King Fahd University of Petroleum Minerals Systems Engineering Department

1. King Fahd University of Petroleum & MineralsSystems Engineering Department Maintenance Planning Workshop Dr. Omar Al-Turki Prof. Salih Duffuaa Yanbu Maintenance Exchange Meeting 29 th November, 2005

2. Maintenance Systems Types: Planned Maintenance Routine and preventive maintenance Scheduled overhauls involving shutdowns Corrective maintenance Other scheduled overhaul, repair, building, .. Emergency / breakdown maintenance Load: The sum of the two types (uncertain)

3. Maintenance Planning Why? For more effective and efficient maintenance operations resulting high quality operations Why? To achieve organizational objectives: Availability, Reliability, quality, and delivery dates, � How? Capacity Planning Maintenance Planning and Scheduling

4. Capacity Planning What? The determination of the maintenance resources needed to meet maintenance load. Manpower (number and skills), overtime capacity, contract maintenance, healthy level of backlog, etc. How? Maintenance forecasting

5. Maintenance Forecasting What? The estimation and prediction of the maintenance load Why? For better capacity planning How? Qualitative techniques Quantitative techniques

6. Forecasting Methods Evaluation Accuracy: How good it predicts future Simplicity and data needed Flexibility: The ability to adjust to changes in conditions

7. Selection Considerations The purpose of the forecast The time horizon for the forecast The availability of the data for the particular approach.

8. Steps for developing a quantitative forecasting model Identify the item to be forecasted and understand its nature. Define the purpose of the forecast and its time horizon. Screen and validate available data for errors and outliers. Identify additional data needed and the methodology for collecting it. Use the available data and graphical techniques to hypothesize appropriate models. Use the major part of the data to estimate the parameters of the models. Keep part of it for testing and validating the model. Test and validate the models and select the most appropriate one. Monitor the selected forecasting process and model to detect out-of-control conditions and find opportunities for improving forecasting performance.

10. Qualitative Forecasting Techniques What? Estimates of experts and their judgment. How? Systematically extract information from the mind of the expert by using structured questionnaires or interviews. Why? Identify which variables influence the forecast and the impact of each one. How? Use cause and effect diagrams and the Delphi method to identify relationship among the variables. Get an agreement on the magnitude of the variables. Best case, expected case and worst case scenarios are usually used to estimate the magnitude of the variables. An interactive approach can be used to present arguments to the expert, such as why his estimate differs from the average estimate.

11. Quantitative Forecasting Techniques Time-series models assume future values follow historical trends Structural models a predictor (independent) variable exists that can provide a model or a functional relationship that predicts the characteristic under study

12. Simple Moving Averages The average of the last n observations Example 1 If the maintenance load in man-hours for the last 6 months is given as Month 1 2 3 4 5 6 Maintenance Load 200 300 200 400 500 600 Find the load forecast for periods 7 and 8 using a 3 month moving average. The forecasted load for month 7 using is We did not observe x7, so if the load in month 7 is estimated as 500 as calculated above The forecast for the 8th month is obtained as:

13. Weighted Moving Average Give each observation a different weight. Example: Same example with

14. Regression Analysis If an independent variable exists that can predict a characteristic (dependent variable) and a reasonable correlation exists between the two variables Example: the cost of maintenance y(t), is a linear function of the number of operational hours in the previous period, x(t-1). Then the model would be a,b = parameters to be determined

15. Exponential Smoothing Assigns weights to observations of previous periods in an inverse proportion to their age. where = the forecast for period t and all future periods in the case of a constant model. x(t-1) = actual demand at period t-1 = the forecasted value for t-1 ? = smoothing constant,

16. Seasonal Forecasting 1. Plot the data and visually determine clear time-series characteristics. 2. Determine the growth model and remove the growth component from the data. One way to remove the growth component from the data is to determine an average period for each cycle and divide each data value by the average. 3. Determine if a significant seasonality is present in the data as it appears with the growth component removed (de-growthed). The seasonality index can be computed by averaging the de-growthed data over the seasons (periods exhibiting similar behavior). 4. Deseasonalize the original data and analyze the growth factor. A plot of the deseasonalized data will reveal the form of the growth component. The deseasonalizing is accomplished by dividing each data by the appropriate seasonal index. 5. Fit the data by some appropriate method, least squares regression, exponential smoothing, etc. 6. A forecast for the future consists of a combination of seasonal and growth trends.

