guide for refinery inspection

8/12/2019 Guide for Refinery Inspection

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LIBRARY

AMERICAN PETROLEUM INSTITUTE

Guide for Inspection of

Refinery Equipment

Chapter I I-Conditions CausingDeterioration or Failures

Refining Department

SECOND EDITION, 1973

COPY PROIDED FOR

!I"#ORIC$% P&RPO"E" O'%Y

This publicatin is !istribute! "as is" an! is nlnger a current publicatin f the #merican$etrleum Institute% It is furnishe! slel& frhistric purpses an! sme r all f theinfrmatin ma& be ut!ate!% #$I '#(ES NO)#RR#NT* O+ #N* (IND, E$RESS ORI'$-IED, #ND S$ECI+IC#--* T.ERE IS NO)#RR#NT* O+ 'ERC.#NT#/I-IT* OR+ITNESS +OR # $#RTIC0-#R ISS0E%

OFFICIAL PUBLICATION

REG. U.S. PATENT OFFICE

Repr!uce! /& -O/#-ENGINEERING DOCUMENTSWith The Permission Of API

0n!er R&11t& #2reement

pri4ht #merican $etrleum Institute

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COPY PROVIDED FDR

!("#GRIC$% P&RPO"E" ONLY

Nothin !ont"ine# in "n$ API %&'(i!"tion is to 'e !onstr&e# "s r"ntin "n$ riht) '$im%(i!"tion or other*ise) for the m"n&f"!t&re) s"(e) or &se in !onne!tion *ith "n$

metho#) "%%"r"t&s) or %ro#&!t !o+ere# '$ (etters %"tent) nor "s ins&rin "n$one ""inst

(i"'i(it$ for infrinement of (etters %"tent.

API %&'(i!"tions m"$ 'e &se# '$ "n$one #esirin to #o so) "n# e+er$ effort h"s 'een

m"#e '$ the Instit&te to "ss&re the "!!&r"!$ "n# re(i"'i(it$ of the #"t" !ont"ine# in them.

,o*e+er) the Instit&te m"-es no re%resent"tion) *"rr"nt$) or &"r"ntee in !onne!tion

*ith API %&'(i!"tions "n# here'$ e%ress($ #is!("ims "n$ (i"'i(it$ or res%onsi'i(it$ for

(oss or #"m"e res&(tin from their &se/ for "n$ +io("tion of "n$ fe#er"() st"te) or

m&ni!i%"( re&("tion *ith *hi!h "n API %&'(i!"tion m"$ !onf(i!t/ or for the infrinement

of "n$ %"tent res&(tin from the &se of "n API %&'(i!"tion.

Co%$riht0 1234 Ameri!"n Petro(e&m Instit&te


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PREFACE

This !h"%ter is one of " series *hi!h m"-e &% the m"n&"() Guide for Inspection ofRefinery Equipment. It is '"se# on the "!!&m&("te# -no*(e#e "n# e%erien!e ofenineers of the %etro(e&m in#&str$. A(( &sers "re in+ite# to s&'mit s&este# re+isions tothe #ire!tor of the Refinin De%"rtment) Ameri!"n Petro(e&m Instit&te) 1556 L Street)N.W.) W"shinton) D.C. 56667.

The inform"tion !ont"ine# in this %&'(i!"tion h"s 'een "rr"ne# in its %resent form "s" me"ns of f"!i(it"tin !ontin&it$ of %resent"tion "n# !on+enien!e of referen!e. It #oesnot !onstit&te) "n# sho&(# not 'e !onstr&e# to 'e) " !o#e of r&(es) re&("tions) orminim&m s"fe %r"!ti!es. It is not inten#e# th"t the %r"!ti!es #es!ri'e# in this %&'(i!"tions&%%("nt %r"!ti!es th"t h"+e %ro+en s"tisf"!tor$. Nor is it inten#e# th"t this %&'(i!"tion

#is!o&r"e inno+"tion "n# oriin"(it$ in the ins%e!tion of refineries. Users of the%&'(i!"tion "re remin#e# th"t no 'oo- or m"n&"( is " s&'stit&te for the 8ment of "res%onsi'(e enineer.The Guide for Inspection of Refinery Equipment is s&'#i+i#e# "s fo((o*s9

Ch"%ter ICh"%ter IICh"%ter IIICh"%ter I:Ch"%ter :Ch"%ter :ICh"%ter :IICh"%ter :IIICh"%ter I;Ch"%ter ;Ch"%ter ;ICh"%ter ;IICh"%ter ;IIICh"%ter ;I:Ch"%ter ;:Ch"%ter ;:ICh"%ter ;:IICh"%ter ;:III

Ch"%ter ;I;Ch"%ter ;;A%%en#i




Intro#&!tionCon#itions C"&sin Deterior"tion or F"i(&resGener"( Pre(imin"r$ "n# Pre%"r"tor$ Wor-Ins%e!tion Too(s

Pre%"r"tion of E ,e"tE!h"ners) Con#ensers) "n# Coo(er Boes Dire!t?Fire# Boi(ers "n# A&i(i"r$ E


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TABLE OF CONTENTS

PAGE

561 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

561.61 Re("tionshi% of the Ins%e!tion Pro'(em to C"&ses of Deterior"tion. . 3561.65 S&mm"r$ of C"&ses of Deterior"tion. . . . . . . . . . . . . . . . . . . . . . . . . 3565 CORROSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . @565.61 Intro#&!tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . @565.65 Corrosi+e Com%onents of Cre Oi( . . . . . . . . . . . . . . . . . . . . . . . . . 55565.64 Corrosi+e M"teri"(s A##e# to the Pro!ess. . . . . . . . . . . . . . . . . . . . @565.6 En+ironment"( Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53565.67 Corrosion "t ,ih Tem%er"t&res. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41565.6 Im%ort"nt Corrosion Phenomen". . . . . . . . . . . . . . . . . . . . . . . . . . . . 4565.63 Corrosion O!!&rren!es *ith Attem%ts "t Corrosion Contro(. . . . . . . . 6564 EROSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6564.61 Intro#&!tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 564.65Dis!&ssion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 56 EFFECTSOF ,IG, TEMPERATURES. . . . . . . . . . . . . . . . . . . . . . . 4 56.61 ,ih?Tem%er"t&reStrenth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 56.65 Met"((&ri!"( Str&!t&r"(Ch"nes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

56.64 Met"((&ri!"( Chemi!"( Ch"nes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76567 SUBNORMAL AND AMBIENT TEMPERATURE EFFECTS. . . . . 75

567.61 Britt(e Fr"!t&re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7556 E;CESSI:E PRESSURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

56.61 Intro#&!tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7456.65 C"&ses of E!essi+e Press&res. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7456.64 Effe!ts of E!essi+e Press&res. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74563 O:ERLOADING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7563.61 Intro#&!tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

563.65 E+i#en!es of O+er(o"#in........ . . . . . . . . . . . . . . . . . . . . . . . . . . 756@ EART,UAES AND EART, SETTLEMENTS.. . . . . . . . . . . . . . 7

562 MEC,ANICAL AND WIND DAMAGE. . . . . . . . . . . . . . . . . . . . . . . . 7562.61 Intro#&!tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

562.65 E"m%(es of Me!h"ni!"( "n# Win# D"m"e. . . . . . . . . . . . . . . . . . . . 7562.64 C"&ses of Me!h"ni!"( "n# Win# D"m"e. . . . . . . . . . . . . . . . . . . . . 7@

516 FAULTY MATERIAL AND EUIPMENT..................... 6516.61 Intro#&!tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

516.65 Sit&"tions Le"#in to Im%ro%er Se(e!tion of M"teri"( "n# E13 >


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COPY PRO:IDED +OR,ISTORICAL $0R$OSES ONLY

GUIDE FOR INSPECTION OF REFINERY EUIPMENT

C,APTER II

CONDITIONS CAUSING DETERIORATION OR FAILURES

561 GENERAL

561.61 Re("tionshi% of the Ins%e!tion Pro'(em to

C"&ses of Deterior"tion

Pr"!ti!"(($ "(( refiner$ e


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@

CONDITIONS CAUSING DETERIORATION ORFAILURES

piping "n# +esse(s th"t o%er"te &n#er !$!(in !on#itions*i(( often %ermit re%"irs or re%("!ement 'efore f"i(&re.Lo!"tions *here met"(s h"+in #ifferent therm"( !oeffi?!ients of e%"nsion "re 8oine# '$ *e(#in "re oftens&s!e%ti'(e to therm"( f"ti&e) "n# !r"!-s sometimes st"rt*hen e


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1. 1.

CORROSION

2

The "forementione# !orrosi+e !om%onents in !re oi(first 'e!ome "%%"rent in the %rim"r$ %ro!essin &nit of therefiner$) the !re %i%e sti(() or the #isti(("tion to*ers. Inener"() "s the !re oi( f(o*s from t"n-"e thro&h the!re #isti(("tion &nit) one or more of these !hemi!"(!om%onents !"n !"&se +"rio&s t$%es of !orrosion %ro'(ems.Tem%er"t&re (e+e(s !h"ne) the !om%onents se%"r"te orform ne* ones) "n# the en+ironment for !orrosion !h"nesin e"!h se!tion of the #isti(("tion &nit. For e"m%(e) thee. So#i&m "n#%ot"ssi&m !h(ori#es #o not h$#ro($e "n# !onse?;=;>13 >


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CORROSION 11

FIG. 4?T&'es Remo+e# From the Con#enser B&n#(e Sho*n in Fi. 5.

These se+ere($ !orro#e# "#mir"(t$ t&'es *ere (o!"te# 8&st &n#er the !on#enser in(et.

" *"ter #e* %oint is re"!he#. If s&!h !ontro( is in"#e


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irl

I

N 96 6

NN9N

6 BN

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0 ,%%%% ,,,,%%

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15


immerse# or *"she# *ith (i on the iron!h(ori#e) to %ro#&!e iron s&(fi#e =FeS> *ith there"%%e"r"n!e of h$#ro!h(ori! "!i#. The #o&'(e "rro*sin#i!"te th"t the !hemi!"( re"!tion m"$ %ro!ee# in either#ire!tion #e%en#in on s%e!ifi! !on#itions.

One metho# for re#&!in !orrosion '$ s"(ts "n# h$?#ro!h(ori! "!i#) *hi!h is ener"te# '$ the h$#ro($sis ofs"(ts) is the e(imin"tion of the 'rine from the !re oi(.Most of the %ro#&!in fie(#s en#e"+or to #o this '$sett(in. This) of !o&rse) "!!om%(ishes the remo+"( of 'oth*"ter "n# s"(t) *hi!h "re the !orro#ents. In some !"ses)"#sor%tion s$stems "re em%(o$e# to #r$ the !re oi(

f&rther. In ener"() these "re the on($ ste%s t"-en to re#&!e!orrosi+e !onstit&ents %rior to the time the !re oi( entersthe refiner$.

E+en in the !"ses *here 8i!io&s !ontro( of 'rine in!re oi( is eer!ise# in the %ro#&!in fie(#s) it is fo&n#th"t !onsi#er"'(e s"(t is ener"(($ !ont"ine# in the !re "sit is re!ei+e# in the refiner$. The s"(t !ontent is ener"(($hiher in the *inter 'e!"&se oi(?fie(# 'rine sett(ers "re (esseffe!ti+e "t (o* tem%er"t&res.

Most mo#em refineries o%er"te #es"(tin e13 > Corrosion of this t$%e o!!&rs in !oneroof stor"et"n-s in the %resen!e of moist&re "n# o$en u "n# h"s'een -no*n to %enetr"te 1?in.thi!- t"n- roofs "n#&%%er she(( rins in 5 to 4 $e"rs. S&ffi!ient o$en is"(*"$s "+"i("'(e for the !orrosion to %ro!ee#) "n# moist&re!on#enses on the roof "n# she((. In +ie* of the f"!t th"tmoist&re is nee#e# for this !orrosion to t"-e %("!e)!orrosion of this t$%e is ener"(($ more se+ere on the sh"#$si#e of the t"n- in *"rm !(im"tes. In !oo(er !(im"tes)tem%er"t&re !on#itions m"$ 'e s&!h th"t !on#ens"tiono!!&rs "ro&n# the entire t"n-) "n# the !orrosion r"te *i(( 'ehihest on the hottest =s&nn$> si#e. ,$#roen s&(fi#e "(so!"&ses !orrosion '$ the form"tion of iron s&(fi#e s!"(e inthe o+erhe"# s$stems of #isti(("tion e


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S0-+0R $ERCENT DETER'INED /* H0#RTJ T0/E 'ET.OD

FIG. ?Corrosion Me"s&re# "s " F&n!tion of Tot"( S&(f&r Content of :"rio&s Cre Oi(s.




fr Resale, >?;=;>13 >


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1

CONDITIONS CAUSING DETERIORATION K FAILURES

en s&(fi#e "re h$#roen '(isterin "n# h$#roen em?'ritt(ement. These "tt"!-s h"+e 'een serio&s in the "s?!om%ression "n# fr"!tion"tin e forme# "s " %ro#&!t ofthe !orrosion re?

