Managing Alarms to Support Operational Discipline

Process alarms are frequently cited as a safeguard in a Process Hazard Analysis (PHA) and an Independent Protection Layers (IPL) in a Layer of Protection Analysis (LOPA), but does the alarm management system really support the safeguard/IPL?

According to ISA-18.2 / IEC 62682 to be valid an alarm must indicate an equipment malfunction, process deviation, or abnormal condition and it requires a timely operator action. If no action is taken, then the alarm is either invalid or the operator is not doing their job, Both scenarios represent a breakdown in operational discipline for alarm management  as does the presence of nuisance alarms and alarm floods. This breakdown in operational discipline for alarms has been cited as a contributing factor in many significant safety incidents (some of which will be analyzed in this paper). If operational discipline for alarms is lacking, then it is very possible that the desired risk reduction for a process alarm used as an IPL will not be achieved (the probability of an ineffective operator response will increase).

As systems have evolved from hardwire to computer control, alarms have become easier and less expensive leading to more and less purposeful alarms.  Operators must contend with multiple alarms at one time with only their experience to determine priority. Alarms may be added to or removed from a control system without proper management of change. Systems may include alarms for which there is no possible action, or inadequate action time. What can an organization do to take control of their process alarms and improve operational discipline?

This paper will review some of the conditions that precipitate poor alarm management systems, and the negative conditions and behaviors that evolve as a result. We will discuss the steps to develop a written Alarm Philosophy reflecting the risk tolerance and operating objectives of the organization. Requirements of an alarm will be defined and alternatives to alarms will be identified.  Key elements of the alarm rationalization process are discussed. Finally Alarm set point evaluation and advanced alarming techniques will be introduced.