5 Planned Maintenance Document

7/21/2019 5 Planned Maintenance Document

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Planned Maintenance

Planned maintenance should establish and maintain

optimal equipment and process conditions; it should also be

efcient and cost-eective. In a TPM development program,

planned maintenance is the deliberate, methodical activity o

building and continuously improving such a maintenance

system.

EQUIPMENT MANAGEMENT IN PROCESS

INDUSTRIES

!quipment management in a process industry is

prooundly in"uenced by its unique types o equipment, the

nature o is process and equipment ailures, and the s#ill

levels and roles o its maintenance personnel.

Equipment Ca!acte!i"tic"

Production plants in process industries consist o static

equipment, such as columns, tan#s , and heat e$changers, all

connected by pipes to rotating equipment such as pumps and

compressors. Measuring instruments and control devices that

#eep conditions constant or vary them according to a preset


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program continuously or intermittently control and monitor

processes. Individual equipment units that are systematically

combined and integrated sub%ect ra& materials to various

chemical, physical, and biological changes as they undergo

the process that transorms them into 'nal product. (ncillary

equipment, installed at each end o the production process,

receives and stores the ra& materials, and pac#ages,

&arehouses, and ships the 'nal product. )sing the production

system ully requires careul control o all this equipment.

*ome equipment in process industries is very large, and

the stored energy o its contents can be enormous. (s

rotating equipment become bigger and aster, plants otenoperate them under conditions that push their structural

materials to the limits o their perormance. Maintaining the

intrinsic and operational reliability o such equipment at high

levels is thereore essential.

Most o the equipment in process industries is designed

and abricated separately and installed on site. +onsequently,

it has no usually bene'ted rom a lengthy program o

re'nement and improvement. )ncorrected design and

installation &ea#nesses oten handicap its operation.

(dditionally, many plants &ere 'tted &ith distributed digital

control systems in recent years, and sot-&are bugs or


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spurious control signals sometimes cause process problems.

Maintaining control devices and sot&are, thereore, is also

important.

Table - indicates some o the special eatures o

process-industry equipment. *hutdo&n losses due to

equipment ailure are generally very high, so equipment

&ea#nesses should be corrected systematically to ensure

eective operation and prevent accidents, ailures, and quality

deects.

Equipment #ailu!e and P!$ce"" P!$%lem"

In addition to equipment problems, process industries

are plagued by process problems such as bloc#s, lea#s,

contamination, and po&der spills. Preventing sudden plant

shutdo&n due to such problems is crucial.


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Process problems are oten chronic, resulting rom a

comple$ combination o causes. or e$ample, the e$ternal

shape or internal construction o a piece o equipment many

create local nonuniormities in "uidity, dispersion,

temperature, composition, or other properties o the

substances being processed, and this in turn may produce

un&anted physical o chemical changes.

!quipment ailures and process problems /losses0 in

process industries can be classi'ed into 've broad categories.

- !quipment ailures or process problems that cause

shutdo&n

- 1uality abnormalities- )nit-consumption abnormalities

- +apacity reductions

- *aely and environmental problems

Most o these problems result rom equipment disorders o

abnormalities. ( plant can prevent them by bringing

equipment and processes into their ideal state. igure -

sho&s these main problems together &ith the equipment

disorders and hidden deects that cause them.


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#i&u!e 5' C$mm$n P!$%lem" and Tei! Cau"e"

Maintenance Pe!"$nnel in P!$ce"" Indu"t!ie"The ratio o maintenance proessionals to equipment is

generally small in process industries, and the maintenance

department2s principal tas# is planning and organi3ing. Its

role is mainly administrative, &ith subcontractors perorming

most o the actual repair and maintenance &or#. +ompany

maintenance personnel oten receive insufcient training to

improve their s#ills.

P*ANNED MAINTENANCE #OR PROCESS INDUSTRIES


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combines time-based maintenance /T8M0 , condition-based

maintenance /+8M0, and brea#do&n maintenance /8M0 as

rationally as possible.

Time-based maintenance /T8M0. Time-based

maintenance consists o periodically inspecting, servicing, and

cleaning equipment and replacing parts to prevent sudden

ailure and process problems. It should be part o both

autonomous maintenance and speciali3ed maintenance

activities.

+ondition-based maintenance /+8M0. +ondition-based

maintenance uses equipment diagnostics to monitor and

diagnose moving machinery conditions continuously orintermittently during operations and on-stream inspection

/9*I0 chec#ing the condition o static equipment and

monitoring sign o change by nondestructive inspection

techniques.0 (s its name implies, condition-based maintenance

is triggered by actual equipment conditions rather than the

elapsing o a predetermined interval o time.


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#i&u!e 5'+ T,pe" $- Maintenance

8rea#do&n maintenance /8M0. )nli#e the preceding

t&o systems, brea#do&n maintenance means &aiting until

equipment ails to repair it. 8rea#do&n maintenance is used

&hen ailure does not signi'cantly aect operation orproduction or generated and 'nancial losses other than repair

costs.

