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GE Power Generation

Gas Turbine Compressor Operating Environment and Material Evaluation

R.W. Haskell GECompany Schenectady, New York

GE TURBINE REFERENCE LIBRARY

GAS TURBINE COMPRESSOR OPERATING ENVIRONMENT AND MATERIAL EVALUATION

R. W. Haske ll GE Company

Schenectady, New York

ABSTRACT

The reliability and pc,form:lIlce ofa gas Il lluinc c<)UlI)rcssor is strongl y defM! udc nt upon tile e nviron. ment in which il operm!'s, the malerials thm :Ire used. and the f, I(IOI(ion syscem. Erosion and. to a (e"a;n extent, fouling can be controlled by the fil tration system. but oolTO$ion is largely com rolled through site and material sclooion. TIle factors which dete Tmine the corrosivi ly of a silt: arc humidity, the concentration of acid·fonning gases, and the cOinposilion o f ,)".ticulates. The illlcrrcl,,­,ions hillS oflhcse factors are discussed wilh :m aim of reducing their imp;lci on compressor oper.llion. A neceH;u)'condi\ion foroolTOSion is the preseno:c o f moistu rc. l1u:: acidity of the moistu re resul ts from ilS imc l'lIctio n with the g;ISCS and panieulmes o rthe e nvirOlime nL The det:li ls of th<:se in(cr:u:ti o ll s which arc irnponll rll 10 !Urnine opcnlto rs :1I'e dis­cussed . A considenlblc amount o f corrosion lesting ofb:lsc m:lteriah :lnd CO;ltin~ hasbcen IICrfonlled, a nd Ihis is rcvie,,-ed. A mble is presentoo for sclt:<tion of compressor m:llcri:lb based o n Ihe nalure of ,he sile <:nvironment and Ihe 1)1><: of coml>l"essor fil tration.

INTRODUCTION

The envi ronment is a mosl imponant factor in dete mtining Ihe rc!i:lbil ilY a nd perfonnance o f a g;1S Ilubine compressor. The nature of Ihe :Iir entc t'ing Ihe compn:ssor in lemlS of ils humidity, u~lce g;1St.'QUS species, ",'d Ila niculme detenni ne the fouling, corrosion. ami erosion which occuron the blading. T he erosion and, 10 a cenain e~t el1 t, Ihe fouling can be controlled b y filtratio n, but the ool'TOSio n may be ahno!)t indq><:ndent of flltnl1ion li nd o nly limiled by Ihe sile environmem a"d compressor material$.

Compn:ssof corrosion i, " n aqueous phCllome­non a nd, Iherefo re, requires moisture . The amount of moisture. ilS chemi$lry, and the coml"l'ssor • natc liab i,wo h-ed ,,·i ll dete n nine the oolTosion nlte

and ultimalely how ofte" rcblading andl or Iccoat­ing b necessary_

J'ining corrosion is Ihe USIl:lI Iype of cOlTosio n found o n SI :linlcss-steei comprcssor blading. In cascs wilen: severe pilling occurs at pl:lccs of high Slress. corrosion fatigue wi ll result and blade f:. ilure bct:ottles a possibility.

It follows thai gl·eat Gue should be taken in choosing the site for a gas lurbine, in lllise$Sing Ihe n allIre of the etlvironmem. and in selecting the l" o l><:r nmlel'ials for the ~ :ompressor. This ~ec l11s more impon:lnt IOd"y whe n il appears e nviron­mentally produced cOllosion 1)l'Oblem5 ha\'e in­creased in r«ell! years.

MOISTURE FORMATION

Compressor corl'Osion i ~ the result of moi~Uire­cottl:li tting salts a nd acids co lleClin g on 1 he bl:ldi ng. During OJ><:ration, mois"" 'e can be preS<:nt due to the ingeRion ofwaler from ra in. When the turbine is not in operatio n, the compressor c:an still become ..... et :IS a result of condensation from w-~mt nloist air circulating through Ihe compressor (clmsed by chill.ney dTcrts). 'n,is circulat ion is substllnlial when:t turbine firSI cumes down and 1:lI'ge lempe r­ature difTerences exist belwccn inside ~nd outside_ Conde nsation is aJso possible within :1 un il Ih"l is not o perating " 'hen w-~Iln humid air COItl:.(U cold metal surf:lces. -mis can happen to uni ts in storage,

