ML20084Q655

Answers Questions Raised at 700426 Meeting,Outlining Alternative Procedures to Repair safe-ends & Future Actions to Minimize Possibility of Unexpected Stress Corrosion

ML20084Q655
Person / Time
Site:	Nine Mile Point
Issue date:	04/09/1970
From:	Staehle R PARAMETER, INC.
To:	Engelken R US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084P985	List: ML20084Q227 ML20084Q318 ML20084Q633 ML20084Q644 ML20084Q655 ML20084Q663 ML20084Q676 ML20084Q686 ML20084Q738 ML20084Q901 ML20084Q905
References
NUDOCS 8306130522
Download: ML20084Q655 (8)

Text

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@ O R. W. Starhlu 5060 hvens Co r.a n Rcod CMutita, 0:iio Address reply to:

Dr. R. W. St achle Dept. of Metalhtrgical ID r.

116 We: t 19th Aveme Ohio State UniversUy Cohrd>s, Ohio 43210 .

9 A:ril,1970 Mr. R. H. Eb3elken Assistant Dirccitr of Inspcction an-1 I:nforecrient Divinicn c': Cr 11;nce Unitcd E'nt n A'xeJc rn:r:gy Ccrminsicn 7920 "xfolk l ,c:.:a rctheda, *aryhn3 DaTr lab, ,

Daring our twaring on 26 April,1970 in ycur o.Tfice you requestcd my ccrrycnts in tw arcas: (1) With resp.rt to the varicus rcrair prcccdu es t/aich night ha used to repair the eafe crds,1icat are they ard wlut are Iraaibic difi"ultics v;hich might b2 enecantere3. (2) Acc.ning tlnt sensitinol stainicas cteel continucs to b2 usci idnt kinds of prceautions micht be enrciscd in cparatin: plcnts ard durira plant construction to mininize t!'.e possibility of unc:poctal stress corrosion failurcs? This 1ctrer trancaitu my ans;;ers to these questions.

Repair Proccdres ani "' heir Inherent Probles Listcd balcr.; are a numbar of possible prcccdures by which safe erds

.now rade from sensitized stainless steal tr.ight b2 rextired. Discussed og with cnch of thcco alte rutives are possible con:ecns daich Iray effcct gg adversely the quality of the resulting repair.

ng .

88 1. Weld enerlav Sn o ~

.tv The nuin considerations in weld cuerlay procedures are the 00 c,. s follcuing: .-

no -

q< a. Type of rutcrial urol: 3 pes 304L,303L,316L,321, om no In:oloy-800, Incenal-600 "L' b. Thickness of overlay

c. Proccdure for suld overlay inch.diny hoat input, size of weld bead SCO attaChad table.

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( d. Irg tetion p.cccdure to aurare abacrce e2 Thws

[ which effcetively cgocc unicrlying -a tecial. ,

c. Over]ay of Poth inside nrd outside va. enly the inside,

f. Residual strcr.s in resulting onrlay.

g. Susceptjbility of weld overlay r,nterial to other forns of aLtcch.

Prob 2bly tiu most sericus quanticns of cuality in resulting we]d cr/crleys are:

a. UnrM +r cf r.;:MnicTl ric7crues o" t.he cemite prcAu'; d by tha cver2ny. It is r.ot 1 car tbt r.i;;h infomation is available, for exanole, in tha high strain-lea cycle fatitjuc, cr the th,.rcal check behavior of such structures.

b. The possibility of lack of fusion c Tosirg the urderlying t materiill to the cr/ironment.

Clrnairry the rutt al itself s6uld irclu-Je considration2 cf the type of failura s.hich is rcat Jihely. Since the prir,nry failure raie hre is intergrara]ar as associated with cnsitiation it is most roaccmble to rc".cVe the carbon (L-newleu) or use a stahlli zed rate-ial. Ecnicr, the a.~n tnc

=i of scnsitintti5n hre remitiny frc n wahl ove" Jay is not so significant as tMt in furnace sensitizirg.

