Industrial safety of pressure vessels - structural integrity point of view

I dustrial safety of pressure essels – Structural i tegrity poi t of ie

Fa ult of Me ha i al E gi ee i g, U i e sit of Belg ade, Belg ade, Se ia U i e sit of Si te, Si te, Li a

I o atio Ce te of the Fa ult of Me ha i al E gi ee i g, Belg ade, Se ia Te h i al S hool, Tuti , Se ia

A st a t

This pape p ese ts diffe e t aspe ts of p essu e essel safet i the s ope of i dust ial safet , fo used to the he i al i dust . Qualit assu a e, i ludi g appli atio of PED / has ee a al sed fi st, follo ed sho tl the isk assess e t a d i details the st u tu al i teg it app oa h, hi h has ee illust ated ith th ee ase studies. O e i po ta t o lusio , follo i g su h a app oa h, is that so- alled ate p oof testi g a a tuall jeopa dize i teg it of a p essu e essel i stead of p o i g it.

Ke o ds: p essu e essel safet , st u tu al i teg it , ate p oof testi g, isk assess e t.

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P essu e essels, used i he i al i dust , o -o l ha e the f-o -of li de s, sphe es, ellips-oids -o so e o i atio of these. I p a ti e, essels a e usuall o posed of a p essu e- o tai i g shell togethe ith o e s a d fla ge i gs, t pi all o e ted eldi g. Thei ai pu pose is to o tai a edia u de p essu e a d te pe atu e to e su e safe a d lo g life.

The ost iti al pa t of a p essu e essel is elded joi t, e ause a k-like defe ts a e i e ita le, due to e atu e of eldi g p o ess [ ]. The efo e, o o -de that the e a e u e ous efe e es -deali g ith

eld e t eha io i p ese e of a k [ – ]. This effe t is also e ide t f o a failu es, as illust ated

th ee e a ples elo .

Co espo de e: A. “ed ak, Fa ult of Me ha i al E gi ee i g, U i e sit of Belg ade, Belg ade, “e ia.

E- ail: ased ak@ as. g.a . s Pape e ei ed: Ap il, Pape a epted: Ja ua ,

The fi st e a ple o e s the sto age ta k fo li uid a o dio ide CO , p odu ed of high st e gth

i o-allo ed steel DIN “t.E , t ade a k Nio al “teel o ks, Jese i e , thi k ess , ith i o- - a ks i fe ite-auste ite elded joi t, as sho i Fig. [ , ]. T o e o e tio s at the uppe lid had ee ade to o e t the oute f eo u it to the i e uilt-i heat e ha ge . “i e Nio al is ot p odu ed i fo of tu es, the a ufa tu e used tu es a d fla ges of auste iti steel, . i

dia-ete , . all thi k ess. It as diffi ult to e su e ualit of hete oge eous elded joi ts ith la ge dif-fe e e i thi k esses. The efo e, ei fo e e ts of si ila thi k esses e e elded to the lid, usi g utile ele t ode, allo ed ith % C a d % Ni, a d the the

o e ti g tu es e e elded to the ei fo e e t. A ho , due to etallu gi al p o le s ith dissi ila ase etals, i o- a ki g appea ed i HA), as sho i Fig. , leadi g to the leakage of this p essu e essel.

As the se o d e a ple, leakage of la ge sphe i al ta k, used fo sto age of a o ia, is iefl p ese ted. It as aused u dete ted i o- a ks i elded joi t, hi h ha e g o th ough the thi k ess du i g p oof testi g old- ate test ith p essu e up to % a o e the ope ati g p essu e [ ]. The testi g of

sto-age ta ks efo e a d afte i spe tio has lea l sho the ad e se effe t of p oof test i se i e, si e it has i di ated la ge u e of e a ks i the positio s of the old o es. T pi al positio s of lo gi-tudi al a d t a s e se a ks o i e essel all of ta k a e sho i Fig. a– , he eas the a os opi ie of th ough a k ausi g leakage is gi e i Fig. d.

a

d

Figu e . Mi o- a ks i HAZ i NIOVAL steel elded joi t [ ]; a– ) t pi al positio s of lo gitudi al a d t a s e se

a ks o i e essel all of ta k; d) the a os opi ie of th ough a k ausi g leakage.

