HAZOPs: Should You Include a Risk Assessment?

Exploring the two main approaches to HAZOP studies

Hazard and Operability Studies (HAZOPs) are a cornerstone of process safety.

It applies a structured, systematic technique to identify hazards and operability issues in a process design or operating system so that risks can be understood and managed.

HAZOPs follow an established methodology, formalised in international standards such as IEC 61882 and supported by guidance from organisations like the Center for Chemical Process Safety (CCPS).

The HAZOP study process is familiar across industries — and the usual steps of

• defining study nodes,

• selecting a process parameter (e.g., flow, pressure, temperature),

• applying a deviation guideword (e.g., No, More, Less),

• identifying the causes, consequences, existing safeguards, and

• capturing recommendations for process safety improvement,

  
  

...are well known and applied. However — this is where approaches begin to differ.

There are two schools of thought on whether a HAZOP should include risk assessment as part of the workshop:

• One perspective argues that introducing risk scoring during a HAZOP can distract the team from exploring hazards thoroughly, especially low-frequency but high-consequence scenarios.

• The other perspective believes that incorporating risk assessment adds valuable context — helping teams prioritise actions, communicate findings more clearly, and make better-informed decisions.

  
  

In this post, we explore both viewpoints, discuss where each approach adds value, and offer guidance on how to choose the approach that aligns best with your project stage, organisational needs, and process safety objectives.

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The Qualitative HAZOP Approach

Traditionally, HAZOPs are conducted as purely qualitative studies, where the focus is on identifying deviations from design intent, their causes, consequences, and safeguards — without an assessment of risk.

The emphasis is on asking:

• What could go wrong?

• What would happen if it did?

• What protections are currently in place?

• Are they sufficient?

• What is needed to ensure that protections are sufficient?

… without attempting to quantify likelihood or severity.

Strengths and Weaknesses of the Qualitative HAZOP Approach

The value of this HAZOP study approach lies in the depth of exploration and clarity of reasoning. This approach:

• Encourages deep, unbiased exploration of process systems

  Teams spend time understanding each deviation thoroughly without being influenced by perceived likelihood or previous assumptions.

• Avoids a false sense of precision

  Numbers and scoring systems can sometimes imply accuracy that simply isn’t there. A qualitative approach prevents this.

• Keeps the workshop collaborative and inclusive

  Participants focus on the scenario itself rather than debating numerical scoring, which can streamline discussions and reduce conflict.

  
  

Qualitative HAZOPs work particularly well when a highly experienced technical team is responsible for interpreting the findings and making decisions directly from the study findings and recommendations.

However, in many organisations — particularly larger organisations with multiple hazardous sites — decisions about risk management, resourcing, and implementation are often made outside the technical team. When HAZOP outputs remain purely qualitative, it can become difficult to communicate the significance of risks, justify priorities, and drive action.

As a result, a qualitative HAZOP may cause organisations to face challenges such as:  

• Difficulty prioritising HAZOP recommendations

  Without risk ranking, every hazard can appear equally urgent — making it difficult to allocate limited resources effectively

• Barriers in communicating process safety concerns to leadership and non-technical stakeholders

  Without a sense of scale or priority, senior management may struggle to understand why certain actions matter — and which ones matter most, which can be detrimental to strategic decision making on process safety matters

• Reduced auditability and traceability

  When decisions are based on qualitative reasoning alone, it can be more challenging to demonstrate why certain recommendations were prioritised (or not) during reviews, audits, or regulatory assessments.

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The Risk Assessed HAZOP Approach

In contrast to the purely qualitative approach, a risk-assessed HAZOP combines traditional hazard identification with a semi-quantitative evaluation of risk.

After identifying deviations, causes, consequences, and safeguards, the team assigns values for:

• Likelihood — how probable the event is (based on operating history, design experience, or industry data), and

• Consequence Severity — the potential impact if the event occurs on the receptor of concern (e.g. safety, environment, assets, reputation, etc)

  
  

These values are then combined using the familiar formula:

Risk = Likelihood x Severity

This produces a risk level, which is then interpreted using a risk matrix, helping to determine whether a scenario is Low, Medium, or High risk.

Strengths and Weaknesses of the Risk Assessed HAZOP Approach

Integrating risk assessment into a HAZOP introduces an additional layer of clarity and decision support. It strengthens the study by enabling teams to understand not just what could go wrong, but which risks matter most and why. This brings several tangible benefits:  

• Clear, structured prioritisation of process risk management activities

  Higher-risk scenarios can be addressed first, allowing limited resources to be directed where they will have the greatest impact on hazards management

• Improved alignment with follow-on studies

  Risk ratings help identify which scenarios warrant deeper analysis — such as LOPA, SIL determination or QRA — ensuring the right level of assessment effort is applied where it is most justified.

• Enhanced operational insight and lifecycle risk tracking

  Risk scoring can reveal recurring hazards or signs of safeguard degradation over time — although this can be difficult to achieve when managing process hazards data in manually or in simple tools such as spreadsheets.

  However, with purpose-built digital tools, these insights can be quickly visualised across assets, enabling informed decisions on maintenance, inspections, and asset management throughout the facility lifecycle.

• More effective communication with decision-makers

  Contextualised risk enables leadership, corporate risk teams, and planners to understand why certain actions matter — without needing to interpret technical narrative. This makes the implications of seemingly “low impact” decisions — such as deferring maintenance on a critical piece of equipment due to resource constraints — clear at the moment decisions are made, reducing the likelihood of avoidable incidents.

