What is BOW-TIE?
BOW-TIE is a visual risk management method that lets you map the causes, consequences and control measures for an unwanted event in a clear way.
The name comes from its shape: a bow-tie structure with the incident in the middle, causes on the left and consequences on the right.
The method is widely used in industries with high risks, such as chemicals, oil & gas, aviation and energy.
🧠 How does a Bowtie analysis work?
A Bowtie model consists of:
- Top event (the “incident”)
- Left-hand side (threats): possible causes that lead to the incident
- Right-hand side (consequences): consequences if the incident occurs
- Control measures (barriers): to prevent the incident or limit its impact
🎯 Example: overpressure in a reactor
Top event: Overpressure in reactor vessel
| Left (causes) | Preventive barriers |
|---|---|
| Control valve fails open | Dual valve + SIL2 SIS |
| Operator error | Operator training + alarm on SCADA |
| Temperature too high | Over-temperature protection |
| Right (consequences) | Mitigating barriers |
|---|---|
| Reactor wall ruptures | Pressure relief system + explosion panel |
| Leakage leading to fire | Fire detection and suppression systems |
| Production loss | BCP scenario and emergency procedures |
🔧 Why use Bowtie?
- Visual clarity: makes complex risks easy to see
- Structure: from hazard to control measure in a single diagram
- Communication: understandable to both technical and non-technical audiences
- Audits and compliance: demonstrating that the necessary safety layers are in place
- Input for other analyses: such as LOPA, HAZOP and SIL determination
🛠️ Difference from HAZOP and LOPA
| Method | Focus | Use |
|---|---|---|
| HAZOP | Identifying deviations | Detailed process analysis per line/node |
| LOPA | Quantifying risk reduction | Determining SIL and barrier effectiveness |
| BOW-TIE | Visual mapping of risks | Communication, oversight and barrier management |
✅ Benefits of Bowtie analysis
- Clear and visual for decision-making
- Combination of prevention and mitigation
- Strong basis for barrier management and maintenance strategies
- Broadly applicable in safety, quality and compliance
- Supports risk awareness at operational and strategic levels
📌 In summary
A Bowtie analysis provides a visual overview of how an unwanted event arises, what its consequences are, and which measures you have taken to manage the risks.
It is a powerful tool for communication, training and risk-driven maintenance.