Re%ro#&!e# from Safety in $etroleum Refinin% and Related Industries& '$Geore Armiste"#) r.) !o%$riht 1276. Re%ro#&!e# '$ %ermission of ohn G.Simmon#s "n# Com%"n$) In!.

FIG. 7?A%%e"r"n!e of ,$#roen B(isters on Eterior of "

:esse( She((.




"!tion enters the met"(. If +oi#s s&!h "s ("min"tions ornonmet"((i! in!(&sions =s(") et!.> "re %resent in the stee()h$#roen !o((e!ts in them "n# forms mo(e!&("r h$#roen.Mo(e!&("r h$#roen =,5> !"nnot %"ss thro&h the stee(/therefore) it rem"ins in the +oi#. As more mo(e!&("rh$#roen forms) %ress&re '&i(#s &% "n# e+ent&"(($ !"&sesthe stee( to '(ister or r&%t&re. Fi. 7 thro&h 2 i((&str"te

h$#roen '(isters. C(e"n stee( *itho&t in!(&sions !"nem'ritt(e "n# !r"!- "t *e(#s 1"n# stress r"isers *itho&t'(isters 'ein %resent.

c. 'i%h#"emperature Sulfidic orrosion: Tem%er"t&re%("$s "n im%ort"nt %"rt in !orrosion '$ h$#roen s&(fi#e.KIn the "'sen!e of *"ter) !orrosion is not serio&s "t (o*tem%er"t&res) "n# " met"( tem%er"t&re "'o+e 76 F isne!ess"r$ for hih?tem%er"t&re s&(fi#i! !orrosion to o!!&r"t "n "!!e(er"te# r"te. In refineries th"t %ro!ess s*eet !reoi(s) on($ s(iht !orrosion of

Re%ro#&!e# fromLo! "emperature 'ydro%en (listerin%#(ayto!nRefinery&!o%$riht 1271. Re%ro#&!e# '$ %ermission of Eon Com%"n$) U.S.A.

FIG. ?Cross?se!tion of " L"re ,$#roen B(ister in " Press&re

:esse( She((.


fr Resale, >?;=;>13 >


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CORROSION 17

Re%ro#&!e# from Lo! "emperature 'ydro%en (listerin%#(ayto!nRefinery& !o%$riht 1271. Re%ro#&!e# '$ %ermission of Eon Com%"n$)U.S.A.

FIG. 3?,$#roen B(isters in " Press&re :esse( She((.

Note th"t the ("rest '(ister is "%%roim"te($ @ in. in

#i"meter.

!"r'on stee( m"$ 'e e%e!te#) *ith !orrosion r"tes of"%%roim"te($ 6.61 in. %er $e"r. C"r'on stee( f&rn"!e t&'esnorm"(($ i+e ser+i!e (i+es of more th"n fi+e $e"rs ins*eet !re ser+i!e "n# +er$ (itt(e !orrosion is e%erien!e#in the she((s of #isti(("tion to*ers) "(tho&h) e+en *ith (o*r"tes) thin intern"( e


17/50

1


Re%ro#&!e# fromLo! "emperature 'ydro%en (listerin%#(ayto!n Refinery& !o%$riht 1271. Re%ro#&!e# '$ %ermission of Eon Com%"n$) U.S.A.

FIG. 2?C(oseUP :ie* of the B(isters Sho*n in Fi. @.

Bottom Sement

Re%ro#&!e# from Safery in $etroleum Refinin% and Related Industries&'$ Geore Armiste"#) r.) !o%$riht 1276. Re%ro#&!e# '$ %ermission of ohnG. Simmon#s "n# Com%"n$) In!.

FIG. IO?S%e!imen of " Corro#e# Cre?Oi( Pi%e Sti(( R"#i"nt Se!tion T&'e Th"t E+ent&"(($ F"i(e#) Fee#sto!-

*"s " hih?s&(f&r Ne* Mei!o !re oi(.




fr Resale, >?;=;>13 >


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CONDITIONS CAUSING DETERIORATION OR FAILURES 13

Re%ro#&!e# from Safety in $etroleum Refinin% and Related In#dustries& '$ Geore Armiste"#) r.) !o%$riht 1276. Re%ro#&!e# '$

%ermission of ohn G. Simmon#s "n# Com%"n$) In!.

FIG. 11?Cross?Se!tion of " R"#i"nt T&'e in Corrosi+eCre?Oi( Ser+i!e.

Note the hih #eree of e!!entri! !orrosion. The thin si#e ofthe t&'e *"s net to the fire.

(o!"( !oo(in s&!h "s "t no(es) %("tform s&%%orts) "n# the(i-e. Corrosion t"-es %("!e) ho*e+er) *hen tem%er"t&res"re re#&!e# 'e(o* 266 F) "n# in m"n$ !"ses *here 'oth(i"re %res?


fr Resale, >?;=;>13 >


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1@


ent($ in *i#e &se %"rti"(($ 'e!"&se the$ !"n h"+e " &sef&((ife) "n# !"re #&rin sh&t#o*ns is not re


20/50

CORROSION 19

re"!he# &nti( the !hromi&m !ontent is "'o&t 15 %er!ent)'&t the 5 to 2 %er!ent !hromi&m stee(s !o&(# 'e &se# forshort?term (ife if "n$ iron !"n 'e to(er"te# in the!on#ens"te.

A(tho&h T$%e 46 st"in(ess stee( is *i#e($ &se# "n#h"s 'een fo&n# most s"tisf"!tor+ in *et !"r'on #ioi#e

en+ironments of h$#roen %("nts) sensitie# st"in(essstee(s =!hromi&m !"r'i#es %re!i%it"te# "t r"in 'o&n#"ries>h"+e 'een fo&n# to !r"!- in the he"t?"ffe!te# ones. )Liht($ sensitie# "re"s sho* the interr"n&("r "tt"!- of*e"- "!i#s) *hi(e hih($ sensitie# "re"s h"+einterr"n&("r "tt"!- "n# h"+e f"i(e# *hen o+erstresse# insome re%orte# !"ses. P("sti! !o"tin sho&(# 'e in!(e# inthe (ist of stress?resist"nt m"teri"(s. Both e%oies "n#%heno(i!?e%oies h"+e 'een &se# "s +esse( !o"tins intem%er"t&res "s hih "s 466 F to 476 F.

565.657 DISSOL:ED O;YGEN AND WATER9 Whi(emoist&re "n# o$en in stor"e t"n-s m"$ 'e intro#&!e#*ith the oi() m&!h of it is #r"*n into the t"n-s '$

're"thin #&rin tem%er"t&re !h"nes "n# %&m%ins. The"mo&nt of moist&re "n# o$en) "n# !onse


21/50

2

0


FIG. 17?Se+ere :"%or?S%"!e Corrosion of Cone?Roof T"n-Co(&mn.

these "re"s &n#ero more *ettin "n# #r$in th"n others)Corrosion of the 'ottom "n# 'ottom she(( rin of t"n-sh"n#(in (iht sto!-s is ener"(($ not se+ere &n(ess "'ottom ("$er of !orrosi+e *"ter is !"rrie# in the t"n-. Fi.1 thro&h 12 sho* !orrosion in (iht?sto!- stor"e t"n-s.

Corrosion of (iht?sto!- stor"e t"n-s is ener"(($ of the%it t$%e "n# is 'e(ie+e# to 'e the res&(t of entr"ine# "n##isso(+e# *"ter "n# of #isso(+e# o$en) the !orrosion'ein %ro%ortion"( to the *"ter "n# o$en !ontent. Ther"te of !orrosion m"$ "(so 'e "!!e(er"te# '$ tr"!es of other

!orro#ents in the (iht oi(s.L"'or"tor$ sties of this t$%e of !orrosion in#i!"te th"t(o'&(es of *"ter form on the met"() "n# !orrosion o!!&rs&n#er e"!h #ro%(et in the form of " %it. The %its "re son&mero&s) ho*e+er) th"t !orrosion "%%e"rs to 'e ener"(.The me!h"nism of !orrosion is 'e(ie+e# to 'e the initi"(!on+ersion of iron to ferro&s h$#roi#e) *hi!h iss&'se?;=;>13 >


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CORROSION

51

FIG. 13?C(ose?&% of Corrosion of the Co(&mn Sho*n in Fi.1.

Note (oose he"+$ s!"(e.

ent. The fin"( resi#&e is ener"(($ fo&n# to 'e ferri! oi#e)" re# r&st.

In "(( !"ses of stor"e t"n- !orrosion) it sho&(# 'ere!onie# th"t mi(( s!"(e *i(( "!!e(er"te "tt"!-) %"r?ti!&("r($ on the 'ottom of stor"e t"n-s. Cr"!-s in mi((s!"(e form "no#i! "re"s *ith the rem"inin mi(( s!"(e 'einhih($ !"tho#i!.




565.65 ORGANIC A!ms9 Or"ni! "!i#s "re not +er$!orrosi+e "t (o* tem%er"t&res. At their 'oi(intem%er"t&res) ho*e+er) these "!i#s "re +er$ !orrosi+e) themost se+ere form of *hi!h ener"(($ o!!&rs &%on!on#ens"tion. Un#er these !on#itions) !orrosion r"tes "shih "s 6.47 in. %er $e"r h"+e 'een re%orte# on !"r'onstee(. 14The r"te #e!re"ses r"%i#($ *ith tem%er"t&re) "n# is

on($ 6.657 in. %er $e"r "t 56 F 'e(o* the 'oi(in %oint. The!orro#e# s&rf"!e of !"r'on stee( is +er$ smooth) "n# met"((osses "re not "%%"rent from +is&"( ins%e!tion.

C"(iforni" "s%h"(ti! !re oi(s !ont"in n"%htheni! "!i#s)"n# these "!i#s m"$ 'e +er$ !orrosi+e "t hihtem%er"t&res.+ L" The (o*er mo(e!&("r?*eiht "!i#s from(iht (&'ri!"tin #isti(("tes "%%e"r to 'e more !orrosi+eth"n the hiher mo(e!&("r?*eiht "!i#s from he"+$(&'ri!"tin #isti(("tes. These or"ni! "!i#s "re +er$!orrosi+e "'o+e 766 F) "n# the re"!tion is most se+ere inthe (i is norm"(($ +er$ resist"nt to n"%htheni! "!i#.,o*e+er) in "re"s of hih +e(o!it$ or im%inement) T$%e41 st"in(ess stee( h"s 'een fo&n# to 'e "tt"!-e# 1i in. to*s in. %er $e"r. St"in(ess A((o$ 56 "n# "(&min&m =ifse!&re($ he(# in %("!e> "re resist"nt.

Or"ni! "!i#s) s&!h "s "!eti!) %ro%ioni!) %"(miti!)ste"ri!) "n# o(ei!) re"!t *ith "(&min&m "t " +er$ (o*!orrosion r"te "t 566 F/ '&t "t 736 F the re"!tion is +er$r"%i#.K The re"!tion r"te "t hih tem%er"t&res is "%%"rent($in#e%en#ent of o$en !on!entr"tion) '&t is re"t($inf(&en!e# '$ the %resen!e of *"ter. The "##ition of 6.67%er!ent of *"ter %r"!ti!"(($ inhi'its "(( !orrosion "s " res&(tof form"tion of " st"'(e oi#e fi(m/ *here"s in the"nh$#ro&s =#r$> st"te) the r"te of !orrosion is +er$ r"%i#

ne"r the 'oi(in %oint of the "!i#s.

565.653 NITROGEN COMPOUNDS9 Nitroen !om?%o&n#s in !re oi( "(one #o not !ontri'&te to " !orrosion%ro'(em. ,o*e+er) "fter #e!om%osition in !"t"($ti!!r"!-in) the "mmoni" "n# !$"ni#es forme# !ontri'&te to%ro'(ems #is!&sse# in e"r(ier %"r"r"%hs) s&!h "s hih %,for h$#roen '(isterin in *hi!h the !$"ni#es remo+e the%rote!ti+e %o($s&(fi#e s!"(e. In h$#ro!r"!-in) the"mmoni" "n# h$#roen s&(fi#e form "mmoni&mh$#ros&(fi#e *hi!h !"&ses serio&s !orrosion %ro'(ems "ttem%er"t&res 'e(o* the *"ter #e* %oint. A(so) the%resen!e of "mmoni&m h$#ros&(fi#e in so&r *"terstri%%in s$stems is 'e!omin " *i#es%re"# %ro'(em.