Att often overlooked source of 11wislllre, but peThal)s the most d~nu.ging in tenns of c:lusing cOllIpressot" conosion. is Ihm pl'Oduced whcn humid air is :Iccclcr.ued :lI thc comprcssor ittlet during turuine o pcration. Wh e n airis:tC(cienIlL..:I, there is a drop in its stalic telllllCrallJre. If Ihi, lel11IICral" re drop is sufficient 10 ClIU S<: the air to become saUintled with moisture, the n contlcnsation will occur if sufficient s uhmicron !l:micle" c:IJied COlt­

de nsmion nuclei. arc presem. Mosl siles will have sufficietll nuclci. T:lble I shows the tellllICnlUire depressio n for VllriOUS in le l Mach numbers :lnd Ihe in let humidity which would result in satunttion. GE co.npressors have inlet Mach numbers of about 0.5 .

which from Table 1 gives a lempermUre depression o f 24 of . If 80 OF ai r having a re lative humidity of 46% i5 cooled 24 ••.. its relalive humidity will reach 1000and condensatio n wi ll occnron condcnsatiOIl nuclei. upcrience shows that an ambient humidity o f aOOut 50% wi ll result in condcnsaliOIl, and humidities of 75% or greater result in extensive droplet fonnalion.A model for droplet fonnation in gas turb ine compressors has been developed by Zerkle (l982.l>p, 101 -111).

Table I

TEMPERATURE DEPRESSION DUE TO ACCELERATION AT INLET

TDEPJt£SSION (' F)

1.0 U 9.5

16.7 24.2 37.6

(T I",b - 80 . F)

Inlet Humidity Resulting in

Mach No. Satul'ltion

0.1 98 0.2 88 0.3 73 0.4 55 0.5 46 0.6 'n

A$ air goes un'Ough a compre$$or, its tempenilure will rise due to compression. Calculations show droplets will grow 10 aOOul a micron in size before they begin to evapomle. O f COUT5C. the droplets fonned from oondellJalioll wi ll impinge on the blading and collecL F.ventually. larger dl'Ops wi ll fonn o n the blading, be removed by aerodynamic forces, :md tnwel furthe r into the compressor. It is difficu lt to ca lculate the detai ls of Ihis process, bUI field obselV .. llions make it clear Ihat liule moisture 5ulV;ves the eighlh oomllrcssor siage as liquid (Kolkman a nd Mom 1984). as oolTOsion is generAlly nOI obscl>'ed beyond Ihis stage in bascJoad machines. T he reason for Ihis becomes dear whcn one plou the OOil ing temllCr.lIure of W3te rand stage tempcr~ture vcrsus Stage number. As shown in Figure l.the CUlVel cross al aOOutthe eighth stage.

CORROSION, MOISTURE, AND DEPOSITS

TIIC £inc drops occuning because of oondensa­tion of humid air in the inlet, togelherwi\h Ihe ,,'ct b lading. make for a very high sUlface arca and a n ellCCllent scavenger (indeed Jeo,bber) for ...... riOU! ga$CS emering the oompres.sor. In scrubbing the air. ule moist surfaces and Ihe droplets almost cen:linly

,

... ' ..

t '" ! ." ~ ... ...

'" .... "," '."",, .. ...... "'00: ""'-IT

f'GA3eOH

Figure L Approximate temperature and boil­ing point versus comprcssor stage.

become acidic. for the 1f.lS<:5 being Kr11bbed from the ai r are usually C02. SOx. NOx, He l. and 02. A possible exception to this might be NHs, but experi­cnce has shown th"t there is sufficie nt chloride and sulfate in m05l environments to resu lt in deposits which are am monium sulfatC$, nitrates. and chlorides. Solutions orthes<: 5..~lts are acid ic.

'n le acidity of [he moisture o n the blading. and certainly pal1 of it5 COlTOsive characte r. is deter­mined by the partial pressures of the gases being scavenged. Table 2 gives some idea of the magni­wdel involved. He rc the acidity of the moisture in equi librium with ceruin le\'Cls of a ga5eOUS specie has been calculated. TIle two cases are for a gas fonning a strong acid (hydrochloric) and a weak acid (sulfurous). In the C-dSC orS<>.!, "mbienllcvcls o f 100 ppo :.I'C not uncommon. which llCcording to lhe table lead to a pH of ~5. For the strong :.cid­fonner (HCI), even one PI'" can lead to extremely acidic conditions.

