(54p) Common Bow Tie Errors and How CCPS Concept Book Rectifies

The bow tie risk analysis method is growing in its applications as it is a powerful tool for visually communicating major accident risks and the barriers deployed to prevent or mitigate these. The ease of communication can mislead users to think that bow tie creation is also easy, and this is not the case. A new CCPS Concept book, Bow Ties in Risk Management, thoroughly reviews how to create bow ties and provide detailed guidance on how to avoid errors.

This paper provides several examples of common errors seen in current bow ties. These cover structural errors where degradation factors and controls are misplaced onto main pathways,barriers that do not comply with guidance on required barrier core attributes, and it addresses incorrect hazards, top events, and consequences. The paper also covers poor treatment of human errors in bow ties by making these main pathway threats. These can lead to structural errors in the bow tie and a better means to treat human error is presented.

A final part of the paper presents a novel multi-level approach to bow ties that can be helpful got human error and mechanical integrity applications where deeper degradation controls are important to display.