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# OAR Box 

# 1778
Prepped by Ollie Stewart



## Document

Number: 

# 222 ) 11-1- 2
Docket Number: 

# A-90-0 6

Printed 10/28/20089:51:02 AM Sheet 222 of 276P. 2

II-I- 2

IF E EXTENSIO N

- A GLORIFIE D MAINTENANC E PROGRAM ? by

. A . Derdiger , R . J . Hollmeier , an dG . Shibayam a

Man y lif e extensio nprogram s hav e bee ndevelope dove r the las t fe w years . Sinc e systemati c proble m

solvin g technique s ca nb e applie djus t a s easil y t o lif e extensio na s t o an y othe r busines s o r engineerin g problem , i t i s no t surprisin g tha t mos t o f th e program s ar e simila r inconcept . Becaus e mos t program s are tailore dt o a specifi c application , th e difference s amon g the program s ar e i nth e details , a s woul db e expected . Befor e discussin g ou r program , w e wil l firs t defin e lif e extensio nanddiscus s the confusio nsurroundin g it .

Plan t Lif e Extensio n(PLE ) need s t o b e clearl y define dbecaus e th e ter m i s ofte n misinterprete dan dabused . Ther e are a s man y definition s o f PLE a s ther e are programs , bu t ther e i s a grea t dea l o f similarit y amon g the bette r one s (thos e tha t agre e wit hours , o f course) . Anothe r though t a s t o wh y PLE i s diversel y define di s becaus e i t i s a ne w concep t o r though t proces s tha t look s suspiciousl y lik e a lo t o f othe r thing s tha t hav e bee ndon e inthe past . T o determin e a goo d definition , therefore , on e shoul dstar t b y differentiatin g PLE from everythin g else . Thi s bring s t o min dthe positio no f marketin g som e twent y year s ago . A t tha t time , marketin g professor s an dprofessional s spen t muc ho f thei r effor t tryin g t o differentiat e marketin g from sale s s o tha t the res t o f the worl dwoul d appreciat e tha t marketin g i s a mor e advance dconcept .
Admittedly , PLE , lik e marketing , need s differentiatio nan ddefinition , an dno t jus t fo r the nonbeiievers , bu t t o kee pu s focuse do nthe rea l objective : lowerin g generatin g cost . Accordingly , Fluo r ha s define dPLE a s "a norganize dprogra m t o investigate , evaluate , an dpla nfo r prolonge d utilizatio no f existin g generatin g unit s inorde r t o satisf y futur e syste m

electri c load. "

Thi s definitio nembodie s a commitmen t t o determin e whethe r andho w existin g unit s ca nb e bette r utilized , rathe r tha nreplaced , t o lowe r futur e generatin g cost .P. 3



## ar , 

## ii
I nit s mos t restricte dapplication , PL E involve s th e determinatio no f th e remain in g lif e o f critica l components , andth e economi c feasibilit y o f reliable , ex tende dplan t operatio nbeyon deithe r th e origina l desig nlif e o r th e currentl y planne dretiremen t date . PL E als o include s identificatio no f plan t upgrade s and operatin g an dmaintenanc e technique s require dt o exten dlife .

Mor e generally , however , increase dutilizatio nthroug hPL E mean s takin g a ne w loo k
a t th e existin g asset s o f th e plan t t o determin e ho w t o cost-effectivel y mee t futur e generatin g requirements . Dependin g upo nspecifi c utilit y needs , thes e requirement s ma y

b e me t by :

• Recapturin g los t efficienc y

• Improvin g availabilit y

• . Modifyin g fo r cyclin g

• Improvin g operatin g an dmaintenanc e technique s t Repowerin g

• Convertin g fuel s

T o determin e whic hcours e o f actio ni s bes t fo r a particula r utility , aninte grate dapproac hto : develo pa norganize ddat a base , evaluat e options , anddevelo p a nimplementatio npla ni s required . Fou r majo r activitie s ar e addresse di n Fluor' s programmati c approach . Thes e activitie s ar e a s follows :