The imponant l)(Iint to be made from these themlodyn:ul1 ic consider.otion5 is that low levels of cen ain gases may result in very acidic conditions: Lhus, the imponance not only of where a tumine is sited. but in what direclion it face s. It should be appreciated that the low le\'els o f 8".lSCOUI con­taminants which produce acidic moiSture C'..oll De generaled locally. T hus, careful considernt ion should be given 10 what is in the local e nvironme11l ofthe lumine. What chcmicalsare ncar the turbine? Will Ihese chemicals produce :m acidic dew or moisture? As noted ill Table 2. even minute a,,)(IUllts ofsoL11e chemicals can result in a very acidic dew or

o

I

O~

I

Table 2

AClDrIY OF AMBIENT GASES

Sulfurous Acid Ambient Sulfur

Dioxide Dissolved SO:! (ppb)- (ppm)- pH

1 0.20 55 10 0.&1 5.0

11111 2.0 1.' 1111111 6.< <.0

10000 19.8 3.5

Hydroch loric Acid

Ambient HCI Dissolved HCI (pp!» - (ppm)- pH

1 1600 1.44 10 ';00 0.9-\

11111 17600 0.44

'~""W"'K moiMure. Although there may not be mnch choke where a turbine is to be sited. a choice should exist :10$ 10 what dirCt:tion il wi ll face and ",·hal chemicals will be pl:lced nearby.

The chemistry of the moisture enlering a com­pressor is dctennined not only by the gascs in the environment, but also by the parneulate present. IndUMrial gas lurbi llcs ingest hundreds of pounds of:lireach second and .... ith il aboul 0.03 to 0.3 ppm of dust (fatge 1983). Much of this dust is relmively insoluhle and can be filtered out. Thatpa" of the dust which is W"~ter soluble will tr.l.vel"$(' the fihcl"$ when they are weI and ultimately enter the com­pressor. ·Ilt is i$Shown by Ihe observation of puddles ialUr;ued in wate r-soluble salts on filter comp:ln­men! nool"$ behind the high·dliciency fiiten;, cer­t:linly a result of the water moving through the Hitcl"$, :lIld di ssolving matenal up to the salUnuion limit .

C E experience is that most fouling deposits on compressor blading consist of SOOt, lube oil, w:uer­soluble constituents, insoluble ditt, and rust. These fouling deposits arc probably held together by moiS1\1'·e and lube oil. If con"Osion has occurred. it wilt help in holding the deposit together by in­creasing the adhesion with the substrdte. Ccnainly 'he hulk of ,he pankulate which would enter a compressor and foml deposits can be controlled by f,ltr.ltion· but fine material « I"m) is not removed

' 1I~n<y fih ... ohouId ..- _ po".d •• p .......... " ......,.c """"""'"_t.. tO __ larJ«wilp«><Iw<- ...........

,

by rillr"dlion and, ofcoursc, there i, no control O\"e~ the moisture lirocluced by condensation .... ·hen humid air enters the compressor as described earl ier.

Deposits affect the colT05ion process by COII­

tributing Woller-soluble m:uerial snch as chlorides. sulrates, and nitr~tes to the moisture. In faCt, the moisture is usually sa turated in these s,llts. Also, dellOsits sctup crcvices and baniers which promote elc<:trochcmieal activity.

MATERIALS AND COATINGS

t ·OT handling l' wide vanety of environmen tS, CE has used I he following ml.teri .. ls for the wet stages of compressor bl:lding: nickd-cadmiulll (NiCd) or Semtetcl cOlnings on AISI403 stainless blades ;II1d unco:tteu GTI)-4~Oj , a precipiwtion-hardened m:,"ensi,ie Ml.inless steel.

NiCd/ AlSI 403

·Ille nickcl-cadmium (NiCtI) ekClroplated coating Ims been usc<i foraoout 20 yean; byCE.ltcombines a tough banier COining, nickel, with a Il:lCri ficial cadmium layer. The coating is applied by first dCt:lroplating about 0.2 mil of nickel followed by 0.1 mi l of cadmium. TIle plate is then chromate­dipped and heatol.rcated at 650 OF for an hour to C\-<e n out the cadmium o'<er the nickel and to promote a diffusion bond. °lll is heat treatment also drives off any absorbed hydrogen. Although the chromate coating is resllO'15ible forthe color of the coating, it serves no role other than protCt:lion of the cadmium byer I)rior to heat treatment (Its usefulness is destroyed by Ihe heat ,reatment. ) This coat ing has outstanding COIT05ion resistance in ncutral (pH · 7) and near_neutr.ll environments. It is excellent : '8"~inst sea salt environments. It is also Illore erosion reSistantlhan most coatings.