Ammoni" forme# in "n$ !r"!-in or h$#ro!r"!-in &nit(imits the &se of "n$ !o%%er "((o$s in %ro#&!t !oo(ers'e!"&se of their "tt"!- in "re"s *here %rote!ti+e s!"(e m"$h"+e s%"((e#. Both "mmoni" "n# !$"ni#es "tt"!- !o%%er"n# 'r"sses ="n# %ro'"'($ other !o%%er "((o$s> in " %ittinor *orm?ho(in t$%e "tt"!-. With 'oth !hemi!"(s %resent)there h"+e 'een re%orte# in#i!"tions of re+ers"( of "no#e"n# !"tho#e *here


fr Resale, >?;=;>13 >


23/50

22 CONDITIONS CAUSING DETERIORATION OR FAILURES

FIG. 1@?C(ose?&% of Corrosion on Un#ersi#e of F(o"tin?Roof T"n- in Liht?Sto!- Ser+i!e.

'1.) is in !ont"!t *ith stee() *ith the 'r"ss 'ein!orro#e#. S&!h (o!"tions h"+e 'een *here 'r"ss t&'es %"ssthro&h e!h"ner !ross '"ff(es "n# *here !o%%er "s-ets!ont"!t stee( f(o"tin he"#s "n# t&'e sheets.

Consi#erin so&r!es other th"n e(ements in !re oi()nitroen !om%o&n#s =oi#es of nitroen> !"n form "t hihtem%er"t&res in the f(&e "ses of f&rn"!es from thenitroen in the !om'&stion "ir. These !om%o&n#s !"n 'ehih($ !orrosi+e to stee( if !oo(e# to (o* or "m'ient

tem%er"t&res in the %resen!e of *"ter !on#ens"te. A hih%er!ent"e of e!ess "ir "n# s&(f&r trioi#e in the f(&e "s!"n in!re"se !orrosion "%%re!i"'($ if these "ses "re%ress&rie#. St"in(ess stee( or %("sti! (inins m"$ 'ere


24/50

CORROSION 54

FIG. 12?Corrosion of the To% She(( Rin of " F(o"tin?Roof T"n- in Liht?Sto!- Ser+i!e.

*eiht>) "s " !"t"($st. Tr"!es of "!i#i! m"teri"( in the%ro#&!t "re s!r&''e# o&t '$ me"ns of *"ter) or ne&tr"(ie#'$ !"&sti!) or 'oth. This s!r&''in ste% m"$ not 'e

!om%(ete) so th"t in "(-$("tion &nits it is %ossi'(e to h"+e+er$ hih !on!entr"tions "n# +er$ (o* !on!entr"tions ofs&(f&ri! "!i# %resent. The (o*er !on!entr"tions !ome "s "res&(t of either #ire!t !"rr$o+er into the fr"!tion"tine


25/50


"!i# is "ir free) %"rti!&("r($ in !riti!"( "re"s) mone( !"n 'e&se# o+er " *i#e r"ne of !on!entr"tions "n# tem%er"t&res.Other*ise) the more e%ensi+e m"teri"(s) ,"ste((o$ C or%("tin&m) miht 'e !onsi#ere#. A((o$ 56 !"n %ossi'($ 'e&se# "t "m'ient tem%er"t&res 'e(o* 76 %er!ent!on!entr"tion *ith re"son"'(e (ife. A((o$ 56 sho&(#ener"(($ not 'e &se# "'o+e 137 F for " !on!entr"tion of 17

%er!ent or (ess.b. -lefin#Etraction ,nits: In the etr"!tion of o(efins)s&(f&ri! "!i# is &se# in !on!entr"tions from 7 to 2@%er!ent ='$ *eiht>) the tem%er"t&re +"r$in from"tmos%heri! to 576 F. Be!"&se of the *i#e r"ne of!on!entr"tions "n# tem%er"t&res) !orrosion in these &nitsm"$ 'e +er$ se+ere.

In these o%er"tions) o(efins "re "'sor'e# in s&(f&ri! "!i#of " s&it"'(e !on!entr"tion. The "tt"!- of hot) stron "!i#on !"r'on stee( is &s&"(($ in the form of #ee% %its in "n$!re+i!es or #e"# s%ots in the e?;=;>13 >


26/50

CORROSION

57

ener"(($ &se# on m&(ti%(e?t&'e "ssem'(ies. ,ih?si(i!on!"st?iron he"tin e(ements ehi'it "(most !om%(ete re?sist"n!e to "(( !on!entr"tions of s&(f&ri! "!i#. ,"ste((o$ Dhe"tin e(ements "re +er$ resist"nt to s&(f&ri! "!i#) e!e%tin the r"ne of 77? to 6?%er!ent !on!entr"tion ='$ *eiht>"t 'oi(in tem%er"t&res of the "!i#. At these !on!entr"tions)

!orrosion r"tes +"r$ *i#e($) #e%en#in on the!ont"min"nts th"t "re %resent. Corrosion of ,"ste((o$ Do!!&rs in m"n$ forms. There m"$ 'e " ener"( thinnin ofthe he"ter?e(ement '"rre() "tt"!- of the t&'e "n# !"% oneither si#e of the 8oinin *e(#) #ee% roo+in of the*e(#e# "re"s) "n# Kis("n#K t$%e of !orrosion on 'oth the'"rre( "n# !"%. A se+ere($ !orro#e# ,"ste((o$ D he"tert&'e is sho*n in Fi. 56 "n# 51. Where +"!&&m?t$%e!on!entr"tion is em%(o$e#) the !orrosion of ,"ste((o$ Dt&'es is of the ener"( thinnin t$%e) *hi(e the %ittin "n#roo+in is se+ere *here %ress&re !on!entr"tion is &se#.The %rim"r$ #ifferen!e 'et*een the t*o metho#s =%ress&re"n# +"!&&m> is th"t of tem%er"t&re) the +"!&&m %ro!ess&sin the (o*er tem%er"t&re.

Pi%e &se# to !on+e$ the hot !on!entr"te# s&(f&ri! "!i# to"!i# !oo(ers is &s&"(($ m"#e of !"r'on stee( *ith " (e"# "n#!"r'on (iner. Corrosion in this %i%e is ni() e!e%t "t the8oints *here some ener"( thinnin m"$ o!!&r on thee%ose# (e"# "s-et f"!es.

The she((s of s&(f&ri! "!i# !oo(ers "re ener"(($ !on?str&!te# on the s"me or#er "s the !on!entr"tors. Le"#!oo(in !oi(s "re &se# "t the hiher tem%er"t&res "n#ehi'it ener"( thinnin. C"st iron "n# !"r'on m"$ "(so

FIG. 56??A Se+ere($ Corro#e# ,"ste((o$ D ,e"ter T&'e.

Note ho(e ne"r !"% "t en# of t&'e.




FIG. 51?C(ose?&% of the T&'e Sho*n in Fi. 56.

Note ho* !orrosion h"s !on!entr"te# ne"r the !"% "n# onthe *e(# 'et*een !"% "n# t&'e.

'e &se# for this ser+i!e. P&m%s "n# +"(+es for the hot!on!entr"te# "!i#s "re m"#e from hih?si(i!on !"st iron),"ste((o$ D) or !"r'on. The hih?si(i!on !"st iron "n# the!"r'on ehi'it %oor %h$si!"( %ro%erties) '&t #o not!orro#e. ,"ste((o$ D is "tt"!-e# in the s"me m"nner "s#es!ri'e# for the he"tin e(ements. Where +e(o!ities "re ine!ess of ft %er se!on# "n# the tem%er"t&re is 'e(o* 176F in (o!"tions s&!h "s %&m%s "n# +"(+es) A((o$ 56 st"in(essstee( is often &se#. The !orrosion resist"n!e of this m"teri"(+"ries *ith the #eree of he"t tre"tment) "n# #ee%interr"n&("r et!hin m"$ 'e fo&n# on "(( s&rf"!es e%ose#to the "!i#) "s sho*n in Fi. 55/ ho*e+er) this !on#ition is

not &s&"(($ serio&s.

565.644 P,ENOL9 Pheno( =!"r'o(i! "!i#> is &se# inrefiner$ o%er"tions in the m"n&f"!t&re of (&'ri!"tin oi(s"n# "rom"ti! h$#ro!"r'ons 'e!"&se of its "ffinit$ forn"%hthenes "n# "rom"ti! h$#ro!"r'ons. A %heno(tre"tin&nit &s&"(($ !onsists of three se!tions9 tre"tin)#e%heno(iin) "n# %heno( re!o+er$.

The tre"tin se!tion) *here the fee# is !ont"!te# *iththe %heno() o%er"tes "t tem%er"t&res 'e(o* 66 F. C"r'onstee( resists "tt"!- in this se!tion %ro+i#e# th"t *"ter is not%resent.

The #e%heno(iin se!tion) *hi!h %ro!esses the (&?'ri!"tin sto!-?%heno( mit&re from the tre"tin se!tion)

se%"r"tes the %heno( from the tre"te# oi(. No !orrosionof !"r'on stee( o!!&rs in this se!tion. The %heno(?re!o+er$ se!tion %ro!esses s%ent %heno(

from the tre"tin se!tion "n# remo+es the etr"!t. A(?tho&h e%erien!e in#i!"tes th"t e"!h %ie!e of e


27/50

5


FIG. 55?C(ose?&% of " Se!tion of " 56 Chromi&m?52 Ni!-e( Stee( P&m% C"stin Th"t ,"s Been in S&(f&ri! A!i# Ser+i!e.

Note #ee% interr"n&("r et!hin.

hih?+e(o!it$ ser+i!e. A'o+e 66 F) !"r'on stee( m"$!orro#e r"%i#($ in %heno( ser+i!e. In 'oth (i


28/50

5. CORROSION

51

FIG. 54?C(ose?&% of Phos%hori! A!i# Corrosion of " C"r'on?Stee( Re"!tor Fee# Re"!tor Pro#&!t E!h"ner T&'e i11 "Po($meri"tion Unit.

This !orrosion res&(te# from *"ter in the re"!tor %ro#&!t.

!orrosion !r"!-in in or "#8"!ent to *e(#s or "t other%oints of hih stress !on!entr"tion "t tem%er"t&res o+er

"%%roim"te($ 66 F. Mone( "n# ni!-e( "re resist"nt to"tt"!- e+en "t tem%er"t&res in e!ess of 66 F) %ro+i#e#the !ontent of s&(f&r !om%o&n#s is (o*.

565.64 MERCURY9 Mer!&r$ is sometimes &se# ininstr&ments in " refiner$. O!!"sion"(($) it m"$ 'e for!e#into the o%er"tin e?;=;>13 > "n# "!om%o&n# of the '"se met"() s&!h "s "n oi#e) "!tin "s "!"tho#e =e(e!tron re!ei+er>. 15Th&s the on($ other f"!tornee#e# is *"ter. *hi!h %ro+i#es the e(e!tro(+te =e(e!tron%"th>. If im%&rities "re %resent in the *"ter it 'e!omes "'etter e(e!tro($te "n# the r"te of !orrosion is in!re"se#.Th&s) to %re+ent "tmos%heri! !orrosion) it is ne!ess"r$on($ to e(imin"te the *"ter from the s&rf"!e of the met"('$ me"ns of " %rote!ti+e '"rrier or !o"tin.51?54

The norm"( r"te of "tmos%heri! !orrosion of &n%"inte#stee( in r&r"( "tmos%heres is (o*/ it r"nes from 6.66623 to6.6634 in. %er $e"r.5,o*e+er) in some "tmos%heres it!orro#es m&!h more r"%i#($) "n# " !orrosion r"te of 6.67

in. %er $e"r is !ommon. The r"te f !orrosion is "(so"!!e(er"te# "t "n$ 're"- in " %rote!ti+e !o"tin. At s&!h're"-s) #ee% %its *i(( form "n# the stee( *i(( !orro#e "te+en re"ter r"tes 'e!"&se the '"se stee( "t the 're"- *i((form " "(+"ni! !e(() the

stee( "!tin "s the "no#e "n# "n oi#e "!tin "s " !"tho#e.Fi. 5 i((&str"tes the "!!e(er"tin effe!t of 're"-s in "%rote!ti+e !o"tin. There "re &s&"(($ !ert"in "re"s th"t "res&'8e!te# to "!!e(er"te# !orrosion. E


29/50

9 %%%

: %G%B BAB %G%%%%G%Bl 7, -~~:. @li.9.9/)999 #r.VV I %

%%% %M .9 "" %% % % BB %

O . 99O?9.V9W9V

%fBBfA%B

A7"r7 %%G ?t9?(f? ##:&. %

+1% 5?F"&(t$ P"int o' on this T"n- Roof h"s Res&(te# in A!!e(er"te# Corrosion.




fr Resale, >?;=;>13 >


30/50

CORROSION 2

9

"n# is often o+er(oo-e#. The fo((o*in %"r"r"%hs #is!&sss%e!ifi! e"m%(es of "tmos%heri! !orrosion.

a. orrosion (eneath Insulation and ,nder /ire#proofin%: Cr"!-s in ins&("tion "((o* moist&re to %enetr"teto the stee() "n# hi##en !orrosion t"-es %("!e. This o!!&rsin +esse(s "n# %i%in o%er"tin 'e(o* "%%roim"te($ 576F) "n# is often +er$ se+ere in refrier"tion s$stems. Cr"!-sin fire%roofin !on!rete) %"rti!&("r($ "t the to% *here the!on!rete en#s) "(so "((o* moist&re to %enetr"te to the stee("n# !"&se hi##en !orrosion =see Fi. 57 "n# 5>.

