Reliability and Maintenance Engineering Lecture 8
Introduction Job Planning Steps of Job Planning Job Manual Steps in preparing Job Manual Uses of Job Manual Short Term Planning Long Term Planning References
Effective planning and scheduling contribute significantly to the following: Reduced maintenance cost. Improved utilization of maintenance workforce by reducing delays and interruptions. Improved quality of maintenance work by adopting best methods and procedures and assigning the most qualified worker for the jobs.
Planning of maintenance jobs basically deals with answering two questions, “what ” and “How” of the job; i.e., “what jobs/activities are to be done” and “how those jobs and activities are to be done. The job planning forms the basic foundation, over which the efficiency and cost of further actions (e.g. scheduling, execution and control etc) will be decided. Person responsible for job planning should have adequate qualities/capabilities, such as knowledge about jobs and available techniques facilities and resources.
Knowledge Base: It includes knowledge about equipment, job, available techniques, material and facilities etc. Job Investigation at Site: It gives a clear perception of the total job and also helps in ascertaining the physical access and space limitation. Lifting & handling facilities Disposal of oil/gases/hazardous material facility Safety enclosures for m/c under repair Identify and document the work: knowing earlier two steps and knowing the needs of preventive, predictive and other maintenance jobs, a complete job/work list is made.
4. Development of Repair Plan: Preparation of step-step procedures which would accomplish the work with the most economical use of time, manpower and material. (see fig(a)).5. Preparation of Tools, Tackles & Facilities Lists: Job Plan sheet6.Estimation of Time Required to do the Job: For smaller jobs, it is easier, but for bigger jobs it may need knowledge of “Work simplification”, “Work measurement” and Critical Path analysis.
Planning sheet for Changing V belt of Blower-XEquipment Name: Blower W.O Number Planner Date SeqX ---- Mr, --- ----- -----Equipment Code----Job Title- Change V belt (Cracked & worm)Job scope Material, Tools & EquipmentsJob Steps Cre w Est. hours Description Qty Stock as on Co st1. Look out, disconnect & 0.25 Tag Motor starter,2. Remove belt guard, loosen & jack motor, remove 0.75 Sheave guage(tool kit) bolts3. Check both sheaves for Mag. base dial Indicator 1set 4, SH-1 side wall wear & radial 1.0 •Big sheave (Part No.) 1 set 4 ,SH-1 run-out (should not be •Bushing (Part No.) 1 set 3, SH-1 more the +1mm for big & •Small Sheave(Part No.) 1 set 3, SH-1 +0.25 for small end), •Bushing (Part No.) Replace Worn-out sheaves if neededDrawing No:- Total time:- Total cost:-
Open repair file ok Check planning spares waiting time &matl Postpon e repair noDiscuss with Plant Engineermaintenance no I/c and others for Finalization of alternative repair plan Print Repair plans/work-orders
Job manuals includes methodologies, tools tackles and facilities for all maintenance jobs which may have to be done in future. This also involves saving the different plans and modifying and expanding those plans for other similar machines.
1. Make a list of all major and medium jobs of the plant and codify for proper identification,3. For each coded job, a separate job manual is to be made in the form of job plan, indicating job steps, tools, tackles, spares, consumables and facilities needed and also indicating safety and statutory clearance.5. Each job manual, thus prepared, should and cross checked and cleared by maintenance in-charge.
4. Different job manuals should be bunched and sent to respective potential users.5. Necessary updating of job manuals, as needed, in consultation with respective users.
For actual planning and scheduling of any job, the job manuals provide ready information for use as it is or for further micro-planning. The executing agencies refer to the job manual before starting the job, to avoid frequent visits to stores and thus save time. Material department may also use job manual for better material procurement strategy.
Short term plans are generally short term schedule and its duration may be hours, day weeks or months and it is tactical(particular goal) planning. It covers 10% to 15% of the schedule of total job. These jobs are normally derived from master schedule of total job and carried out on day-to-day basis or at shorter notice.
1. Lubrication plans and schedules,2. Small defect rectification3. Vibrating monitoring of few critical equipments,4. Lubricant monitoring, thermography and other monitoring as per need,5. Small predictive maintenance and preventive maintenance jobs etc.,6. Occasionally, small shutdowns, for some urgent repairs, may also be included in short term planning.
Long term plans are generally for future purpose and the duration may be months or years. It includes the jobs/actions which are helpful in maintaining original level of performance in terms of output, efficiency and reliability. These jobs call for more resources, coordination with many agencies and planning much in advance.
Major Repairs: It includes jobs required to restore a seriously deteriorated or broken-down equipment . The frequency of such repair is normally once or twice a year. Capital Repairs: It includes major dismantling and nearly rebuilding of the equipment /plant, needing lot of resources. Frequency of such repairs is once in two years or even later.
Annual overhauls :- These apparently appears like major repairs/overhauls and may include job of similar nature but it is generally taken on yearly basis and mainly taken for following reasons –1. Annual maintenance cleaning, painting and corrosion prevention of equipments, machines, tanks, reservoirs, filters and heat exchangers etc.,2. Annual operational cleaning and painting jobs, like removal of mill-scales, dust & debris, cobbles and crop- pieces and reconditioning of deflectors, diverters etc.,
Renovation & Revamping: After the equipment has deteriorated to such an extent that the amount of major/ capital repairs, PM,PdM and other maintenance repairs do not yield desired result and maintenance becomes uneconomical. These includes almost total rebuilding of the equipment, using either similar type of technology with some redesign or improved technology and equipment. Up-gradation of equipment availability and reliability are definitely the aim for such plans.
Modernization: It is planned when the operation and profitability of the plant or section uneconomical and no improvement can be made. Five year Rolling Plan(3 to 10) Turn around Planning(for total maintenance jobs) Corporate Maintenance Plans(like 5-yr or 10-yr rolling plan)