The Crossroads of Alarm Management and Process Safety

The role of alarm management in process safety 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 (link goes to exida document on the ISA 18.2 lifecycle) is the standard for alarms in North America.  It has an IEC counterpart dubbed IEC 62682 (this link goes to a nice presentation on 62682 from the 2015 ARC Forum in Orlando).  However, 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 (link to ISA article on ISA 84) and IEC 61508/61511 (link to NORSOK application of these standards) are the safety standards. In alarm management, there are lots of different classes of alarms, all with their own requirements.  

The same can be said for process interlocks.  Process interlocks, for example, prevent incorrect operation and possible damage to process equipment, while safety interlocks prevent hazards presented to humans and are designed to prevent death, injury, or a major process incident.  A a third classification of interlocks is also emerging that can be called Independent Protection Layer (IPL) interlocks.  These count as a layer of protection, but are not actual safety interlocks that address an abnormal situation.  In other words, IPLs protect against abnormal situations, while safety interlocks respond to abnormal situations 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. So, we now have multiple classes of alarms with multiple requirements, but how is that 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 some pretty significant coordination between the safety standards committees and the alarm management standards committees.  

Recently, a joint working group (JWG) was formed between ISA 18 and ISA 84.  The charter of the recently proposed working group 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)." Here's some more information from the proposal for the working group (thanks to Todd Stauffer of exida and Nicholas Sands of DuPont who serve on ISA 18 and ISA 84 for providing this information):

Functional Safety of Safety Controls, Alarms, and Interlocks Working Group 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 be in compliance to 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.