? To my know1c3ge there is littic information on the ECC behavior of p sensitizcd Incolcy and Inconal. Despite the fact that the weld sensitization is not so as the furnace sensitizing, there is no clear indication as to hcra much is too btd when related to the other variables such au stress,

, contamination, ard oxygen. Regarding a specific choice ard priority of possible materials it muld secm tMt a Ica carbcn In: cloy-SCO offers the nest rcasonabic ccmprcaise. This alloy has a high resistance to the

. transgratular chlo-ido cracking which might start frcm the cutside, especially bccause of the nature of the weld cie-lay stresses. Altra, it does not appear

_i to be so susceptible to the ECC t.hich cccurs in Irron21-600 linen expoce-i to m ter--02 environments. Typa 316 stainless should be avoidcd due to its high susceptibility to ECC.

It secms to me tMt the weld overlay procc ure 4 prcduces tco much

uncertainty, especially where these safe erds are likely to be subjected to i

high stresses, to be cuploycd withcut substantial ccgerimental justification.

I 2 Replacanent Piping ,

i- Rather than using weld crierlay, there is the possibility j of cutting out the pipe directly and rep 3acin7 it with a seccially fabricatol pipe. The nuin considerations here are the followirg:

m-U a l mNm ',

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. a. Th2 we]diro of the rc.nlacerant to t.hc vessel muut be consideral with resget to &c mld sLre , , relief. . .

i b. Tlo choice of traterjnis v.culd be the suo as abo re.

l The major probicn here is prolubly the choice of allaf. It secn"; that the most conservative choice s.culd he a lov carbon g Incoloy 800. Itwaver, an 3noc]cy 800 maid 1.e acccptabic since f the aaoant of sen-itination during weldirg is prolably not I suff!cicat to cause difff aaltica. The usa of a stardard car.crcial p nnterial which can he ::tchine.1 a:d premrcl in the shop sccTs

to 00 Pr rcre nMme t' -

- c]- c/ cla". La c mr t of l testira to vinilcate the c;a.tlicy of the weld cr/erlay v.ould bc greatcc than tint for the fabricatcd pipe.

r

3. ' General Discus 31on of Materialrs, 2 There are a n'raber of general considerations in clnosing the 5 nnterjals t.tcther the weld o/erlay or solid rqdac;.n=t is uscd:

p k a. Type 304L cn3 304 a

s TTnen the cat on is 30 arcd fer the relativclv 1ceer Z nickcl 't;c 30 :L the clicy becc.nas very unstable .'eith '

rcy.d.L to ferr...sj the Zahtm 'bcdy centcca cubic) j l pluse. The nub;. rial can be e gceted to inve tw pinses '

r as it beccr.cs prcnrossively recre pure. Ecwc/cr, it is a not clear tlnt this duplcs structure is h2d. Tha tm a

pinse stracture is usually less sensitive to transgranular e KC induccd bf chloride although the amount of sccord r

plusc which will result in this structure is not clear.

Also, the tw tahase nutcrial teMs not to becone casily '

[ sensitizcd.

s As this less stable nnterial is deformd, it will - - -

transfona to an intermediate nnrtensitic phase; this will F-strengthen the alloy.

R i- The 304L stainless steel generally lus no better

, resistarce to chloride induccd transgranular stress corrosion I cracking than the ncimul grade. -

m Type 304L Ins a lower allombic strength than type 304.

E -

f 'r -

• In sununry, it is not unreasonable to use type 304L h .

if appropriate allomnce is nnde for lo.eered streryth f aM caterior protection is pro /idcd against chloride -

E .

irducM TC. hhile the amount of sensitization in either ER b -

r

=

= 4 L

mp .' _~__--.--

l .. n

. . g +

o.I I attachu.nt wolds er the ve1C overlay wi)) be less tlan - --

the furr na senaltirem ca n o, i t i c not n' e1. ntly -

c]etu: Mt cu bimtion o? strcns, tr.gerature, oxygen, ard oth= conta.mirar:t im!d esce tEc weld rcnsitirul maler.ial tn unic;. ja the intergnmuMr NC. If it were sin.n e::pri.nentally that this v.culd not cccar, the imentive to une the low carbon grades nny be lessen 21.