If st"in(ess stee( is ins&("te#) "n inhi'ite# ins&("tion orone *ith +er$ (o* !ontent of *"ter so(&'(e !h(ori#eins&("tion m"teri"( sho&(# 'e &se# to %re+ent stress!orrosion !r"!-in. Co"tins m"$ 'e &sef&( es%e!i"(($ inse"!o"st "re"s *here the !h(ori#e !"n !ome from the "irr"ther th"n from the ins&("tion.

b. orrosion of $ipelines: The inst"(("tion of %i%e(ines#ire!t($ on the ro&n# (e"#s to se+ere !orrosion on the'ottom of the (ines 'e!"&se of #"m%ness. Fi. 53 "n# 5@i((&str"te the #"m"in effe!ts on %i%e(ines ("i#

Re%ro#&!e# from Safety in $etroleum Refinin% and Related Industries&'$ Geore Armiste"#) r.) !o%$riht 1276. Re%ro#&!e# '$ %ermission ofohn G. Simmon#s "n# Com%"n$) In!.

FIG. 57?Disinter"tion of " Con!rete?En!"se# Be"m

S&%%ortin " ,e"te# :esse() Res&(tin from W"ter See%"e

Thro&h the Con!rete.

Note "(most !om%(ete #is"%%e"r"n!e of *e' *hi!h *"s

&n-no*n 'efore !on!rete ins&("tion *"s remo+e#.




Re%ro#&!e# from Safety in $etroleum Refinin% and Related Industries&'$ Geore Armiste"#) r.) !o%$riht 1276. Re%ro#&!e# '$ %ermission of

ohn G. Simmon#s "n# Com%"n$) In!.

FIG. 5??Corrosion of " Stee( Co(&mn on " Pro!ess

Str&!t&re) Res&(tin from W"ter See%"e Behin# Bri!-

Ins&("tion O+er " Lon Perio# of Time.

#ire!t($ on the ro&n#. If r"ss or *ee#s "re "((o*e# toro* 'ene"th "n# "ro&n# %i%e(ines) the %i%e *i(( rem"in#"m% for (on %erio#s "n# !orro#e. Lines ("i# #ire!t($ ons&%%orts or h&n '$ !("m%s often !orro#e "t the %oint ofs&%%ort 'e!"&se of !re+i!e !orrosion


fr Resale, >?;=;>13 >


31/50

4.46 CONDITIONS CAUSING DETERIORATION OR FAILURES

FIG. 53?,"(f.B&rie# Lines S&!h "s These S&ffer Se+ereCorrosion of the T$%e Sho*n in Fi. 5@.

=see Fi. 52 "n# 46>. =See "(so referen!es 57 "n# 5 forother %i%e(ine %ro'(ems.>

c. orrosion of Structures: Str&!t&res th"t %ro+i#e!re+i!es *here *"ter m"$ enter "n# rem"in for (on%erio#s m"$ s&ffer se+ere !orrosion. E"m%(es of s&!h!onstr&!tion "re str&!t&r"( mem'ers %("!e# '"!- to '"!-)"n# %("tforms inst"((e# !(ose to the to%s of to*ers or#r&ms. Str&!t&res (o!"te# ne"r f&rn"!e st"!-s or ne"r!oo(in to*ers "re %"rti!&("r($ s&s!e%ti'(e to this t$%e of"tt"!-.

d. oolin% 0ater orrosion: M"n$ enineers !on?!entr"te their !orrosion %rote!tion efforts on the %ro!ess

si#e of " refiner$ &nit "n# #o not !on!ern themse(+es "sm&!h "s the$ sho&(# *ith !orrosion res&(tin from the &seof !oo(in *"ter. E?;=;>13 >


32/50

&n%"inte# "re" imme#i"te($ )s&%%orts. on e"!h (ine.

!orrosion "t %oint QGof !ont"!t of %i%e "n#

s&%%ort.

FIG. 52?Lines Restin on Con!rete Pi%e S&%%orts.

In ) most tre"te# !oo(in *"ter s$stems) stee( t&'es) %i%eor !"st or *ro&ht iron %"rts !"n 'e &se# if *"ter +e(o!ities!"n 'e -e%t "'o+e 7 ft %er se!on#. Other*ise) inhi'ite#"#mir"(t$ t&'es *ith *"ter +e(o!it$ 'e(o* 16 ft %er se!on#h"+e 'een fo&n# more effe!ti+e if t&'e sheets "re of !o%%er"((o$. In some s$stems "(&min&m '&n#(es h"+e 'een fo&n#to 'e effe!ti+e.

FIG. 46??Corrosion Un#er C("m%s on " Pi%e(ine.

Mo+ement of (ines h"s !"&se# !("m%s to s(i% "n# s&%%ortto ti%.




E!onomi! !on#enser t&'e m"teri"(s for 'r"!-ish or se"*"ter "re s%e!i"( %ro'(ems) "n# +e(o!it$ is "n im%ort"nt!onsi#er"tion. C&%ro?ni!-e( =%"rti!&("r($ the iron?'e"rint$%e> is *i#e($ &se#. A(&min&m 'r"ss) mone() "n# st"in(essstee(s h"+e h"# +"ri"'(e %erform"n!es. The st"in(ess stee(s!"n 'e s&'8e!t to se+ere %ittin "n# stress !orrosion!r"!-in. For %i%in) %("sti!s "n# !ement (inin sho&(# 'e!onsi#ere#.

Where+er !"r'on stee( is &se# "n# se+ere !orrosion isen!o&ntere#) %ro%er($ "%%(ie# !o"tins "n# !"tho#i!

%rote!tion m"$ 'e &se# to eten# e


33/50


Re%ro#&!e# from Safety in $etroleum Refinin% and Related Industries&'$ Geore Armiste"#) r.) !o%$riht 1276. Re%ro#&!e# '$ %ermission of ohnG. Simmon#s "n# Com%"n$) In!.

FIG. 41?E"m%(e of " ,e"ter T&'e B"#($ S!"(e# "s " Res&(t of O+erhe"tin.

sho*n in Fi. 41. Oi#"tion in "ir in!re"ses *ith in!re"sinmet"( tem%er"t&res "n# #e!re"ses *ith in!re"sin!hromi&m !ontent of the met"(. M"im&m met"(tem%er"t&res for (o* oi#"tion r"tes "re i+en in thefo((o*in t"'&("tion. A'o+e these tem%er"t&res oi#"tion'e!omes "%%re!i"'(e.+? ;7G ;

1)6761)676

1)637

1)166

1)176

1)137

1)137

1)566

1)576

1)766

1)766

1)66

5)666

5)166O$en "t hih tem%er"t&res re"!ts *ith ni!-e( "((o$s to!"&se s!"(in. S%"((in) *hi!h #e%en#s on the e%"nsion!h"r"!teristi!s "n# !om%osition of the oi#e forme#) "n#on tem%er"t&re !h"nes) "!!e(er"tes oi#"tion of ni!-e("((o$s. The tem%er"t&re "'o+e *hi!h oi#"tion in s&(f&r?free "ir 'e!omes sinifi!"nt is i+en in the fo((o*int"'&("tion for ni!-e( "n# some of the !ommon ni!-e("((o$s.1@ 52?44




M"teri"(

Ni!-e( ................

Tem%er"t&re

=Derees F"hrenheit>

1)2661)6665)6665)6661)661)@665)666

Mone( .................................... .........In!one( ............................................In!o(o$ ............................................,"ste((o$ A) B) D .............. .....,"ste((o$ C ......................,"ste((o$ ; .............................

Att"!- of !o%%er "n# its "((o$s '$ o$en is se(#om "%ro'(em in refineries 'e!"&se these m"teri"(s "re not &se#*here o%er"tin tem%er"t&res e!ee# 366 F. At!onsi#er"'($ hiher tem%er"t&res) s&!h "s miht 'e en?!o&ntere# in fires) !o%%er m"$ 'e "tt"!-e# '$ o$en)*ith !onsi#er"'(e s!"(in. .

Li-e !o%%er "tt"!-) o$en "tt"!- of "(&min&m "n# its"((o$s is se(#om " %ro'(em 'e!"&se these m"teri"(s "re notor#in"ri($ &se# *here o%er"tin tem%er"t&res e!ee# 66F. A(&min&m "n# its "((o$s "re hih($ resist"nt to "tt"!- '$#r$ "ir. This resist"n!e is the res&(t of the form"tion of "%rote!ti+e fi(m !om%os9e# of "(&min&m oi#e. A'o+e 366F the %resen!e of *"ter +"%or in "ir (e"#s to intern"(

oi#"tion)%"rti!&("r($ in those "(&min&m "((o$s !ont"inin"%%re!i"'(e "mo&nts of m"nesi&m. The %resen!e of sm"(("mo&nts of s&(f&r #ioi#e in!re"ses) "n# "%%re!i"'(e"mo&nts of !"r'on #ioi#e inhi'it this form of "tt"!-.1@

565.674 ,IG,?TEMPERATURE STEAM9 Ste"m "t hihtem%er"t&res m"$ 'e #e!om%ose# to h$#roen "n#o$en) "n# the free o$en m"$ !"&se se+ere s!"(in ofstee(s) *hi!h) in t&rn) *i(( !"&se re#&!tion of !ross se!tion"n# &(tim"te f"i(&re. The r"te of s!"(in in?


fr Resale, >?;=;>13 >


34/50

CORROSION

44

!re"ses *ith ste"m ="n# th&s met"(> tem%er"t&re) *hi(este"m %ress&re seems to h"+e (itt(e effe!t. In ener"() theste"m tem%er"t&re "t *hi!h s!"(in 'e!omes sinifi!"ntin!re"ses *ith in!re"sin !hromi&m !ontent of the met"(.A'o+e the met"( tem%er"t&res i+en in the fo((o*int"'&("tion) s!"(in m"$ 'e!ome "%%re!i"'(e. 1@ 5@

M"teri"(

C"r'on stee( ..........................C"r'on?mo($'#en&m stee( .. ........ . %er!ent !hromi&m stee( . ........ .1 %er!ent !hromi&m stee( .......5 %er!ent !hromi&m stee( ...........5 Gi?1%er!ent !hromi&m stee( .4%er!ent !hromi&m stee(.7 %er!ent !hromi&m stee( .3 %er!ent !hromi&m stee( .9%er!ent !hromi&m stee( .

Tem%er"t&re =DereesF"hrenheit> 276

2371)6661)6761)6@61)1661)1571)1761)1371)566

The "&steniti! !hromi&m?ni!-e( st"in(ess stee(s resistste"m oi#"tion to e+en hiher tem%er"t&res) '&t "s "res&(t of their (imite# &se in ste"m ser+i!e) "!t&"( (imitintem%er"t&res "re not "+"i("'(e. The resist"n!e of these"&steniti! stee(s to ste"m oi#"tion %ro'"'($ "%%ro"!hes to*ithin 76 F or 166 F the m"im&m tem%er"t&re to *hi!hoo# resist"n!e to oi#"tion in "ir is o't"ine# *ith them.

In ener"() *here s!"(in is " %ro'(em) f(&!t&"tintem%er"t&res in!re"se the r"te.1@A !o"tin of s!"(e oftenh"s some %rote!ti+e effe!t/ it re#&!es the s!"(in r"te "fterthe initi"( %erio#. ,o*e+er) on !oo(in or he"tin thes!"(e# met"() #ifferenti"( !ontr"!tion or e%"nsion of s!"(e"n# met"( m"$ !"&se s%"((in) there'$ e%osin the&n#er($in met"( to fresh "tt"!-. A(tern"tin oi#iin "n#

re#&!in !on#itions !"n "(so in!re"se the r"te of (oss.A'o+e !ert"in (imitin tem%er"t&res) ste"m m"$ !"&se

em'ritt(ement of ni!-e( "n# its "((o$s from interr"n&("roi#"tion. In the fo((o*in t"'&("tion "re (iste# them"im&m ste"m tem%er"t&res "t *hi!h &se of hihni!-e(m"teri"(s "re s&it"'(e.1@ 52 s, 45

M"teri"(

Ni!-e( .......................Mone( ...........................................In!one( 66In!o(o$ @66,"ste((o$s .

Tem%er"t&re=Derees F"hrenheit>

@66366 to @66

1)@661)@66No inform"tion

Ste"m is not #"m"in to "(&min&m "n# its "((o$s "ttem%er"t&res &% to 476 F to 766 F. A'o+e this tem%er"t&rer"ne) ste"m m"$ "tt"!- "(&min&m "n# its "((o$s to form"(&min&m oi#e "n# h$#roen.1@

Co%%er "n# its "((o$s "re se(#om &se# in ste"m ser+i!e"t tem%er"t&res "'o+e 76 F 'e!"&se their me!h"ni!"(%ro%erties #iminish m"r-e#($ "'o+e these tern?

