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How to succeed at alarm management

Find out how you can improve the effectiveness of your distributed control alarm systems by better managing the techniques, tools, standards, and procedures you use in your process plant.

04/13/2005

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Do operators change alarm limits?
  • Do operators use alarms to inform them of non-critical changes in the plant, such as end-of-batch?
  • Are there alarms that operators do not know how to respond to?
  • Does any operator not understand why each alarm is the priority it is?
  • If the answer to more than one of these questions is "I don’t know" or "yes", then your Alarm Management system needs improvement, or at least an assessment. Poorly-managed alarms are a disaster waiting to happen. At best, they distract the operator from important events and slow down the response to the upset. At worst, the alarms will not be noticed, won’t occur at all, or will not be understood-- not a situation you want to deal with in an EPA/OSHA or insurers audit.

    What will Alarm Management do for me?
    Without effective alarm management, you cannot be certain that your operators will respond effectively when there is an upset. Alarms should define the boundary between normal operation and abnormal operation.

    The following figure shows this relationship:

    • Continuous monitoring detects disturbances that the operator must respond to in order to assist the automatic control system regulate the plant
    • DCS alarms alert the operator to significant upsets that must be corrected
    • Safety system alarms indicate the onset of critical events that require fast, sometimes radical, action, such as shutting down the plant.

    A properly applied Alarm Management program ensures that the alarms are:

    • Configured properly and enforced, so they are set at the right operating conditions
    • Understood by the operator, and so are effective
    • Practical, so the operator has enough time to respond to the alarms before a significant loss occurs

    How do I do it?
    There are essentially two routes to improved Alarm Management:

    1. Continuous improvement of normal operations
    2. A new Alarm Management program

    Both approaches start with an assessment.

    Assessment
    The Alarm Management Assessment (AMA) is an evaluation of your current operation by trained, experienced personnel, who examine all aspects of your existing alarm management systems. The AMA evaluates your current exposure to risk as a result of poor alarm management, and provides you with a grade in each of the different areas of Alarm Management, as well as an overall grade for your plant. Depending on the grade, the AMA recommends one of two different courses in each area.

    The areas of Alarm Management evaluation are:

    Alarm Definition: the existing procedures for defining and configuring alarms, alarm settings and priorities; the documentation of alarms and alarm-related procedures.

    • Management of Change: the effectiveness of the plant organization in maintaining the alarm settings once defined, and in ensuring that alarm settings are updated when physical equipment, procedures and plant operating parameters change.
    • Operator Readiness: the current state of operator training in response to alarms, and the systems in place to ensure operators are trained, qualified, and able to respond to alarms.
    • Alarm System Effectiveness: the actual performance of the alarm system during normal operation and upsets; the frequency of nuisance alarms and alarm floods; the availability of the alarm documentation as and when needed; and the effectiveness of the alarm system during significant operating incidents.

    If the existing practice in an area receives a grade of B or A, then there is no urgent need for improvement in that area. You may need some management systems to ensure that performance is maintained or improves continuously over time; however, large amounts of effort are unnecessary in that area.

    If the existing practice receives a grade of C or lower, then there is an organizational need to improve in that area, as described in the following sections.

    Approaches to Alarm Improvement
    There are two alternative approaches to alarm improvement. The appropriate approach depends on the grade from the Alarm Management Assessment. If the existing Definition, Management of Change and Operator Readiness processes are effective, then the alarm system can be improved by relatively simple continuous monitoring and continuous improvement. If the support processes are not in place, a more thorough approach is necessary.

    Continuous Improvement
    If all is well, or if there are other organizational priorities, then you can apply a continuous improvement philosophy. You can greatly reduce nuisance alarms during normal operation by this method, however, this approach is effective at improving and maintaining only an already well-managed alarm system.

    1. Collect data. Collect alarm history for at least a month, including all alarms for all consoles along with all operator actions. This data will provide both an original benchmark and the basis for alarm analysis.
    2. Analyze. Typically, most nuisance alarm occurrences result from a surprisingly small number of actual configured alarms. The initial alarm analysis will quickly identify those alarms most in need of reconfiguring. It will also provide insight into the severity of the current problem.
    3. Benchmark. Analyze the alarm history to determine whether the current rate of occurrence is within the EEMUA guidelines for standing alarms, alarm occurrences per shift, and for alarm bursts. Analyze alarms area-by-area, since some operating units or areas are more prone to alarms than others. Using the alarm history, measure the original performance as a benchmark for comparison to show improvement in nuisance alarms over time.
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