• Plan t assessment . A quick , low-cos t assessmen t o f th e overal l condition , operations , an davailabilit y o f a plant .
Syste m planning . Conceptua l evaluatio no f futur e syste m configuratio n options , particularl y th e economi c valu e o f extende dlif e an denhancemen t o f existin g generatin g units .
Detaile dinspection , testing , andevaluation . A nintensiv e inspectio no f plan t system s andcomponent s t o determin e condition , estimat e remainin g life , an dcalculat e cos t fo r upgrad e o r replacement . Implementatio nplan . Anintegrate dlong-ter m pla ninvolvin g upgrades , training , an dongoin g monitoring .P. 4

Ou r approac hemphasize s clos e coordinatio nbetwee nmaintenanc e an d operation s practices . Fundamentally , som e PL E activitie s ar e closel y relate d an d ma y

overla p int o th e maintenanc e aren a whil e other s ar e quit e independent . Th e scop e o f activitie s whic hfal l unde r th e categor y o f maintenanc e varie s fro m utilit y

t o utilit y dependin g o nfactor s suc ha s economics , accountin g methods , o r operatin g philosophy . Fo r example , whil e mos t utilitie s includ e boile r tub e repair s i n thei r PL E programs , som e exclud e it , categorizin g thes e repair s a s norma l mainte nance . Fro

m ou r viewpoint , whe nth e decisio nt o replac e tube s i s dependen t solel y o nhistor y

(i.e. , curren t an d pas t tub e leaks) , thi s ca nb e considere d t o b e correctiv e maintenance . Wher e tub e sampl e analysi s an d high-stress-poin t engine erin g ar e performed , thes e activitie s ma y b e considere d predictiv e maintenance , and fal l unde r th e categor y o f plan t lif e extension .

Let' s now

revie w th e distinction s betwee nmaintenanc e an d lif e extensio nina fe w genera l areas .

COMPONENT S COVERE D Whil e correctiv e maintenanc e encompasse s al l plan t equipmen t an d preventativ e maintenanc e cover s equipmen t tha t require s periodi c attentio nfo r changeou t o f lubrication , filters , gaskets , etc. , lif e extensio nfocuse s onheavy wal l compo nent s wit hfinite , analyticall y determinabl e lif e alon g wit hthos e element s usefu l i ncontrollin g an d monitorin g plan t life . Th e mos t importan t suc helement s ar e modernize d turbin e an d boile r contro l systems , which , i nadditio nt o makin g th e uni t easie r t o operate , permi t th e operato r t o bette r minimiz e creepan d fatigue relate d stresse s o nth e plan t systems , thu s maximizin g uni t life .

PRIMAR YFOCU S
Norma l maintenanc e focuse s oncorrectiv e an d preventativ e activities , whic htend t o suppor t continue d operatio no f component s an d subcomponents . Lif e extensio n programs , onth e othe r hand , focu s primaril y onpredictiv e activitie s whic hensur e safe , reliabl e uni t operation . Whil e safet y i s alway s a paramoun t consideration , i t i s no t ordinaril y a proble m

durin g th e initia l desig nlife , sinc e th e heavy wall , high-pressur e part s wer e ver y conservativel y

designed . However , wit h extende d life , w e ma y intrud e int o th e margi no f safet y o r beyond ; s o i t i s necessar y

t o determin e th e expende d an d remainin g lif e o f critica l component s b y usin g mor e accurat e techniques .P. 5



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Wit hregar dt o methodologie s tha t ar e usedt o determin e remainin g usefu l life , utilitie s ar e sometime s confronte dwit hwidel y divergen t conclusion s tha t ar e draw nfro m th e "experts " wh o ar e calle dupo nt o evaluat e remainin g usefu l lif e i n components .

CONDITIO N

MONITORIN G Conditio nmonitorin g o nconventiona l unit s tha t ar e inoperatio ntoda y i s usuall y minima l o r nonexistent . A s previousl y stated , desig nconservatis m minimize dth e necessit y

o f conditio nmonitoring .