  
  

When done well, the result is a richer and more actionable HAZOP — one that not only identifies hazards but provides the clarity, priority focus, and organisational alignment needed to effectively manage hazards across operations, maintenance, safety, engineering, and leadership teams.

However — quality matters. There potential pitfalls that can introduce bias or complexity that undermines the quality of a HAZOP study if risk assessment is applied ineffectively.

For example:

• Risk scoring may detract from comprehensive hazard evaluation

Teams may become focused on whether a scenario is likely to occur (e.g.: based on past experience of plant operation) before fully exploring its consequences and safeguards, potentially underestimating the true impact and overlooking the need for additional measures to ensure effective risk reduction.

• Inconsistent interpretation of likelihood and severity

Without clearly defined criteria, risk scores can vary widely between teams, sites, or facilitators, reducing the usefulness of trend analysis  

• Variable familiarity with risk matrices and scoring methods

Participants unfamiliar with structured risk assessment may find the process confusing, slowing workshops or affecting scoring reliability.

These challenges do not make risk-assessed HAZOPs flawed — they simply require thoughtful planning and facilitation to be effective.

Below are a few strategies can you can apply to ensure that your risk assessed HAZOPs are targeted and effective:

• Incorporate risk assessment after evaluating causes, consequences, and safeguards

  This ensures the core hazard analysis is completed first, so risk scoring enhances rather than replaces the HAZOP process.

• Use a single, consistent process safety risk framework across the organisation

  Standardise the risk matrix and criteria for likelihood and severity across all relevant receptors (safety, environment, assets, etc.) and train personnel to apply this framework consistently before conducting a HAZOP. This ensures comparability within and across projects and enables meaningful trend analysis over time.

• Leverage digital, 'risk assessment–native' tools built for process hazards management

  These tools help maintain scoring consistency, provide clear visualisations, and allow both engineering and non-engineering teams to quickly interpret trends and insights.

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Which Method Should You Apply To Your HAZOP Study?

The choice between a traditional qualitative HAZOP and a risk-assessed HAZOP is nuanced and depends on both the complexity of the system and how you intend to use the HAZOP data.

A qualitative HAZOP is highly effective for thoroughly identifying hazards, but it may not always provide the clarity, prioritisation, and traceability needed to support decision-making across an organisation.

For small, low-hazard systems, a risk assessment may add unnecessary complexity and deliver limited additional value, and in such situations, a qualitative HAZOP study may be sufficient.

For larger, complex, high-hazard or multi-facility operations, risk assessment can be a powerful addition to the HAZOP process. It improves visibility of risk across sites, systems, and the organisation as a whole, enabling leadership, operations, and maintenance teams to understand where risk is concentrated, how it evolves over time, and what actions should be prioritised. In such situations, a qualitative HAZOP may not be sufficient. For these type of facilities, a risk assessed HAZOP is essential to ensuring that process safety hazards are clearly understood at both the site level and at the organisational level, so that risk management decisions are informed, targeted and effective.

When paired with the right digital tools, insights from risk assessed HAZOPs can be quickly visualised and leveraged to enhance operational resilience, drive proactive risk management, and ensure that process safety understanding translates into actionable outcomes across the organisation.

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Summary

HAZOPs are a powerful tool for identifying and understanding process hazards, but their true value lies in the interpretation and communication of its findings to relevant stakeholders so that action can be taken to manage risk.

Risk assessments can enhance the value of a HAZOP by providing context, prioritisation, and visibility of risk trends across a facility or portfolio of assets - all of which are crucial for improving communication across teams.

When applied thoughtfully, they complement the traditional qualitative approach, helping organisations identify which hazards need immediate attention, track changes over time, and support informed decision-making across operations, maintenance, safety, and leadership teams.

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Understanding process risk depends not only on identifying hazards, but on how insights are interpreted, communicated, and acted upon across both technical and non-technical teams. When applied effectively, risk assessments can enhance this understanding across an organisation.

Here are five key takeaways to help you understand how to get the most value from HAZOP studies, and choose the most effective approach for your needs.

1. Choose the right HAZOP approach – Qualitative-only HAZOPs are ideal for deep hazard exploration and work well for smaller, lower-hazard systems. Risk-assessed HAZOPs add prioritisation and decision-making context, making them particularly valuable for complex, high-hazard systems and multi-site operations.”.

2. Prioritisation drives action – Assigning risk scores helps focus limited operational resources on the highest-impact scenarios, ensuring critical hazards are addressed first.

3. Integration with follow-on analyses – Risk-assessed HAZOPs help to highlight the scenarios that may require further study such as LOPA, SIL determination, QRA, or other analyses, improving efficiency and alignment.

4. Track trends over time – When applied effectively, Risk assessment enables organisations to monitor recurring hazards, safeguard degradation, and evolving risks, supporting proactive maintenance, inspections, and operational resilience.

5. Leverage digital tools – The right software transforms raw HAZOP data into accessible insights, enabling visualisation, cross-facility comparisons, and faster, more informed decision-making for both technical and non-technical stakeholders.

Choosing the right HAZOP approach doesn’t have to be an either/or decision — by understanding the strengths of each method and applying them thoughtfully, organisations can turn hazard identification into actionable insight and build safer, more resilient operations.