Preventive maintenance /PM0. Preventive maintenance

combines time based and condition : based methods to #eep

equipment unctioning by controlling equipment components,

assemblies, subassemblies, accessories, attachments, and so

on. It also maintains the perormance o structural materials

and prevents corrosion, atigue, and other orms o

deterioration rom &ea#ening them.

+orrective maintenance /+M0. +orrective maintenance

improves equipment and its components so that preventive


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maintenance can be carried out reliably, !quipment &ith

design &ea#nesses must be redesigned.

R$le $- planned Maintenance in Equipment Mana&ement

!quipment management ensures that equipment

unctions and perorms as e$pected throughout its lie, rom

planning through abrication, installation, and operation until

'nal scrapping. igure - sho&s the position o planned

maintenance &ithin the lie cycle o an item o equipment.

The useul lie o most ordinary equipment is not

clearly speci'ed at the design stage. +onsequently, it is more

oten determined not by the equipment2s physical lie spanbut by the decrease in economic perormance o the process

to &hich the equipment contributes. The useul lives o

measuring equipment and control devices may also be

determined by ho& long parts are still available ater the

devices themselves are no longer manuactured.


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Planned maintenance is e$tremely important or

equipment lie. It can even determine the success or ailure

o a line o business over the long term.


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indicates the responsibilities o each department and outlines

the maintenance technology, control technology, and control

systems the company need to support the planned

maintenance system.

Time'%a"ed Maintenance in Planned Maintenance

The goals o planned maintenance are to eliminate

equipment ailures and process problems and minimi3e losses.

The 'rst step to&ard achieving those goals, is time : based

maintenance that is perorming maintenance tas#s such as

those sho&n in igure -= according


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to a '$ed schedule, >eciding &hat maintenance to perorm

on &hich equipment &ill depend on a company2s policies,

long : and mid : range plants, annual plans, and so on. To

maintain equipment and processes in their ideal state,

ho&ever, it is vital to use all available maintenance data and

technology. +lose cooperation bet&een the maintenance

department an other department and other departments is,

thereore, essential.

C$nditi$n'%a"ed Maintenance in Planned Maintenance

The second principle activity o planned maintenance,

condition-based maintenance, has t&o main thrusts5


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- +ondition monitoring5 This most occur &hile equipment

is running to gauge its unctions and perormance

accurately.

- 9n-stream inspection /9*I05 This helps increase the

precision o shutdo&n maintenance planning. In process.

In process plants, many maintenance tas#s are

perormed during annual shutdo&n maintenance. I

inspections during shutdo&n maintenance reveal deects

that must be corrected. Maintenance personnel must

modiy the shutdo&n maintenance plan. This can cause

a delay in restarting the plant among other problems.

Time : based and condition-based maintenance control thecondition o the assemblies, subassemblies, and components

that comprise a piece o equipment. It is critical to accurately

identiy and control all those components &hose ailure might

lead to equipment brea#do&n or lost perormance, cause

quality deects, compromise saety, or harm the environment.

1!ea2d$3n Maintenance in Planned Maintenance

The third main activity o planned maintenance, brea#do&n

maintenance, consists o replacing parts or perorming other

repairs and prevention, ma#e it easy or operators to detect


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abnormalities &hen they perorm their daily chec#s or

routinely monitor the equipment.

T4E P*ANNED MAINTENANCE SSTEM

+lose cooperation bet&een production and maintenance

department is the single most important actor or ensuring

that planned maintenance is cared out eectively, !ective

maintenance also requires, at dierent time, the 've support

o other departments, such as production management,

production engineering, saety and environment, saety and

environment, administration, personnel, 'nance development,

and mar#eting. These departments must also cooperated andcoordinate closely &ith maintenance.

+ompanies organi3e their speciali3ed maintenance

unctions dierently, pending on their si3e, type o business,

stafng arrangements, past history and so on. Table -6

sho&s some characteristics o maintenance systems used in

dierent industries at present. +onsider &hat eatures &ill

best suit the needs your particular plant.


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In a centrali3ed maintenance system, maintenance

technicians are assigned permanently to a maintenance center

managed by the maintenance department. The technicians go

out to the shop"oor or production site as required. This

system is common in medium : si3ed plants &ith e&

maintenance personnel.

In a decentrali3ed system, maintenance technicians are

assigned permanently to dierent &or#places. This system is

common in large plants. !ven in large plants, ho&ever, onlymechanics and usually decentrali3ed5 electrical and

instrumentation maintenance personnel typically remain

centrali3ed.

In a mi$ed system, some maintenance personnel are

assigned permanently to dierent &or#places, &hile the rest

are based in a maintenance center. (gain, plants usually

adopt the mi$ed system or mechanical maintenance and the

centrali3ed system or electrical and instrumentation

maintenance.

