A Guide To HAZOP (Hazard And Operability Study)

HAZOP stands for Hazard and Operability Study. It is used across a number of sectors to identify potential hazards. HAZOP is a very thorough process and so this guide will explain in more detail what HAZOP is, and how relevant industries can complete a HAZOP study. 

In this guide: 

1. What Is HAZOP?
2. What Is A HAZOP Study Used For?
3. The Difference Between HAZOP And A Risk Assessment
4. The Pros And Cons Of A HAZOP Analysis
5. The Four Phases Of A HAZOP Analysis
6. How To Complete A HAZOP Study

What Is HAZOP?

HAZOP (Hazard and Operability Study) is a structured and systematic approach used to identify potential hazards and operational issues within a system, process, or facility. HAZOP is known by the terms HAZOP study or HAZOP analysis, but each refers to the same system and process. HAZOP studies are primarily utilised by industries that involve complex processes and hazardous materials, such as chemical manufacturing, oil and gas, pharmaceuticals, and nuclear power, where safety and operational risks must be thoroughly understood and controlled.

A HAZOP study involves a multidisciplinary team that reviews the design and operations of a system. They examine any deviations from the intended design in order to pinpoint risks, assess their potential impacts, and recommend necessary measures to mitigate problems. HAZOP is an essential tool for enhancing safety, reliability, and efficiency in complex systems, helping to prevent accidents and ensure regulatory compliance. 

What Is A HAZOP Study Used For? 

The main goal of HAZOP is to examine how deviations from normal operations can lead to safety risks or operational problems. The primary purpose is to: 

• Identify potential hazards – Whether that’s risks to people, the environment, or the facility where work is being completed
• Identify operational issues – This includes any issues that could affect the efficiency or performance of the system, even if they do not necessarily pose a direct safety risk
• Understand possible deviations – By assessing and predicting possible ways machinery or processes could go wrong, hazards are caught earlier on
• Ensure safety compliance – A HAZOP study ensures that all regulatory and safety standards are met, therefore reducing the risk of accidents
• Mitigate risks – HAZOP provides a foundation for eliminating or minimising risks by helping to determine safety measures and control strategies

The Difference Between HAZOP, Risk Assessments And HAZID

HAZOP and risk assessments are both essential tools used to identify and mitigate risks in various industries. There is also a third method called HAZID that you may have heard of. Each differs in their primary focus and the methods used. 

HAZID vs HAZOP

HAZOP is a systematic, structured approach primarily aimed at identifying potential hazards and operational issues in a process or system through team discussions and brainstorming sessions. It examines deviations from the intent of existing processes or designs and how these deviations could lead to hazards, systematically analysing each part of the process in detail. 

Risk assessments encompass a broader evaluation that identifies hazards but also estimates the likelihood and severity of potential incidents. This allows risks to be prioritised and managed in order to reduce them. While HAZOP delves deeply into the specifics of individual processes and their operational integrity, risk assessments provide more of an overview of risks across a range of activities, so that organisations can develop an overall risk management strategy. 

HAZID is a preliminary method aimed at identifying potential hazards in a system early in the design process. It helps in recognising what could go wrong before detailed designs are created. HAZID is an initial screening tool, while HAZOP is a deep dive into operational aspects when designs are more established. Both methodologies work together, so although there are some differences in HAZID vs HAZOP, both are needed to ensure optimum safety across working systems.

The Pros And Cons Of A HAZOP Analysis

The primary benefits of a HAZOP analysis are:

• Improved safety – HAZOP helps prevent accidents and incidents by systematically identifying hazards 
• Compliance – The Health And Safety Executive (HSE) dictates that all workplaces must manage health and safety for employees and visitors. Certain industries are further required to conduct hazard analysis studies like HAZOP as part of their safety management systems. Doing so maintains compliance with current regulations 
• Operational efficiency – By identifying and addressing operability issues, HAZOP can lead to smoother, more reliable operations
• Multiple perspectives – HAZOP is a collaborative process, requiring teamwork and bringing together expertise from different disciplines to ensure a thorough analysis

There are also some limitations with a HAZOP study, including:

• Time – Completing a HAZOP study thoroughly can be time-intensive, especially when used for large and complex systems
• Expertise – The effectiveness of a HAZOP depends heavily on the expertise of the team, so having knowledgeable and experienced professionals is key to getting a HAZOP analysis right
• Deviations focus – HAZOP is specifically designed to explore deviations from the norm. This could mean it might fail to address risks that arise from normal operations, and a separate risk assessment will be necessary

The 4 Phases Of A HAZOP Analysis

A HAZOP analysis is done in four main phases. These are: 

1. Preparation Phase

Before starting the HAZOP, it’s essential to define the system or process under review and set the objectives for the study. This is the preparation phase and could involve a specific unit, piece of equipment, or the entire facility, depending on the scope. Those carrying out the HAZOP will gather necessary documentation, such as process flow diagrams, manuals, and data sheets. The team is also assembled during this initial phase and roles are assigned to each team member. 

