Equipment classification for maintenance.

With the complexity of modern plants and the sheer number of assets the capture of all assets into an asset inventory or listing is essential.

What level should the asset register go down to?

This depends greatly on the kind of production/process operation being maintained. However, a recognized method is by defining the…

Lowest Maintainable Unit (LMU)

This can be defined as an item that would reasonably have a maintenance plan produced for its care.

This should be ‘balanced’ with the function being maintained. For example a single light may not be a LMU, but if the lighting in an area is critical to production or safety the lighting function should be considered a LMU. The planned maintenance routine produced for such an asset might be...

PM: L12-3M           Tech (M/S)        Estimated time (up to) 1 Hr
Check lighting in QC cell. Ensure sufficient (80%) of units functional with no failures in inspection area. Replace filaments as required to restore function.

Functional Location
With the complexity of modern plants a ‘map’ of asset locations is also desirable. Usually based on Process and Instrumentation Diagrams (P&ID) the functional location of an asset is a distinct tag that identifies the location of an asset and where it ‘fits’ into the production or utilities processes.

A site has two buildings with mirrored production lines.

production line asset identification
How might you identify; Production unit 2 on line 1, the conveyor between the grinder and former?

From a functional point of view the asset location might be identified as follows…


Equipment Type Classification
Similarly to be able to classify asset by type is very useful in helping manage their maintenance plans, spares etc. Again a coding system is beneficial both for physical asset identification at its location (tag) and for use in a Computerised Maintenance Management System (CMMS).

Example of Equipment Type Classification

 AGT  Agitator  GRD  Grinder
 AHU  Air Handling Unit  HOMO  Homogeniser
 CIVIL  Civil/Building  LIGHTS  Lighting
 CHART  Chart Recorder  MIX  Mixer
 CMP  Compacter  PACK  Packer
 COMP  Compressor  PAST  Pasteuriser
 CONV  Conveyor  PHE  Plate Heat Exchanger
 DOS  Fruit Dosing System  PRNT  Printer/Labeller
 DRY  Dryer  PUM  Pump
 ELECT  Electrical Systems  SEP  Separator
 FAN  Fan/Blower  SILO  Silo
 FLOW  Flowmeter  TANK  Tank
 FLT  Filter  VALV  Valve
 FORM  Former  WGR  Weigher

Equipment Identification
Bringing functional location and equipment type classification together in our example plant…

production asset identification

If we use the location code and the equipment type code together as shown in the red ‘tags’ above we can create a logical location and identification code.
Looking at the question we posed before:

How might you identify; Production unit 2 on line 1, the conveyor between the grinder and former?


Physical labels/tags fixed to the machine identify its location help Production staff report accurately which machine they might be having trouble with and from a maintenance viewpoint positively confirms to a technician (or contractor) that they are on the correct asset.

Part Number and Bill of Material (BoM)
Each asset and its constituent parts are an assembly. The assembly will normally be assigned a part number by the Original Equipment Manufacturer (OEM).
On larger assemblies it is common to find a serial number (unique to that equipment) and a part number on a plate attached (or etched or stamped) on to the equipment.

A bill of materials (BoM) is a list of the sub-assemblies, parts or components that are required to build an asset. The BoM provides the manufacturer's part number and the quantity needed for each component (usually supplied by OEM).

BoM Bill of Materials

At its most complex, a BoM is a multi-level document that provides build data for multiple sub-assemblies (products within products) and includes for each item: part number, approved manufacturers list (AML), mechanical characteristics and a whole range of component descriptors. It may also include attached reference files, such as part specifications, CAD files and schematics.

(The above article is a small extract taken from our maintenance training programs.)

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