Se .. metel 5380/ AISI 403

The Senuctcl 5380 coating is an lt luminum spray coating which contains chromate and phosphate corrosion inhibitors. The COilling is spmyed on and cured:ll 650 OF for 30 min and then burnisht."d to prolllote electrical conductivity. A ehromate-tfP<: t0l'co:tt is applied :Uld abo cured :It 650 OF for 30 min. °111is co;lIiug has better colTOSion resiMance than NiCd in acidic ellvironmenlS. TIlis b a result of the hetter colTOSion resiMance of alunlinum rdat;'·e

to cad'nium in acid envi ronments. An approxi 'nate represcnlalioll oflhe depelldence oflhe corrosion rolle on pH for thesc melals is shown in Figure 2.

, , I ~ i

I

\ \ "

,,\ \

, , • ! I 7 eo

I I I" . 1

1011 un

PGA36OI ·2

Figure 2. Rela tive corrosion rate of cadmium and aluminum versus pH (adapted from Uhlig 1948, 842; Uhlig 1963, 299).

GTD·450

GTD450 is an age-hardenable, marten~ilic slain­less sleel, reccndy int roduced by CE for Ihe com_ pressor in the MS700 1 F. It has the st renglh characlerist ics of a martensilic sla inlo:u steel comhined wilh a corrosion resiSlance comparable to an 18 Cr. 8 Ni stainless.

Its excellent corrosion resistance derives from a composilion which includes IS% Cr. 6% Ni and 0.8% Mo. Its Slrength and corrosion-res istance properties relative 10 other stainleu steels are shown in Figure 3. GTD-450 offers imprm'ed stress­corrosion cracking resistance al higher strength levels than docs a conventional man ensitic steel such as AIS! 410. TIlis is shown in Figltre 4.

GTD-450 has an advantage over coated AISl 403 becauscthecoali ngs wearawayon the pre$Sure side of the first stator and rotor bl:lding. This side oflhe bladi ng on the early Slages is subjt.'Ct 10 both erosion and corrosion. This is tme even for turbines having high-efficiency fillration. In addition, the usc of nutshelling 10 clean a C0111pres~r is acceptable wilh GTD450bul is nOI good prdclice where coatings are present

Corrosion tests ha"e been 11m on the above Ihree matcl;als and a variety of others. TIu'se tests con·

4

sisted of Ihe ASfM 8 117 salt fog tesl (S% N .. CI, (' '1' - 9S OF) .. nd a CE-devised acid salt im'nersion teSt T he latler u:st in"olved the inl mersion of specimens in S% NaCI wilh sulfurous acid 10 give pH _ 4 at 170 0.". A 2: I mixture of oxygen to nitrogen was bubbled into the solution. This lest was considered a worsH:asc compre$SOr environment.

Most coatings providedexcellelll re~istance in the ASfM B 117 sa lt fog test Figure 5 shows Ihe protection provided by NiCd ove~ AlSl 103 in this test. The results of the acid Sollt l:lbor:l\ory te~s arc shown in Figure 6. Coatings were applied to both AISI 403 and GTD-450 in th"sc tests. It was found that uncoated GTD-450 was comparable or beller than any coating applied to AISI 403, and W'dS superior to coated GTM50 for aluminum .spray­.. nd-hake-type coatings and NiCd.

Resuhs of (he acid sail exposure for NiCd and Sermelcl S3$O over AISI 403 arc shown in Figure 7. ll1esc results show the limit:lIions of NiCd in an acid environmetH. TIley also showlhat the Sermetel cO:lIingisauacked in this environment. T he blisters shown on lhe Scrmelel coating arc sites where auackof the underlying AlS[ 403 has occurred. The mst fonn;uion in the AIS! 403 produces a blister on the surf<lce of the Sennelel coating. Figure 8 shows that pitti ng of GTD-450 docs occur in Ihe add salt C test but the ,mack is minor, the pit size being about . I mi l in 3000 hr.

In St.,,"ere acid ic environments in the field the NiCd coaling is undermined and a\lack o r the basc me.al occurs as shown in FigllTe 9. Our investiga­tions show the NiCd coming Can endure loss of cadmium and nickel over $111all areas (al)proxirnately 0.2S in.) 3S the surrounding cadmium will sacrifice itselffor the eXllOscd steel. Cadmium loss o\'er largc areas is 1110re likelytooccll rin acid icenv;ronments. If the nickel is breached in such environments. scrious pitting corrosion C:UI occur, dl;ven hy the prcsence of a large cathode (nickel) and a sllmll anode (steel).