!ach o the three systems has advantages and

disadvantages, as Table -7 sho&. In a ?line maintenance


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system@ /decentrali3ed, &ith maintenance personnel reporting

to production0, or e$ample, problems o s#ill and motivation

can arise, reducing maintenance quality. *elect a system only

ater assessing the &hole situation, including the need or %ob

rotation.

IMPRO6ING MAINTENANCE E##ECTI6ENESS

To improve maintenance eectiveness, start by reducing

equipment ailures, process problems, and losses such as

quality deects, high unit consumption, underproduction, and

saety and environmental problems.

The basic indicator or eectiveness is output divided by

input. irst measure e$isting eectiveness using the ollo&ing

improvement indicator5


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Ae$t, strive or a brea#through in eectiveness by reducing

the cost o the inputs /the denominator o the preceding

improvement indicator0 by optimi3ing the overall

T8MB+8MB8M system. Cou might need to e$plore ne&

approaches to maintenance to assist &ith this, such as

reliability-centered maintenance /D+M0.

Eo& is maintenance eectiveness being measured by most

companiesF ( GHG IPM survey reveals the measures

commonly used in apanese companies. /*ee igure -J0


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1UI*DING A P*ANNED MAINTENANCE SSTEM

The goal o TPM is to strengthen a company2s basic

constitution by achieving 3ero deects, 3ero ailures, and 3ero

accidents, and eliminating every #ind o loss. The most

important o these is 3ero ailures.

Acie7in& 8e!$ 1!ea2d$3n"

Most serious accidents in production plants occur in the

course o responding to problems such as equipment ailures.

Kery e& occur &hen processes operate normally and

operators merely monitor or chec# their equipment.eect rates are naturally very lo& in plants

that continue to operate normally or long periods. In other

&ords, achieving 3ero brea#do&ns is the quic#est &ay to

eliminate accidents and deects.

To prevent accidents and deects, prevent the possibility o

serious ailures that shut do&n ma%or systems or complete

processes. The #ey is to construct a planned maintenance

system that combines various speciali3ed maintenance

activities.


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Te Si9 8e!$'1!ea2d$3n Mea"u!e"

(s discussed in +hapter 7 in connection &ith loss

reduction, many plants neglect basic equipment conditions

/cleaning, lubricating, and tightening bolts0 and do not

comply &ith conditions o use. !quipment in such plants is

sub%ect to accelerated deterioration. Idling, minor stops, and

minor ailures are rie, and ailure intervals vary &idely. It is

pointless to attempt to carry out periodic or predictive

maintenance in such a situation.

The maintenance department cannot achieve 3ero

brea#do&ns through planned maintenance alone, Aor can theproduction department achieve it solely through autonomous

maintenance. 8oth can achieve signi'cant results, ho&ever,

by combining planned and autonomous maintenance and

painsta#ingly implementing the si$ 3ero-brea#do&n measure

detailed earlier on pp.=-==.

Te #$u! Pa"e" t$ 8e!$ 1!ea2d$3n

The si$ 3ero-brea#do&n measures introduced earlier

involve tremendous &or#. Implementing all at the same time

is &ell-nigh impossible. !ven i you could put all si$ into

eect at once, you &ould still &aste time trying to carry out


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Implementin& Maintenance Acti7itie" Step'%,'Step

(n important issue or the maintenance department is ho&

to plan and systematically implement the various planned

maintenance activities over time. The generic activities and

step-by-step approach oered belo& distill the practical

e$perience o many successul TPM companies by

companies.

The goal o the maintenance department in carrying out

planned maintenance is, o course, to eliminate ailures. The

si$ 3ero-brea#do&n measures and the our phases to 3ero

ailures described in +hapter 7 orm an e$cellent basis or any

step-by-step program. Table - sho&s ho& a si$-stepprogram or developing maintenance department activities

coordinates &ith the overall our-phase approach to 3ero

brea#do&ns and the autonomous maintenance program

described in +hapter . The goal o this program is to build

a solid and eective planned maintenance system.

The advantages o the step-by-step approach are that

concrete result accumulate as the activities unold and they

are chec#ed and reinorced as an internal part o the program.

To utili3e these advantages ully, the planning team must

spell out clearly &hat is to be done at each step. Table -=


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lists typical activities perormed at each step, and Table -J

sho&s a master plan or these activities.

The activities selected &ill depend on the level o

equipment maintenance in the particular plant. Plants &ith a

&ea# maintenance system and requent ailures must

implement every step. Plants that already have a airly strong

system should ocus on the steps designed to reduce ailures

and upgrade perormance by eliminating &ea#nesses.


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Audit"

The #ey to the success o a step-by-step approach is to

loc# in improvements by auditing results on completion o

each step 4hen preparing audit chec#sheets, clariy &hat

must be done and &hat results must be achieved at each step.

Table -H provides a sample audit chec#sheet or *tep . It

is important to proceed through the program in a controlled

&ay, decisively mar#ing the end o each step and the

beginning o the ne$t.

