Importance of Alarm Management and Process Safety Intersection

Alarm management and process safety are closely intertwined, and there is a high degree of importance of alarm management and process safety intersection.  Your alarm management system and associated operator intervention are often the last line of defense before a safety system trip.  However, the role of alarm management is also important when you consider other layers of protection, such as the process control system.  The ISA 18 and IEC 62682 standards govern alarm management for the process industries, while the ISA 84 and ISA 61511 standards cover safety instrumented functions (SIF).

The role of alarms in safety instrumented functions and process safety, however, can be a gray area, with some overlap between the ISA 84 and ISA 18 standards.  Both standards bodies have more work to do when it comes not only to the role of safety alarms, but also highly managed alarms that fall in between the categories of everyday process alarms and critical safety alarms.  The ISA 84 and ISA 18 standards committees have created a joint working group to address these issues.  This JWG will help end users better classify alarms and more clearly define the role of alarms in the safety system versus the role of alarms in process control systems.  This includes those "highly managed" alarms that can be so important, but may not have an immediate impact on plant safety.

Understanding Importance of Alarm Management and Safety Instrumented Functions

The role of alarm management as it relates to safety instrumented functions can be unclear.  A good understanding of the role of alarms in process safety is necessary both for optimum operator effectiveness and plant safety.  Many end users are undergoing alarm management projects at their respective plants or across their companies right now.  In some cases, they are migrating from an old alarm management system.  In others, they are initiating a new alarm management program.  In either case, if you are undertaking such a project, it's a good idea to have a comprehensive understanding of where process alarms and safety intersect.

The internationally recognized standards are a good place to start. ISA 18.2 is the standard for alarms in North America.  Its IEC counterpart is IEC 62682.  However, as previously mentioned, these standards could do more to define the roles of alarms in safety applications. The internationally recognized safety standards fall into different buckets, which can be an issue.  ISA 84 and IEC 61508/61511 are the safety standards.

In alarm management, there are many different classes of alarms, all with their own requirements.  The same can be said for process interlocks.  Process interlocks prevent incorrect operation and possible damage to process equipment.  Safety interlocks prevent hazards to humans and are designed to prevent death, injury, or a major process incident.  A third classification of interlocks is also emerging that provide an independent protection layer (IPL).  While these count as a layer of protection, they are not actual safety interlocks that address an abnormal situation.  In other words, IPLs protect against abnormal situations, or an “undesired consequence,” while safety interlocks respond to undesired consequences and take the process to a safe state.

The same logic can be applied to alarms.  All alarms should require an operator response per ISA 18, but not every operator response will be a critical safety-related response.  A disruption in the process for a food plant, for example, must be documented in a certain way to satisfy regulatory requirements as a food safety alarm.  This kind of an alarm is not an everyday process alarm that you would find in a downstream petrochemical plant, nor is it a safety alarm.  Instead, it falls into a class called "highly managed" alarms.

ISA 18 and ISA 84 Joint Working Group (JWG)

So, we now have multiple classes of alarms with multiple requirements, but how is this reflected in the current standards for both alarm management and process safety?  ISA 84/IEC 61511 and ISA 18 don't currently provide adequate guidance on how to classify alarms into these different categories. This is enough of a problem to warrant significant coordination between the safety standards committees and the alarm management standards committees.  The charter of the recently proposed JWG between ISA 18 and ISA 84 is to "Develop standards, recommended practices or technical reports on Functional Safety of Safety Controls, Alarms, and Interlocks for the Process Sector (ISA84.91.03)."

More information from the proposal for the working group follows. (Thanks to Todd Stauffer of exida and Nicholas Sands of DuPont for providing this information.  Both serve on ISA 18 and ISA 84.)

JWG Scope

This committee will address the lifecycle of instrumentation and control system functions that are classified as safety controls, alarms, or interlocks.

Background

The ISA84.91.03 working group, a subcommittee of the ISA84 committee, has been working on a draft standard for a number of years. The scope of the standard has been found to have significant overlap with the scope of ISA18.2 Management of Alarms Systems. To resolve this overlap, in compliance with the ISA Standards and Practices Procedures, a joint working group (JWG) is being formed between ISA84.91 and ISA18.

Assumptions

The formation of the JWG does not impact the scope of the ISA84, ISA84.91, or ISA18 committees. The JWG is expected to develop ISA84.91.03 to comply with existing ISA standard requirements.

This JWG should help end users better classify alarms and more clearly define the role of alarms in the safety system versus the role of alarms in process control systems, including those "highly managed" alarms that can be so important, but may not have an immediate impact on plant safety.  ARC will write more about this topic as we lead up to our ARC Forum session on Alarm Management at the 2017 Orlando Forum.

Recommendations

Process automation end users should strive to conform to the ISA 84 and ISA 18 standards for process safety and alarm management, respectively.  End users should also be aware of the overlap between alarm management and process safety.  Each standard has its own lifecycle that must be managed continuously.  The interrelationships between safety and alarms affect multiple facets of both lifecycles.  Managing these lifecycles can be a real challenge for end users. 

Most people don’t have time to participate in standards committees, however.  This can make it a little trickier to choose and, more importantly, install and execute a process safety or alarm management system.  Any vendor solution should be evaluated for conformance to the standards.  Many suppliers have gaps in functionality that they fill with solutions from partners.  Some have gaps they don’t fill.  In some cases, it can take a third party both to help manage the lifecycle and make sure all the required areas of functionality are covered. 

Even if you work for a smaller company that is short on resources, ARC recommends that you “do your homework” and gain a familiarity with both alarm management and safety standards because they are so critical to safe plant operations and achieving operational excellence.  Even some of the larger end user companies that have good discipline in these topics at the corporate or central engineering level don’t always do a good job of making sure this information finds its way down to the plant or operations level. 

Downtime continues to be one of the greatest avoidable expenses in the process industries.  Practicing good process safety and alarm management are two of the fundamental ways you can avoid this downtime.  Both ISA 18 and ISA 84 standards are also “recognized generally accepted good engineering practices” by OSHA.  If you have an incident and are investigated, establishing conformance to these standards can help you avoid both fines and damage to your corporate reputation. 

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Keywords: Alarm Management, Process Safety, Interlocks, Layers of Protection, Standards, ISA 18, ISA 84, IEC 61511, IEC 61508, IEC 62682, ARC Advisory Group.