maintenance planning systems
TRANSCRIPT
Maintenance System
A.K.Mohindru
Ex-General Manager
NTPC Ltd.
Presentation Overview
Machinery Failure Maintenance Objectives Maintenance Types Maintenance Cost Availability Integration of Maintenance Maintenance Department Engineers Duties Efficient Maintenance Service Maintenance Records Overhaul Management
Machinery Failure
Total damage Loss of asset Loss of
production Loss of life
Machinery failure
Equipment malfunctions have a direct impact on:
Production capacity Production costs Product and service quality Employee or customer safety Customer satisfaction
Problems in Maintenance
Lack of management attention to maintenance
Little participation by accounting in analyzing and reporting costs
Difficulties in applying quantitative analysis
Difficulties in obtaining time and cost estimates for maintenance works
Difficulties in measuring performance
Problems Exist Due To:
Failure to develop written objectives and policy
Inadequate budgetary control
Inadequate work quality
Infrequent use of standards
To control maintenance work
Absence of cost reports to aid maintenance planning and control system
Bath Tub Curve
Machinery Failure
Mean Time Between Failure (MTBF)Mean Time Between Failure (MTBF)
Frequency of FailureFrequency of Failure
Routine failures Routine failures follow normal follow normal distributiondistribution
Machinery failure
Maintenance Objectives
1. Increased Availability
2. Maximize useful life of equipment
3. Reducing Cost of production
4. Safety Requirements
5. Customer Satisfaction
Increased Availability at optimum cost with safety
Maintenance Types
Breakdown Maintenance Planned Maintenance Preventive Maintenance Predictive Maintenance
Maintenance Types
Run the equipment till breakdowns
No services except occasional lubrication unless failure occurs
No maintenance men on regular basis
Maintenance done by sub-contractors
Breakdown Maintenance
Increased Down Time Increased costs & Pressures
No organized efforts to find out reasons
•No stock of spares• •No budget
•No records and No Safety
* Initially it looks economical
Maintenance Types
In this type of service, the emphasis is placed on the machines condition
What does the manufacturer prescribe? Is it working under normal load?
Are the conditions as good as those envisaged by the manufacturer?
Do we allow for extra attention owing to corrosion, wear etc
Planned Maintenance
Putting the machine in good condition timely e.g replacement of filter/oil, plant overhaul based on manufacturer recommendation
Maintenance Types
Instructions are more detailed than in routine
Schedule is drawn with dates/Hrs
Need for establishing the work-load for the crew
Entails considerable planning effort, faithful implementation
and recording
Detailed instructions reduce the chance of missing any activity. Unforeseen work is greatly reduced
Planned Maintenance advantages
Maintenance Types
PM increases reliability
PM reduces work-load
PM reduces down time
PM reduces unplanned work
PM reduces maintenance cost
Preventive Maintenence
Maintenance Types
System which strives to reduce the likelihood of failures.
Parts are replaced on time basis that could prevent failure though the part maybe in good condition
Locates weak spots of machinery and equipments
Provides them periodic/scheduled inspections and minor repairs to reduce the danger of unanticipated breakdowns
Preventive Maintenance System is more expensive due to
more of planning and replacement of parts
Preventive Maintenance
Maintenance Types
Description Week
1 2 3 4 5 6 7 8 9 10 11 12
Check Oil Filter O O O
Replace Oil O
Inspect bearing O
Replace Bearing O
Check liner condition
O O
Check vibration O O O O
Tighten bolts O O O O
Check Motor Insulation
O
Check terminals O O
Preventive Maintenance Schedule
Maintenance Types
System based on predicting the failure.
In predictive maintenance, machinery conditions are periodically monitored and this enables the maintenance crews to take timely actions, such as machine adjustment, repair or overhaul
It makes use of human sense and other sensitive instruments, such as audio gauge, vibration analyzer, amplitude meter, pressure, temperature and resistance strain gauges etc.