As the thi d e a ple the leakage i the tu e-to- -tu esheet o e tio is sho , ausi g failu e of feed ate heate o po e ts i a o ia o e te s i the Che i al I dust ial Pla t HIP i Pa če o.

Ha i g i i d the o ple it of p ese ted p o -le , the asi ai of this pape is to p ese t diffe e t aspe ts of p essu e essel safet i the s ope of i d-ust ial safet , fo used to the he i al i dd-ust . Qualit assu a e, i ludi g appli atio of PED / has ee a al sed fi st, follo ed sho tl the isk assess e t app oa h. Mo e atte tio is gi e to the st u tu al i teg it app oa h, hi h is des i ed i so e details a d illust ated ith th ee ase studies.

QUALITY ASSURANCE - PED 9 /

I o de to a oid failu e of p essu e e uip e t the defe ts a d hete oge eities ha e to e u de st i t o t ol a d i spe tio , espe iall elded joi ts [ ]. The asi app oa h is to appl ualit assu a e s ste , i ludi g odes a d ules defi ed fo that pu -pose, like P essu e E uip e t Di e ti e PED / /EC [ – ], hi h a e appli a le o l to e p odu ts. The se o d, o e ad a ed app oa h, a e the isk ased i spe tio , ai te a e a d o t ol, as

des-i ed des-i [ – ]. It des-is elatdes-i el e app oa h, stdes-ill de elopi g a d pote tiall the ost i po ta t o e, espe iall if o i ed ith othe app oa hes. Fi all , the thi d app oa h, hi h ill e a al sed a d

dis-ussed i details he e, the st u tu al i teg it assess-e t, appli a lassess-e also i thassess-e asassess-e of da agassess-ed p assess-essu assess-e e uip e t, he the de isio of its fu the e ploit-atio is possi le u de gi e o ditio a d o l afte

a eful a d detailed o side atio .

I a ase, the ope atio al safet of elded p es-su e essels p i a il depe ds o eld e ts eha io . The app oa h, a epted i sta da ds fo eld e t desig , is to defi e the a epta le defe t size. All effo ts i ate ial p odu tio a d i p o e e ts i eldi g a d o -dest u ti e testi g te h i ues, togethe ith st i t e ui e e ts i ualit assu a e, a ot e lude the appea a e of a k-like defe ts du i g fa i atio , st ess elie i g, h d ostati p oof tests o ope atio al se i e [ , ]. Fu the o e, i eal elded p essu e essels st ess o e t atio aused

geoet i al ha ges, i ludi g i e ita le eld e t i pe -fe tio s, su h as a gula disto tio o isalig e t,

auses lo al plasti st ai s. I these i u sta es the uestio a ises of ho a ked elded joi t ill eha e.

Full s ale tests of elded p essu ized e uip e t a e the ost i fo ati e he safet is o side ed [ ]. I so e ases the a e i e ita le despite high ost e ause the a gi e ealisti a s e s elati g the se i e eha io of elded joi ts. H d ostati p essu e p oof test a e lassified as the full s ale test.

Di e ti es fo te h i al sta da ds fo statio a p essu e essels p es i ed that the egula pe iodi p oof p essu e test of essels should e pe fo ed efo e si ea s i se i e, if ot othe ise e ui ed the egulatio s o the te h i al sta da ds fo e tai t pe of p essu e essels a d sto ed su sta es.

H d ostati p essu e fo p oof test is ofte al ul-ated usi g the fo ula pi = . p, he e pi is p oof test a d p is the desig p essu e. The logi ehi d this app oa h is that o e a p essu e essel has ithstood p oof test, it ill e safe i the e ploitatio u de desig p essu e. Ne e theless, e pe ie e i di ates o e o ple situatio , as as the ase ith u e of la ge p essu e essels, used i he i al i dust . Al ead e tio he e, he e the p oof test has p

o-oked a ki g a d leakage, i stead [ ].

