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Mid-Life Metrics (Stage)
Attributes of assets, systems or buildings during the mid stages of their respective asset life cycle.

This is, generally speaking, the mid-point in the life of the asset when some wear and tear deterioration has occurred. This phase is therefore focused on a combination of maintenance and some periodic repairs to address emerging problems with the aging of the asset.The challenge for the owner is to ensure consistency in the maintenance program.

Mid-life period is a relative concepts. For example, a short-life asset (of say 10 years) will have a mid life stage of perhaps the years 3-6, whereas a long life asset (say 35 years) may have a mid life period of perhaps years 15-25.



Attributes
Listed below are some of the key attributes of this life stage of assets:
  • The asset is no longer covered under warranties or limited coverage.
  • Maintenance practices have settled down (stabilized).
  • The owners have a few years of expenditure experience under their belt.
  • Any idiosyncracies associated with the asset are now well known.
  • Early signs of aging may manifest. 
  • Some leading indicators, lagging indicators, and possible idiosyncracies are well known at this stage in the life of the asset.
  • Managing the risk of failure as the asset approaches the point of functional failure ("F") on the P-F Interval.
  • The maintenance-to-repair ratio (MtR) starts to change. Some repairs may arise from time to time in addition to maintenance costs
  • A heavier reliance on condition-based maintenance (CbM).


Determining the Arrival of the Mid Life Stage
How do we know that we have arrived at the mid- life of an asset. Listed below are some of the techniques for making this determination:

The mid life is essentially established by statistical averages rather than empirical data.



Management Principles
Mid life metrics are necessary for the following asset management principles, policies and strategies:
  • The goal is to be consistent in the maintenance of the assets.
  • Recordkeeping. Detailed operating histories on the assets will provide critical information for the last stage in the life of the asset. These histories will help to identify patterns/trends to develop a corresponding risk management plan. Keep good recordkeeping on the operating histories of the assets as this information is going to be essential during the late life of the asset.
  • Establish priorities relative to other aging asset
  • Plan for a shift to condition-based maintenance and inspections.
  • Monitoring.  Once the asset is exhibiting signs of wear it will be necessary to set up a monitoring program. The strata should identify a consultant who can assist as necessary. Depending on the asset, the monitoring program may include sampling surveys. The monitoring program will identify leading indicators to guide the timetable for eventual replacement of the asset. Start to set up an asset monitoring program in preparations for the late life of the asset. Identify a consultant who can assist as necessary. 
  • Arrange for sampling surveys to identify patterns and trends.(see: Schedule of Historical Events).
  • Meet with the maintenance contractor to get feedback and suggestions for ongoing stewardship of the asset.
  • Reserves.  Evaluate the amount of the annual reserve allocations for the replacement of the asset. Make adjustments as required.
The risk spectrum extending along the P-F interval to illustrate the varying strategies in the Pre-P and Pre-F periods. For example, a shift from Time-Based Maintenance (TbM) to Condition-Based Maintenance (CbM)
Fig. The risk spectrum extending along the P-F interval to illustrate the varying strategies in the Pre-P and Pre-F periods. For example, a shift from Time-Based Maintenance (TbM) to Condition-Based Maintenance (CbM).


Decisions should consider the whole life of assets, including the I-P interval and the P-F interva
Fig. Decisions should consider the whole life of assets, including the I-P interval and the P-F interval.



Early life, late-life and mid-life stages of an asset reflected on the PF Curve.
Fig. Early life, late-life and mid-life stages of an asset reflected on the PF Curve.


Illustration of a deterioration model for a roof system.
Fig. Illustration of a deterioration model for a roof system with distress metrics at different life stages.


Major maintenance tasks mapped to the P-F Curve
Fig.  Different types of maintenance activities at various life stages of an asset.

See also:
  • Recordkeeping
  • Operating histories
Compare with:


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