Bow-Tie Risk
Analysis
Bow-Tie has matured from a Shell-developed visualisation aid in the 1990s into the dominant barrier-based risk model across upstream oil and gas, COMAH safety cases, and increasingly hydrogen, ammonia, and battery-storage operations. The CCPS Bow-Tie Guidelines (2018) and Energy Institute Bow-Tie Standard (2019, rev. 2024) codify the discipline — Threat → Preventive Barrier → Top Event → Mitigative Barrier → Consequence — with explicit treatment of escalation factors, degradation controls, and barrier effectiveness scoring. The technique's strength is communicating major-accident logic to non-specialists: directors, operators, and regulators see the same picture. Its execution risk is barrier inflation (claiming non-independent or non-effective controls), missing degradation factors, and disconnection from LOPA. A defensible Bow-Tie programme integrates with HAZOP findings upstream, with LOPA / SIL allocation in parallel, and with barrier-health KPIs and SCE (Safety Critical Element) performance standards downstream.