RISK BASED APPROACH

too o ple , a d ill ot e o side ed he e. I stead, e p ese t he e o l the isk at i app oa h, as illust aillusted i Ta le . This app oa h uses ellk o defi -itio of isk ei g the p odu t of the p o a ilit a d the

o se ue e [ – ].

I the isk at i sho i Ta le , o se ue es a e atego ized, ased o se e al pa a ete s health, safet , e i o e t, usi ess, se u it as A to E; A i di ates lo , al ost egligi le o se ue es, a d E efe s to fatal a d se ious o se ue es. P o a ilit atego ies a e g aduated to , sta ti g ith e u likel e e t, o e i o e a ea s × – , e

d-i g d-ith hd-ighl p o a le e e t o u d-i g at least o e i a ea × – .

Ta le . S he e fo isk- ased ualitati e e aluatio of ai te a e

P o a ilit atego

Co se ue e atego

A B C D E

Ve high

High isk

Mediu isk

Lo isk isk Ve lo

isk

It is self-e ide t that o se ue es of failu e of p essu e essels used i he i al i dust a e e

t-e t-el st-e ious, t-e t-e atast ophi , as i tht-e ast-e of Bopal disaste , i di ati g atego E, as the ule. Fo safe a d elia le use of p essu e essel i he i al i dust it is of ut ost i po ta e to assu e e t e el lo f e ue of su h e e ts, lassified as p o a ilit atego , si e o l i this ase isk is ot igge tha ediu . This a e a hie ed spe ial easu es i all steps of desig , o st u tio a d ope atio , i lud-i g st u tu al lud-i teg lud-it assess e t. The appllud-i atlud-io of

isk at i to e su e safet of iti al o po e ts i pet o he i al i dust , ostl p essu e essels, is illus-t aillus-ted a d e plai ed i o e deillus-tails i [ – ].

It is also i te esti g to ote that p essu e essels a e t eated i so e hat si ila a PED / , si e the ha e to e atego ized f o to , a o d-i g to pV alue p sta ds fo p essu e, V fo olu e . Although this looks like isk ased app oa h, o e should oti e that o se ue e a d p o a ilit a ot e sepa ated i this app oa h, aki g it o e-di e sio al, o let sa isk e to app oa h.

Fi all , o e should oti e that the p o a ilit of e e t is a tuall i eased ate p oof test, push-i g up push-isk alo g the e tpush-i al a push-is of the push-isk at push-i . The efo e, this app oa h lea l , e e g aphi all , i

di-ates possi le p o le s ith ate p oof testi g.

STRUCTURAL INTEGRITY ASSESSMENT

I -se i e eha io of a st u tu al o po e ts e ealed that a ks lead to the fatal failu e. O e possi ilit to p e e t su h a s e a io is to use ualit assu a e s ste . Ho e e , it a ot o e all situ-atio s i hi h p essu e e uip e t a ope ate, a d this s ste is ot appli a le o pletel fo p essu e e uip e t i ope atio . P o le ight e sol ed appl i g fit ess-fo -pu pose app oa h a d f a tu e e ha i s a al sis fo a a ked o po e t, i the s ope of its st u tu al i teg it assess e t.

This app oa h as fi st used i Alaska pipeli e i U“A [ ]. Afte fi al o -dest u ti e testi g NDT , efo e pipeli e i t odu tio i e ploitatio , a la ge u e of shallo a ks has ee dete ted, ot a epta le a o di g to sta da ds. The epai of def-e ti def-e pipdef-eli def-e ould ha def-e def-edef-e too def-e pdef-e si def-e, a d possi le ei g o e ha ful tha e efi ial if p

o-oki g e a ki g , so additio al i estigatio has ee pe fo ed the Natio al I stitute of “ta da ds a d Te h olog NI“T to assess a ks sig ifi a e f a tu e e ha i s app oa h. It as fou d that less tha % of dete ted a ks had to e epai ed a o d-i g to st u tu al d-i teg d-it app oa h, a d % of the

e e a epted ithout affe ti g st u tu al i teg it a d i -se i e safet [ ]. This has ee a epted the Natio al autho ities as the pe issi le e e ptio f o the sta da d p o edu e, si e it has p o ed, i easo a le a d o se ati e a e , that the pipeli e safet ill ot e jeopa dized.