*peciali3ed maintenance audits require e$pert #no&ledge

and are, there ore, more difcult than autonomous

maintenance audits. They are useul learning opportunities,ho&ever, so senior managers at the department level and

above should attend them.

STEP'1'STEP IMP*EMENTATION O# P*ANNED

MAINTENANCE

*etting up a planned maintenance system requires careul

preparation and hard &or#. Trying to do everything at once is

ineective. >evelop the activities in the ollo&ing sequence,

&ith all relevant departments cooperating at each step5

*tep 5 !valuate equipment and understand current

conditions.


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*tep 65 Destore deterioration and correct &ea#nesses.

*tep 75 8uild an inormation management system.

*tep 5 8uild a periodic maintenance system.

*tep 5 8uild a predictive maintenance system.

*tep =5 !valuate the planned maintenance system.


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Step : E7aluate Equipment and Unde!"tand Cu!!ent

C$nditi$n"

Process plants use many dierent types o equipment.

!ven equipment units o the same type can dier in

importance depending on their unctions in the process. To

decide &hich equipment receives planned maintenance,

prepare equipment in accordance &ith pre established criteria.

Equipment *$&" S$uld P!$7ide Data -$! Equipment

E7aluati$n

!quipment logs are ra& data or evaluating equipment.

They must give sign data and sho& the equipment2s operatingand maintenance history. The simple log in Table -G

suggests items to include.


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E7aluate and P!i$!iti;e te Equipment

!valuate each piece o equipment in terms o its eect on

saety, quality, operability, maintainability, and so on. Dan#

equipment /as (, 8, or +, or e$ample0 and perorm planned

maintenance on all units ran#ed ( or 8, as &ell as those or

&hich 3ero ailure is a legal requirement. Dan#ing criteria&ill vary depending on the process, so the maintenance,

production, production, production engineering, and saety

departments must cooperate in scoring each attribute.

igure -H sho&s a sample "o&-sheet or selecting

equipment or planned maintenance. Table -L oers sample

criteria or assessing equipment characteristics.


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Ran2 #ailu!e"

Dan# ailures as ma%or, intermediate, or minor depending

on their eect on equipment. or ma%or and intermediate

ailures, implement measures to present their recurrence and,

also, to prevent similar ailures rom occurring in other

equipment.


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accelerated deterioration, correcting design &ea#nesses, and

restoring equipment to its optimal condition.

To support *tep through 7 or the autonomous

maintenance program, help operators restore deterioration. (t

the same time, correct &ea#nesses and lengthen equipment

lie, prevent ailure recurrence, and reduce process ailures.

!ach o these activities is described in more detail belo&.

4elp Ope!at$!" Re"t$!e Dete!i$!ati$n

Eelp operators understand and overcome the eects o

deterioration in their equipment in the ollo&ing &ays5

- >eal promptly &ith any deterioration or irregularitiesthat operators discover but cannot deal &ith themselves.

- Prepare one-point lesson sheets and teach operators

about the structure and unctions o their equipment.

- ive hands-on guidance to operators on inspection,

restoring equipment, and ma#ing small improvements.

To abolish environments that promote accelerated

deterioration5

- (dvise operators on ho& to address contamination

sources and hard-to-lubricate places.


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investigate the possibility o similar ailures that occur in

other equipment and ta#e steps to prevent them. The "o& :

sheet in igure -G outlines a procedure or preventing the

recurrence o une$pected ma%or and intermediate ailures.

Table -6 oers a ormat or reporting ailure analyses and

preventive measures ta#en.

Reduce P!$ce"" #ailu!e"

Process ailures are usually caused by combinations o

equipment and process actors such as5- +orrosion, crac#ing, bloc#s, lea#s, and accumulation o

oreign matter in static equipment; vibration and

bloc#ing o pipes5 peroration o heat e$changer tubes;

and so on

- +hanging properties o ra& materials and subsidiary

materials, disrupted services, misoperation, catalyst

deterioration, and other process disorders


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*ince causes o process ailures are combinations o

actors, it is oten difcult to pinpoint &here and &hen they

start. The causes o a ailure may disappear by the time

someone notices the ailure. Then only the obvious

phenomena can be analy3ed, and measures to prevent

recurrence are hard to implement.

To minimi3e process ailure losses, restore process

conditions to normal as soon as possible ater spotting signs

o impending ailure. To acilitate process ailure prediction5

- Ma#e sure the people involved accurately understand the

process status. +alibrate measuring instruments careully

and chec# them regularly to maintain their accuracy.- 9verhaul control systems and constantly con'rm that

they are unctioning correctly.

- *tudy past ailures. )se the results to train operators to

restore disrupted processes to normal as quic#ly as

possible.

- or every process ailure that occurs, prepare a detailed

report that describes &arning signs, the nature o the

ailure, and the action ta#en.

- (naly3e each ailure using M!(, P-M analysis, or

other techniques, and recast the ailure report orm in

the light o the results.


