What is Plant Maintenance

8/6/2019 What is Plant Maintenance

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What Is Plant Maintenance?

Plant maintenance usually refers to the methods, strategies, and practices used to keep anindustrial factory running efficiently. This can include anything from regular checks of equipmentto make sure they are functioning properly, to cleaninggarbage bins and toilets. The general aim

of plant maintenance is to create a productive working environment that is also safe for workers.

Since there are many different types of plants and factories, the ways to maintain these facilitiesoften vary. For example, a steel mill will have different machinery than a food processing plant.This means that eachplace of business generally has its own maintenance plan, tailored to itsparticularities. A maintenance plan can include scheduling times for equipment checkups, trouble-shooting, and general clean-up.

Most plants employ their own maintenance staff. This can include workers such as on-siteengineers, whose job is to make sure that machines continue to operate effectively. This is anespecially important for plants that use equipment designed for assembly lines, since a stoppageof the line can be financially damaging.

Reliability centered maintenance(RCM) is a maintenance strategy that is often employed infactories. This is an approach that not only seeks to maintain minimal levels of plant efficiency,but also looks for ways to improve production. RCM can include determining how to increaseoperating procedures, such as maximizing a machine's uptime, which means increasing theamount of time the equipment is actually producing. Such an increase can be accomplished byvarious means, like adding more workers to a machine or by makingengineeringchanges.

Power Plant Maintenance

It is the powerplant managers job to provide reliable electrical service using the mostefficient methods available. Although a powerplant managers duties are varied, his orher main task is to manage people.

Powerplant operator jobs include a variety of options. In general, powerplant operatorscontrol, operate, maintain and repair machines that generate electricity.

Electrical Plant Maintenance

Many times, janitors will be responsible for the maintenance of the factory floor andkeeping it clean of any spills that could be dangerous to equipment operators. There arealso many private plantmaintenance companies. These firms are generally contractedby a factory to check equipment and make repairs.

In the case of industrial installations, these procedures are often carried outduring plantmaintenance shutdowns. Residential substations are a little more difficult to

plan for and generally require switching the supply over to auxilliary equipment during theprocess.
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Basic Techniques of Plant Maintenance

Plant maintenance activities generally fall into one of five broad

categories.

Run To Failure

This method is exactly as the name implies; equipment is run until it fails. While not an optimum strategy, it

can be relatively cheap when dealing with equipment that would not cause a plant shutdown upon failure.

Preventive Maintenance

This is essentially a schedule of maintenance based on the manufacturer's recommendations and plant

experience. The major disadvantage of straight preventive maintenance is that real-life operating conditions

are not always predictable. Thus, a component may fail sooner than expected causing an unnecessary

shutdown, or a piece of equipment may last much longer than expected, resulting in unnecessary

maintenance expenditures.

Predictive Maintenance

This strategy uses various devices and techniques to predict when a component is going to fail. Generally,

predictive maintenance solves the problems of too much or not enough maintenance.

Reliability Centered Management

This technique can be thought of as a form of risk management. Components of a plant are identified,

ranked and the risk of their failure evaluated. Once these steps are taken, appropriate maintenance

strategies are defined and implemented.

Total Productive Maintenance

TPM is the technique of Total Quality Management (TQM) applied to machinery. Unlike the other methods,

TPM focuses on the causes of equipment failure rather than centering on only predicting and fixing the

equipment.

While it is convenient to think of these techniques as separate strategies, the reality is that most

maintenance programs combine elements of many, if not all of these techniques, Indeed, the more

sophisticated the technique the more it depends on the implementation of less sophisticated techniques, for

instance a Reliability Centered Management program is dependant upon the existence of a Predictive

Maintenance program.

The standard technologies used to implement a Predictive Maintenance program are:

Vibration analysis is used on rotating equipment to find problems such as misalignment, out-of-balance

conditions, and bearing defects. Periodic readings are taken and recorded, the data then compared to the

equipment's baseline. When wear reaches a certain point, equipment replacement is scheduled.

As far as rotating equipment is concerned, ultrasound functions primarily for leak detection, particularly for

steam and air leaks. Ultrasound equipment detects the sounds made by leaks and gauges the severity of

the leak.

Oil and Wear-Particle Analysis are two techniques to determine the condition of lubricants.. Oil analysis

determines the condition of a lubricant. Wear-particle analysis determines the condition of equipment based

on the concentration of wear particles in the lubricant.

Thermographydetects components that are hotter than normal. This allows technicians to perform

maintenance on only the electrical components that need attention without requiring that all components get

the same level of attention. For example, the correct torque is essential on electrical components to ensure

that no heat is generated from a loose connection.


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Many predictive techniques can be used in conjunction as a form of cross checking. For example, a problem

indicated by an oil sample could also be checked by vibration analysis or thermography.

From the above discussions, a basic distinction between preventive maintenance and predictive

maintenance can be stated like this: predictive maintenance is time based (i.e. when is it time to perform the

maintenance) while predictive maintenance is condition based (what is the actual condition of the

equipment.) With the development of Computerized Maintenance Management System (CMMS) programs,

both approaches can be integrated into a reliability-based maintenance program. The data collected through

predictive maintenance is used to formulate a realistic preventive maintenance program. In addition,

sophisticated analysis of data acquired through condition monitoring is used to identify the root causes of

failure and appropriate actions designed to prevent future failures. Typically, these failures are start-up

failures, random failures and wear out failures. At this point, a maintenance program may be verging on a

TPM type program.

