5. Follow up on outcomes
The insights from the HAZOP study should translate into actionable improvements. Share the final report with all stakeholders, including team members, management, and any external parties involved. You’ll then assign specific action items, with a clear timeline, priority level, and responsible party.
As you implement the action plan, review progress regularly and address any challenges or delays promptly, with periodic check-ins. By ensuring follow-through, your organization can close the loop on risk management, enhance safety, and continually improve their processes.
How to write a HAZOP analysis (with an example)
HAZOPs usually deal in heavily technical information, but the audit should still be s clear and intelligible to all who read it, especially interdisciplinary team writes hazards and operability studies. 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.
To start off, you can try out any of Lumiform’s pre-made HAZOP checklists, which you can easily customize for your organization. They’re also easily downloadable as professional reports.
We’ll also walk you through an example report here based on the failures that eventually lead up to the Flixbourough disaster. This shows 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 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: 11-12-2025
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
Measures
Deviation
- Circuit leak
Safeguards
- Process alarms
- Standard operating procedure (SOP)
- Pressure safety valves
Guide Word
- Low
- High
- Early
Comments
- 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)
Element
- The objective is to reduce the risk of explosion via a circuit leak.
Possible causes
- Corrosion
- Faulty seals
- Improper repair
- Inspection failures
Note: It is my recommendation that we install a warning system to alert personnel to any sudden or undetectable leaks. Measure the pressure gauge, valves, and Caprolactum output.
Effects
- 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
Use a digital technology for the HAZOP Form
Lumiform is a powerful inspection app that enables you to streamline HAZOP data collection and reporting.
With the mobile app, you can easily perform any type of quality and safety inspection via tablet or smartphone – online or offline. With the desktop software, you’ll create inspection lists 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 AI form builder helps to convert any individual paper list into a digital checklist within minutes.
- View audit results in a report with analytics that you can send to stakeholders.
- Generate real-time data via internal processes. This makes quality and safety measurable and allows you to continuously optimize processes based on data.
- Get an overview of everything that’s going on-site.
- Depending on the application, you can carry out tests about 30%-50% faster.