Case study of alarms rates in two pipeline companies vs. Alarm rate standards

Industry controllers using alarm systems in the past have successfully handled pipeline failures, interruptions, leakages and miscellaneous alarms. Several recent repmts and legislation have brought human factors to the forefront for operators of gas and hazardous liquid pipelines. In 2005, the National Transpmtation Safety Board (NTSB) released their Safety Study, "Supervisory Control and Data Acquisition (SCADA) in Liquid Pipelines." In that report, they reviewed the role of SCAD A systems in 13 hazardous liquid line accidents from April 1992 to October 2004. In ten of the accidents, SCADA systems played some role. One key element of SCAD A systems are alarms. This paper discusses data gathered from alarm reports of two oil companies show alarms occur at variable rates throughout various time intervals. Segregating alarms received into time-interval-lots allowed the authors to compare actual operating systems existing standards (e.g., EEMUA and ISA) as to what human operators were handling without discrepancy. The resulting analysis indicates a discrepancy between established standards and actual operator workloads. Further review of alarm rate standards and what constitutes an alarm requires evaluation.