Definition:
Bowtie analysis (or bowtie diagram) visually maps the relationship between hazards, causes, preventitive barriers, the central accident of concern, mitigating measures, and consequences. The accident of concern is at the knot.
Bowtie analysis is most commonly used as a tool to facilitate discussion and risk awareness with various stakeholders, rather than for detailed quantitative analysis.
It visually links preventing the event (left) –> the central event (knot) –> mitigating the event (right)
Some texts will oversimplify and say a bowtie combines an FTA and ETA; rather, it integrates the basic logic of both for high-level barrier management and communication.
Key Points:
- Often used to communicate complex scenarios as simply as possible to stakeholders.
- It is especially valuable for ongoing barrier management and operational risk assurance.
- Complements fault tree and event tree analysis. But is distinct from it.
Example:
In a biogas facility a major accident is an biogas storage explosion. This forms the knot. The left will show all credible initiating events (like loss of containment and a ignition source). The right shows mitigation and consequence management measures, such as emergency response.
See Also: FTA, ETA, Layer of Protection Analysis (LOPA), Process Hazard Analysis (PHA)