The p a ti al appli atio of f a tu e e ha i s is f o the e egi i g ased o t ofold i te p et-atio of its pa a ete s: the ep ese t loadi g a d st u tu al geo et , i ludi g a a k, o o e ha d side, he eas thei iti al alues ep ese t ate ial p ope ties a d a k esista e, o the othe ha d side. E gi ee i g p a ti e had ee ha ged adopti g f a -tu e e ha i s ite ia i stead of t aditio al a d igo-ous sta da ds o ad issi le defe ts ega di g e es-sit of epai . This e a led a epta e of f a tu e

e ha i s a al sis as a sou d ase fo allo a le e lusio s f o e isti g sta da ds u de e tai i u -sta es, i.e., if su h a al sis esults i justified a d

o se ati e safe assess e t of the i teg it of a st u tu e.

F a tu e e ha i s has o e ted th ee a ia les st ess, defe t di e sio s a d f a tu e tough ess , as sho i Fig. , e a li g e aluatio of the thi d alue, ased o t o k o a ia les. Based o this, se e al p o edu es e e de eloped i o de to assess st u -tu al i teg it [ – ]. He e, the o pa iso of at-e ial a k at-esista at-e at-e p at-essat-ed J i tat-eg al i at-e pat-e i-e tall o tai i-ed J–R u i-e a d a k d i i g fo i-e CDF , o tai ed a al ti al o u e i al odel, ill

APPLIED STRESS

CRACK

DIMENSIONS TOUGHNESS FRACTURE

FRACTURE MECHANICS

Figu e . F a tu e e ha i s t ia gle.

It is possi le to esta lish ite io fo f a tu e p edi tio , appl i g a k g o th esista e u e, e p essed J-R u e, a d CDFs, as sho i Fig. fo fi e diffe e t le els of load st ess . The si ple e pla -atio of this app oa h is that a k of le gth a ill g o i sta le a e u de e tai load, i the ase p ese ted i Fig. it is st ess σ, u til it ea hes its iti al alue poi t A , i.e., le gth a+Δa, he the

g o th ill e o e u sta le, leadi g to the f a tu e of a o po e t. It is e i po ta t to u de sta d full su h a eha io a d e e tual o se ue es of sta le to u sta le a k g o th fo the safe e ploitatio of a p essu e essel.

Figu e . P o edu e fo f a tu e p edi tio ased o a k esista e J–R u e.

CASE STUDIES

Leakage of CO storage ta k [ , ]

As al ead e tio ed i the i t odu tio , du i g the ate p oof testi g of sto age ta k fo li uefied a o dio ide d oplets of ate had ee e ealed o the oute all of its a hole [ , ]. The sto age ta k is of li d i al fo , the all i sulated, . i olu e. The a tle a d ta k lids a e p odu ed of high st e gth i o-allo ed steel, i thi k ess. The lo est ope ati g te pe atu e of the ta k is – °C, the

highest ope ati g p essu e a , the p oof p essu e test a . The sto age ta k is lassified as II lass of p essu e essels, a o di g to pV ite io . A ge e al ie of ta k a d positio of a a hole is p ese ted i Fig. .

Figu e . Ge e al ie of ta k fo li uefied CO sto age [ ].

Afte e o i g the the al i sulatio f o the a hole, the oistu e is lo ated a ou d the elded joi t et ee the a tle a d fla ge e k. The a -hole o sisted of a tle, p odu ed of the sa e high st e gth i o-allo ed steel, thi k, a d a fla ge asti g of high allo ed auste iti steel [ , ]. The fla ge a d the a hole a e elded shielded a ual a eldi g “MAW , usi g high allo ed auste iti o -su a le [ , ]. Detailed a al sis of auste ite-fe ite

eld e t eha iou is gi e i [ – ].

Bet ee the fla ge a d a hole a tle a utt elded joi t as ade. Fla ge e ki g to a ds the elded joi t e ded a li d i al pa t of dia ete a d thi k ess that a e e ual to the dia ete a d thi

k-ess of the a hole a tle of idth . C a ks ha e ee dete ted i the li d i al pa t of the fla ge e k, i a li ited zo e, ith le gths t pi all et ee a d . I the zo e of i di idual a ks, o l sho t a ks, to lo g, e e dete ted.

