The document discusses maintenance engineering, emphasizing its importance in optimizing equipment, procedures, and budgets to enhance reliability and availability. It outlines various maintenance strategies—reactive, preventive, predictive, and corrective—and highlights the role of reliability-centered maintenance and design for reliability in improving cost-effectiveness and performance. Furthermore, it addresses maintenance practices for specific systems, including piping, wind turbines, and boilers, stressing the necessity of structured maintenance approaches to minimize failures and associated costs.

1. Engineered Maintenance“Maintenance - The work of keeping something in proper condition; upkeep.”By Waqas Ali Tunio (07ME34)Department of Mechanical EngineeringQuaid-e-Awam University of Engineering, Science & Technology, Nawabshah - Pakistan

2. Objectives of Maintenance Engineering• Improvements in the specific asset environment (physical plant and equipment)• Improvements in resource utilization (people, materials, services and Enterprise Asset Management System (EAM System)• Improvements to the maintenance management processes – including the decision support and management systems.

3. IntroductionMaintenance Engineering is the discipline and profession of applying engineering concepts to the optimization of equipment, procedures, and departmental budgets to achieve better maintainability, reliability, and availability of equipment.Maintenance, and hence maintenance engineering, is increasing important due to rising amounts of equipment, systems, machineries and infrastructures. Since the Industrial Revolution devices, equipment, machinery and structures have grown increasingly complex, requiring a host of personnel, vocations and related systems needed to maintain them

4. Reactive MaintenanceReactive maintenance is basically the “run it till it breaks” maintenance mode. No actions or efforts are taken to maintain the equipment as the designer originally intended to ensure design life is reached.

5. Preventive MaintenanceActions performed on a time- or machine run-based schedule that detect, preclude, or mitigate degradation of a component or system with the aim of sustaining or extending its useful life through controlling degradation to an acceptable level.

6. Corrective MaintenanceEquipment is maintained after break down. This maintenance is often most expensive because worn equipment can damage other parts and cause multiple damage.

7. Predictive MaintenanceMeasurements that detect the onset of system degradation (lower functional state), thereby allowing causal stressors to be eliminated or controlled prior to any significant deterioration in the component physical state. Results indicate current and future functional capability. Basically, predictive maintenance differs from preventive maintenance by basing maintenance need on the actual condition of the machine rather than on some preset schedule.

8. Reliability Centered Maintenance“A process used to determine the maintenance requirements of any physical asset in its operating context.”It recognizes that all equipment in a facility is not of equal importance to either the process or facility safety. It recognizes that equipment design and operation differs and that different equipment will have a higher probability to undergo failures from different degradation mechanisms than others.It is generally used to achieve improvements in fields such as the establishment of safe minimum levels of maintenance, changes to operating procedures and strategies and the establishment of capital maintenance regimes and plans. Successful implementation of RCM will lead to increase in cost effectiveness, machine uptime, and a greater understanding of the level of risk that the organization is presently managing.

9. Maintenance ReliabilityMost misunderstood about maintenance is the true objective of the function. The objective of maintenance is to maintain the assets of a company so that they meet the reliability needs at an optimal cost.In Webster’s dictionary it defines maintenance as:MaintenanceTo maintain

10. Keep in existing condition

11. Preserve, protect

12. Keep from failure or declineThe ultimate goal of maintenance is to provide optimal reliability which meets the business needs of the company. Many people do not know the definition of reliability and it is:“The probability or duration of failure-free performance under stated conditions”

13. Reliability EngineeringReliability engineering is an engineering field, that deals with the study of reliability: the ability of a system or component to perform its required functions under stated conditions for a specified period of time. It is often reported as a probability.

14. Design for Reliability (DfR)Design For Reliability (DFR), is an emerging discipline that refers to the process of designing reliability into products. This process encompasses several tools and practices and describes the order of their deployment that an organization needs to have in place to drive reliability into their products. Typically, the first step in the DFR process is to set the system’s reliability requirements. Reliability must be "designed in" to the system.Reliability design begins with the development of a model. Reliability models use block diagrams and fault trees to provide a graphical means of evaluating the relationships between different parts of the system. These models incorporate predictions based on parts-count failure rates taken from historical data. While the predictions are often not accurate in an absolute sense, they are valuable to assess relative differences in design alternatives.

15. Design for Reliability (DfR)Design TechniquesRedundancy: This means that if one part of the system fails, there is an alternate success path, such as a backup system. Redundancy significantly increases system reliability, and is often the only viable means of doing so. However, redundancy is difficult and expensive, and is therefore limited to critical parts of the system.Physics of failure:Relies on understanding the physical processes of stress, strength and failure at a very detailed level. Then the material or component can be re-designed to reduce the probability of failure. Component derating:Selecting components whose tolerance significantly exceeds the expected stress, as using a heavier gauge wire that exceeds the normal specification for the expected electrical current.

16. Design for Reliability (DfR)Reliability consideration has tended to be more of an after-thought in the development of many new products. Many companies' reliability activities have been performed primarily to satisfy internal procedures or customer requirements. Where reliability is actively considered in product design, it tends to be done relatively late in the development process. Some companies focus their efforts on developing reliability predictions when this effort instead could be better utilized understanding and mitigating failure modes, thereby developing improved product reliability. Organizations will go through repeated (and planned) design/build/test iterations to develop higher reliability products. Overall, this focus is reactive in nature, and the time pressures to bring a product to market limit the reliability improvements that might be made.

17. Design for reliability (DfR)Finally, the company should begin establishing a mechanism to accumulate and apply "lessons learned" from the past related to reliability problems as well as other producibility and maintainability issues. These lessons learned can be very useful in avoiding making the same mistakes twice.Specific Design for Reliability guidelines include the following:Design based on the expected range of the operating environment.

18. Design to minimize or balance stresses and thermal loads and/or reduce sensitivity to these stresses or loads.

19. De-rate components for added margin.

20. Provide subsystem redundancy.

21. Use proven component parts & materials with well-characterized reliability.

22. Reduce parts count & interconnections (and their failure opportunities).

23. Improve process capabilities to deliver more reliable components and assemblies.MaintainabilityMaintainability is defined as the probability of performing a successful repair action within a given time. In other words, maintainability measures the ease and speed with which a system can be restored to operational status after a failure occurs.

24. Design for MaintainabilityDesign is the transformation of an idea into a product, process, or service that meets both the designers requirements and end users needs. Second, maintainability is the degree to which the design can be maintained or repaired easily economically and efficiently. We can now define design for maintainability as a design strategy, involving both the designer and end user, with the following objectives:Identify and prioritize maintenance requirements.

25. Increase product availability and decrease maintenance time.

26. Increase customer satisfaction.

27. Decrease logistics burden and Life Cycle Costs.Design for MaintainabilityConsideration of product maintainability/serviceability tends to be an after-thought in the design of many products. Personnel responsible for maintenance and service need to be involved early to share their concerns and requirements. The design of the support processes needs to be developed in parallel with the design of the product. This can lead to lower overall life cycle costs and a product design that is optimized to its support processes. When designing for maintainability/serviceability, there needs to be consideration of the trade-offs involved. In high reliability and low cost products or with consumable products, designing for maintainability/serviceability is not important. In the case of a durable good with a long life cycle or a product with parts subject to wear, maintainability/serviceability may be more important than initial product acquisition cost, and the product must be designed for easy maintenance.

28. Design for MaintainabilityBasic design rulesIdentify modules subject to wear or greater probability of replacement.