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( basic approach to reducing process ailures is to select

the most suitable system o maintenance or each unctionally

important component or equipment item. )se the reliabilitly-

centered maintenance /D+M0 approach to determine this,

based on ailure records and physical principles.

Step +: 1uild an In-$!mati$n Mana&ement S,"tem

In process industries an enormous variety o equipment

needs maintenance, and dierent processes require dierent

maintenance regimes. Managing this colossal amount o

inormation manually is impossible. The company must set

up a computeri3ed data-processing system. +onsider theollo&ing #ey points about computeri3ation5

- 8eore committing to a system, evaluate and improve

the e$isting maintenance system and decide &hich data

are necessary.

- >etermine the degree o computeri3ation required.

- >evise simple data-entry methods or those responsible

maintenance.

- *tart &ith personal computers. (s the level o data

management required rises, consider designing a

comprehensive data management system to be run on a

mainrame computer.


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- ( computeri3ed maintenance management system

/+MM*0 cannot unction eectively i ma%or and

intermediate ailures persist. +onstruct a ailure data

management system, 'rst. 8uild the equipment

maintenance management system only &hen ma%or and

intermediate ailures no longer recur.

1uildin& a #ailu!e Data Mana&ement S,"tem

( ailure data management system should include

certain inormation, &hich shit operators must enter in the

database. *uch inormation includes late and time; ailure

ran# /ma%or, intermediate, minor0; equipment model;component /shat, coupling, bearing, etc.0 nature o ailure

/vibration, abnormal noise, overheating, corrosion, &ear, etc.0

cause; action ta#en; eect in production; and time and

number o personnel required or repair.

The system should be able to generate reports &ith this

inormation each morning or discussion at morning meetings.

The team can analy3e minor ailures or discussion at

morning meetings. The team can analy3e ma%or and

intermediate ailures that &ere '$ed temporarily and consider

mea..res to prevent their recurrence.


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This data should be analy3ed and made available at

regular intervals in orm o periodic ailure summaries and

equipment ailure lists. These help arms determine ailure

requency, do&ntime, and so on or individual process or

types o equipment. The inormation also helps prioriti3e

improvements and prevent recurrence. !quipment ailure lists

also acilitate more penetrating a lyses o the causes o

mechanical and process ailure or dierent ran#s o

equipment and ailure.

igure -L sho&s an e$ample o a periodic ailure

summary; igure - sho&s an e$ample o an equipment

ailure list.

1a"e 5': A Small C$mpute!i;ed Maintenance Mana&ement

S,"tem

4hen management at a certain company installed a

mainrame computer, they decided to use the opportunity to

develop a maintenance management stem to increase the

eectiveness o autonomous and speciali3ed maintenance.

They built the system rom three subsystems5 ailure

management, equipment management, and budget

management. The system &as designed to lo& operators on

the production "oor to enter data using personal computers.


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The primary goals o the system &ere5

- To accelerate analysis o ma%or and intermediate ailure

in order to prevent their recurrence

- To strengthen the maintenance system by enabling

everyone to share the maintenance data

- To reduce the number o personnel required to collect

and analy3e maintenance data

- To improve maintenance &or# and budget management


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1a"e 5'


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Euman %udgment plays a larger part in computeri3ed

maintenance management systems than in other systems, and

things do not al&ays go according to plan. ( company

cannot e$pect the bene'ts o systemati3ation to sho&

themselves immediately. To ma#e the ollo&ing in mind5

- !nsure that data leads to action and use the outcomes o

any action to revise standards.

- *tart &ith a system that matches the e$isting level o

control and upgrade it in stages.

- Ma#e the system as eective as possible or ront :

line maintenance personnel.

igure - illustrates the unctional organi3ation o acomputeri3ed maintenance management system.

C$mpute!i;in& Maintenance 1ud&et Mana&ement

( computeri3ed management system or the maintenance

budget compiles, apportions, and totals maintenance budgets.

It must generate the ollo&ing #inds o inormation5

- 8udget summaries or dierent types o maintenance

&or# that compare budgeted and actual e$penditure over

the same period in dierent years or dierent types o

maintenance &or# or budgeting systems.


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- 4or# and materials usage schedules that provide

inormation on &or# plans, costs, pro%ected materials

usage, and materials inventories. Cou can also use this

inormation or orecasting maintenance unds need to

be disbursed.

- ob priority list orecasts that help ensure that

maintenance is perormed appropriately. The system

should generate past MT8 data along &ith details

about equipment that is due to reach the end o its

useul lie.

- +harts that compare predicted do&ntime losses &ith

maintenance costs and help measure maintenanceeectiveness. The system should generate data that

compares the cost o maintaining equipment &ith the

predicted losses that arise rom its ailure.