17. Error Analysis The following error measures are commonly used for error analysis and evaluation of forecasting models. 1. Mean Absolute Deviation (MAD) Mean Squared Error (MSE) Mean Absolute Percent Error (MAPE) 4. Mean Squared Percent Error (MSPE)

18. Forecasting Maintenance Work The load comprises the following: 1. Emergency maintenance workload. This can be forecasted using actual historical workloads and the appropriate techniques of forecasting and or management experience. This component of the load is random and can be minimized by having a well designed planned maintenance. 2. Preventive maintenance workload. This can be forecasted using actual historical records coupled with new developed preventive maintenance programs. This should include routine inspection and lubrications. 3. Deferred corrective maintenance. This can be forecasted based on historical records and future plans. 4. A forecast for overhaul removed items and fabrication. This can be estimated from historical records coupled with future plans for improvements. 5. Shutdown, turnarounds, and design modifications. This can be forecasted from actual historical records and the future maintenance schedule.

19. Maintenance Capacity Planning To determine the optimal level of resources to meet the forecasted maintenance load Resources: Workers, skills, spares, inventory equipments and tools Load: Future forecast + maintenance backlogs

20. Steps: 1. Determine the total maintenance load. 2. Estimate the required spares and material to meet the load. 3. Determine equipment and tools that are necessary for all types of maintenance work. 4. Determine the skills and the number of crafts from each skill. A special attention should be given to multi-skill crafts. 5. Provide special plans for highly computerized equipment, if required.

21. Techniques for capacity planning Heuristics and rules of thumb: All priority work is met by regular in-house crafts as much as possible. If it is not possible to satisfy priority one work by regular in-house crafts use overtime. No backlog is allowed for grade 1 work. The manning level must be determined based on the average Maintenance load with a healthy backlog from grade 2 work is carried in the system. The priority two work is met with overtime or contract maintenance. The overtime capacity is at most 25% of the regular in-house capacity.

22. Heuristic tableau approach: Cr = hourly cost of mechanical trade on regular time Co = hourly cost of mechanical trade on overtime Cs = hourly cost of subcontracting Bt = Backlog in man-hours at the beginning of period t CRt = capacity of in-house regular time in period t COt = Capacity of in-house overtime in period t CSt = capacity of subcontracting in period t FMt = forecasted maintenance load in period t.

24. Solution methods The least cost heuristic can be used to find a solution Linear programming and integer programming can be used for the optimum solution. Stochastic techniques such a simulation can be used under highly stochastic conditions.

25. Maintenance Planning and Scheduling Why? minimizing the idle time of maintenance workers maximizing the efficient use of work time, material, and equipment maintaining the operating equipment at a level that is responsive to the need of production in terms of delivery schedule and quality. How? 1. Determine job content (may require site visits). 2. Develop work plan. This entails the sequence of activities in the job and establishing the best methods and procedures to accomplish the job. 3. Establish crew size for the job.

26. 4. Plan and order parts and material. 5. Check if special equipment and tools are needed and obtain them. 6. Assign workers with the appropriate craft skill. 7. Review safety procedures. 8. Set priorities (emergency, urgent, routine, and scheduled) for all maintenance work. 9. Assign cost accounts. 10. Fill the work order. 11. Review backlog and develop plans for controlling it. 12. Predict the maintenance load using an effective forecasting technique.

27. Who? Qualifications: full familiarity with production methods used through the plant, sufficient experience to enable him to estimate labor, material and equipment needed to fill the work order, excellent communication skills, familiarity with planning and scheduling tools, preferable with some technical education.