The CMMS will typically contain the following components:

Plant data management: descriptions of all plant operating areas in one database.

Spare parts management: tracks stock and inventory

Technical support management: tracks major repairs and modifications.

Maintenance management: plans and documents maintenance activities.

Documentation management.

Environmental management.

In terms of rotating equipment, important modules in a CMMS program are a coordinated control system

and remote diagnostics. The first controls and coordinates the steam generator and the turbine during

operation. The second enables remote real-time monitoring of equipment.

The only way to project failure rates and consequences (i.e. risk management and reliability based

management) is the use of data collected from the actual equipment in operation, historical data and

manufacturers data. The closer all of this data can come to the actual operating conditions in the plant, themore valuable it is.

Simply put, all of this data collection is aimed at answering a basic question: "When was the last time I was

at this operating point and what happened?" Once that question is answered, plant personnel can make an

informed decision as to when to schedule an outage or a borescope inspection. While the question is simple

in the abstract, the real-life implications are complex. To answer the question, plant personnel must commit

to a condition-based monitoring program; that is to closely monitor equipment, in particular rotating

equipment, and perform maintenance as required. If done right, condition monitoring can extend the length

of time between outages by years and same large sums of money. If done half heartedly, the result can be

emergencies and the waste of large sums of money.

While condition monitoring may be the holy grail of plant maintenance, it can be hard on nerves of plant

personnel. Rather than planning for an outage at a known point in time, conditions may warrant an outage

on relatively short notice. The key to success, then , is to plan ahead by developing good working

relationships with vendors and suppliers. The up side is that prices can be negotiated in advance and often

result in savings.

Plant maintenance, then, is no longer a matter of which particular maintenance schedule to follow, or which

diagnostic technique is best for which equipment components. Plant maintenance has become a process

whereby a variety of technique and functions are integrated and support each other


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plant maintenance methods and its importance

plant and machine maintenance

Manufacturers are very averse to down time . Any downtime in plant is direct production loss

which nobody want .Every factory manager wants the downtime to minimum .To acheive this

you require skilled manpower in your maintenance deptt.Normally a gang of four to five

people including a foreman , an electrician , a fitter and one or two helpers are minimum

requirement for shift coverage .

Plant manager along with his engineer schedules a maintenance plan which can be

implemented on weekly/fortnightly/monthly basis

Main method of plant andmachine maintenancearePreventive :

This kind of maintenance methods have regular maintenance programm say weekly where

jobs are planned out during the weeks with all spares planned .Based on the observations

and breakdown the machines are attended with regular cleaning ,oiling and tightening

operations.Gear oil are replaced , worn out bearings to be replaced .Similiarly worn ot switch

gear to be replaced .

Predictive:

With advent of microprocessors and computers datas can be collected for of each machine .

Predictive maintenance rely on data and many tools are available for analysing the health of

machinery like vibration analysis ,tribology , thermal sensing , lube oil testing etc .

Break down maintenance or Run to failure

Maintenance is done only when machine or equipment fails or there is a break down .

Normally the availability of spares is must in this kind of maintenance and vendor response

should be very swift . This kind of maintenance is done in all seasonal plants like cold drinks

or ice cream or sugar plant s where they have complete one month or two month shut down

and complete ooverhauling of equipments is done during this period

Annual overhauling:

Annual overhauling is must for any manufacturing plant . O/h plans are made in advance and

date fixed normally these are on holidays or any plant shut down .Machines completely

overhauled .so that It runs for longer period .

Tools

Maintenance personnel have to be equipped with latest tools which are available in market

for quick and timely break down attendance and regular maintenance.eg power wrenches ,

box spanners , pullers ,drill machines etc

Training

Technicians have to be trained about handling of tools , functions of machnery and

operations and handling . Dismantling techniques to be learned .
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Spares management

Conventional wisdom of keeping critical stocks still hold goods. We should have one or two

nearby vendors who can deliver spares in time .Small workshop with basic workshop

machine is a critical requirement.

Maintenance methods

Plant Maintenance - Deciding if Components should be Inspected or Not?

Have you ever been in a situation where someone says: we dont have time to inspect this equipment; there arejust not enough people in our plant maintenance department, or perhaps: Why would we start inspecting theequipment now, its never been done before.

You feel in your gut that the equipment should be inspected, but how do you present a compelling argument foryour plant maintenance organization? Here is a simple analysis of the situation IDCON uses.

First, there are only three ways of maintaining any component in your plant, they are:

1. Operate To Break-Down (OTB)2. Fixed Time Maintenance (FTM)3. Condition Based Maintenance (CBM) Some call this inspection.

Therefore, if an inspection is skipped, we end up with either changing out the equipment on a set frequency (FTM),or operating the equipment until it breaks down (OTB). Now, OTB and FTM will be more cost effective in somecases, but not very often because:

1. We dont know the life of most components in order to apply FTM.2. OTB is usually more expensive than FTM and Condition Based Maintenance (But not always)

To make a long story short, next time someone decide to skip an inspection or not to add an inspection, ask if thatcomponent should be operated to Break-Down, or if Fixed Time Maintenance should be used, and if so, on whatfrequency.

There are instances where it is not obvious which Maintenance method is most cost effective. A financial estimateshould be performed in these instances. A three page description of the simple calculation is outlines in chaptertwo of ourPreventive MaintenanceManual.
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What is Plant Maintenance