How difficult is the emergency response of your process units? What minimum staffing level is needed to secure the units during an emergency shutdown? Do any of the upset response tasks impose excessive risk or difficulty to the operators?
Managers often have to provide information about their process units emergency response requirements to community leaders, regulatory agencies, and even internal auditors. Without performing some kind of analysis, managers are forced to rely upon subjective opinions, which are never quantifiable nor comparable. Beville has been studying processing unit upset response for the past thirteen years and has developed a systematic approach to evaluating response requirements. Using the approach, Beville has compiled a database of response requirements for processing units from across the petrochemical industry. The database has proven valuable in setting targets for upset response operator loading.
Beville’s approach for analyzing upset response is to examine the human performance requirements for reasonable, worst case upset scenarios; the logic behind this approach is that staffing for worst case will be adequate for any less severe upsets. The stopping point in the analysis is that point at which the unit is no longer at unacceptable risk, and at a safe, stable condition.
Beville’s approach to upset response analysis examines two items, (1) the risk of not performing a task, and (2) the difficulty of performing the tasks. Beville has developed a general hierarchy for rating both the risk and difficulty of upset response tasks. Risk and difficulty information is gathered in an iterative manner in which operators and supervisors perform walkthroughs of their tasks while being observed and queried. Risk and difficulty ratings are then assigned to the tasks and the ratings are summed to form a risk/difficulty rating for each individual task. The tasks are then summed to form a risk/difficulty rating per operating position that can be compared to others in the plant as well as others in the industry.
Beville has found that most facilities studied have been conservative on upset response loading. For example, Beville has found an average risk/difficulty rating per post position to be 33.3. Through analysis of the data, Beville believes a reasonable target loading to be 60 per position, a number that is substantiated at many units.
When comparing individual units, the ones with lower loads often have one or two “bottleneck” tasks that necessitate higher manpower. In one plant, automating a manpower bottleneck of switching from series to parallel hydrogen usage lowered the manpower requirements from three to one operator. This example also illustrates why counting equipment is not an accurate predictor of job loading.
With the risk/difficulty data, managers can perform costs/benefits analyses to ensure their limited budgets are spent wisely. Managers can compare across units and prioritize the automation expenditures to ensure the tasks with the greatest potential to reduce risk and difficulty are the first to be automated.
Copyright © 1997 Beville Engineering, Inc., All Rights Reserved
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The dates for this year's Fall meeting for the Center for Operator Performance will be announced soon. For more information, please contact Lisa Via. Guests are always welcome!
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David Strobhar's book, "Human Factors in Process Plant Operation," is now available in both hardcover and Kindle e-book.
Copyright © 1996-2017 Beville Engineering, Inc. All rights reserved. (937)434-1093. Beville@Beville.com