Asset Strategies define the Maintenance Activities and Activity Sets that are applied to manage the consequences on functional failures associated with equipment. Strategy Based Maintenance groups all the Maintenance Strategies and associated Maintenance Activities that are developed through the RCM (Reliability Centered Maintenance), FMECA or equivalent risk-based maintenance program development methodology.
These asset strategy or maintenance tactics must be written in a consistent and approved style and in a manner that is clear, factual, concise, and understandable. The instruction must include what the task is, what it applies to, and what is to be done if corrective actions are found.
Asset strategies are developed based on failure characteristics and industry best maintenance practice is chosen to ensure it continues to perform its intended function. The types of PM programs on a site include – The basic (routine visual inspections, lubrications, adjust/tighten procedures), Proactive Replacements, Schedule Refurbishing, Predictive Maintenance and Condition Based Maintenance and Reliability Engineering.
Items identified as technically feasible and economically viable to be maintained on a condition based predictive asset management program, during the economic site life of the equipment. This includes the method of condition monitoring, the specification of the limits of acceptable measurement and an estimation of the remaining life at that limit (for planning purposes).
Asset Strategies define the following three approaches:
- Condition Based Maintenance (CBM)
- Usage Based Maintenance (UBM)
- Run To Failure Based Maintenance (RTF)
It is important in the Strategy content to maintain the relationships between the Primary and Secondary Activities under these strategies as these activity sets have to be assessed in combination when cost-effectiveness and life cycle cost analyses are done and it also supports how these activities are to be presented in the SAP Master Data to effectively support the Primary and Secondary work execution with its appropriate resourcing.
The selection of the appropriate Maintenance Strategy needs to be robust and is facilitated by the application of the Maintenance Strategy Selection Logic as it applies to Failure Behavior and the defined FMECA content. The selection of the appropriate strategy is through assessment against Technically Feasibility, Safety and Environmental Friendly and Cost Effectiveness criteria. Depending on how strategies are filtered out based on this criteria, all maintenance strategies making it to the cost-effectiveness analysis together with changes to design and operating alternatives are to be evaluated to select the most appropriate outcome.
In applying the Maintenance Strategy Selection Logic, all three the available Strategies must be explored. Often, more than one Strategy may be Technically Feasible and safe and Environmentally Friendly and the only final degerminator may be Cost-Effectiveness. When doing Cost-Effectiveness Analysis, it is important to assess and compare Life Cycle Costs and not just the cost of single occurrences of the activities. The selection of the appropriate life span (period over which to assess the costs) is important and it is generally proposed to use the remaining life or significantly suitable life span.
The application of template maintenance strategies provides a robust and consistent mechanism to accelerate the development and deployment and further optimisation of maintenance strategies. These templates are developed at component level where components are categorised by make, model and variants to allow clear distinction between components that are to be maintained differently.
When building maintenance strategies for specific plant and equipment, the process followed is to define the equipment hierarchy down to the lowest maintainable items (LMIs) and then to associate these LMIs to the component libraries.