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1uildin& S,"tem -$! C$nt!$llin& Spa!e Pa!t" and Mate!ial"

To analy3e reasons or holding long : term stoc#s and

to cut do&n on the labor required or calculating usage and

#eeping trac# o issues and receipts, the ollo&ing

inormation is necessary5

-


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>esign the dra&ing control system to 'le and retrieve

maintenance dra&ing, equipment dra&ings, equipment logs,

detailed dra&ings o part to respect, piping layouts, "o&

diagrams, &iring diagrams, dra&ing lists, catalogs, and so on.

Step =: 1uild a Pe!i$dic Maintenance S,"tem

In periodic /or time-based0 maintenance, standby units,

spare parts, section equipment, lubricants, and technical

inormation such as dra&ings may be required to carry out

the scheduled &or#. Maintenance &or# proceeds smoothly

only i these resources are properly prepared in advance.

Pe!i$dic Maintenance P!$cedu!e

(s the "o&-sheet o igure - sho&s, equipment can

be overmaintained &or# is scheduled unthin#ingly at rigidly

set intervals. 4henever you perorm a maintenance %ob,

consider &hether the interval and the type o &or# scheduled

are appropriate. 4hen equipment ails beore the set

maintenance interval elapses, analy3e the reasons and use the

results to revise the maintenance interval and tas#s beore the

ne$t service.


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Selectin& Equipment and C$mp$nent" -$! Pe!i$dic

Maintenance

(ssess the equipment designated or planned

maintenance and select equipment rom the ollo&ing

categories or periodic maintenance5

- !quipment that, by la&, requires periodic inspection


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- !quipment &ith maintenance intervals determined by

e$perience

- !quipment that requires regular chec#ing because o its

importance to the process

- !quipment &ith an established replacement interval

based on the serviceable lie o its components

- !quipment, such as heat e$changers, &hose perormance

begins to deteriorate ater a #no&n period as a result o

scale buildup and so on

- Important equipment or &hich it is difcult or

impossible to detect or correct abnormalities operation

P!epa!in& Maintenance Plan"

8ase maintenance plans on mid : range /appro$imately

've : year0 production plans. >etail the shutdo&n

maintenance or the entire plant or section along &ith the

periodic maintenance required or individual equipment items.

Include shutdo&n maintenance plans; annual, monthly,

&ee#ly, and daily plans; individual plans; and plans or

opportunity maintenance@ /maintenance perormed on

machines &henever they are shut do&n or other reasons0

4hen dra&ing up periodic maintenance plans, try to

incorporate the ollo&ing5


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- *et up and abricate in advance to reduce the time the

actual maintenance &or# ta#es.

- Minimi3e personnel movement during maintenance &or#

by multi s#illing maintenance technicians and outside

&or#ers.

- Prepare everything in advance /scaolding, lighting,

materials, electrical po&er, compressed air, &ater

supplies, purging and opening : up o equipment, etc.0

- The severity o equipment deterioration depend on the

operating conditions since the equipment2s last service.

8eore dra&ing up the maintenance plan, e$amine

inormation such as daily chec#ing records and note anychanges in operating conditions.

#$!mulatin& Pe!i$dic Maintenance Standa!d"

To ensure that people perorm periodic maintenance

accurately efciently and to build up a solid base o

maintenance technology &ithin the company, ormulate the

ollo&ing #inds o standards and update them as necessary5

Materials selection standards. !ven though the best

materials may have seen selected &hen equipment &as

originally designed, subsequent process ranges o changes in


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*pare-parts control standards. *pare parts are essential or

assuring equipment reliability, e$tending equipment lie, and

reducing equipment do&ntime. 9n the other hand,

unnecessary stoc#s tie up capital and increase &arehousing

costs, so it is vital to establish eective control standards.

+lassiy and control spare parts in accordance &ith a

scheme such as the ollo&ing5

- *tandby units : pumps, motors, and other standby

equipment. The maintenance department should control

and #eep constantly ready or use.

- Priority components : rotating part o important

machinery, etc. The maintenance department shouldcontrol and chec# regularly.

- eneral parts : regularly : issued items such as

bearings, nuts, and bolts. The stores department should

control, using a '$ed : number system to issue items

such a bearings, and the pac#age B batch system to issue

items such as nuts, bolts, and so on.

- Tools and testing equipment. The maintenance

department should control tools and issue them on loan.

Testing equipment should be controlled by the

department that uses it.


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*aety standards. >ra& up saety standards or

maintenance &or#. Devie& and partially revise these annually,

and revise them completely at least once every 've years.

Include the ollo&ing items5

- >uties o &or#ers and supervisors

- (ction beore starting &or#

- (ction in the event o an accident

- *tandards or seiri /sort out the unnecessary0 and seiton

/set in order : arrange efciently0

- Eandling radioactive substances

- !lectrical saety precautions.

Table -7 is an e$ample o a saety standard to be

applied beore commencing maintenance &or#.

The most important preparations or ensuring the saety

o maintenance &or#ers are5

- >ra& up standards that cover speci'c problems in the

area &here they are to &or#

- (llo& &or#ers to inspect the &or#site in advance

- Ma#e the &or#site sae or the use o na#ed "ames

Table - is an e$ample o a maintenance &or#

commencement authori3ation and completion report.