Afte e pt i g the ta k a d ope i g the a hole, its i e side as tested. O the i e side t o la ge po es a e fou d, as ell as the i di idual a ks, to i le gth. Figu e p ese ts the oss se tio th ough the e te of li d i al pa t of fla ge e k, ith the zo e ith the highest a ki g de sit sho i Fig. a, a d po es i Fig. . A la ge u e of a ks, app o i atel pe pe di ula to the fla ge su -fa e, a e isi le. Testi g d e pe et a ts i di ated a la ge u e of a ks pe et ati g to diffe e t depths, so e of the th ough the thi k ess.

a

I Fig. the oss-se tio lose to the po es dete ted o the i e side of a a hole is p ese ted. T o po es, hi h a e i fa t the o ti uatio of po es dete ted o the i e side of the a hole, a e lea l isi le. Most i te si e leakage o the oute side of the a hole is e ealed just opposite of these po es, aused a ks, pe et ati g to the oute su fa e of the ta k. It as o luded that the dete ted a ks affe t the safet ope atio of the ta k, a d he e the o plete st u tu al i teg it assess e t as pe fo

-ed, as follo s [ , ].

Fi st, “EN B spe i e s ha e ee tested to o tai J–R u e, as the ate ial p ope t elated to the a k esista e, i a o da e to the “ta da d A“TM E , oth at a ie t te pe atu e, °C a d at ope ati g

te pe atu e, – °C. F o this u e it is possi le to

dete i e iti al JI, a easu e of f a tu e tough ess, o e t it to pla e st ai f a tu e tough ess KI, a d e if a k sig ifi a e i espe t to ittle f a tu e. The o plete J–R u e is e e o e useful, e a li g dete i atio of st ess le el fo i itiatio of sta le a k g o th, i o i atio ith C a k D i i g Fo es CDF [ ].

As a e a ple of this p o edu e, the J–R u e o tai ed fo the heat-affe ted-zo e HA) is p ese ted i Fig. , a d applied to the CDFs diag a to assess st u tu al i teg it fo a ked sto age ta k, as sho i Fig. .

Figu e . J–R u e a d dete i ed alue of JI, fo spe i e

i HAZ [ ].

O e a see f o Fig. the iti al poi t that the a k a g o f o . . × up to

. i sta le a e u de the p essu e MPa % of ield st e gth . O e a k has ea hed the iti al alue, o ditio s fo u sta le a k g o th, i.e., ittle f a tu e, a e fulfilled. It is e i po ta t to oti e that su h a s e a io is also possi le i eal p es-su e essel, espe iall if a i u st ess app oa hes the Yield “t ess, hi h is t pi al situatio du i g ate

p oof test. F o Fig. , o e a see that st esses less tha % of ield st e gth ill ot p o oke a k g o th. Usi g this e a ple, o e a thi k of situatio i hi h the desig st ess is safel elo the iti al o e, let sa % of ield st e gth, ut % of additio al ate p oof st ess ill ot e, si e it ould ea h % of ield st e gth.

Figu e . St u tu al i teg it assess e t fo sto age ta k [ ].

Leakage of large spherical storage ta k [ , ]

E pe i e tal a d u e i al a al sis of eld e ts f a tu e eha io is pe fo ed to assess the st u tu al i teg it of sphe i al sto age ta ks i Ma edo ia, [ , ]. The a al sis as pe fo ed o t o sphe i al sto age ta ks fo a o ia sto age olu e , dia ete D = a d all thi k ess t = , Fig. . The ope ati g p essu e as p = . a a d p oof test p essu e p = a as applied i a d togethe ith NDT. The ta ks ha e ee o s-t u s-ted i usi g i oallo ed steel DIN “t.E ,

ield st e gth Rp . = MPa, ulti ate te sile st e gth R = MPa, elo gatio A = % , elded ele t i a p o edu es ith asi o su a les.