2. Identification Phase

This is when the actual HAZOP analysis is conducted. The team systematically reviews each part of the process using guide words, such as ‘more’, ‘less’, ‘as well as’, and ‘none’. They will discuss potential hazards and operability issues that could occur, allowing the team to identify deviations from normal operating conditions and assess any potential consequences.

3. Evaluation Phase

In the evaluation phase, the hazards and operability issues that were defined during the identification phase are assessed in terms of their severity, likelihood, and risk. The team will talk about the implications of each deviation and rank them based on certain criteria, such as the potential impacts on safety, health, environment, and production. For particularly high-risk deviations, mitigation strategies are also proposed.

4. Documentation and Follow-Up Phase

Finally, all findings from the HAZOP analysis must be documented, including any recommendations for corrective actions and improvements. A follow-up plan should be put in place to ensure that the recommended actions are implemented and reviewed. This documentation can be referred back to for future analyses and audits to improve safety and operations.

How To Complete A HAZOP Study

Although there are four main phases of a HAZOP study, in order to complete it effectively, there are a number of key steps to follow. These are:

1. Define the Scope

You should begin by determining the boundaries of the HAZOP study, which involves identifying the system, process or equipment that will be analysed, and outlining its operational parameters and intended outcomes.

2. Assemble a Multidisciplinary Team

It’s important to gather a team of experts from various disciplines; most often from engineering, safety, operations, maintenance, and, if necessary, environmental management. Having a range of expertise will provide a more comprehensive analysis.

3. Review Relevant Documentation

Collate all existing documentation related to the system and review the information. This typically includes:

• Process flow diagrams (PFDs)
• Piping and instrumentation diagrams (P&IDs)
• Operational manuals
• Safety data sheets (SDS)

4. Identify Parameters

Define the parameters that are to be examined during the HAZOP study. Common parameters are:

• Flow rate
• Temperature
• Pressure
• Composition
• Any other operational variables that could impact safety

5. Break Down the System into Nodes

The process or system is divided into smaller, manageable sections called nodes. A node might represent a pipeline, a vessel, a pump, or any other part of the process. This breakdown ensures that every aspect of the system is studied thoroughly.

5. Determine Deviation Guide Words

A set of guide words is used to help the team systematically identify possible deviations from normal operations. These are applied to each node to assess how deviations could occur. Common guide words include:

• No  – no flow, no pressure, etc
• More – more flow, more pressure, etc
• Less – less flow, less temperature, etc
• As well as – additional components or actions
• Reverse reverse flow, reverse reaction, etc
• Other than something different happens to what is intended

6. Conduct HAZOP Analysis Sessions

The team will need to meet to discuss each parameter using the guide words. They will talk about potential deviations, their causes and their consequences, and document all findings using detailed notes.

7. Assess Consequences

Analyse the potential consequences of each identified deviation, considering their severity and any possible impacts on safety, environment, and operations. 

8. Identify Safeguards and Controls

Review current safety measures and controls that have been implemented to mitigate identified risks for each node. The HAZOP team should assess the effectiveness of the measures and determine if additional controls are necessary.

9. Develop Recommendations

Using the findings from the HAZOP analysis, compile recommendations to address any risks that have been identified and to enhance safety. Examples of these recommendations include:

• Design modifications
• Operational changes
• Additional training
• New safety equipment

10. Document Findings

The HAZOP analysis should be written up in a comprehensive report. This report should detail the methodology, findings, recommendations, and action items that have arisen from the HAZOP. The report should then be communicated to all relevant parties.

12. Review and Revise the HAZOP Process

Establish a plan for implementing any recommended actions, and assign responsibilities to ensure these actions are completed. The HAZOP study needs to be reviewed often to accommodate any operational changes, new equipment, regulatory updates, or lessons learned from incidents that have occurred. Update the HAZOP as necessary to maintain safety standards.

When to Conduct a HAZOP Study

HAZOPs are typically conducted at several key stages in the lifecycle of a facility or process:

• Design stage – A HAZOP may be conducted during the early design stages, but in most cases this will be referred to as a HAZID
• Prior to operational changes – If modifications or upgrades are planned, a HAZOP helps identify potential new risks caused by the changes
• Periodically – Regular HAZOP reviews are performed to ensure ongoing safety and compliance, particularly as systems age or as new regulations emerge
• After incidents – If an incident or accident occurs, a HAZOP study can help identify what went wrong and prevent future problems

Using Health And Safety Experts

At Rhino Safety, we are experts across all areas of health and safety, offering a range of services for every sector. To find out how we can support your business with health and safety for total compliance and a safe working environment, contact us now.