%er"t&res. A(tho&h ste"m "tt"!- !"n o!!&r "t hihertem%er"t&res) it h"s no %r"!ti!"( sinifi!"n!e.

565.67 :ANADIUM O;IDE9 :"n"#i&m eists insome f&e(s) s&!h "s the resi#&"( f&e(s #eri+e# from !ert"in!re oi(s) "n# oi#ies to +"n"#i&m %entoi#e *hen thef&e( is '&rne#. This oi#e) or !om%(e mit&re of

+"n"#i&m oi#es "n# so#i&m s&(f"te) %re!i%it"tes "n#forms " (o*?me(tin f(& th"t %re+ents %rote!ti+e oi#esfrom formin on stee( %"rts of f&rn"!es) "s t&r'ines) "n#the (i-e) "n# %romotes "!!e(er"te# oi#"tion "tt"!-.A%%"rent($ these !om%o&n#s re"!t #ire!t($ *ith the stee( insome m"nner) *hi(e "tmos%heri! o$en ser+es toreener"te the +"n"#i&m oi#e. 4

Sties of the s&'8e!t in#i!"te th"t +"n"#i&m !orrosion#oes not t"-e %("!e 'e(o* "%%roim"te($ 1)166 F. This is'e!"&se +"n"#i&m %entoi#e !om%o&n#s m&st 'e mo(tenin or#er to !"&se the re"!tion. A(tho&h %&re +"n"#i&m%entoi#e me(ts "t " tem%er"t&re some*h"t "'o+e 1) 166 F)other s&'st"n!es in the f&e(?oi( "sh) s&!h "s so#i&m!om%o&n#s "n# s&(f&r oi#es) &nite *ith the +"n"#i&m

%entoi#e "n# (o*er the me(tin %oint !onsi#er"'($. Themo(ten +"n"#i&m %entoi#e forms " s(" *ith stee(. Themo(ten s(" r&ns off "n# e%oses fresh met"( to "tt"!-.Corrosi+e "!tion of f&e(oi( "sh in!re"ses sh"r%($ *ithin!re"sin tem%er"t&re "n# +"n"#i&m !ontent. Fore"m%(e) the to(er"'(e (e+e( of +"n"#i&m in f&e( oi(s is inthe !on!entr"tion of 56 to 176 %%m 'et*een 1)566 F "n#1)776 F) #e%en#in on the so#i&m?+"n"#i&m r"tio. Un#erthe %ro%er !on#itions) fe*) if "n$) of the stee(s seem to 'eimm&ne to this t$%e of "tt"!-) '&t the 6?6 "n# 76?76!hromi&mni!-e(s h"+e %ro+e# more resist"nt to "tt"!- th"nother "((o$s.

Firin !on#itions in the fire'o !"n 'e !riti!"() "s the$!"n re"t($ "ffe!t the tem%er"t&re of the t&'es "n# t&'e

s&%%orts. Poor f("me %"tterns !"n res&(t in hih met"(tem%er"t&res "n# hen!e hih !orrosion r"tes.

Com'&stion *ith (o* e!ess "ir "(so offers " me"ns ofre#&!in +"n"#i&m !orrosion. With +er$ (o* e!ess "ir(e+e(s) form"tion of s&(f&r trioi#e in the fire'o isminimie#) "n# the res&(t"nt +"n"#i&m?so#i&m !om%(ees"re (ess !orrosi+e.

A !onsi#er"'(e "mo&nt of st$ h"s 'een #e+ote# to this%ro'(em. Sho&(# " +"n"#i&m oi#e !orrosion %ro'(em 'een!o&ntere#) the !&rrent (iter"t&re sho&(# 'e !ons&(te# forthe ("test inform"tion. The API h"s 'een +er$ "!ti+e ins&%%ort of these sties.

565.677 EFFECT OF SULFUR DIO;IDE AND

,YDROGEN SULFIDE9 The %resen!e of s&(f&r #ioi#e "thih tem%er"t&res) "s in f&rn"!e "ses) in!re"ses the r"te ofs!"(in of stee( thro&h form"tion of " (o*?me(tin%ointiron oi#e?iron s&(f&r !om%o&n#.K ,$#roen s&(fi#e h"s "simi("r effe!t in in!re"sin s!"(in r"tes.

The etent of the !orrosi+e "tt"!- of stee(s '$ hot s&(f&r!om%o&n#s #e%en#s on !on!entr"tion) tem%er"t&re) "n#the oi#iin %o*er of the en+ironment. In !om'&stion"ses) min&te


35/50

4


the !orrosion r"te. The so#i&m !om'ines to form (o*?me(tin so#i&m s&(f"te =N"5SO.> "n# the !orrosion r"tefrom h$#roen s&(fi#e or s&(f&r #ioi#e "%%e"rs toin!re"se. A!t&"(($) the in!re"se !omes *ith in!re"se# s"(t=norm"(($ so#i&m !h(ori#e '&t "n$ so#i&m s"(t *i(( #o> .Pr"!ti!"( o'ser+"tions in#i!"te th"t the hiher the!hromi&m !ontent of the stee() the more se+ere the s&(f&r

!on#itions th"t !"n 'e to(er"te#.S&(f&r in "n$ form h"s " +er$ #etriment"( effe!t on

ni!-e( "n# hih?ni!-e( "((o$s. S&(f&r re"!ts "(on r"in'o&n#"ries of ni!-e( "n# ni!-e( "((o$s to form " (o*?me(tin ni!-e(?ni!-e( s&(fi#e mit&re *hi!h !"&ses 'rit?t(eness.+? 45 47?43 At tem%er"t&res "'o+e "%%roim"te($1)126 F this mit&re) 'ein mo(ten) %enetr"tes the r"in'o&n#"ries "n# (e"#s to #isinter"tion of the met"(.

At "'o&t 5)666 F) or (o*er tem%er"t&res if st"in(essstee( is sensitie#) s&(f&r !orrosion of the "&steniti!st"in(ess stee(s =T$%es 462) 416) et!.> t"-es the form ofinterr"n&("r %enetr"tion. This !"n res&(t in " serio&s (ossof strenth if the met"( is 'ein s&'8e!te# to tensi(e(o"#ins.

In oi#iin "tmos%heres the ni!-e( s&(fi#e is !on+erte#to ni!-e( oi#e *hi!h is " semi%rote!ti+e oi#e s&rf"!e("$er. In re#&!in "tmos%heres) ho*e+er) the form"tion ofs&(fi#e is !&m&("ti+e) "n# "tt"!- is more se+ere.

A##itions of !hromi&m) iron) "n# m"n"nese to ni!-e("((o$s in!re"se resist"n!e to s&(f&r "tt"!-/ in or#er to%re+ent or minimie it "s ser+i!e tem%er"t&res in!re"se)the !hromi&m !ontent of the "((o$ is in!re"se# "n# theni!-e( !ontent #e!re"se#.

The ni!-e( m"teri"(s "re &ns&it"'(e for &se in s&(f&ro&s"tmos%heres m&!h "'o+e the m"im&m tem%er"t&resi+en in the fo((o*in t"'&("tion.1@ 52 46 45 44 49/

Tem%er"t&re=Derees F"hrenheit>

M"teri"(

Ni!-e( ............. .Mone( ............In!one( 66 ..In!o(o$ @66 ..,"ste((o$s B) C .,"ste((o$ ;

Oi#iinAtmos%here66 661)766

A'o&t 1)276 F ENe"r 5)666 F5)666 F

Re#&!inAtmos%here766 7661)666

E The effe!t of !ree% "t these hih tem%er"t&res sho&(# "(so 'e!onsi#ere#.

S&(f&r em'ritt(ement of ni!-e( "n# its "((o$s in therefiner$ m"$ o!!&r in e) or *here s&(f&r?!ont"inin%ro!ess stre"ms "re 'ein h"n#(e#.

Ni!-e( "n# hih?ni!-e( "((o$s) *hen he"te# in "tmo?s%heres th"t f(&!t&"te 'et*een oi#iin =e!ess of "ir>"n# re#&!in =e!ess of !"r'on monoi#e or h$#roen>)s&ffer se+ere interr"n&("r "tt"!- *ith res&(t?




in em'ritt(ement) e+en tho&h the "tmos%here is s&(f&r?free. rs) 46

Em'ritt(ement of ni!-e( "n# hih?ni!-e( "((o$s) s&!h "smone( "n# the ,"ste((o$s) often o!!&rs #&rin *e(#in.Not on($ s&(f&r) '&t "(so (e"#) %hos%hor&s) "n# some (o*?me(tin met"(s "n# "((o$s re"!t *ith ni!-e('e"rinm"teri"(s "t the hih tem%er"t&res en!o&ntere# #&rin

*e(#in.K Gre"se) oi() m"!hinin (&'ri!"nts) %"int) m"r-in!r"$ons) %i%e?thre"# #o%e) so"%) #irt) "n# resi#&es from%ro!ess stre"ms m"$ !ont"in one or more of the&n#esir"'(e s&'st"n!es.

At tem%er"t&res for *hi!h !o%%er "((o$s "re em%(o$e#in refiner$ ser+i!e) the$ "re resist"nt to "tt"!- '$ s&(f&r"ses.

A(&min&m "n# its "((o$s "re hih($ resist"nt to "tt"!-'$ s&(f&r "ses.

565.67 T,E EFFECT OF ,OT CORROSI:EGASES ON CAST IRON =GROWT, ANDEMBRITTLEMENT> 9 At tem%er"t&res "'o+e @66 F "((r"$ !"st irons 'ein to #eterior"te) res&(tin in etreme'ritt(eness) (oss of strenth) s!"(in) "n# ro*th. Gro*thres&(ts in " %erm"nent in!re"se in sie. Gener"( s!"(in is)of !o&rse) !"&se# '$ the s"me hot "ses th"t !"&se s!"(inof stee(s) "n# it res&(ts in " ener"( *"stin "*"$.

Gro*th of !"st irons res&(ts 'oth from r"%hiti"tion"n# from infi(tr"tion of !orrosi+e "ses into the str&!t&re.9KGr"%hiti"tion is #is!&sse# e(se*here in this !h"%ter. Theinfi(tr"tion of !orrosi+e "ses =o$en) s&(f&r "ses) et!.>"%%"rent($ !"&ses some sort of intern"( s!"(in"!!om%"nie# '$ s*e((in. S&!h !"stins "re *e"-)missh"%en) "n# 'ritt(e. Some h"+e 'een -no*n to in!re"se76%er!ent in +o(&me.4@The "mo&nt of ro*th is or#in"ri($%ro%ortion"( to the m"im&m tem%er"t&re re"!he# "n# tothe n&m'er of he"tins. Gro*th m"$ 'e fo&n# in '&rner"n# other f&rn"!e %"rts "n#) &n#er &n&s&"( !on#itions) in!om%ressor %istons.

Irons most resist"nt to ro*th "re those *ith st"'(e!"r'i#es "n# !(ose r"in str&!t&re) *ith (o* tot"( !"r'on. 4@For this re"son) (o*?!"r'on irons *ith 6.46 to 1.66%er!entof !hromi&m =" !"r'i#e former> "re m&!h more resist"nt toro*th th"n &n"((o$e# r"$ irons. The "##ition of moreth"n 1 %er!ent of !hromi&m %ro#&!es s&'st"nti"(im%ro+ement in oi#"tion resist"n!e. Irons !ont"inin 1%er!ent of !hromi&m h"+e 'een &se# "t tem%er"t&res &% to1)66 F) "n# irons *ith 47 %er!ent of !hromi&m h"+e not'een h"rme# '$ re%e"te# short %erio#s "t tem%er"t&res "shih "s 5)166 F.1@

The "&steniti! !"st irons !ont"inin 1 %er!ent or more

of ni!-e() "%%roim"te($ 5 %er!ent of !o%%er) "n# 1 to %er!ent of !hromi&m?th"t is) Ni?Resist?sho* oo#resist"n!e to ro*th "n# oi#"tion &% to 1)766 F.K

565.6 Im%ort"nt Corrosion Phenomen"

565.61 INTRODUCTION9 There "re " n&m'er of!orrosion %henomen" th"t "re r"ther &ni?;=;>13 >


36/50

CORROSION

47

!orrosion %henomen" of this t$%e "re #is!&sse# in thefo((o*in %"r"r"%hs.

