Bowtie Analysis & Barrier Management
Understand major accident hazards. Define the barriers that keep people, assets and the environment safe.
See the risk.
Make barriers visible.
Bowtie analysis presents the threats that can lead to a loss of control, the top event itself and the credible consequences in one picture. Prevention barriers sit to the left; mitigation barriers sit to the right. Good Bowties turn the picture into accountable barrier performance standards, verification tasks and operational decisions.
Hazard and top event
Define the hazardous inventory and the precise loss of control, such as an unplanned hydrocarbon release. The top event is not the original cause or the final consequence.
Threats and preventive barriers
Identify credible initiating pathways such as corrosion or overpressure, and the distinct controls intended to stop each pathway reaching the top event.
Consequences and mitigation
Examine possible escalation after loss of containment: ignition, exposure, injury or environmental harm. Identify detection, isolation and response functions where applicable.
Degradation and assurance
Consider failed proof tests, bypasses, overdue inspections, common-cause failures and other factors that undermine critical controls. Assign owners and assurance requirements.
Trace a loss-of-containment
Bowtie from left to right.
Follow the pathways from corrosion and overpressure through preventive barriers to a hypothetical release, then through mitigation to possible consequences. This illustrative example is not a validated site-specific barrier assessment.
Connect each initiating cause to the top event and avoid combining different scenarios without a defensible basis.
Describe the required function, performance expectation, owner and how effectiveness is assured.
Check independence, dependencies, impairments and degradation factors. A generic safeguard label does not establish risk reduction.
Connect the Bowtie to maintenance, testing, operational procedures, impairment response and management of change.
Practical questions.
Defensible controls.
Bowties support major accident hazard communication, engineering reviews and operational barrier assurance. They complement, rather than replace, HAZID, HAZOP, LOPA and quantitative risk analysis. Not every Bowtie barrier meets the independence and effectiveness criteria to qualify for LOPA credit.
What makes an effective barrier?
A specific function and success criteria, demonstrated availability, named ownership and traceable inspection, testing or verification activities.
How are degraded barriers managed?
Identify the degradation factor, assess its impact on the barrier function, determine interim controls and track restoration under the facility’s risk management processes.
When should a Bowtie be revalidated?
At defined intervals and following material changes to threats, equipment, barriers, operating conditions, risk assessments or incident learnings.
Is Bowtie a quantitative risk assessment?
Typically no. Bowtie is primarily a qualitative barrier-based model. Numerical risk estimates require additional justified inputs and appropriate quantitative methods.
Need a Bowtie workshop or barrier review?
Discuss your facility, major accident hazard scope, existing Bowties and assurance requirements. Pro Engineers can help with technically defensible Bowtie development, revalidation and barrier management support.
Email Pro EngineersCall 0422 354 755