HAZID AND HAZOP: A Brief Comparison

HAZID AND HAZOP: A Brief Comparison

13 Sep 2023

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This informal CPD article ‘HAZID and HAZOP: A Brief Comparison’, was provided by Synergen Oil and Gas UK, an independent engineering consultancy specialising in Process Safety, Technical Risk Management and Operational Safety services.

Effective risk management, using risk assessment tools like Hazard Identification (HAZID) and Hazard Operability (HAZOP) studies, is crucial for process industries. These PHA methods offer structured ways to identify and assess risks, each with distinct methodologies and areas of focus.

What is HAZID and HAZOP?

HAZID and HAZOP are two distinct risk identification techniques. Both involves brainstorming sessions to identify potential hazards. HAZOP is a more detailed and systematic method that examines deviations in process parameters, focusing on process flow and operability issues. HAZOP employs multidisciplinary teams and a structured approach to comprehensively identify hazards and recommend corrective actions in a process or system.

HAZID (Hazard Identification) and HAZOP (Hazard Operability) studies are fundamental processes in ensuring workplace safety and risk management, particularly in industries like oil and gas, chemicals, manufacturing, and pharmaceuticals.


A HAZID study typically involves a multidisciplinary team comprising subject matter experts from various fields such as engineering, safety, operations, and maintenance. The process can be broken down into several key stages:

Preparation: The study begins with defining the scope and objectives, selecting the team, and establishing the methodology. This phase sets the groundwork for the entire analysis.

Hazard Identification: The core of HAZID involves systematically identifying and listing potential hazards that could arise from a particular process, system, or operation. Techniques like brainstorming, checklists, or flow diagrams are used to ensure comprehensive hazard identification.

Risk Analysis and Evaluation: Once hazards are identified, the team assesses their likelihood and severity, assigning a risk rating. Tools such as risk matrices or fault trees may be employed to analyze risks effectively.

Risk Mitigation: Practical and effective preventive measures are proposed and evaluated to avoid, eliminate, or reduce the likelihood and impact of identified hazards.

Documentation and Reporting: All results and findings from the study are meticulously recorded, and recommendations for necessary corrective actions are prepared. This documentation serves as a crucial reference for future safety measures.


Like HAZID, HAZOP studies also involve a multidisciplinary team consisting of experts from various disciplines such as process engineering, operations, maintenance, and safety. The key steps involved in a HAZOP study are:

Preparation: Defining study objectives, selecting team members, and establishing the methodology.

Deviation Identification: Systematically analyzing the process or system to identify potential deviations from intended design parameters, using a guideword approach to provoke thoughts.

Consequence Analysis: Assessing each identified deviation's potential consequences on safety, operability, and performance, considering severity factors like fires, explosions, chemical releases, and more.

Cause Analysis: Identifying the causes or factors leading to the deviations and their consequences, which can include equipment failures, design flaws, procedural errors, or other factors.

Preventive Measures: Proposing corrective actions or preventive measures to address the deviations and mitigate associated hazards. These measures can involve design modifications, improved operational procedures, safeguards, or system redundancies.

Documentation and Reporting: Documenting all findings, recommended actions, and conclusions in a comprehensive report for future reference during design changes, modifications, or operational improvements.

Comparing HAZID and HAZOP

Both HAZID and HAZOP are group-based brainstorming exercises utilizing structured guidewords and multidisciplinary inputs to generate risk improvement recommendations.

HAZID is typically conducted early in projects or when risk profiles change significantly, focusing on identifying all hazards and safeguards.

HAZOP, on the other hand, can be done at any stage, often during mid-design and ongoing operations, requiring more mature design data than HAZID.


In summary, both HAZID and HAZOP studies are essential tools for identifying, assessing, and mitigating potential hazards, ensuring workplace safety, and preventing accidents across various industries.

We hope this article was helpful. For more information from Synergen Oil and Gas UK, please visit their CPD Member Directory page. Alternatively, you can go to CPD Industry Hubs for more articles, courses and events relevant to your Continuing Professional Development requirements.

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Synergen Oil and Gas UK

Synergen Oil and Gas UK

For more information from Synergen Oil and Gas UK, please visit their CPD Member Directory page. Alternatively please visit the CPD Industry Hubs for more CPD articles, courses and events relevant to your Continuing Professional Development requirements.

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