Ib'.:cver , ruch a bort.:c should 1r taktn only with careful delibarction. - -

b. Typa; 316 ani 316L The :,ain bria for usinJ tn:o 316 is its greater resistance to general corrosion ard pitting which is achicved by the acidition of nolylrierna. Ibwevcr, this alloy is smez!nt raore susceptible to chloride irduccd TC than tn>2 304.~70icse allofs contain slightly higher Ni tlun 304 to stabilize the structure against the ferrite fc=1rg tc.demica of tPc .io. Frcr. a practical poirt of -

vic; the.m alloys precily diffcc little frem Tupes 304 - -

and 30b. -

c. The hight nichel stainless steals: 303, 309, 310 Thesa alkyo c 2c- tM aic.n'r;a c2 pro;rcesively improvc3 resistance to chlorife inluccl FCC. In their -

low carl:on fom the increasc of chrcmium and nickel t.culd off set tJ:e loszerirry of strength in the 304L. Tha b2havior >

of these alleys in tha weld sensitized cordition with respect . .

to intergranular TC is not known. It is reasonable that - -

these alleys i.culd prcvide general imprcuenents only because of their inercased alloy content.

d. The stabilizcd stainless steels: 321, 347 These offer innunity to censitization litt no improvencnt in resistance to chloride-TC. Difficulties are of ten encountercd in achicting good weld quality uith these materials ard spccial care rust b2 taken during the welding

. operation an3 subsegacnt inspcction.

I -

e. The intermediate nickel alloys: Incoloy 800 ard 825 -

~,

These alloys offer the optimum canbination of resistance -

, - - 4 to various forms of corrosion kncr.m in this alloy systan.

The nore car.on alley is the 800 ard its use in .this application is prohiblj the most conservation decision.

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6 6M E& mN d

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f. The high nickel alloys: Inco]ey 713, 000 .

'those allovs of fer al;nolute resist /trce to the chloridc-inium 1 FCC but are micceptible to crackJ:rt (

Jn Iwo t-Acr . 0 pre '.:atcr containiry trace tc.ounts of eggcc cr 1 cad.

4. Cource ~of Act.i._en .

Pro!xibly the rnnt conservat.ive overall ccm:se of action wculd be to ure sh;; fiirica w". :afe ca:., of Ircoluj JC0 '..:hich .culd i n @ul j e , ~ 5 t i.- ._ tE m , .

t c.mn'. an1 c ."r of R nriti u : c: ti ec ct _ esi ' , x21:ly r.1 be sufficio:rc to rcqaire the use of a Jo ; carica allcy. The Ica carbon grade of this alloy is not a widely teal rnaterial. My next choice tuuld b2 a Type 310 stainless steel bccause of its ranc.drit jmprovcd resistance to chloride FCC. I muld not suggest the Icw carbon hcre lxmuse of tha bck of carcrcial c:qnrie:ce with such a orade an3 tha fact that tha higher Cr in tha alloy r;xy protcat the grain iraMarica.

Sfety ar i nrctetive "carmes fc>: Prczentin, St' ess Co' rosion Crackim ot Stainb. s allces W er" recreci : ar.dir.g c: stainicaa % c allvg is s ifici."cly .

fregacnt that spccial attention cheuld be given to pro:chren for re?.ucing the protnhility of its occurre:ce. Enile these alloys are gaite resistant to corrosien in the c hsence of sLrcss, they can fail rapidly (within a ,

fcw hours) under cc-tain miironmntal circostances when stresssi. A nomally -

corrosion resistant r:aterial givea a falco cense of security to users despite tha possibility of such a virulent failure prccess.

Because of the wide use of stainless steels in reactor plants ard bccause of the ever present possibility of unevpectcd failure it is appropriate to take special prceautions not only during power operation b2t at all times (testing, construction, shut down) . Spo ific measures which might -

be considered are as follcws:

1.