565.65 INTERGRANULAR CORROSION9 When"&steniti! stee(s "re he"te# in the tem%er"t&re r"ne of 376F to 1)76 F) or !oo(e# thro&h this r"ne) " !om%(e!"r'i#e %re!i%it"tes "(on the r"in 'o&n#"ries to form "n

en+e(o%e "ro&n# the r"ins. A(tho&h !"r'i#e %re!i%it"tionin itse(f is not %"rti!&("r($ h"rmf&() stee(s in this !on#ition"re s&s!e%ti'(e to interr"n&("r !orrosion '$ re("ti+e($ mi(#!orro#ents) es%e!i"(($ the !orro#ents !ont"inin !h(orine)f(&orine) or io#ine. E"m%(es of interr"n&("r !orrosion "resho*n in Fi. 45 "n# 44. A f&rther #es!ri%tion of this t$%eof "tt"!- is %resente# in "nother se!tion of this !h"%ter =seeP"r. 565.6 "n# P"r. 565.67>.

565.64 GRAP,ITIC CORROSION OF CAST IRON9Gr"%hiti! !orrosion of !"st irons) sometimes &nfort&n"te($!"((e# Kr"%hiti"tion)K sho&(# not 'e !onf&se# !ithr"%hiti"tion =the #e!om%osition of !"r'i#es "t hihtem%er"t&res> "s #is!&sse# e(se*here in this !h"%ter.Gr"%hiti! !orrosion is (o*?tem%er"t&re !orrosion

of r"$ !"st irons in *hi!h met"((i! iron is !on+erte# into!orrosion %ro#&!ts) (e"+in the r"%hite int"!t. 1@ =SeeA%%en#i I for the str&!t&re of r"$ !"st iron.> This!on#ition res&(ts in " %oro&s str&!t&re) (oss of #ensit$) "n#etreme($ (o* strenth) '&t there is no o&t*"r# "%%e"r"n!eof "n$ #"m"e. This t$%e of "tt"!- o!!&rs in +er$ #i(&te"!i# stre"ms) s"(t *"ters) or in soi(s) %"rti!&("r($ those

!ont"inin s&(f"tes. Gr"%hiti! !orrosion h"s 'een fo&n# in#isti(("tion?to*er intern"(s) s&!h "s tr"$s "n# 'e(( !"%s.

565.6 STRESS CORROSION CRACING9 Stress!orrosion !r"!-in is the s%ont"neo&s f"i(&re of met"(s '$!r"!-in &n#er the !om'ine# "!tion of !orrosion "n#tensi(e stress.1@ 5 K2The !orro#ent is) of !o&rse) somes&'st"n!e in the en+ironment. Stress m"$ 'e resi#&"( or"%%(ie#. Resi#&"( stresses res&(t from f"'ri!"tiono%er"tions) s&!h "s 'en#in "n# *e(#in) "n# from &ne


37/50


FIG. 44?Interr"n&("r Corrosion in " S"m%(e Remo+e# from "n

1@ Chromi&m?@ Ni!-e( Stee( Dr&m.

Note ho* !orrosion h"s o!!&rre# in the *e(# he"t?"ffe!te# one.

nite in (o!"(ie# "re"s) "re of more im%ort"n!e th"n"%%(ie# stresses in !"&sin stress !orrosion !r"!-in)%"rti!&("r($ in +ie* of the f"!tor of s"fet$ &se# in #eter?minin *or-in stresses. ,o*e+er) "%%(ie# stresses in!omers or *here stress r"isers o!!&r m"$ 'e of !onsi#?er"'(e m"nite.

The me!h"nism of stress !orrosion !r"!-in is not!(e"r($ &n#erstoo# "n# is the s&'8e!t of m&!h #e'"te) *ith+"rio&s theories 'ein offere#. It h"s 'een noti!e#)ho*e+er) th"t !r"!-in se(#om o!!&rs *here ener"(!orrosion is more th"n s(iht. More often th"n not there isno me"s&r"'(e ener"( !orrosion. This (e"#s to the 'e(iefth"t !orrosion res&(tin in stress !orrosion !r"!-in ishih($ !on!entr"te# in " min&te "re" "n# %ro#&!es "netreme($ sh"r% not!h. This stress !on!entr"tor (e"#s to!r"!-in &n#er tensi(e stress. If the




initi"( !r"!-in #oes not %ro!ee# thro&h the se!tion) the!$!(e m"$ 'e re%e"te# &nti( f"i(&re is !om%(ete.

In "##ition to " !orro#ent "n# stress) there is " thir#f"!tor in stress !orrosion !r"!-in?time. The time re13 >


38/50

CORROSION

43

Stress !orrosion !r"!-in h"s "(so 'een e%erien!e# in"&steniti! st"in(ess stee( +esse(s h"n#(in !"&sti! so(&tionsin the tem%er"t&re r"ne of 66 F to 76 F. The r"ne of!orro#ent !on!entr"tions) tem%er"t&res) "n# %ress&res!"&sin stress !orrosion !r"!-in of st"in(ess stee(s is *i#e)"n# the (imits "re &n-no*n.

Stress !orrosion !r"!-in in the "&steniti! st"in(ess

stee(s m"$) "t times) 'e #iffi!&(t to #istin&ish from in?terr"n&("r !orrosion 'e!"&se 'oth t$%es of "tt"!- m"$o!!&r "#8"!ent to *e(#s. At times) the t*o t$%es of "tt"!-m"$ 'e re("te# in th"t interr"n&("r !orrosion m"$ %ro+i#e%oints of stress !on!entr"tion "t *hi!h stress !orrosion!r"!-in m"$ #e+e(o%. Stress !orrosion !r"!-in #oes not)ho*e+er) #e%en# on the %re!i%it"tion of !"r'i#es) "n# m"$o!!&r *ith or *itho&t their %resen!e.

The on($ %ositi+e *"$ to #istin&ish 'et*een inter?r"n&("r !orrosion "n# stress !orrosion is '$ mi!ros!o%i!e"min"tion. Ch(ori#e stress !orrosion !r"!-s in "&steniti!"((o$s "re &s&"(($ tr"nsr"n&("r "n# 'r"n!hin) *hi(einterr"n&("r !orrosion fo((o*s the r"in'o&n#"ries.+? "s

In ener"() ni!-e( "n# ni!-e( "((o$s sho* oo# re?sist"n!e to stress !orrosion !r"!-in. F&se# !"&sti!so(&tions) "n# %erh"%s other +er$ hot) hih($ !on!entr"te#so(&tions) m"$ !"&se !r"!-in of hih($ stresse# ni!-e()mone() "n# In!one(. ts) 45 4O

In "##ition) mone( on($ is s&'8e!t to stress !orrosion!r"!-in in the %resen!e of met"((i! mer!&r$ =*hi!h m"$enter " +esse( from 'ro-en instr&ments> or mer!&r$!om%o&n#s. ts

Stress !orrosion !r"!-s in ni!-e( "n# ni!-e( "((o$s "re&s&"(($ interr"n&("r.

Stress !orrosion !r"!-in of the !o%%er "((o$s is ne"r($"(*"$s the res&(t of the !om'ine# "!tion of threes&'st"n!es9 "mmoni" or "mmoni"?%ro#&!in m"teri"(

=or"ni! "n# inor"ni! s&'st"n!es !ont"inin nitroen>/*"ter/ "n# o$en. Cr"!-in of !o%%er "((o$s o!!&rs in%i%e sti(( o+erhe"# e "n# (o*!"r'on r"#es =46L "n# 41L> h"+e 'een either &se# orteste#. Most of the ser+i!e f"i(&res re%orte# h"+e 'een inf&rn"!e t&'es or e!h"ner t&'es/ the net most fre?;=;>13 >


39/50

4@


f&rn"!e t&'es !"n 'e s&s!e%ti'(e to f"i(&re "fter 'ein in(on ser+i!e re"r#(ess of "((o$in.

At %resent) the res&(ts of in+esti"tions on !"stins sho*th"t ferrite in st"in(ess "((o$s "##s to the resist"n!e to stress!orrosion !r"!-in. 4 In some !"ses !r"!-in *"se(imin"te# in the ferrite !ont"inin st"in(ess so th"t thism"teri"( (oo-s %romisin in " ser+i!e *here %o($thioni!"!i# !o&(# 'e e%e!te#. At the time of this *ritin) there "resome fie(# "%%(i!"tions "n# no re%orte# f"i(&res #&rin thisshort %erio#. ,o*e+er) the) %resen!e of ("re "mo&nts offerrite in "&steniti! st"in(ess stee(s) fo((o*e# '$ o%er"tion "t" tem%er"t&re o+er @66 F !"n (e"# to em'ritt(ement. =Referto P"r. 56.65.>

565.6 DEJINCIFICA TION9 Dein!ifi!"tion is "t$%e of !orrosion th"t !"n o!!&r in !o%%er?in! "((o$s='r"sses> !ont"inin (ess th"n @7 %er!ent of !o%%er *hen&se# in *"ter ser+i!e. Jin! is (ost from the 'r"ss "n# (e"+es"s " resi#&e) or '$ " %ro!ess of re#e%osition) " %oro&s in!?free m"ss of !o%%er h"+in +er$ (itt(e me!h"ni!"( strenth.Dein!ifi!"tion m"$ 'e one of three t$%es9 %(&) ("$er) orinter!r$st"((ine.

P(&?t$%e #ein!ifi!"tion o!!&rs in (o!"(ie# "re"s.If the 'r"ss !"n 'e 'ent) the %oro&s %(&s of !o%%er *i(( %o%o&t) (e"+in %its. P(&?t$%e #ein!ifi!"tion m"$ 'e"sso!i"te# *ith *hite) 'ro*n) t"n) or other !o(ors oft&'er!(es) !"%s) or f("-es of !orrosion %ro#&!ts th"t form#ire!t($ o+er the %(&s. The %(&s h"+e " re##ish"%%e"r"n!e.

L"$er?t$%e #ein!ifi!"tion !o+ers ("rer "re"s. The!o%%er ("$er h"s " ro&n#e#) no#&("r "%%e"r"n!e "n# is"#8"!ent to the 'r"ss s&rf"!e. Thi!- ("$ers of !o%%er m"$'&i(# &% in time "n# m"$ 'e %ee(e# from the 'r"ss) (e"+in"n irre&("r s&rf"!e. This t$%e of #ein!ifi!"tion m"$ "(so'e "sso!i"te# *ith the form"tion of !o(ore# !orrosion%ro#&!ts.

Inter!r$st"((ine #ein!ifi!"tion o!!&rs "(on the r"in'o&n#"ries of the 'r"ss. In this t$%e of #ein!ifi!"tion themet"( is *e"-ene# "s " res&(t of the 'ritt(eness of theinter!r$st"((ine #e%osit of !o%%er.

Dein!ifi!"tion is most (i-e($ to o!!&r in non?s!"(e?formin fresh or s"(t *"ters. An in!re"se in tem%er"t&re"!!e(er"tes the r"te of #ein!ifi!"tion.

Re# 'r"ss) *ith @7 %er!ent of !o%%er) resists #e?in!ifi!"tion/ 'r"sses *ith (ess th"n @7 %er!ent of !o%%er)s&!h "s M&nt) n"+"( 'r"ss) "n# "#mir"(t$ 'r"ss) m"$ 'e"tt"!-e#. M"n$ of the 'r"sses &se# in mo#ern refineries "re"((o$e# *ith "rseni!) "ntimon$) or %hos%hor&s. S&!h'r"sses "re !"((e# Kinhi'ite# 'r"ssesK 'e!"&se "((o$in *ith"rseni!) "ntimon$) or %hos%hor&s inhi'its #ein!ifi!"tion.

Other K#e"((o$inK "tt"!-s s&!h "s remo+"( of "(&min&m"n# ni!-e( se(e!ti+e($ from their "((o$s "re (ess fre !orro#esr"%i#($. This is essenti"(($ *h"t h"%%ens in o%er"tin &nits*hen met"(s h"+in " !onsi#er"'(e #ifferen!e in %otenti"("re %ermitte# to !ont"!t e"!h other in e(e!tro($tes s&!h "ss"(t *"ter or "!i#i! so(&tions. T"'(e 1 in#i!"tes) '$ thero&%ins) *hi!h m"teri"(s !"n 'e !o&%(e# *itho&te%erien!in !orrosion. Met"(s from #ifferent ro&%s ofthe t"'(e h"+e sinifi!"nt #ifferen!es of %otenti"(. Thef"rther "%"rt the m"teri"(s "%%e"r in the t"'(e) the re"terthe !orrosion r"te of the !orro#e# ="no#i!> en#.

The re("ti+e %osition of " met"( *ithin " ro&% some?times !h"nes *ith etern"( !on#itions) '&t se(#om #oes "met"( !h"ne from ro&% to ro&%. It *i(( 'e seen th"tse+er"( m"teri"(s "%%e"r in t*o %("!es in the t"'(e. Thee"!t %osition is #etermine# %rim"ri($ '$ the oi#iin%o*er "n# "!i#it$ of the e(e!tro($te "n# '$ the %resen!e of"!ti+"tin ions) s&!h "s !h(ori#es.