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Imp!$7in& te E>cienc, $- Sutd$3n Maintenance

It is standard practice in the chemical industry to

perorm shutdo&n maintenance at least once a year, and this

helps to improve operational saely. *ome other process

industries also improved their efciency &hen they introduced

..anned shutdo&n maintenance in place o maintenance ater

&or#ing hours on holidays.

*hutdo&n maintenance can consume up to hal o a

company2s annual maintenance budget. This is because it

includes equipment modi'cation, the list o stopping and

restarting the plant, as &ell as the cost o maintaining,equipment /such as columns, tan#, heat e$changers, and

piping0 that cannot opened up during normal operation.

+ompanies also carry out capital investment pro%ects during

the shutdo&n maintenance period, thereore improving the

efciency o shutdo&n maintenance is important.


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?


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/$!2 1!ea2d$3n St!uctu!e -$! Sutd$3n Maintenance

*hutdo&n maintenance is the most e$tensive

maintenance activity or any process plant. It involves much

&or#, starting &ith shutting do&n production, purging the

system, chec#ing saely, perorming and accepting the

maintenance and construction &or#, preparing or startup, and

'nally, restarting production. It involves almost every

department &ithin the company. Including saety, purchasing,

and accounting, as &ell as production, maintenance,

inspection, and engineering. 9mission : ree, error : ree

shutdo&n maintenance is impossible unless the entire process

is careully planned. irections or TPM, published

by Productivity Press.

The 48* method includes the ollo&ing activities5

Prepare an on-site &or# operation sheet in net&or#

orm. 9n : site &or# during shutdo&n maintenance is

usually delayed by a multitude o unanticipated events such

as the discovery o une$pected deterioration, late arrival o

materials, and adverse &eather conditions. The bar : type o


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operation sheet is less useul in such cases because it

conceals the relationships among dierent tas#s and the eect

o delays on the overall pro%ect.

To avoid this, prepare a net&or# diagram that clearly

sho&s the relationships among dierent tas#s. Oeep a

constant chec# on the critical path /the bottlenec# or the

overall process0. This is the #ey to e$pediting the process

eectively.

Prepare a net&or# diagram. )se a net&or# scheduling

method such as P!DT /program evaluation and revie&

technique0 or +PM /critical path method0 to prepare an on :

site &or# operation sheet sho&ing the tas#s detailed in the48* diagram. Eighlight the bottlenec# processes.

*horten the process. *horten the bottlenec# process by

giving it 'rst claim on personnel and materials, reducing

delivery times o purchased materials, and devising e$ternal

setup techniques, that is, gathering and setting up tools

materials, parts, and equipment needed or the &or# as much

as possible beore actual shutdo&n. )se the net&or# diagram

to assess the eect o these eort and identiy the ne$t

bottlenec# process. To shorten the overall schedule, #eep

repeating this procedure.


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Deduce shutdo&n maintenance costs. !liminate

unnecessary e$penditures or personnel, materials, electrical

po&er, equipment hire, and so on, or each

/HJ-HH0

- Ma#e every eort to level the number o people &ho

enter the site during shutdo&n maintenance each day.

*et an upper permissible limit.

- 8eore starting shutdo&n maintenance, give saety

training and issue attendance certi'cates to everyone

&ho &ill be entering the site.

- In addition, ta#e the saety measures described earlieron pp.H7-H.

C$ncludin& Sutd$3n Maintenance

(t the conclusion o shutdo&n maintenance, prepare a

report that details the &or# accomplished, the progress made,

the organi3ation used, the budget, and so on. 8e careul to

report all problems that concern saety, progress; and budget,

and use this inormation in planning the ne$t shutdo&n

maintenance pro%ect.

The length o this report varies &ith the si3e o the

shutdo&n maintenance pro%ect, and in some cases may run


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intro do3ens o pages. Table - lists the general

inormation the report should generally include, and Table -

= sho&s an e$ample o the type o &ee#ly progress report

that the shutdo&n maintenance pro%ect manager should submit

to the plant superintendent.

Ca"e 5'+: Sutd$3n Maintenance Mana&ement

igure -J sho&s ho& >aicel +hemical industries2

(boshi Plant improved the quality o its shutdo&n

maintenance management. The company not only reduced the

time and cost o shutdo&n maintenance; it also achieved

e$cellent results in increasing the number o ocusedimprovement pro%ects accomplished and reducing ailures and

deects. This success &as probably due to the careul practice

o collecting data needed or planning shutdo&n maintenance

and incorporating it into the plans.

or e$ample, as part o their autonomous maintenance

program, operators at the (boshi plant hold daily ?T

Meeting@ /?3ero-trouble@ meetings0 at &hich they discuss

?trouble cards@ /cards &ith brie descriptions o problems

ound0. (ny problems the operators have not addressed by

the time shutdo&n maintenance is due are incorporated into

the shutdo&n maintenance plans.