Leaks ard drips arry.inere in the reacter should be stopperi, collecto1, or directed to the drain. The drip by itself is not necessarily Inrmful bat dripping on hot surfacca where imarities can corcentrate by c/aporation can lead to rapid ECC. Ezen if the drip water is pure, it nay pick up impurities fran the surfaces over which it travels airl deposits than on the hot surface. , ,,

2 Any fonn of chanical contamination should be avoided until approvcd 1ry a person with authcrity. This includes cleaning agents, lubricants, ard organic wastes.

4 a.

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3. Aslestoa t.y,m irreilation natc ~ial frca 'zhich conir irants can le 3erl xl shold M m uid .1 L uny toint in the plant. 4 It mald c 1 m to vu .'. .t tc w:' . . ci nc. #7 the metal cirror insalatiam cu.rrrJy u: :d en rrecur.t >1 ants. .

L 4 Scra? concic.n tion :V ild 1. cicca to cultire; the ente::nal surfaces of stajnless type alleys with a suital;1y protcctive material to prezent dircct contni. nation of the surfcce. The spoi.ic ccatirq to ba nao3 is nat pre:mnt clear. Po :J/cr, a suitabi s - r citeri:.1 ..t.uld Irmj& a g>mt rRasure of prctcetion j agairrit crachirg frm the cW:sile r."r#ac~ .

5. FL9d $.;JC 1: -

~.c 'cc s's:U 1- cse u l .1  : c' :Pir " qi~ e high nu _ ; me.mc.; t:ere/ coa .uve b;ea car;.m to cauce extensive FCC (Oystcc Creek) .

6.

Surface inopcetion chculd not. rely alone on penetrant testing since existira cracks are often minsci bf such a tcchnione. Such tests chaald be supplc anted at least by ultraronic techniques.

7. Careful atec. . ic a 4. a lci te ciw.<' to c:a birima srvcc.rcs of a --hd it piping rpt.- s :n ten coE aul i ^t cc:viitiens. Furthur, the later a0 lition c:? tt.r;'ci"ra ' 1mi.ures c;;h as seit ic restraints thculd Le acco',mn. cl by an ay copria c' cly ccmide c'? strt m analysis.

R. Pridicch;.- ~'- ~

c n chc.:'.2 bc adc to c'.;c:: fc,r contami:.:.nta cuch as chierina, trcmine, f]uorine, iodine, sulfur, lead, arac:.ic, ccrper. a .:rcury, an.i cad:aitra. Such chceks v.ould bc :rade unirc dilute acid s' abs '.>hich cro eJbsecucntly cralyzcl for th;Le elcacnts. Lccations for such arnlyses should considcr equially those m cas 'iciere drips might collect. Also points of high stress (applicd plus residual) in critical areas should be checked.

9.

Methods sought. for rcducing high residttal stresses should be rcre extensively Procedures of fabrication for large piping systcms should be carefully revic.eed to ro-luce residual stresses.

I hope the ahoye meets your needs. If you inve arrf questions, please contact me.

&. cr ly.ycurs,

/ -

1

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w R. W. Sta > le w[h -

RWS:lah Consultant cc: Richard Infy 4

tan! I: I-Cin ial Co.cno%n 1.ie Jts .ru1 l'ap for su N meh C..'d;;  : cent.ps) i Q b IkQnatkna y

or }

type E:n Si P S Nur. A r C W s. E s. 5f n. E s.

Ca Ni 0:1.ct l.lmirnh.

1. L!n.nhic ( h r#.a.n .w. !s 403 0.15 tin. 1.00 0.50 0.0-t o 0.030 11.50-1100 410 0.15 ?dn. 1 00 1.00 OW0 0.0 L 11.5&13.f 0 414 0.15 hin. 1.00 1.00 0.040 u.02 J l l.50-l M 0 1.25 2.50 416 0.15 h n. 1.25 1.00 0.05 0.15 Siin. 12 00 14.00 416 Sc 0.15 hin. 1.25 1.00 51o:0.60 Siu.

0.05 0.0G 12.00 14.00 420 0.w 015 1.00 Se:0.15 !.!ia.