T"'(e 1) or "n$ simi("r t"'(e of the e(e!tromoti+e series)in#i!"tes on($ the ten#en!$ to set &% "(+"ni!

TABLE I?G"(+"ni! Series of Refiner$ Met"(s

"n# A((o$s ??O G:

=Met"(s "n# "((o$s %roress from the "no#i!) or (e"stno'(e) to the !"tho#i!) or most no'(e.>

Corro#e# en# ="no#i!)

or (e"st no'(e>

M"nesi&mM"nesi&m "((o$s

Jin!

A(&min&m 1) 166

C"#mi&m

A(&min&m 5)613

Stee( or ironC"st iron

14 %er!ent !hromi&miron ="!ti+e>

Ni?Resist

1@?@ St"in(ess ="!ti+e>1@?@?4 St"in(ess ="!ti+e>

Ch(orimet 4,"ste((o$ C

Le"#?tin so(#ersLe"#

Tin


fr Resale, >?;=;>13 >

Z

Z

Z

Z

Z

Z

Z

Z

Z

Z

Z


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CORROSION

42

!orrosion. The "!t&"( "mo&nt of !orrosion is #etermine# '$the e"se *ith *hi!h !&rrent !"n f(o* "n# '$ ho* m&!h!&rrent f(o*s. These f"!tors "re ener"(($ !ontro((e# '$ thefo((o*in fi+e !onsi#er"tions9

a. $otential (et!een the )node and athode: This is'"se# %rim"ri($ on the e(e!tromoti+e series) "s in#i!"te# in

T"'(e 1.b. onductivity of the ircuit: The !on#&!ti+it$ of the!ir!&it is "ffe!te# '$ the resist"n!es of "n$ met"(s in the!ir!&it "s *e(( "s the resist"n!e of the e(e!tro($te. Theresist"n!es of fi(ms *hi!h o!!&r "t e+er$ s&rf"!e "re%"rti!&("r($ im%ort"nt "n# fre 9 This t$%e of !orrosion o!!&rs "t the %ointof !ont"!t or in " !re+i!e 'et*een " met"( "n# nonmet"( or'et*een t*o %ie!es of met"( in the %resen!e of " !orro#ent.

An e(e!tro($ti! !e(( is est"'(ishe# 'e!"&se the!on!entr"tions of the !orro#ent insi#e the !re+i!e "n#o&tsi#e "re #ifferent. A #ifferen!e in e(e!tri!"( %otenti"( isest"'(ishe#) "n# the res&(t"nt !&rrent f(o* !"&ses"!!e(er"te# "tt"!- *hi!h often res&(ts in %ittin.

Cont"!t or !re+i!e !orrosion m"$ o!!&r "t *"shers/&n#er '"rn"!(es) s"n# r"ins) or "%%(ie# %rote!ti+e fi(ms/"n# "t %o!-ets forme# '$ thre"#e# 8oints. E"m%(es of!ont"!t or !re+i!e !orrosion "re sho*n in Fi. 5) 5@) "n#52.

565.62 BIOLOGICAL CORROSION9 Cert"in %rimi?ti+e (i+in or"nisms m"$ inf(&en!e !orrosion in one of the

fo((o*in *"$s9 '$ #ire!t($ inf(&en!in the r"te of!orrosion/ '$ %ermittin the #e+e(o%ment of "nen+ironment !orrosi+e to the met"(/ or '$ %ro#&!ine(e!tro($ti! !on!entr"tion !e((s (e"#in to !ont"!t or !re+i!e!orrosion. Or"nisms th"t inf(&en!e !orrosion m"$ 'e#i+i#e# into9 1) those of mi!ros!o%i! %ro%ortions) s&!h "s'"!teri") s(ime) "n# f&ni/ "n#) 5) those of m"!ros!o%i!sie) s&!h "s m"rine or"nisms ='"rn"!(es) et!.>.

The most im%ort"nt mi!roor"nisms th"t #ire!t($inf(&en!e the r"te of met"((i! !orrosion "re the s&(f"te?re#&!in '"!teri" fo&n# in m"n$ soi(s. There "re m"n$s%e!ies "n# str"ins of these '"!teri") '&t the$ "(( h"+e one!ommon !h"r"!teristi! in th"t the$ &se h$#roen to re#&!es&(f"te !ont"ine# in the soi(s. Corrosion of met"(s "(*"$sres&(ts in the re(e"se of h$#roen "t some %oint on themet"( s&rf"!e. If this h$#roen is not remo+e# in some*"$) it forms " '("n-et o+er the met"( "n# re#&!es the r"teof !orrosion. S&(f"te?re#&!in '"!teri" !ons&me thish$#roen) th&s s%ee#in &% the r"te of !orrosion. There#&!tion of s&(f"te res&(ts in the form"tion of h$#roens&(fi#e/ this) in t&rn) !"&ses f&rther !orrosion. This t$%e of'io(oi!"( !orrosion m"$ res&(t in se+ere %ittin of&n#erro&n# %i%e(ines


fr Resale, >?;=;>13 >


41/50

4

0


"n# other e13 >


42/50

EROSION ?1

o+er the interior s&rf"!e of the e. Ther"te of erosion in!re"ses "s the so(i#s !on!entr"tion in thestre"m in!re"ses.

. Tem%er"t&re. The erosion resist"n!e of stee( ener"(($#e!re"ses "s the o%er"tin tem%er"t&re in!re"ses.

Erosion is &s&"(($ (o!"(ie#/ '&t "t times it is +er$ener"() "n# this m"-es it #iffi!&(t to #ete!t +is&"(($/ L"reero#e# "re"s h"+e " 'riht) shin$ "%%e"r"n!e "n# fee( s(i!-"n# irre&("r. Lo!"(ie# ero#e# "re"s "re (i-e($ to o!!&r*here the stre"ms !h"ne #ire!tion or "re restri!te#) s&!h

"s "t s(i#e +"(+es =Fi. 4 "n# 47>.

FIG. 4??Erosion of " S(i#e :"(+e in " C"t"($ti! Cr"!-in Unit.


i!e! b& I.S un!er license 5ith #$I repr!uctin r net5r6ing permitte! 5ithut license frm I.S

-icensee/l8 lnternatinal:9;1 Ntfr Resale, >?;=;>13 >


43/50

?; CONDITIONS CAUSING DETERIORATION OR FAILURES

FIG. 47?S(i#e :"(+e from " C"t"($ti! Cr"!-in Unit.




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EFFECTS OF ,IG,TEMPERATURES

4

orifi!es) +esse( in(et "n# o&t(et no(es) "n# +esse( ri#s=Fi. 4 "n# 4 3>. Are"s s&!h "s "er"tion !onne!tions)thermo!o&%(es) ste"m no(es) %i%e 'en#s) !$!(one se%?"r"tor intern"(s) ri# se"(s) e!h"ner intern"(s) im?%inement '"ff(es) "n# miin !o(&mns "re "(so s&'8e!t to(o!"(ie# erosion. Fi. 4@ sho*s the !om'ine# effe!ts of

erosion "n# !orrosion in " ("re f(&e?"s (ine. W"ter s%r"$s*ere &se# #&rin the r&n) "n# this "##e# to the#eterior"tion of the (iner. F(&i#ie# so(i#s) (e"-in thro&hsm"(( !r"!-s or %inho(es "t hih +e(o!ities) !"&se se+ereerosion "n# !r"!-s) "n# the %inho(es r"%i#($ ro* in sie.Serio&s "tt"!- m"$ o!!&r on intern"( e?;=;>13 >


45/50


FIG. 43?Reener"tor Gri# from " C"t"($ti! Cr"!-in Unit.

ser+i!e (ife r"ther th"n to (imit #eform"tion. In these !"ses)stress?r&%t&re #"t" "re more +"(&"'(e th"n !ree% #"t".Stress r&%t&re re("tes the time?to?f"i(&re *ith tem%er"t&re"n# stress. A!t&"(($) stress?r&%t&re tests "re +er$ simi("r to!ree% tests) e!e%t th"t the (o"#s"n#) !onse+"(&es "re etr"%o("te# for shorter time tests. Stress?r&%t&re

te!hni for finishe#%ro#&!ts h"+e 'een re+ise# to in!(e (imits on the

%ro%erties of en# %ro#&!ts) s&!h "s %("te) %i%e) "n# the (i-e.St"n#"r#s) s&!h "s ASME Co#e C"se 1457 for In!o(o$)in!(e t*o !("sses of m"teri"(s9 C("ss Pfine?r"ine# fortem%er"t&res ne"rer "tmos%heri! tem%er"t&re) C("ss 11??!o"rse?r"ine# for e(e+"te# tem%er"t&re ser+i!e. ASTM B63 !o+ers on($ C("ss II for In!o(o$. Both !ree% "n# stressr&%t&re %ro%erties "re im%ro+e# in the !o"rse?r"ine#m"teri"(s. The #es!ri%tion "s K!o"rse?r"ine#K is &se# sin!eit is the


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46/50

EFFECTS OF ,IG, TEMPERA TURES 45

FIG. 4@?Deterior"tion of Liner in F(&e?G"s Line on " C"t"($ti! Cr"!-in Unit.

most "+"i("'(e metho# of #eterminin if m"teri"( h"s 'eenso(&tion?"nne"(e#. The "!t&"( effe!t on hih tem%er"t&re isth"t the !"r'i#es h"+e 'een t"-en into so(&tions. Whi(e thisis o!!&rrin) r"in !o"rsenin ener"(($ o!!&rs. Theso(&tion "nne"(in in!re"ses hih?tem%er"t&re strenth ofmost m"teri"(s "n# &s&"(($ "t the e%ense of hih?tem%er"t&re #&!ti(it$.

56.65 Met"((&ri!"( Str&!t&r"( Ch"nes

56.651 INTRODUCTION9 A(( met"(s "n# "((o$s &n?#ero !h"nes *hen he"te# "'o+e " !ert"in tem%er"t&re.These !h"nes m"$ 'e !("ssifie# into t*o 'ro"# !"teories9str&!t&r"( !h"nes "n# !om%osition"( !h"nes.

Met"(s "n# "((o$s "re !om%ose# of one or more t$%es oftin$ !r$st"(s) often !"((e# Kr"ins.K Str&!t&r"( !h"ne refersto "n$ !h"ne th"t o!!&rs in the !r$st"(s or r"ins.

In or#er to &n#erst"n# ho* e!essi+e tem%er"t&res!"&se h"rmf&( str&!t&r"( !h"nes "n# *h"t these !h"nes




"re) the re"#er sho&(# refer to A%%en#i I for " ener"(#is!&ssion of the !ommon refiner$ met"(s "n# "((o$s.

56.655 STRUCTURAL C,ANGES9 The most serio&sstr&!t&r"( !h"nes th"t m"$ o!!&r in refiner$ met"(s "n#"((o$s "re #is!&sse# in the fo((o*in %"r"r"%hs.

a. Grain Gro!th: In ener"() the sm"((er the r"in siein " met"( or "((o$) the hiher the tensi(e strenth "n# the(o*er the r&%t&re "n# !ree% strenths =ener"(($ "t hihest!ree% tem%er"t&res>. Met"(s "re) therefore) %ro#&!e# *ith "

r"in sie 'est s&ite# to the o%er"tin !on#itions &n#er*hi!h e"!h met"( is to 'e &se#) "n# "n$ !h"ne in this sieis #etriment"(.

When ferriti! stee(s "re he"te# "'o+e " !ert"in tem?%er"t&re ="'o+e () 166 F for mi(# stee( #e%en#in on !o(#*or- > ) r"in ro*th o!!&rs "n# (e"#s to " ener"((o*erin of the tensi(e strenth. For this re"son) "n$ mi(#?stee( e?;=;>13 >


47/50


oriin"( strenth of the %"rt m"$ h"+e 'een (o*ere# "n# theoriin"( f"!tor of s"fet$ re#&!e#. The "mo&nt of#eterior"tion #e%en#s on the m"im&m tem%er"t&reen!o&ntere# =*hi!h sets the m"im&m %ossi'(e r"in sie>"n# the (enth of time "t this tem%er"t&re =*hi!h#etermines *hether there *"s s&ffi!ient time to re"!hm"im&m sie> . Note th"t the "'o+e tem%er"t&re (e+e(

!"nnot 'e firm($ est"'(ishe# 'e!"&se of t$%e of stee()#eree of !o(# *or-) "n# time of e%os&re. Tem%er"t&rese+en "'o+e 1)476 F m"$ 'e re) "n#str&!t&r"( !h"nes #&e to e!essi+e tem%er"t&res *i(( o!!&ron($ in &n&s&"( !ir!&mst"n!es) s&!h "s fires.

b. Incipient 3eltin% (urnin%6: If the ferriti! stee(s "rehe"te# "'o+e "%%roim"te($ 5)66 F) me(tin "n# oi#"tion*i(( 'ein "t the r"in 'o&n#"ries. Stee( in s&!h " !on#itionis !"((e# K'&rne#K "n# is +er$ (i-e($ to %"rt interr"n&("r($&n#er its o*n *eiht. Sho&(# f"i(&re not o!!&r "t the hihtem%er"t&re) the stee( *i(( 'e +er$ *e"- "n# 'ritt(e &%on!oo(in.