Figu e . Sphe i al p essu e essels i Ma edo ia [ ].

joi ts. The last o e, i o i atio ith fluo es e t light, tu ed out to e the ost effi ie t fo dete tio of su fa e a d s all su su fa e a ks. A la ge u e of t a s e se a ks i eld etal a d lo gitudi al a ks i HA) alo g fusio li e of i e elded joi ts ha e ee dete ted, like o e sho i Fig. [ ]. The lo gitudi al a ks e e o side ed as o e da ge ous due to thei size highest le gth up to , depth up to . a d positio . The a ks e e aused i p ope eldi g, esidual st esses effe t a d st ess o osio due to hostile e i o e t [ ].

Figu e . C a ks alo g fusio li e [ ].

Fo detailed e a i atio te sile spe i e s idth W = , thi k ess B = , le gth L =

e e a hi ed out of the spa e t ial elded plate

× .I additio , plates ×

e e ut out f o oth ta ks to assess a k sig ifi a e a d st u tu al i teg it , usi g spe i e fo he -i al a al s-is, e ha -i al p ope t-ies a d etallog aph-i i estigatio .

F a tu e e ha i s testi g fo dete i atio of a k esista e i the fo of J–R u es a d iti al J i teg al alue, JI, as pe fo ed usi g te sile, si gle edge ot hed spe i e s. C a ks i spe i e s had ee p odu ed ele t i al dis ha gi g p o edu e, si e sta da d fatigue p o edu e it as ot possi le to lo ate the a k tip i the e a o HA) egio s fi e g ai – FGHA) o oa se g ai – CGHA) . To p odu e e sha p a k tip adius less tha . , Fig. the a pe age of A had ee applied.

O e agai the HA) is the ost iti al egio [ ], so its J–R u e as plotted agai st CDFs to defi e i sta ilit iti al poi t, as the ta ge t poi t of o

es-po di g CDFs, Fig. . Co side i g the spe i e ith la gest lo gitudi al a k alo g fusio li e,

lo g a d = . deep, ith the atio /h = . fo thi k ess h = , the iti al p essu e fo u sta le a k p opagatio ea hed . a , Fig. , a o e p es i ed p oof test p essu e, a , p o i g safet of p essu e essel a d its st u tu al i teg it . A ho , o e agai it is eas to thi k a out situatio i hi h the p oof test shifts the iti al poi t i to the u safe

egio .

Figu e . C a k tip o tai ed ele t o-e osio [ ].

Leakage of feed ater heater [ , ]

O e of the f e ue t p o le s i a o ia o e te s is the leakage i the tu etotu esheet o -e tio , ausi g failu -e of f-e-ed at-e h-eat-e o po-e ts. “u h a p o lpo-e o u po-ed i thpo-e p odu tio of a o ia i the he i al i dust ial pla t HIP i Pa če o [ , ]. I -se i e i spe tio e ealed leakage i se e al tu e-to-tu esheet joi ts of the feed ate heate , e ui i g ot o l epai , ut also edesig . The o igi al joi t desig o sisted of tu es olli g i to tu esheet a d thei e ha i al e pa sio Fig. , o side i g o l the seali g, a d egle ti g the al a d e ha i al loads. Afte a sho t se i e ti e, leak-age o u ed due to displa e e ts of tu es i the tu esheet, aused the al a d e ha i al o e -load. To p e e t the leakage, the tu e-to-tu esheet joi ts e e edesig ed a d the heate epai ed.

The heade a d tu esheet a e oth ade of a o steel, a d the tu es of a allo ed, C / Mo steel. O i-gi al desig of tu e-to-tu esheet o e tio s e ui ed a p essed joi t alo g % of sheet thi k ess

0 100 200 300 400 500 600 700 800

0 0.2 0.4c/h0.6 0.8 1

J

[N

/mm]

5.13 bar 7.7 bar 10.26 bar 12.8 bar 14.8 bar 17.95 bar 20.5 bar 23.1 bar 25.6 bar 28.21 bar 30.8 bar 33.3 bar JR

a d p o ided seali g i the i itial ope ati g stage. Joi ts e e pe fo ed olli g tu es i to the tu e-sheet, follo ed e ha i all e pa di g. Ne desig i t odu ed eldi g the tu e-to-tu esheet o e tio at all tu e e ds i additio to the fo e desig that e ui ed o l olli g a d e ha i al e pa sio [ ]. The a epted e tu e-to-tu esheet joi t desig ith additio al eldi g is p ese ted i Fig. . It is pe -fo ed appl i g additio al su fa i g ith a soft la e , usi g I o el o su a le.