1.09 0.0:0 0.030 12.0414.00 431 0.2011u. 1.00 1.00 0.0 ;0 0.030 440A 15.00 17.00 1.25 2.50 0.00 0.75 1.00 1.00 0.0 :0 0 010 16.00-1".o] Eto:0.75 ?.l.it 4403 0.'i51 M 1.00 1.00 0.0;0 o.m o 16.001100 110:0.75 .' ! :t 410C 0% 1. .'o I rn 1.00 0.0 :a C.c m IUn p :.0 .h 0.75 :i s 501 0.cr D.10 1M 1.0a 0 01'] t.. ') 4.00 a >!o:0 4 0 G 502 0.10 T!n. 1.00 1.00 0.00 0.0: 0 4.006.00 Afo:0.40-0.65

11. I craitic Chromium Stet b 405 0.08 Tfn. 1.00 1.00 0.040 0.030 11.50-14.50 At:0.10 0.30 430 0.12 :4n. 1.00 1.00 0.040 0.030 14.00-10.00 430!' O.12 mt 1.25 1.00 0 06 0.15 . Min. 14.00 13.00 h!o:0.60 5f n.

410F Sc 0.1 : Sin. 1.25 1.00 0.06 0. ~. 14.001 M S::0.15 .%.

416 0.20 Lt 1.50 1.00 0.040 0.030 23.0327 c0

=- N:0.25 ?!:x.

I!!. Aum nisb Ch:c.mim.W.! Steds 201 0.15 .Mn. 5.507.50 1.00 0.050 0.030 16.00 12 10 202 0.15 :4n. 3.50-5.'0 N.O.25 M u.

7.5& lE c0 1.00 0.000 0.019 201 17.00 19.00 4.00 6.C3 N:0.25 ):n.

0. I '. '.S 2D  !.00 0.0 ;5 C .1.' a 4 T. U,- i :. .

E.:4 2...

304 0.15:1n. 2.00 1.00 0.045 0.020 17.00 19.00 302B 0.15 tn. 2.00 8.00-10.00 2033.00 0.045 0.030 17.00 19.00 8.0010.C 0 303 0.15 Lt 2.00 1.00 0.20 0.15 Min. 17.00 19 00 303Se 0.15 .'.i n. 2.00 8.0010.00 5fo:0.60 Sin.

1.00 0.20 0.05 17.00-19.00 301 0.0S Mn. 8.00-10.00 S :0.15 Min.

2.00 1.00 0.045 0 03a 304L 18.0} 20.00 8.00 12.00 0.03 Mn. 2.00 1.00 0.045 0.030 305 18.0420.00 8.00 12.00 0.12 Mn. 2.00 1.00 0.045 308 0.030 17.00 19.03 10.00513.00 0.0S M:x. 2.00 0.045 1.0Q 0.030 19.00-21.00 10.00 12.00 309 .20 Mn. 2.00 1.00 .045 .030 22.00-24.00 309S 12.00-15.00

.0S Mn. 2.00 1.00 .045 .030 310 22.00-24.00 12.00 15.00

.25 Mav. 2.00 1.50 .045 310s .030 24.00-26.00 19.00-22.00

.08 Mn. 2.0Q 1.50 .045 .030

• 314 24.00-26.00 19.00-22.00

.25 Mn. 2.00 1.50 3.00 .045 .030 316 23.00 26.00 19.0422.00 Mo:2.00 3.00

.03 Mn. 2.00 1.00 .045 .030 316L 16.00 1S.00 10.00-14.00 Mo:2.00 3.00

.03 Mn. 2.00 1.00 .045 .030 317 16.00-18.00 10.00 14.00 Mo:3.00-4.00

.03 Mn. 2.00 1.00 .045 .030 321 18.03 20.00 11.00-15.00 Ti:5 x C. Min.

.03 m s. 2.00 1.00 .045 .030 347 17.00 19.00 9.00 12.00 Cb-Ta:10 x C, Min.

