In recent site assessments and other plant visits, a common thread emerged, one of a poorly implemented asset or functional location hierarchy in the computerized maintenance management systems (CMMS). To many groups, a general listing of systems or high-level equipment in the hierarchy seems sufficient. With others, a much deeper dive is taken of listing parts, instead of stopping the number at equipment levels where you stop your maintenance strategy. For example, we don’t need to list every input and output card on the PLC rack as an asset. There is a functional balance.
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Consider a mixing system containing a mixer (with a motor and gearbox), a discharge pump stuffer (separate pump, gearbox, and motor), a positive displacement discharge pump (pump, gearbox, motor), and piping as examples. Some groups will stop the asset hierarchy at the mixing system and not develop the hierarchy further. This approach leaves a lot to be desired.
Using the positive displacement pump as an example, consider that the motor drives the gearbox, which drives the pump. Individually, each requires its own maintenance strategy and should have its own asset number. The pump pulls product from the pump stuffer assembly, emptying the mixer.
The above approach allows the use of equipment types or classes. For example, include positive displacement pumps, pump stuffers, diaphragm pumps, or centrifugal pumps. Or fractional hp motors, motors less than 10 hp, and motors greater than 100 hp. The equipment class allows you to group like equipment together across parent systems for reliability engineering analysis. When properly implemented, it’s one of the most powerful search and sort fields in the CMMS. With this approach, you can determine which pumps require the most maintenance or have the highest cost.
The lack of properly detailed hierarchies impacts partnerships too. Many sites struggle to build effective bills of materials (BOMs). When a motor is issued from the MRO storeroom and added to the BOM, do you want it to go to the parent mixing system or the child motor with the parent of the positive displacement discharge pump? To the discharge pump, no doubt, but when you stop the asset hierarchy at the mixer level, you cannot do that.
Digging a little deeper, consider a cartoner with eight servo motors. One model of servo (Model 1) is used in three positions, and another model (Model 2) is used in five places due to the OEM trying to standardize motor models to only two size models. In reviewing storeroom issues for the past three years, four Model 1 motors were issued to the cartoner to address failures. If you stopped the asset numbering at the cartoner level, that’s all you know. However, if you continued the motor numbering down to the individual motor locations, the history may be very different. This is especially true if you require the technicians to write work orders to the lowest child level in the parent-child relationship. The history may reveal that one specific motor location required all four motor replacements. Now, reliability engineering has data that shows if the motor problem is an incorrect application issue.
In one of the recent site visits, a supervisor complained about the high-level asset numbering, especially concerning the PM program. Multiple conveyors and other equipment were listed under a single high-level “conveying system” tag. PMs were written for individual equipment, and he could not discern which asset required that specific PM activity. A motor may require a PdM and lubrication frequency different from other equipment on the parent system. All reasons to go deeper with parent-child asset listings.
A commonly accepted standard for developing the asset hierarchy is the ISO 14224:2016 standard, initially developed for the petroleum, petrochemical, and natural gas industries. As a minimum, the standard should be used as a reference when sites build their own. There are other “standards” as well. Be careful of smart (alphanumeric) numbering systems, as you can box yourself into later expansion issues. Focus on what you are trying to achieve from a business perspective and at the maintenance level.
There is no point in building equipment history that adds no value or must be redone later. Realize that everything keys off the asset hierarchy or functional location. Don’t get into analysis paralysis on determining naming or make the process painstakingly slow. Get it done and implemented to leverage your CMMS system effectively.
This story originally appeared in the September 2022 issue of Plant Services. Subscribe to Plant Services here.