28. Levels of Planning Three levels of planning: 1. Long range planning (covers a period of five years). 2. Medium range planning (1 month-to one year plans) 3. Short range planning (daily and weekly plans). For long and medium range planning, the planner needs to utilize the following methods: Sound forecasting techniques to estimate the maintenance load. Reliable job standard times to estimate manpower requirements. Aggregate planning tools such as linear programming to determine resource requirements.

29. Scheduling A reliable schedule must take into consideration the following: A job priority ranking that reflects the urgency and the criticality of the job. Whether all the material needed for the work order are in the plant. (If not, the work order should not be scheduled.) The production master schedule and close coordination with operation. Realistic estimates and what is likely to happen rather than what the scheduler desires. Flexibility should be built in the schedule. The scheduler must realize that flexibility is needed and especially in maintenance. The schedule is often revised and updated.

30. Weekly schedules The weekly schedule should allow for about10 - 15% of the work force to be available for emergency work. The work orders that are scheduled for the current week are sequenced based on priority. Critical path analysis and integer programming are techniques that can be used to generate a schedule. In most small and medium sized companies, scheduling is performed based on heuristic rules and experience.

31. Daily schedules The daily schedule is generated from the weekly schedule and is usually prepared the day before. This schedule is frequently interrupted to perform emergency maintenance. The established priorities are used to schedule the jobs. In some organizations the schedule is handed to the area foreman and he is given the freedom to assign the work to his crafts with the condition that he has to accomplish jobs according to the established priority.

32. necessary requirements for effective scheduling. 1. Written work orders that are derived from a well conceived planning process. The work orders should explain precisely the work to be done, the methods to be followed, the crafts needed, spare parts needed and priority. 2. Time standards that are based on work measurement techniques as explained in Chapter 4. 3. Information about craft availability for each shift. 4. Stocks of spare parts and information on restocking. 5. Information on the availability of special equipment and tools necessary for maintenance work. 6. Access to the plant production schedule and knowledge about when the facilities may be available for service without interrupting the production schedule. 7. Well-defined priorities for the maintenance work. These priorities must be developed through close coordination between maintenance and production. 8. Information about jobs already scheduled that are behind schedule (backlogs).

33. Scheduling procedure : 1. Sort backlog work orders by crafts, 2. Arrange orders by priority, 3. Compile a list of completed and carry over jobs, 4. Consider job duration, location, travel distance, and possibility of combining jobs in the same area, 5. Schedule multi-craft jobs to start at the beginning of every shift, 6. Issue a daily schedule (except for project and construction work), and Have a supervisor make work assignments (perform dispatching). For large jobs or maintenance projects, quantitative techniques for generating the schedule and balancing manpower requirements can be used. Critical Path Analysis (CPM) Program Evaluation and Review Techniques (PERT), Integer Programming, and Stochastic Programming.

34. Maintenance Job Priority System Priorities are established to ensure that the most critical and needed work is scheduled first. The development of a priority system should be well coordinated with operations staff The priority system should be dynamic and must be updated periodically to reflect changes in operation or maintenance strategies. Priority systems typically include three to ten levels of priority. Most organizations adopt four or three level priorities.

36. Scheduling techniques Gantt charts Critical Path method (CPM) Project Evaluation and Review (PERT) Math Programming Stochastic Programming

37. Turn Around Maintenance A periodic maintenance in which plants are shutdown to allow for inspections, repairs, replacements and overhauls that can be carried out only when the assets (plant facilities) are taken out of service. During turnaround maintenance, the following types of work will be performed: work on equipment which cannot be done unless the whole plant is shutdown, work which can be done while equipment is in operation but requires a lengthy period of maintenance work and a large number of maintenance personnel, defects that are pointed out during operation, but could not be repaired, will be maintained during turnaround period.

38. The schedule for TA maintenance should consider the following: Legal or contractual limitations. Operation schedule. Nature of the process. Enough lead time for preparing an overall plan, material purchase, and assuming manpower availability. Operation schedule of other related industries.

39. Thank You