As the primary tool for identifying plant incidents and helping personnel return processes to operational targets, alarm systems play a key role in plant safety and profitability. But according to an article for ISA by Kevin Brown, global alarm management best practices leader at Honeywell Solutions, some common mistakes result in poorly configured systems that can overwhelm operators when they need specific direction.
While alarming systems may be used on many different scales and in many different manufacturing contexts, the overall functioning of the systems remain the same. According to ISA, this includes benchmark, alarm philosophy, rationalization, implementation, continuous improvement and maintenance.
Benchmarking involves identifying the most pressing alarm system problems and the areas for biggest improvement. After benchmarking, operators should prepare an alarm philosophy document—an engineering document focused on all aspects of the alarm management system including governing rules and risk categories. ISA recommends reviewing ANSI/ISA-18.2-2009, Management of Alarm Systems for the Process Industries for the full requirements of an alarm philosophy document.
Rationalization means determining the causes, consequences and corrective actions for an alarm. Once rationalization is complete, successful implementation of an alarm system will include control logic, alarm designs and graphics. The dynamic nature of alarms means they will be affected by process or control changes, so routine performance monitoring is key.
However, even with proper execution plans in place, operators may still face some common issues in implementing a successful alarm management program. Brown’s article identifies the 10 most common alarming blunders.
The first is a facility’s operations group assuming the alarming system is the sole responsibility of the controls or instrumentation group, since this group’s primary focus is computer system maintenance. Operations groups will benefit from taking ownership of the alarming system, as its functions are dictated by operational needs.
Brown identifies the second mistake as having a missing or incomplete alarm philosophy document. The document should include methodology and rules for setting alarms, an alarm review to consolidate training and an audit process to ensure the implementation of best practices.
The third common alarming blunder is using the wrong tools. Operators should utilize alarm and event archiving with analysis tools to ensure maximum return for time spent correcting problems. While all alarms should be reviewed, ISA cautions against inefficient and costly corrections to minor nuisances while problems that pose more serious risks to plant safety and profitability remain.
ISA also warns against neglecting to benchmark as the fourth common pitfall in alarm system management. Progress cannot be determined without measuring current levels, so ISA recommends keeping track of alarm rates for several weeks to obtain a baseline measurement. That baseline should be compared to industry standards to identify areas for improvement. Tracking key performance indicators can help indicate improvements or deteriorations in the alarm system.
Only tracking alarms is ISA’s sixth blunder. Alarm rationalization requires tracking more data than just when an alarm goes off. It should also track whether personnel responded and how quickly. Brown calls tracking operator data “an effective way to identify control problems and automation opportunities and audit the effectiveness of the alarms strategy.” One tool for identifying poor alarm strategies is to examine the ratio of operator auctions to audible response alarms. An approach with every alarm requiring operator intervention yields a ratio of over 2:1. Operators should also track controller setpoint, mode changes and system errors.
Seventh on the list is cutting resource corners. ISA says alarm rationalization is a manpower-intensive effort with excellent results when executed correctly, but some facilities try to minimize costs by reducing the rationalization team. According to the article, it is “disturbingly common” for facilities not to include the end-user and primary stakeholder, the operator.
ISA’s eighth error is incorporating alarm rationalization into incident investigations, hazard and operability studies (HAZOPs) and layer of protection analyses (LOPAs). Doing this causes alarms to be added without proper rationalization because a manufacturer has identified a safety issue, loss of production or environmental excursion. It remains important to review corrective action, response time, alarm setpoint and severity in these situations so they result in rationalized alarms. ISA recommends manufacturers modify procedures for incident investigations, HAZOPs and LOPAs to include rationalization when an alarm is defined.
Adding dynamic alarming too early is a common error for manufacturers trying to fix alarming issues. ISA argues that rationalization must be completed before instituting dynamic alarming, and should resolve the issues in most cases. In fact, rationalization should help identify opportunities for dynamic alarming.
Finally, ISA says lack of accountability is the most common issue in alarm system management. It recommends a strategy of “accountability through visibility,” or ensuring everyone has access to everyone else’s data.
Instituting proper alarming procedures in an operation can result in increased productivity and decreased cost. If your company has not examined its alarm system for these common errors, you may be missing a chance to increase efficiency.
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