Extende d lif e ca nb e mor e cos t effectiv e tha nne w generatio no r wholesal e replace ment . Detaile dinspectio nan dtestin g serv e tw o purpose s t ntha t end :

• Establishe s a norganize ddat a bas e t o supplemen t existin g record s fo r us e a s a basi s f o r continuin g uni t operation .

• Establishe s a basi s t o estimat e cos t an devaluat e extende dlif e options . Figur e 1 (se e pag e 5 ) summarize s th e overlappin g andmutuall y exclusiv e area s o f maintenanc e andPLE . Fluor' s plan t lif e extensio nprogra m emphasize s th e import anc e o f reviewin g an dintegratin g th e identified , require dPL E inspection s and activitie s wit hth e plan t maintenance , operations , an dreliability/availabilit y programs . Som e utilitie s hav e foun dtha t man y inspection s performe dunde r thei r lif e extensio nprogra m wer e als o performe da s par t o f thei r routin e maintenanc e program . Thi s integratio nminimize s duplicate deffort .

Th e approac ht o PL E wil l certainl y b e differen t fo r a plan t tha t ha dcurtaile d maintenanc e r o r planne duni t retirement , from a plan t whic hha s operate dwit h satisfactor y

availabilit y

an dkep t upmaintenance . Fo r a plan t whic hha s bee n operate dandmaintaine da s designe d(i.e. , bas e load , peaking , loa dfollow) , th e so-calle dfata l flo w approac hi s appropriate . Fo r thi s situation , a nevaluatio n o f th e followin g component s ma y b e al l tha t i s necessary :

• Boile r drum , header s andwaterwall s

• Turbin e rotor , shel l andsteamches t

• Critica l pipin g

• Structura l foundation s andsupport sP. 6

MAINTENANC E BOT H 

### PL E

Corrective/Preventativ e

Periodi c

Lubricatio n Cleanin g Repai r Replacemen t

Annua l Operatio n Expens e Predictiv e

Conditio nMonitorin g Cree p Measuremen t Critica l Pipin g Lo w Cycl e Fatigu e Structura l Evaluatio n

Capitalize d Expens e

Figur e 1 . Overlap s o f Maintenance/PL E

Al l othe r modification s coul d b e considere d a s upgrade s o r maintenance .

Fo r a retire d uni t tha t i s bein g revive d fo r dut y o r fo r a uni t tha t i s operate d wit hcurtaile d maintenance , a comprehensiv e PL E approac hwoul d b e appropriate .
Ther e i s no doub t tha t th e hig hleve l o f earl y attentio ngive nt o extensiv e detaile d inspection-testin g program s and t o extensiv e plan t rebuild s hav e cause d
man y t o labe l PL E a s a glorifie d maintenanc e program . Furthermore , i t ha s reache d th e poin t tha t some individual s labe l ever y valv e o r pum

p replacemen t a s plan t lif e extension .P. 7



### I s Plan t Lif e Extensio nmerel y a glorifie dmaintenanc e program ? Obviousl y Fluor' s answe r i s "no. " Eve nwit ha well-operate dplan t wit hgoo dmaintenance , i t i s pruden t t o evaluat e andmonito r th e critical , heavy wal l component s fo r reason s o f safet y a s wel l a s fo r economics . Thi s evaluatio nrequire s activitie s andcapabi litie s no t normall y

require di nplan t maintenanc e programs . O na mor e typica l near-end-of-lif e uni t wit hcurtaile dmaintenance , man y maintenanc e function s becom e a par t o f th e PL E program ; fo r thes e reasons , anintegrate dapproac hmake s sense . Th e reade r shoul dals o kee pi nmin dtha t i nsom e situations , th e expande d vie w o f PL E ha s some additiona l publi c relations ' benefits . W e hop e thi s explana tio nha s helpe dt o clarif y th e distinction s andoverlap s betwee nPL E andmainte nance , a s wel l a s th e nee dfo r plan t lif e extension .