A simi("r !on#ition *i(( o!!&r in the "&steniti! st"in(essstee(s *hen the$ "re he"te# "'o+e "%%roim"te($ 5)766F.

C"st irons "n# ni!-e() !o%%er) "(&min&m) "n# their

"((o$s !"n "(so s&ffer in!i%ient me(tin.c. Graphiti2ation: Cert"in ferriti! stee(s) *hen o%er"te#

for (on %erio#s in the r"ne of @57 F to 1)66 F) m"$s&ffer " t$%e of str&!t&r"( !h"ne !"((e# r"%hiti"tion. The!ementite or !"r'i#e *hi!h i+es ferriti! stee(s theirstrenth is &nst"'(e "n#) in this tem%er"t&re r"ne) m"$#e!om%ose into iron =ferrite> !r$st"(s "n# r"%hite =!"r'on>no#&(es. This #e!om%osition is -no*n "s r"%hiti"tion. 3

Re%("!ement of the h"r#) stron !"r'i#e *ith soft) *e"-iron "n# r"%hite (o*ersthe strenth of the stee(.

Some stee(s "re m&!h more s&s!e%ti'(e to r"%hiti"tionth"n others) "n# r"%hiti"tion seems (imite#) for "((%r"!ti!"( %&r%oses) to !"r'on "n# !"r'on? mo($'#en&m

stee(s. E"!t($ *h"t !"&ses some stee(s to r"%hitie *hi(eothers "re resist"nt h"s not $et 'een #etermine#/ ho*e+er)+"rio&s !orre("tions h"+e 'een fo&n# *hi!h in#i!"te th"tsm"(( "mo&nts of minor !onstit&ents !"n inf(&en!e theten#en!$ to r"%hitie. Th&s) stee(s *ith more th"n 6.617%er!ent "(&min&m ten# to 'e %rone to r"%hitie.?.


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EFFECTS OF ,IG, TEMPERATURES 4

7

Re%ro#&!e# from3aterials and 3ethods& !o%$riht 127. Re%ro#&!e# '$%ermission of B"tte((e Memori"( Instit&te.

FIG. 6?S!hern"ti! Lonitin"( Me#i"n Se!tion Thro&h "

Sin(e?: B&tt*e(#e# Pi%e oint.

m"te f"i(&re. Be!"&se of its "%%e"r"n!e) r"%hite form"tion"t the (o*?tem%er"t&re e#e of he"t?"ffe!te# ones is !"((e#the Ke$e'ro*K t$%e. Another t$%e of (o!"(ie#r"%hiti"tion sometimes o!!&rs "(on %("nes of (o!"(ie#$ie(#in in stee() !"((e# Lers (ines. S&!h (ines "reforme# in !o(#?*or-in o%er"tions (i-e 'en#in.

Tem%er"t&re h"s "n im%ort"nt effe!t on the r"te ofr"%hiti"tion. Be(o* @57 F the r"te is etreme($ s(o*.The r"te in!re"ses *ith in!re"sin tem%er"t&re to "m"im&m "t 1)176 F to 1)566 F. At hiher tem%er"?

Re%ro#&!e# from3aterials and 3ethods& !o%$riht 127. Re%ro#&!e# '$%ermission of B"tte((e Memori"( Instit&te.

FIG. 1?Gr"%hiti"tion "t the Lo*?Tem%er"t&re E#e of the

,e"t?Affe!te# Jone of " We(#e# Pi%e oint.




t&res the r"te #e!re"ses) "n# r"%hiti"tion %ro'"'($ !e"ses"'o+e 1)476 F to 1)66 F.

To #"te) no f"i(&res #ire!t($ "ttri'&t"'(e to r"%hiti"tionh"+e o!!&rre# in the refinin in#&str$/ ho*e+er)r"%hiti"tion h"s 'een fo&n# in !"ses *here f"i(&re *"s%rim"ri($ 'e!"&se of other !"&ses "n# m"$ h"+e

!ontri'&te# to s&!h f"i(&res. Se+er"( serio&s !"ses ofr"%hiti"tion h"+e "%%e"re# in the re"!tors "n# %i%in of!"t"($ti! !r"!-in &nits) "n# there h"s 'een one !"se in!"r'on?stee( therm"( !r"!-in?&nit f&rn"!e t&'es. In"nother !"se) f"i(&re of se"( *e(#s '$ r"%hite o!!&rre# in" !"t"($ti! !r"!-er *"ste he"t 'oi(er "t the 'ottom t&'esheet of the +erti!"( 'oi(er. The %o*er in#&str$ h"se%erien!e# f"i(&res !"&se# '$ r"%hiti"tion of 'oth!"r'on "n# !"r'on?mo($'#en&m ste"m %i%in.

Where !on!entr"te# Ke$e'ro*K forms of r"%hite o!!&r"(on he"t?"ffe!te# ones) the !ree% r&%t&re strenth m"$'e #r"sti!"(($ (o*ere#/ ho*e+er) s(iht to mo#er"te"mo&nts of r"%hite "(on the he"t?"ffe!te# ones #o not"%%e"r to (o*er room? or hih?tem%er"t&re %ro%ertiesm"teri"(($.K

d. 'ardenin%: When the ferriti! stee(s "re he"te# "'o+e1)476 F) "&stenite) " so(i# so(&tion of iron "n# !"r'on)'eins to form. On s(o* !oo(in) "&stenite tr"nsforms""in to form ferrite "n# !ementite. If the stee( is !oo(e#r"%i#($?"n# this !riti!"( r"te of !oo(in +"ries *i#e($ *iththe stee( !om%osition?m"rtensite) r"ther th"n ferrite "n#!ementite) is forme#. M"rtensite is "n etreme($ h"r#)'ritt(e s&'st"n!e) the form"tion of *hi!h is the o'8e!t ofh"r#enin he"t tre"tments.

In ener"() the !oo(in r"te re


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@ CONDITIONS CAUSING DETERIORATION OR FAILURES

rest of the %"rent met"( is re("ti+e($ !o(# "n#) '$ !on?#&!tion) r"%i#($ !oo(s the one "#8"!ent to the *e(# "n#!"&ses h"r#enin. This effe!t o!!&rs to " (esser etent in(o*?!"r'on?!ontent) %("in !"r'on stee(s 'e!"&se the !oo(inr"te is not f"st eno&h. In %("in !"r'on stee(s *ith o+er 6.47%er!ent of !"r'on) "n# in most of the "((o$ stee(s) the!oo(in r"te is f"st eno&h to !"&se h"r#enin "n# the

"!!om%"n$in 'ritt(eness. This is %"rti!&("r($ tr&e of thestr"iht !hromi&m stee(s 'e!"&se e+en "ir !oo(in h"r#ensthem.

In *e(#in) hardening a! "e #re$en%ed "! #rehea%in"n# %osthe"tin. Prehe"tin the s&rro&n#in met"( -ee%sthe !oo(in r"te) '$ !on#&!tion) #o*n to the %oint *here!om%(ete h"r#enin of the oi(? "n# *"terh"r#enin r"#esis &s&"(($ %re+ente#. Prehe"tin #oes not -ee% the "ir?h"r#enin r"#es from h"r#enin) '&t it #oes -ee% themfrom !r"!-in from stresses res&(tin from the !ontr"!tionof the s&rro&n#in met"( '$ r"%i# !oo(in. Posthe"tinre#&!es the 'ritt(eness "n# !"n 'e #one in t*o *"$s. Thefirst metho# is to &se " f&(( "nne"(in tre"tment in *hi!hthe met"( is he"te# to " hih eno&h tem%er"t&re to !on+ert

the m"rtensite to "&stenite) fo((o*e# '$ +er$ s(o* !oo(into %ro#&!e ferrite "n# !ementite. The se!on# metho# is tohe"t the met"( to " (o*er tem%er"t&re *hi!h "((o*s them"rtensite to tr"nsform to " (ess 'ritt(e !onstit&ent. Thisse!on# metho# is !"((e# Kstress re(ie+in)K or s&'!riti!"("nne"(in. These tre"tments "re re"(($ tem%erin or#r"*in tre"tment simi("r to those i+en to he"t?tre"te#stee(s.

Another *"$ in *hi!h refiner$ stee(s m"$ 'e!ome h"r#"n# 'ritt(e is from he"tin to f"!i(it"te 'en#in. Inf"'ri!"tin %i%e "n# %("te) for inst"n!e) it is often the%r"!ti!e to he"t %ortions of the stee( in or#er to m"-e'en#s. Sometimes the he"tin "n# 'en#in is fo((o*e# '$!oo(in *ith *"ter. From the foreoin #is!&ssion it !"n 'e

seen th"t "(tho&h this %r"!ti!e m"$ not res&(t in h"r#enin(o*?!"r'on stee() it *i(( s&re($ !"&se h"r#enin of the hih?!"r'on stee(s "n# str"iht !hrome stee(s. If the hih?!"r'onstee(s "n# str"iht !hrome stee(s "re he"te# for f"'ri!"tion"n# not %ro%er($ he"t?tre"te# to restore me!h"ni!"(%ro%erties) the$ m"$ !r"!- or f"i( in ser+i!e.

Simi("r to he"tin for 'en#in is the he"tin th"t m"$res&(t from fires. This he"tin m"$ 'e fo((o*e# '$ r"%i#!oo(in '$ *"ter from fire fihtin) *hi(e e+en !oo(in in"ir is eno&h to !"&se h"r#enin of m"n$ of the ferriti!"((o$ stee(s.

,"r#enin of the ferriti! "((o$ stee(s m"$ "(so res&(tfrom o+erhe"tin in ser+i!e?"s " res&(t of h&m"n error)ste"m?"ir #e!o-in of f&rn"!e t&'es) o+erfirin) !o-in) or&%sets?fo((o*e# '$ r"%i# !oo(in. A(tho&h !hromi&m?stee( f&rn"!e t&'es "re %"rti!&("r($ s&s!e%ti'(e to this t$%eof #"m"e) the$ #o not or#in"ri($ h"r#en in ser+i!e 'e!"&seof the +er$ s(o* r"te of !oo(in in " f&rn"!e. ,o*e+er)&n#er !ert"in !on#itions the %henomenon of !"r'&ri"tion)*hi!h *i(( 'e #is!&sse# ("ter) "!t&"(($ in!re"ses the !"r'on!ontent of




the stee(. If !"r'&ri"tion h"s o!!&rre# %re+io&s($) thein!re"se# !"r'on !ontent !h"nes the %ro%erties of themet"( so th"t e+en the s(o* !oo(in of the f&rn"!e 'o isf"st eno&h to !"&se h"r#enin. S&!h h"r#enin is often."!!om%"nie# '$ !r"!-in thro&h the t&'e *"(( or '$s%"((in of the 'ore.

Simi("r o+erhe"tin of %i%in) %ress&re +esse(s) "n#

other e


50/50

EFFECTS OF ,IG, TEMPERATURES 2

nomenon) '&t the !hromi&m?im%o+erishment theor$ is%ro'"'($ the most %o%&("r.K This theor$ %ro%oses th"t "s!hromi&m !"r'i#es "re %re!i%it"te# from the r"ins) the%ortions of the r"ins "#8"!ent to the r"in 'o&n#"ries "re#e%(ete# of !hromi&m "n# (ose their !orrosion resist"n!e.The effe!t of interr"n&("r !orrosion is m&!h the s"me "sth"t *hi!h miht 'e e%e!te# if some !orro#ent #isso(+e#"(( the mort"r in " 'ri!- '&i(#in. There *o&(# 'e nothinto ho(# the 'ri!-s toether.

In or#er to %re+ent interr"n&("r !orrosion) "&steniti!st"in(ess stee( for !orrosi+e "%%(i!"tions is s&%%(ie# in theso(&tion he"t?tre"te# st"te. The so(&tion he"t tre"tmentin+o(+es he"tin the stee( to "%%roim"te($ 5)666 F for "(on eno&h time to ens&re th"t "(( the !"r'i#es "re#isso(+e#. The stee( is then r"%i#($ !oo(e# =&s&"(($ in*"ter>. In"sm&!h "s it t"-es time for the %re!i%it"tion too!!&r in the sensitiin r"ne) r"%i# !oo(in thro&h thistem%er"t&re r"ne %re+ents "n$ sinifi!"nt "mo&nt of%re!i%it"tion. The fin"( str&!t&re is " s&%ers"t&r"te#"&stenite) "n# "(( the !"r'i#es "re in so(&tion. A&steniti!stee(s #o not h"r#en *hen . This so?!"((e# em'ritt(ement o!!&rs mostr"%i#($ ne"r @@7 F) '&t re

guide for refinery inspection

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