Figu e . Desig of plate p epa atio a d di e sio s of sa ple fo eldi g p o edu e ualifi atio ith tu e dist i utio [ ].

Nu erical odels a d results of a alysis [ ]

Th ee diffe e t odels ha e ee de eloped fo u e i al a al sis. The ate heate is odeled fi st i

o de to defi e the state efo e the epai . Mai o -po e ts of the heate li d i al a tle, tu esheet a d ei fo e e ts a e odeled as plates, as

des-i ed des-i o e detades-ils des-i [ ]. I thdes-is odel o l se e al tu es a e i ol ed, i fo of ea s, defi i g eha io of all tu es [ ]. Dist i utio of displa e e ts due to i e p essu e a d the al loadi g of the heate is sho i Fig. . The a i al displa e e t of the heate as . , e a li g to o lude that tu e-sheet defo atio allo s fo the heate epai .

f a = .

Figu e . Dist i utio of displa e e ts o the heate odel [ ].

The e ha i al a d the al displa e e ts e e al ulated sepa atel i the se o d odel i o de to o side thei i di idual effe ts, si e it as ot possi le to sepa ate the i total displa e e ts s he e. “t ess i te sities a e gi e i Ta le .

The a al sis of st ess dist i utio e ealed that a i u st ess o espo ds ell to the hoop st ess σt = pR/t; p – p essu e, R – i e adius, t – all thi

k-ess . The uppe side of tu esheet i positio of tu e eldi g is e posed to te sio , that ould e i o -e i-e t fo s-eali g -et -e-e tu -e a d tu -esh-e-et, ak-i g ak-it the ost p o a le ause of leakage. Both a ak- i-u st esses, i a tle . MPa a d i tu esheet

. MPa a e ell elo ield st e gth. A ho , te sile st ess i tu esheet is i o e ie t fo tu es seali g, o t i uti g to the leakage.

The thi d odel ep ese ts uppe heate pa t, as ge e ated fo the a al sis of lo al heati g i elded

Figu e . O igi al desig of tu e-to-tu esheet o e tio [ ].

Ta le . St ess dist i utio i adial a d hoop di e tio s i the egio of uppe tu esheet, [ ]

“t ess o po e ts Co t i utio to adial st ess MPa f o Co t i utio to hoop st ess MPa f o

Positio P essu e Te pe atu e Total P essu e Te pe atu e Total

Ma tle, e ote of tu esheet, up ± ≈ ± ± ≈ ±

Ma tle, lose to tu esheet, up  ±   ± 

Tu esheet – e t e  – ± ±  – ± ±

Tu esheet – lose to a tle  ± ± ± – . ± . ±

Ma tle, lose to tu esheet, do     .   .

egio du i g the post- eld heat t eat e t. Model of odes, defi i g solid fi ite ele e ts fo su st u tu es of a tle, tu esheet a d tu es [ ], as ell as the D odel of sele ted heate seg e t a d its p oje tio s.

A p og a fo o statio a o li ea heat o -du tio as used to o tai te pe atu e fields -du i g heat t eat e t. Heat sou e of kW pe ete of pe i ete is si ulated o the uppe a tle pa t, ased o e pe ie e [ ]. Ph si al p ope ties of steel a e used, o espo di g to e pe ted heati g te pe atu e. Te pe atu e field is al ulated e e i up to h,

he °C is a hie ed, as e ui ed Fig. .

Tubesheet

Central tube Mantle wall

Figu e . Te pe atu e field si ulati g post- eld heat t eat e t [ ].

