Remember the story of Goldilocks and the Three Bears? Goldilocks found one bed too soft and another bed too hard! But the third bed was “just right.” Likewise, we need a credible priority system, one that is not too simple and not too hard. Not all priority systems will do! It needs to be “just right” to help us in our maintenance mission of peaceful and quiet, profitable operation.
In the Maintenance Planning and Scheduling Handbook, I state the second principle of scheduling as “The work order priority system must adequately define the relative urgency and importance of new work orders to determine if any should break into the current daily or weekly schedule.” To build and use an effective weekly schedule, we must know if something should break the schedule (and how soon) and if something can wait (and how long).
Agreement between operations and maintenance
The priority system is a critical “coordinating device” for operations and maintenance. It helps us talk together about selection of the best work. Generally, organizations are good at specializing but weak at coordinating. We specialize into operations and maintenance. But we must coordinate together, that is, deal with the interfaces. We see coordinating weakness when we hear the phrase “things are falling in the cracks.” The operations group wants a plant that runs and runs well. The maintenance group wants to do the appropriate work with its limited resources. Out of all the work that has been identified, what work is the best work to keep the plant running and running well; and when should maintenance do it? The priority system helps provide agreement or coordination between operations and maintenance for these decisions on work.
One of the most important aspects of any priority system is showing the degree of urgency. Separating work by urgency can be with a simple number of levels or with a more sophisticated calculated score. Let’s consider simple levels first and then calculated scoring.
Work priority levels and coordination
Many plants have three levels for work priority. The first two levels are “no brainers.” “Emergencies” have to be started right away. Then there is “Urgent” work that doesn’t have to start now, but should not wait until next week. Other work is considered “Routine.” Many plants have 50% or more of their work that cannot wait beyond the current week. These plants spend most of their time battling new work each week that suddenly pops up and cannot wait. They are not focused on maintenance beyond the current week. These plants are satisfied with three levels because they are not in control. They are not very good at identifying less urgent proactive work or productive enough to do much proactive work that is identified in time.
But three levels, Emergency, Urgent, and Routine, are simply not enough. A decently operating plant should expect to have only 20% of all its work as emergency or urgent and the 80% being able to wait longer. Having 80% of a plant’s work as “Routine” is simply not good enough to help with scheduling. The plant should have more than a single week of proactive work in its backlog! Having 80% is too much for a single “routine” level so we need at least four levels: Emergency, Urgent, Next Week, and Longer. Five levels are even better to distinguish among less urgent work orders. Let’s say Emergency, Urgent, Next Week, This Month, and Longer.
Let’s see how “coordination” happens between the two “specialized” groups of operations and maintenance with five levels:
Operator 1: “I need something done.”
Maintainer: “Does it have to be done right now?”
Operator 1: “Well, it doesn’t have to be done right now, but it can’t wait too long.”
Maintainer: “How about we do it next week?”
Operator 1: “Okay, thanks.”
Operator 2: “I need something done.”
Maintainer: “Does it have to be done right now?”
Operator 2: “No, but it really can’t wait until next week.”
Maintainer: “Okay, we’ll try to work it in tomorrow or the day after.”
Operator 2: “Okay, thanks.”
Operator 3: “I need something done.”
Maintainer: “Does it have to be done right now?”
Operator 3: “No, but I don’t want us to forget about it.”
Maintainer: “Okay, we’ll put it on the ‘Longer’ list and probably work it in sometime when we have something else to do in that system.”
Operator 3: “Okay, thanks.”
Do you see how “coordination” is really just having a basis for talking with each other? The maintainer is just trying to understand the operator’s sense of urgency.
On the other hand, imagine how much more complicated the discussions would have been if the priority system had, say, ten levels.
This article is part of our monthly Palmer's Planning Corner column. Read more from Doc Palmer.
Maintainer: Well, can it wait for at least a month, but not two months?
Operator: “Hmm, I don’t know…”
In practice, with too many levels to finely tune the priorities, the conversation just becomes too lengthy and so does not provide good coordination.
Calculated systems
Calculated systems both help fine tune the relative priorities and minimize the selection time. But they also make the conversation more difficult. For example, the CMMS might multiply the Equipment Criticality by the Work Type and allow adding an Adjustment Factor (EC × WT + AF = Score). An example might be the following two work requests:
WR#1 Paint boiler feed pump:
Priority = 10 × 1 + 0 = 10
WR#2 Electrical short on sump pump:
Priority = 1 × 10 + 0 = 10
The potentially lethal situation on the non-critical sump pump has an equal priority as the very-critical boiler feed pump which is only being painted. The conversation becomes
Maintainer: “The sump pump only gets 10 points. Is it really an emergency?”
Operator: “ Yes. How many points should we add?”
So we would arbitrarily add an “adjustment” of 20 points to the sump pump (Priority WR#2 = 1 × 10 + 20 = 30) to make the sump pump work request get a higher priority. If we are not careful the conversation gets distracted by “points” instead of simply, “Do we need to go ahead and do it now?”
Planning a fully loaded weekly schedule at your plant
Why a weekly schedule is the right timeframe for productivity
Implementing a priority system to create and maintain a profitable plant
Recommendation: 5-level system
In practice, I see a lot of three-level systems, Emergency, Urgent, and Routine. These are too simple. Without upsetting the apple cart, I recommend five levels: Emergency, Urgent, Routine-High, Routine-Normal, and Routine-Low. I have also seen systems with more levels and also calculated systems, many that work successfully, but I think they risk being too complicated for the fast and easy coordination we need from this device.
Just like Goldilocks, we need a credible priority system, one that is not too simple and not too hard. It needs to be “just right” to help us quickly and easily coordinate between operations and maintenance on the relative urgency of work. (We’ll talk more about priority systems next month!)
This story originally appeared in the March 2022 issue of Plant Services. Subscribe to Plant Services here.
