Benchmarking Industry Practices for the Use of Alarms As Safeguards and Layers of Protection

Operator response to alarms is a common risk reduction mechanism considered during layer of protection analysis (LOPA). Industry practices on how to treat alarms as independent protection layers can vary greatly. For example, some companies do not allow any credit to be taken for alarms during a LOPA (zero risk reduction), while others allow up to two orders of magnitude (risk reduction factor of 100, SIL 2) to be taken.

This presentation will discuss current industry practices around the use of alarms as safeguards and layers of protection as established by a recent benchmark survey of over 200 safety practitioners from around the world. Areas explored in the survey include; typical and maximum claimed risk reduction, considerations used to determine whether an alarm can be credited with risk reduction, how often IPL alarms are determined to be invalid or ineffective in operation, and practices for display and annunciation through a Human Machine Interface (HMI). Key results and conclusions will be presented as well as recommendations on where industry should focus on improvement.