Last updated on Jun 26, 2024

What are the best practices for developing and maintaining effective Bow-Tie diagrams?

Bow-Tie diagrams are a visual and practical tool for identifying and managing the risks of major hazards in process safety. They show the causal factors, preventive and mitigative barriers, and potential consequences of a hazardous event in a simple and clear format. But how can you develop and maintain effective Bow-Tie diagrams that reflect the reality and complexity of your operations? Here are some best practices to follow.

Key takeaways from this article

Clarify the diagram's purpose:

Start by defining the hazard, top events, and worst-case outcomes you aim to analyze. This ensures your Bow-Tie diagram remains focused and avoids unnecessary details.### *Assess barrier effectiveness:Evaluate how well your barriers perform using quantitative or qualitative methods. Regular assessment helps in monitoring and improving their reliability over time.

This summary is powered by AI and these experts

1 Understand the purpose

Before you start creating a Bow-Tie diagram, you need to understand its purpose and scope. What is the main hazard or threat that you want to analyze? What are the top events or scenarios that could trigger it? What are the worst-case outcomes or impacts that could result from it? How do you define the boundaries and assumptions of your analysis? These questions will help you define the objective and context of your Bow-Tie diagram and avoid unnecessary details or confusion.

Add your perspective

Mohammad Nurkholik

Process Safety Professional (Oil & Gas, Offshore/Onshore, LNG, Petrochemicals/Chemicals) CCPSC, CFSP, NEBOSH ITC, APM PMQ, CQI IRCA Lead Auditor
Report contribution
Bow tie is a risk management tool to help visualizing the risk and associated prevention & mitigation barriers. It could be used for various purpose starting from a good tool for communicating the risk, barriers healthiness monitoring, support incident investigations, etc. It could be linked with existing risk management process e.g. PHA/LOPA where the organization could stress more focus on the risk associated with major accident hazards. The scenario, from PHA/LOPA, for major accident hazards e.g. tank overfill of class I flammable liquids (to be top event of the bow tie) that linked to all associated causes (threat in the bow tie) and relevant barriers all the way to all credible consequences with all relevant mitigation barriers.

Like
Imran Aslam

Experienced Energy & Petrochemical Professional | Operations & Maintenance Leader | Passionate about Digital Transformation | Driven by Strategy & Innovation | HSE | Asset Management |
Report contribution
Bow-Tie diagrams are commonly used in risk management to visualize potential hazards, their causes, and the resulting consequences. Here are some best practices for developing and maintaining effective Bow-Tie diagrams Clearly Define the Objective Identify Hazards and Consequences Identify Causes and Controls Identify Consequences and Controls Use Standardized Symbols Keep It Simple Review and Update Regularly Involve Stakeholders Provide Training Integrate with Risk Management Systems

Like
Eslam Kandeel

CSP®, CRSP®, CHSC, NCSO®, CMIOSH, IDip NEBOSH, MSc. in Safety and Risk Engineering @ MUN, PMP®, RMP®, FIIRSM, MBA in HSE Leadership, IASP-CSM, ISO Lead Auditor, COR™ Auditor, 6 Sigma practitioner, HACCP certified
Report contribution
Best practices for developing and maintaining effective Bow-Tie diagrams include: 1.Involve Stakeholders: Engage relevant stakeholders to ensure comprehensive risk identification and assessment. 2.Clear Definitions: Define hazards, threats, and consequences clearly and concisely. 3.Identify Controls: Identify and document preventive and mitigative controls accurately. 4.Validate Data: Use reliable data and evidence to support the diagram elements. 5.Regular Updates: Review and update the Bow-Tie diagrams regularly to reflect any changes in processes or risks. 6.Training: Ensure all users are adequately trained in understanding and using Bow-Tie diagrams.

Like

2 Identify the barriers

The core of a Bow-Tie diagram is the identification and classification of the barriers that prevent or mitigate the hazardous event. Barriers are measures or controls that reduce the likelihood or severity of the event, such as design features, procedures, alarms, or emergency response. You should identify the barriers based on your hazard identification and risk assessment methods, such as HAZOP, FMEA, or LOPA. You should also categorize the barriers as preventive or mitigative, and as hardware or human, depending on their function and nature.

Add your perspective

Ir. Adam Maulana Musthafa, CFSP, CCPSC

Process Safety | HSE | Operations Integrity Management | Fire Protection
Report contribution
Actually, we should start from Hazard and Top Event, not barriers like stated here. The wrong top event will lead to inaccuracy of prevention and/or mitigation barriers. From here, we define the scenario by defining the consequence and list down the threat. After these key structures is well defined team can start properly identifying the proper barrier at the proper side of bowtie. Keep it simple, and clean. Bow Tie is tools for communication. The more complex it is, the more diluted the information and the higher the risk of failure of communicating the MAH and SCEs involved in the scenario.

Like

3 Evaluate the effectiveness

Once you have identified the barriers, you need to evaluate their effectiveness and reliability. How well do they perform their intended function? How often do they fail or degrade? What are the causes and consequences of their failure? How can you monitor and improve their performance? You should use quantitative or qualitative methods, such as SIL, RRF, or Bow-Tie XP, to assess the effectiveness of the barriers and assign them ratings or scores. You should also document the sources and assumptions of your evaluation.

Add your perspective

4 Communicate the results

A Bow-Tie diagram is not only a risk analysis tool, but also a risk communication tool. You should use it to communicate the results and recommendations of your analysis to your stakeholders, such as management, workers, regulators, or customers. You should present your Bow-Tie diagram in a clear and concise way, using colors, symbols, labels, and legends to highlight the key elements and messages. You should also explain the logic and limitations of your analysis and solicit feedback and input from your audience.

Add your perspective

5 Update the diagram

A Bow-Tie diagram is not a static or final product, but a dynamic and evolving one. You should update your Bow-Tie diagram regularly to reflect the changes and improvements in your operations, such as new equipment, processes, procedures, or regulations. You should also review your Bow-Tie diagram periodically to verify its validity and accuracy, such as after an incident, audit, or inspection. You should use a systematic and documented process to update and review your Bow-Tie diagram and ensure its consistency and relevance.

Add your perspective

6 Use a software tool

A Bow-Tie diagram can be created and maintained manually, using paper, Excel, or PowerPoint, but this can be time-consuming, error-prone, and difficult to share and update. A better option is to use a dedicated software tool that can help you create, evaluate, communicate, and update your Bow-Tie diagram in a more efficient and effective way. A software tool can offer features such as templates, libraries, calculations, reports, dashboards, and integrations that can enhance the quality and usability of your Bow-Tie diagram.

Add your perspective

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

Add your perspective

What are the best practices for developing and maintaining effective Bow-Tie diagrams?

1

2

3

4

5

6

7

1 Understand the purpose

2 Identify the barriers

3 Evaluate the effectiveness

4 Communicate the results

5 Update the diagram

6 Use a software tool

7 Here’s what else to consider

Process Safety

Rate this article

Thanks for your feedback

More articles on Process Safety

More relevant reading