.0S Mn. 2.00 1.00 .045 .030 348 17.00-19.00 9.00-13.00 Cb-Ta:10 x C, Min.,

.08 Mu. 2.00 1.00 .045 .030 17.00-19.00 9.00-13.00 Ta : 0.10 .'.f u.,

s Co:0.20 Mn.

. n. -: -

w -

l A. ,8 1

fk N-k

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- 4 1 A!.l.t; I (mnfJ.) ~

ILd;na rian or

• 1ype Mn Si l' S t;n u t..r C E s. E x. E s. M n. Cr Ni Orlwr ! tu.i:nts

!V.11ccti in tna fin l'.ilw; mi .le s *it cis Pil!5 7 Mo .07 E s. .70 .40 15.00 7.00 1.15 A1, 2.25Mo 17 4 P1I .0 t Es. 40 .50 16.50 4.25 .25Cb, 34 Cu l 17 7 Pil .07 Mn. .70 .40 '

17.00 7.00 1.15 Al AM-35 0 .lD Mn. .75 .35 16.50 4.25 2.75 M o, 0.10N AM 355 .13 Mn. .65 .35 15.50 4.25 2.75 M o, 0.12 N V. 0:he s ini v:x I 600 .0 i Mn. .20 .20 .007 15.3 76.0 7.201 e 625 .0$ Mn. .15 .30 .007 22.0 61.0 31'c, 4Cb, 9 M o 718 .01 Mn. .20 .20 .007 19.0 $ 2.5 18.01'c 60Al,

.80Ti, 5.2Cb, 3M o X750 .04 Max. .70 .30 .007 15.0 73.0 6.751 c, .80Al.

2.50'l i, 0.S5 Cb Incoloy 80n .04 M n. .75 .35 .007 20.5 32.0 46.0Fe 30Cu 60; .06. h . .9 .007 29 43.7 24.5 0Fe. :Tu H25 .03 Ma. .65 .35 .007 2 t.5 41.8 30Fe,1.E ' .

0.15Al,O E :i.

3.0Mo flimoni.:

75 .10 Mn. .45 .45 .007 20.5 77.6 0.50Fe 20At. 351i Tencion .08 Mn. 14.70 .52 .025 .005 18.0 .13Mo, .l lCu,40N Cro tuy 16 1 .03 Mu. 16.75 1.09 1.51Mo, .90Cu Carpenter 20 .07 .7 20.0 29 2.00Mo, 3.00Cu 7 Mo(') .20 1.0 23-28 2.55 12Mo CD4MCu .04 1.0 25-27 4.7-6.0 1.75-2.25 M o, 2.75-3.25 Cu WCarpenter 7 Mo isT> pc 329.

Of special interest :ue the single p!use a Fe (ferritic) and This equation is valid for the fo!!owing r.mpe of comp +

7-Ni (austenitic) reg' ions and the two phase a 7 region.1he sitions:

7 - a transformation is very slu;gi>h with the result that Element Range of Composition (9) the nominally two phase ta + 7) ai:oys are generally smgle phase unless the alloy is defonned or unless certain gamma .C 0.03 - 0.20 stabilizing impurity elements (su,h as N, C) are absent. hin 0.4 - 4.0 Carbon, nitrogen, manganese, cobalt, nickel, and copper Si 'O.30- 0.50 contribute to the stability of austenite; chromium. Or '

14.0 -25 tungsten, tantalum, mo ybdenum, columtium, silicon, Ni 7.5 -21 titanium, unadium, and aluminum stabilize the ferrite. The hio' O.1 -3 -

amount of nickel necessary to maintam a stable austenitie structure with respect to the presence of other ferrite or austenite stabilizers has been quantitied in an emption by Nitrogen is a ver; potent stabilii.ing element. It lowers Post and liberly as fol!ous: the Fe-N cuteeteid to 590 C at 2.35 wei ht g pereeni compared with 723 C and 0.80 weight percent fer

, (Cr + 1.5 51o - 20)2 h!n carbon. The effect of nickel on stabilizing austenite h

- 35 C + 15 12 2 shown in l'igures 6 and 7. This elemert lowers the

.