A Case Study to Show How Bow-Tie Analysis Can be Used As an Effective Communication Tool in Risk Assessments

Bow-tie analysis is one of the most powerful and increasingly popular risk assessment techniques used to depict and maintain an up-to-date, real-time, working risk management system embedded in daily operations. The biggest advantage of bow-tie is the diagrammatical view which gives the ease of understanding to operations and management. It can be outlined as a combined application of fault tree analysis and event tree analysis which provides a systematic identification of hazards and consequences. The purpose of this paper is to identify an effective communication tool for managing multi-barrier thinking and ways of managing risk during operations.

Many times the risk management philosophy is not adequately communicated to operations, thus limiting full comprehension of how daily and emergency tasks link to barriers and controls. The bow-tie analysis was found to be the best method of communicating the risks related to operations because it provides a diagrammatical representation of safety barriers that are in place to prevent, control or mitigate hazards. The tool clearly illustrates the barriers associated with operations and the effect if one were to be compromised. The important factors contributing to safe operations are the barriers which prevent, detect, control or mitigate hazardous events. The bow-tie diagrams effectively include these safety barriers. To ensure a risk-based approach, hazards are  identified and used as input to the bow-tie methodology.

This case study presents an understanding of safety barriers, their classification and attributes of importance as they relate to operational performance.  Barriers can be physical or non-physical, but are always designed to prevent, control, or mitigate undesired events. Likewise, they can be classified as passive or active barrier systems whether physical, technical, or human/operational in nature. Effective, reliable and high-functioning barriers are critical to the overall safety of the operation. This paper presents an analysis of different types of major accidental events such as fire, explosion, gas release, BLEVE and surface tank fires; and barriers associated with them to prevent hazards.