Monitoring the condition of machine and its components Planning the maintenance based on deteriorating condition parts are
replaced when life is near to finish
Predictive Maintenance Type ( Condition Monitoring)
Maintenance Types
1. Temperature2. Vibration3. Cracks4. Deterioration5. Voltage/current6. Performance evaluation
Predictive Maintenance Monitoring Parameters
Maintenance Types
Unusual sounds coming out of a rotating equipment predicts a trouble
An excessively hot electric cable predicts a trouble
Simple hand touch can point out many unusual equipment conditions and thus predicts a trouble
Predictive Maintenance Condition Monitoring
Maintenance Types
Condition Monitoring
Maintenance Cost
1. Overhead Expanses
2. Labour Cost
3. Spares and Consumables
4. Loss due to down time
Maintenance Maintenance CommitmentCommitment
CostCost
Breakdown CostBreakdown Cost
Maintenance Cost
Maintenance Maintenance CommitmentCommitment
CostCost
PM CostPM Cost
Breakdown CostBreakdown Cost
Maintenance Cost
Maintenance Maintenance CommitmentCommitment
CostCost
PM CostPM Cost
Breakdown CostBreakdown Cost
Total Maintenance CostTotal Maintenance Cost
Maintenance Cost
Maintenance Maintenance CommitmentCommitment
CostCost
PM CostPM Cost
Total Maintenance CostTotal Maintenance Cost
Breakdown CostBreakdown Cost
Optimal Optimal
Maintenance Cost
Maintenance Cost
Mean-Time-between-Failures MTBF
MTBF = Total Operating Time = 1. No Of failures n
Mean-Time-to-Repair, MTTR
MTTR = Total Outage Time = 1. No Of failures r
Availability = ________Total Operating Time_______. Total Operating Time + Total Outage Time
Availability
Actions For High Availability
Failure Investigation Find the cause of break downs Analyze it Take corrective action in next shut down Monitor the performance
Resource Availability Keep spares well in advance Mobilize work force quickly Keep job area ready to work : lighting, scaffolding, power
supply etc
Integration of Maintenance
Company
Trial
Spares Procurement
Maintenance Dep't
Manpower
Fire & Safety
Availability
Permit to Work
Production Dep't
Administration
Maintenance Departments
A maintenance manager typically is a plant engineer who reports to a plant manager
Maintenance departments are usually split into two groups: Buildings Equipment
Maintenance Departments
Fitters/Technicians
EngineerBoiler Maintenance
Supervisor
ForemanPressure Parts
Fitters/Technicians
ForemanRotating Machines
RiggersHelpers
RiggersHelpers
Maintenance Work Force
Maintenance Departments
Repairs often performed on an emergency basis to: Minimize interruptions to production Correct unsafe working conditions Improve product/service quality
In emergency situations: Specialists may work overtime Supervisor/engineers are nearby to collaborate Standby machines may be quickly put in operation
Repair Crews and Standby Machines
Engineers Duties
Preventive Maintenance Schedule
preparation Deliver the work order card with
Quality sheet to Supervisor Inspect the work being done as per
quality and safety Keep inventory control: procurement, store Follow safety guide lines Effort for zero breakdown/failures Mobilize resources for faster completion of work Prepare Reports
Computer Assistance in Maintenance Scheduling maintenance projects
Maintenance cost reports by production department, cost category, and other classifications
Inventory status reports for maintenance parts and supplies
Parts failure data
Operations analysis studies
Efficient maintenance Service
Ensuring work quality Minimum repair time Ensuring safety
Efficient maintenance Service
1. Developing Quality norms
2. Measurements- stage inspections
3. Corrections
4. Recording/report
Ensuring maintenance work quality
Efficient maintenance Service
Work Order Planning and Control
Efficient and effective maintenance requires detailed planning of repairs, plant services, overhauls and projects.
This work must be co-ordinated with the requirements of production to havethe minimum effect on the overall production plan.
The maintenance plan should be easily modified to allow for major emergency work, changes in production methods and improvements in design.
Maintenance control indices can provide a method of assessing maintenance activities. Control indices should function as part of the overall maintenance information system and use dynamic data such as labour costs, spares usage, and delay costs. Analysis of the data provides feedback that the manager can use to assess actual performance against a target, and so monitor the effect of changes in maintenance policy.
Efficient maintenance ServiceComputerised Maintenance Management System
A computerised maintenance management system will contain a number of integrated programs or modules to improve the efficiency and effectiveness of the maintenance engineering function.
the system should be easy to use and provide the engineer with all of the information that is required to make better decisions.