The al ulatio as pe fo ed usi g the se o d odel, ut fo a diffe e t the al field. Displa e e ts a d st esses e e al ulated fo gi e te pe atu e field a d thei dist i utio is sho i Fig. . Results i di ate lo st ess le el, e a li g to o lude that the heate is fit fo se i e.

The efo e, the leakage p o le as sol ed addi-tio al eldi g usi g auste iti ele t ode at tu e e ds a d tu esheet, e ui i g utti g the heate heade a d its eldi g afte epai eldi g of tu e e ds a d tu e-sheet. It has ee p o ed that su fa i g the tu esheet

ith auste iti ele t odes as e efi ial fo its st ess state, i t odu i g o p essi e st ess. “t ess state du i g post- eld heat t eat e t tu esheet a d

a tle as a epta le, si e the a i al st ess i the edesig ed heate as ello Yield “t e gth.

CONCLUSIONS

Based o the esults a d dis ussio p ese ted i this pape o e a o lude the follo i g:

•F a tu e e ha i s p i iples, applied fo st u

-tu al i teg it assess e t, p o ide ette app oa h fo safet , e ause a e aluate the sig ifi a e of a k p ese e, p edi t a k g o th a d p o ide fit essfo -se i e, as e i po ta t e gi ee i g tool. It a e used e e fo o -e isti g a ks i the desig phase of p essu e e uip e t.

•Che i al e gi ee s, i ha ge fo p essu e e

uip-e t, should luip-ea ho to li uip-e ith a ks, athuip-e tha to assu e that eld e ts a e defe t-f ee a d p o oke thei g o th, ith u e essa p oof testi g.

Ack o ledge e ts

We a k o ledge the suppo t of Mi ist fo Edu-atio , “ ie e a d Te h ologi al De elop e t th ough the p oje ts TR a d TR .

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IZVOD

INDUSTRIJSKA BEZBEDNOST POSUDA POD PRITISKOM – TAČKA GLEDIŠTA INTEGRITETA KONSTRUKCIJA

Aleksa da “ed ak , Mahdi Algool , “ eza a Ki i , B a isla Rakiče ić , Ra o Bakić Maši ski fakultet U i e ziteta u Beog adu, Beog ad, S ija

U i e zitet u Si tu, Si t, Li ija

I o a io i e ta Maši skog Fakulteta, Beog ad, S ija Teh ička škola,Tuti , S ija

P egled i ad

O aj ad p ikazuje azličite aspekte p o le a sigu ost posuda pod p itisko , sa fokuso a he ijsku i dust iju. O ez eđe je k aliteta, uključujući p i e u PED / , je p o a alizi a o, zati je dat k atak os t a p o e u izika, a detalj ije p ikaza p istup zas o a a p o e i i teg iteta ko st uk ije, koji je ilust o a opiso t i p i e a iz p akse. P i p i e se od osi a p o u i a je za a e ih spoje a ili d ič og eze oa a za CO , kod koga su p iključ i ap a -lje i od auste it og čelika, dok je o otač od fe it og, iskolegi a og čelika po i-še e č stoće. D ugi p i e se od osi a elike sfe e eze oa e za a o ijak, ap a lje e takođe od iskolegi a og čelika po iše e č stoće, za koje je p aksa pokazala da su osetlji i a asta ak i ast p sli a, što dolazi do iz ažaja pose o p i epa atu o za a i a ju i hlad o p o o p itisku. U t eće p i e u je a alizi a p o le p o u i a ja a spoju e i i e e ploče a ulazu u zag ejač ode u HIP Azota a, što je zahte alo eko st uk iju i pop a ku dodat i za a i-a je e i. Postupi-ak pop i-a ke je p ed ideo ise i-a je gli-a e zi-ag eji-ači-a po zi-a i- a-e o spoju, p ip a-e u i za a i a ja-e a-e i za a-e u ploču, i po o o za a i a ja-e gla e. Kao aža zaključak koji sledi iz o ih p i e a, a odi se ko t a e za u ezi hlad e p o e p itisko , koja ože da ap a iti iše štete ego ko isti, pose o kod čelika osetlji ih a p sli e.

Ključ e eči: Bez ed ost posuda pod p i-tisko • I teg itet ko st uk ija • P o i