The safety philosophy of offshore installations is generally that multiple technical safety devices are installed to prevent escalation of deviations into adverse consequences. This implies that offshore processes are designed to be self-contained in the event of disturbances. If the process control system or the operator fails to keep process parameters within predetermined limits, the process equipment is designed to shut down and prevent adverse development of the situation.

With these redundant safety devices, how can accidents occur? It is evident that in order to reach a critical situation, safety barriers must not function as intended. Barriers can be put out of function intentionally or unintentionally, due to errors or slack in operating procedures on the installation, as well as insufficient component reliability.