ISA TR18.2.5

This technical report was written in support of the widely used ISA international standard, ANSI/ISA-18.2-2016, Management of Alarm Systems for the Process Industries.

This technical report is designed to provide guidance, rationale, and examples of alarm monitoring and assessment, (Clause 16 of ISA-18.2) and audit (Clause 18 of ISA-18.2). This technical report provides guidance and information supplementing ISA-18.2 on the use of alarm system analysis for both ongoing monitoring and periodic performance assessment. Monitoring, assessment, and audit are essential to achieving and maintaining the performance objectives of the alarm system. These activities can identify improvement opportunities in the other lifecycle stages, such as philosophy, rationalization, detailed design, implementation, operation, maintenance, and management of change.

Alarm system performance analysis can also play a part in overall plant performance metrics and be used as an input to process improvement efforts. This is typically in conjunction with process historian data and control loop effectiveness data. However, analyses of control system data, process data, and operator actions are not included in this report except to note the relationship between alarm metrics and other process metrics.

Purpose

This technical report has been written to aid in the collection of alarm system data, the analysis of that data, and the application of that analysis to improvement in the operation of the process. Sections of the technical report explain the calculation of the alarm system performance metrics and the basis for performance targets.