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Let’s explain this through a couple of examples. First let’s imagine that we have a rooftop chiller which needs to be maintained on a yearly basis. It will also need an overhaul every 3 years and needs to be replaced in 20 years. For the yearly maintenance a company might want to establish a rigorous maintenance program where all the steps are planned and processes are defined for such maintenance . We call this “procedural” preventive maintenance. In the case of major overhaul and replacement, the company may depend on the expertise of an outside contractor to analyze, propose and complete the task. We refer to this as “non-procedural” preventive maintenance. Below is a more detailed overview of the procedural and non-procedural preventive maintenance.

Procedural Preventive Maintenance

In Procedural Preventive Maintenance (PPM), the CMMS has to handle the variation of how this is accomplished. PPM should be applicable at the asset catalog level as well as the asset level itself. This means that you should be able to apply PPM to a catalog item such as specific model of a boiler from a specific manufacturer. By such application, CMMS would then need to propagate the PPM and its associated schedule to all assets of that type within the portfolio. As the same time, CMMS should be able to apply a procedure to selected assets as needed.

Manufacturer’s recommended procedures

For some equipment, manufacturers recommend certain steps and procedures for the preventive maintenance based on the type of the equipment and the frequency type of maintenance. CMMS should be able to easily import manufacturer’s recommended procedures into the system and be able to apply it to any of the assets which the company desires. Further, CMMS has to allow the manufacturer’s procedures to be modified based on the specific nature of the company’s portfolio of properties and assets. For example, a manufacturers’ standard yearly chiller maintenance procedure need to be modified for the equipment in more humid or wet climates as well as those in drier climates.

Internal procedures

In addition to the manufacturer’s procedure CMMS should allow the company to create its own set of procedures based on its own experience and knowledge or the recommendation of its consultants and service providers. A company may use a manufacturer’s recommended procedures for certain frequency of preventive maintenance (for example, yearly boiler maintenance) and its own internal procedures for the quarterly inspections and maintenance.

Managing maintenance procedures

The steps to follow for maintaining a certain type of asset at a certain frequency is called a maintenance procedure or sometime a job plan. There can be many maintenance procedures in a typical company to address the variety of assets and frequencies of the maintenance. A CMMS should be able to manage these procedures effectively and make the process of their upkeep simple. It should be easy to assign a selected procedure to a catalog or an asset item. For example, Axxerion provides different methods for the management, storage and assignment of maintenance procedures which accommodates different company needs. Procedures can be stored in a library in a central location in the system. The library has “folders” where each folder would represent a category of an asset. There can be subfolders as necessary to make the navigation and finding the right procedure easy. Procedures can have multiple versions and older versions are kept in the system and can be referred to as necessary. Library procedures can be assigned to any of the catalog items easily and upon assignment all assets of that kind could inherit (be assigned) the procedure. Another approach is creating procedural work orders as templates and assigning them to assets as need be. A procedural work order is a typical work order which includes all the maintenance steps. This approach is simpler for cases where there are not many procedures to upkeep and use.

Non-Procedural Preventive Maintenance

In Non-Procedural Preventive Maintenance (NPPM), the maintenance procedures are left to the people who would actually perform the work. It would be managed outside CMMS though bidding, selection and contract processes or other approaches as needed. CMMS should keep track of the overall task, costs, dates and the assignment to the maintenance resources. An example of NPPM is typical roof maintenance such as roof inspection and repair and/or replacement. Generally for this type of maintenance specialized contractors are invited to inspect the job and bid on it. The bid winner is then selected and a contract is put in place which details what needs to be done at what price. Therefore, CMMS should be able to handle the scheduling of such tasks and their associated estimated cost and effort. The contract for the work should ideally be managed in the system in association with the NPPM. NPPM would be an excellent tool to provide estimates of the maintenance budgets over the year if it is done properly using the right CMMS.

Definition of Assets

In referring to assets, we have a general concept which is broader that many of other CMMS in the market. An asset can be a piece of equipment or a part of a building or a property as necessary. For example, in a CMMS, a part of a roof, an air-conditioning system or a part of a parking lot should all be able to be assets.  It should not be limited only to equipment.

Work order generation

CMMS should be able to create work orders from either of the NPPM and PPM schedules. The generated work orders must include all procedure steps and follow the schedule for assignment of the correct date. The resulting work orders must be manageable together with the corrective work orders. All resource management and resource planboard capabilities much apply to both corrective and preventive work orders the same way.

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About the author

Mehdi Khalvati, Ph.D. is the president of Axxerion USA. Axxerion’s CMMS module addresses corrective, preventive and predicative maintenance as well as asset management.  Please send your feedback, thoughts and comments to

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