plant maintenance basics

PLANT MAINTENANCE BASICS

By, Sangram Patnaik Engineer-Instrumentation

Topics: What do you mean by a Plant ? What do you mean by Maintenance? Objectives of Plant Maintenance. Duties, functions and responsibility of a

Plant Maintenance Engineer. Types of Maintenance. Corrective and Breakdown Maintenance. Scheduled Maintenance. Preventive Maintenance. Predictive Maintenance. Basics for Evaluating Equipment

Performance.

PLANT

A Plant is a place, where men,materials,money,equipmet,machinery,etc.,are brought together for manufacturing products.

MAINTENANCE A formal definition of maintenance

is “that function of manufacturing management that is concerned with day to day problem of keeping the physical plant in good operating condition”

Objectives of Plant Maintenance To Achieve Minimum Breakdown and

to keep the plant in good working condition at the lowest possible cost.

Machines and other facilities should be kept in such a condition which permits them to be used at their optimum(Profit Making) capacity without any interruption.

Duties, Functions and Responsibility of Plant Maintenance Engineering Department Inspection. Engineering. Maintenance. Repair. Overhaul. Housekeeping. Supervision of Labour force etc.

Types of Maintenance

Corrective or Breakdown Maintenance.

Scheduled Maintenance. Preventive Maintenance. Predictive Maintenance.

Corrective or Breakdown Maintenance Corrective or Breakdown

Maintenance implies that repairs are made after the equipment is out of order and it cannot perform its normal Function any longer,e.g. A Control valve struck in the line neither closing nor opening.

After removing the fault, maintenance engineers donot attend the equipment again until another failure or breakdown occurs.

Classification Of Breakdown Maintenance

1. Breakdown of equipment for a period of less than 60 minutes AND / OR

2. Does not effect the stoppage of the street

1. Breakdown of the equipment for a period of more than 60 minutes but less than 240 minutes AND / OR

2. Breakdown leads to partial shut of the particular process

1. Breakdown of the equipment for a period of more than 240 minutes AND / OR

2. Breakdown leads to complete shut of the particular process / whole Plant.

MINOR BREAKDOWN

MEDIUM BREAKDOWN

MAJ OR BREAKDOWN

Breakdown of equipment for a period of less than 10 minutes MINOR STOPPAGE

Typical Causes of Instrument Breakdowns Failure to replace worn out parts. Lack of proper Maintenance. External Factors. Sudden change in Process

Parameters.

Disadvantages of Breakdown Maintenance

Breakdowns generally occurs at inoppurtunate times. This Leads to poor, hurried maintenance and excessive delays in production.

Faster plant deterioration. Direct loss of profit. Reduction in output.

Scheduled Maintenance

Scheduled Maintenance is a switch-in-time procedure aimed at avoiding breakdown.

Breakdowns can be dangerous to life and as far as possible should be minimized.

Scheduled Maintenance Practices incorporates inspection, repair and overhauling of some instruments which if neglected can result in breakdowns.

Preventative Maintenance

The underlying principle of preventative maintenance is that “Prevention is better than cure”.

It is undertaken before the need arises and aims to minimize the possibility of un-anticipated production interruption or major breakdowns.

Upkeep of Plant Equipment to correct such conditions while they are still in a minor stage.

Types of preventive Maintenance

Routine Maintenance : which includes those maintenance activities that are repetitive and periodic in nature such as cleaning and small adjustments in instruments.

Running Maintenance : which includes those maintenance activities that are carried out while the equipment is running ad they represent those activities that are performed before the actual preventive maintenance activities take place.

Opportunity Maintenance: which is a set of maintenance activities that are performed on a instrument when an unplanned opportunity exists.

Window Maintenance : which is a set of maintenance activities that are carried out when a equipment is not required for a definite period of time.

Shutdown PM: which is a set of maintenance activities that are carried when total production line is in stoppage.

Types of preventive Maintenance

Objectives of PM

To minimize the possibility of unanticipated production interruption or major breakdowns by locating or uncovering any condition which may lead to it.

To maintain optimum productive efficiency of the plant equipment and machinery.

To maintain the operational accuracy of the plant equipment.

To reduce the work content of maintenance jobs.

To achieve maximum production at minimum repair cost.

Procedures of PM Who should do PM? Where to start PM? What to Inspect in PM? What to Inspect for? How often to inspect-frequency? When to inspect-schedules? Maintaining PM Records. Storage of spare parts. Control and evaluation of PM.

Advantages of PM

Reduced breakdowns and connected downtimes.

Greater safety for workers. Fewer Large-scale and repetitive

repairs. Low Maintenance and repair costs. Lower unit cost of Manufacture. Better Product quality and fewer

products rejects. Increased equipment life.

Predictive Maintenance Predictive Maintenance is a set of activities

that detect changes in the physical condition of the equipment(signs of failure) in order to carry out the appropriate maintenance work for maximising the service life of the equipment without increasing the risk of failure.

Predictive Maintenance are of Two types: Condition-based predictive Maintenance. Statistical-based predictive Maintenance.

Condition-Based : depends on the continuous or periodic condition monitoring equipment to detect the signs of failure.

Statistical-Based : depends on the statistical data from the trends of the stoppage of the in-plant items and components in order to develop model for predicting failures.

Predictive Maintenance

The drawback of predictive maintenance is that it depends heavily on information and correct interpretation of the information.

The Main difference between preventive and predictive maintenance is that predictive maintenance uses the monitoring the condition of the equipment to predict the actual mean time to failure whereas preventive maintenance depends on the industrial average life statistics.

Predictive Maintenance

Maintenance

Basics for evaluating Equipment Performance

MTBF: Mean Time Between Failure(MTBF) is an indicator of reliability of a equipment. The unit of MTBF is hours. If equipment A has MTBF of 10,000 hours and equipment B has MTBF of 8,000 hours, then equipment A has higher reliability. Higher the MTBF,better is the reliability.

MTTR : Mean Time To Repair is a measure of maintainability. This is the average time to repair an equipment when it becomes defective.

Availability : is the proportion of time the equipment is available for the use out of the total time available.

A = (MTBF-MTTR)/MTBF

To Exist is to change, to change is to mature, to mature is to go on creating oneself endlessly.

- Henri Bergson

For any queries or suggestions please do write me at sangramptk@gmail.com

For any queries or suggestions please do write me at sangramptk@gmail.com orJoin me at linkedin : https://www.linkedin.com/in/sangram-patnaik-0a50171b?trk=hp-identity-name