Features
ALARM MANAGEMENT AND ISA-18 – A JOURNEY, NOT A DESTINATION
Poor alarm management is one of the leading causes of unplanned downtime, contributing to over $20B in lost production every year, and of major industrial incidents such as the one in Texas City. Developing good alarm management practices is not a discrete activity, but more of a continuous process (i.e., it is more of a journey than a destination). This paper will describe the new ISA-18.2 standard -“Management of Alarm Systems for the Process Industries”[1]. This standard provides a framework and methodology for the successful design, implementation, operation and management of alarm systems and will allow end-users to address one of the fundamental conclusions of Bransby and Jenkinson that “Poor performance costs money in lost production and plant damage and weakens a very important line of defense against hazards to people.” [3] Following a lifecycle model will help users systematically address all phases of the journey to good alarm management. This paper will provide an overview of the new standard and the key activities that are contained in each step of the lifecycle.
INTRODUCTION
Alarm systems play a critical role in plant operations. A control room operator in a chemical plant or refinery may have responsibility for multiple unit operations with thousands of instruments. The purpose of an alarm is to draw the operator’s attention to abnormal conditions requiring action. This was clearly and concisely stated by Campbell Brown “the fundamental goal is that Alarm Systems will be designed, procured and managed so as to deliver the right information, in the right way and at the right time for action by the Control Room Operator (where possible) to avoid, and if not, to minimise, plant upset, asset or environmental damage, and to improve safety” [4]
It takes very little effort to add an alarm in modern control systems. Nimmo provided good insight into the problem of Abnormal Situation Awareness or Management (ASA or ASM) associated with the modern control system when he stated “having good situation awareness means that the operator has an accurate perception of the current condition of the process and equipment, and an accurate understanding of the meaning of various trends in the unit. The most common issue raised by operators and supervisors around the world is the loss of the big picture, when a company evolves to computer control rather than the panel mounted instruments. This complaint is echoed by the findings of the Health and Safety Executive in their report on the explosion and fires at the Texaco Refinery in Milford Haven.” [5][6] As a result many alarm systems perform poorly, and can negatively impact an operator’s ability to respond to an event. Poor alarm management was identified as a contributing factor in many major process incidents. A new standard, ANSI/ISA-18.02 Management of Alarm Systems for the Process Industries (ISA-18.2), provides guidance that will help users design, implement, and maintain a well performing alarm system. The recommendations in the standard provide a methodology for preventing and eliminating the most common alarm management problems. Per Reising and Montgomery, “There is no ‘silver bullet’ or ‘one shot wonder’ for good alarm management.” [9]