The basic modules or component part of the maintenance systems are : Preventive maintenance Asset register Maintenance stores system Purchasing Work order planning and control Plant history and analysis
Efficient maintenance ServiceAsset Register
This is an inventory of all of the plant, equipment and services for which a manager has responsibility. Repair work that is generated by the preventive maintenance system will in most cases need to be planned and prepared.
This includes technical details, serial numbers, location, manufacturer etc. and most important a list of the spare parts used on the machine together with the current stock balance.
The purpose of the asset register is to centralise this data for use in planning
maintenance work.
In addition to providing rapid access to information, the manager can be sure that the relevant data is always available and has not been misplaced.
Maintenance Records
History Record: When job is done? What activities were done? When completed? How was the machine performance?
Planning Sheet: When next to be done? What resources will be required? What will be the duration?
Maintenance Records
Identify the equipments Prepare the specs (Number plate details)
Equipment Identification
Maintenance Records
ID Fan1A ID Fan 1B FD Fan 1A FD Fan 1B PA Fan 1A PA Fan 1B Boiler Feed Pump 1A
Equipment Identification
Work InstructionSingrauli Super Thermal Power Station
Equipment: Boiler Feed Pump RPM: 3600 KW 1500 Kw
Scope: Mini Overhauling of Boiler feed Pump Doc No: QSR/039/8
1. Decouple pump from drive turbine or hydro coupling
2. Open the bearing top covers
3. Check bearing conditions
4. Check Thrust collar conditions
5. Check pump centering
6. Check bearing clearances
7. Check pump floats
8. Adjust as per requirements
9. Repair/replace worn out parts
10. Box up bearings
11. Align pump w.r.t drive turbine/hydro coupling
12. Take trial run of pump
13. Refer QSR/039/9/AUX/011 for checks and records
Maintenance Records
Maintenance Records
S.N. Decription Measured Value
1. Bearing Condition:
Scratch marks: Nil
Color: No discoloration
Pitting Nil
Fine scrtch marks seenBluish color from sidesNo pittings
2 Bearing side clearance: 0.020-0.025mm 0.022mm
3 Bearing top clearance: 0.030-0.045mm 0.030 mm
4 Coupling Alignment : < 0.07mm 0.06mm
5 Shaft run out: <0.086 mm 0.089 mm
6 Bearing level 1D < 0.02mm/m 0.011 1D
00
0.5D
Work Protocol
Maintenance Records
The Care and maintenance of Pumps
(Describes Standard Maintenance Practice)1. Objective
2. Operational History
3. Inspection and maintenance
4. Modifications
5. Vibration requirements
6. Bearing Temperature
7. NPSH
8. Pump casing distortion
9. Overspeed test
10. Pump efficiency
Operation Guidance Note
Overhaul Management
Machine needs regular overhaul Periodicity is based on experience or on
manufacturers recommendations Boiler tubes errosion normally in 2 years
Burner life is 1 year Boiler Overhaul : every year for 10 days Furnace deposition 1 year
Turbine efficiency drops 0.5%-1% in 5 years Turbine blade cracks appear in 5-6 years
Turbine overhaul : 5years for 45 days
Overhaul Management
Preparation of resources:
Engineering Declaration: 12 months advance Contract: 3 months in advance Spares procurement; 12 months advance Shut down planning ; rolling plan
Mobilization Pert Chart activitiy listing Allocation of executive team to monitor Daily work progress meeting Overhaul Execution
PERT & CPM
CPMWhat is CPM?
Critical Path Method
What is Critical Path?
CPM is a mathematically based algorithm for scheduling a set of project activities.
• A list of all activities required to complete the project,
• The dependencies between the activities, and
• The estimate of time (duration) that each activity will take to completion.
The longest time is determined
CPM example
Hang a picture on the wall
Choose a place on the wall Buy the screws Choose the picture Drill a hole Screw in the screws Hang the picture
The actions “drill a hole,” “screw in the screws” and “hang the picture” form a sequence of tasks that must be performed in a specific order, one right after the other, to ensure a successful result. Such tasks are called “sequential” activities
CPM
you cannot start some activities until the others are finished. These activities need to be completed in a sequence, with each stage being more-or-less completed before the next stage can begin
CPM
The critical path consists of the longest sequence of activities from project start to end that should be started and completed exactly as scheduled to ensure the project is completed by a certain date in the future