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*ometimes shutdo&n maintenance rivals the scale o a

small construction pro%ect, but it remains, nevertheless a

maintenance tas#. Ao matter ho& s#ill ully personnel carry

out the &or#, the result cannot be ully eective rom the

maintenance vie&point, unless inormation gathered during

operation and relevant to the &or# is ta#en into consideration

in the plans. The maintenance department at this plant has

established a reliable system or incorporating into shutdo&n

maintenance plans critical inormation rom ocused

improvement activities and rom planned periodic chec#s and

inspections.


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Step 5: 1uild a P!edicti7e Maintenance S,"tem

4hile une$pected ailures decrease once periodic

maintenance is established, they still occur, and maintenance

costs may increase. This is because periodic maintenance is

time : based and assumes a hypothetical rate o equipment

deterioration. 9ptimal service intervals cannot be set &ithout

measuring the e$tent o actual deterioration in individual

items o equipment. This requires a condition : based


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approach, in &hich the timing and nature o the maintenance

required is based on the e$tent o actual deterioration as

con'rmed through equipment diagnostics. To conduct

condition : based or predictive maintenance, it must be

possible to measure characteristics that indicate deterioration

reliably /#no&n as ?substitute characteristics@0. *uch

characteristics might include vibration, temperature, pressure,

"o& rate, lubricant contamination, &all thic#ness decrement,

metallurgical deect gro&th, corrosion rate, and electrical

resistance.


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Int!$ducin& Equipment Dia&n$"tic"

Predictive maintenance involves the use o equipment

diagnostics. It is best to start &ith vibration diagnostics,

&hich is a technique developed in the eel and chemical

industries. irst establish the ollo&ing system o diagnostics

or rotating machinery, then use the same method to

introduce diagnostics or static equipment.

Int!$ducin& 6i%!ati$n Dia&n$"tic" -$! R$tatin& Macine!,

*tep 5 !stablish a core team by training people li#ely

to ma#e good vibration diagnosticians.

*tep 65 >esignate certain items o equipment as modelsor practicing ..bration diagnostic. +ore team members

practice their s#ills on this equipment and then pass on their

#no&ledge to others.

*tep 75 >esignate certain items o equipment &ithin

each &or#place as models or implementing vibration

diagnostics. In process industries, eed ..mps or gas

compressors are probably the most suitable types o

equipment N this, as their operating conditions and the

properties o the materials they candle are airly stable.

*tep 5 *et provisional periods and criteria or

measuring the vibration o the model equipment. To begin


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equipment may gro& into large ones that can hal production

and even cause ma%or disasters. It is thereore vital to use

equipment diagnostics to discover, diagnose, and predict

deterioration. Table -J sho&s some e$amples o diagnostic

techniques or columns B tan#s and pipingB heat e$changers,

&hile Table -H sho&s an e$ample o the diagnostic

techniques used during normal operation and shutdo&n

maintenance at a particular chemical plant.


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/$!2 #l$3 -$! P!edicti7e Maintenance

9nce you introduce equipment diagnostics and selectequipment or predictive maintenance as described, prepare a

predictive maintenance "o& diagram. igure -H is an

e$ample. 4hen applying this to static equipment, treat

?simple diagnosis@ as discovering abnormalities and

?precision diagnosis@ as diagnosing them.

Step @: E7aluate te Planned Maintenance S,"tem

The goal o planned maintenance in process industries is

not merely to plan the timing and techniques o maintenance,

but also to plan methods or eectively maintaining

equipment2s e$pected unctionality and reliability. 8asically,


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planned maintenance systemati3es the most eective

maintenance techniques or eliminating ailures that lead to

degradation or total loss o the equipment2s production

unctions.

(s igure -G sho&s, the cru$ o maintenance system

evaluation is assessing ho& &ell the maintenance and

production department &or# together. It should be a t&o-

pronged system5 The maintenance department is responsible

or periodic maintenance in accordance &ith the maintenance

calendar and predictive maintenance using equipment

diagnostics and condition monitoring. The production

department is responsible or #eeping the equipment in pea#condition through regular daily chec#s.

To assess the efciency, timeliness, and economic

easibility o maintenance, loo# at &hat actually happens to

the equipment in the &or#place. To gauge &hether the

planned maintenance system is permanently in place, chec#

&hether the various supporting subsystems : control

standards, technical standards, and so on : are properly

established.

+hapter 6 contains a detailed discussion on evaluating

maintenance results /see also the basic maintenance


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improvement indicators described on pp.-, =H o this

chapter0.


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RE#ERNCES

!.9shima, ed. ( Practical >ictionary o !quipment

>iagnostics and Productive

Maintemance. /in apaness0.. AT* u%i Technosystems,

n.d.

C.*a#aguchi. Plant !ngineer, Kol.75H/GGL0.

T.*u3u#i Ae& >irections or TPM. Portland, 9ne

Productivity Press, GG6

5 Planned Maintenance Document

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