It's OK, we have a back-up

This article was written for IChemE's Loss Prevention Bulletin in 2025 and was awarded the 2026 Lee's Medal for the best article on the topic of safety and loss prevention in an IChemE publication.

A summary is provided below and the full article can be viewed at: https://www.icheme.org/media/28270/lpb302_pg02.pdf

Summary

Electrical power, steam, compressed air, nitrogen, hydraulic systems, other energy sources and key utilities such as cooling water are essential for the safe and reliable operation of many facilities. The provision of reliable back-up systems is necessary in the event that one of these supplies is lost. However, events have occurred where the loss of multiple systems, potentially originating from the failure of a single service or common cause failures, have resulted in consequences that were not considered by either the original or subsequent risk assessments. Back-up systems are not always available, and operations/ maintenance teams are often reluctant to fully test them in case they result in loss of supply or consequences that they were intending to prevent in the first place. Hazard Identification and Risk Analysis (HIRA) should identify the requirement for back-up systems but might not consider events when these systems fail. Complacency regarding the reliability of back-up systems could lead to the “unsinkable Titanic approach”, whereby site management and operational staff mistakenly believe the back-ups are sufficiently robust. This paper provides some examples where back-up systems have failed and offers advice on design, operation, and maintenance to reduce the risk of failure. It discusses procedures, human factors, and emergency exercises that should be considered in the event of a total failure of backup systems.