Although Sermetcl 5380 is more resistant than NiCd in acidic environmeuts. it exhibits 3 similar attack, ;IS shown in Figure 10. Here Ihe coming has become !>re"ched or is penneable to the environ­ment, allowingallackofthe hase metal. FUlhennore, the cO<l ting must have become p;tss;ve, as it is no longer sacrificing itself for Ihe AISI 403.

Although il is e<lrly in our field (esting of GT D-450, it is clear that CTD-450 provides corrosion resistance al least equal to or belief than the co<ltings over AISI 403staillless steel. Results from a ( TQl0rone rainbow test in a severcenvironmelll for a '­domestic !{lIS turbine are given in Table 3. The

(

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w u z '" I-oo [;;;] iii 20Cb-3 W a: Z [][] 0 '" iii 0

~ a: [J[J a: , .. . .. 0 U 0 ~ @] W ." '" > 0 a: @[] ~ ~ [][] .. ... ." '" UDC

;!i

MECHANICAL PROPERTIES (STRENGTH) PGA36(l1·3

Figure 3. Comparison of corrosion resistance versus strength for GTD450 and olher stainle!l$ steels (Henthorne, Debold. a nd Yinger NACE).

GTO-4S0 (l150 °F 14 HRS.) VS. 410 (DOUBLE TEMPER. 1200 °F) TEST CONDITIONS: , % NaCI + 5% ACETIC ACID + H, S

'"

" .. 0 • • " •

, • " • 0 • ,

" t •

"

, "-'-­---

10 100 1,000 TIME TO f"'LURE (lit o.)

... 10,000

.....,.,,~

figure 4. Comparison of applied stress versus lime to failure (stress-corrosion cracking) between GTD450and Type 410 (adapted fro m Schmidt a nd Henthorne).

5

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Figure 5. Results of ASTM 8117 salt fog test.

6

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10

w 0 KEY ; z = c • RANGE ~ PREDOMINANT -w w « z • 0 in 0 « « 8 4

w > ~ ~ 2 w «

o~~~~~~~~~ __ ~ __ ~~ BARE COATED AL MICtI + CEJU.MIC NICD BA.AE

COATINGS TOPCOATS

GTO -4 50 AISI403

Figure 6. OIaft of relative corrosion resistance. Test conditions: pH .. 4.5 sulrurous acid, 5% NaCl, 170 of , immersion.

rainbow consisted of aluminum spray and bake comings (Serrnctech'$ Semletel 538() and Alloy SUlface'S Microfin ish) over AISI 40l and uncoated GTD-150. TIle NiCd va lue of 50 mil is b~d on previous experience. A problem with the coatings which docs not :' ppocar in laoor.ltory corTQSion leSUi is that the coatings arc removed from the pressure side of the rolorbladil 'g oc><:;l.USf! of erosion. 'nl is is an added adva11lagc o f Gll)..450, as shown in lhe mule.

Exlledencc shows that inlet g\'idc vanes usually have more COlTOsive activity lhan olher compressor IIlading. It is bel ieved th is is bt:cause the residence time o r the moisture on these blade~ i~ the longest. Recent e~pt: rience o n ink"1 guide vanes for a nondomestic nn it in a severt:: environment sho .... -ed that neither NiCd<oated nor Sennelel·538O<0at<.-d AISI 403couJdgivc more than oneyear'sservice. ln the case o f NiCd, the blades were 5Cr.lppcd [n the cue o f Sennele!, the blades wen: stripped and rccoated. Now after a year's sen; ce ..... ith CTD450, inspection has shown this material to be in excelle nt

7

condition ..... ith no obscrvable [lining. A snide to mme rial selection has been cOll$lructed

~nd is given in T~ble <I. The table is based on the material I'rollenies and environmemal factors al ready discussed. The mlUerial propcnics art::: CT 0-450 gives e1luivalent o r lleueT COfTOSion ....,.. sismnce than Scnnetel !">380 over AISI 403, and supc riorCOfTOSion resismncelo NiCdoverAIS1403. Ikinga base material, it is not subject 10 the e ros io n restrninls of it coated m;uerial. TIle environme ntal f"ctors ;Ire: compressors will llin wet when humi­dities exceed aoom 50%, a nd the :oggress iveness of the moi~lure wi ll depend on its acid ity, ltS deter­mined from trncecontaminallt s in theenviTonment ;lUd water-soluble species in the deposiu.

CONCLUSION

Site conside rations are most imponant in deter­min ing what environmenl a compressor will experi­e nce. The consider-uion. a re wind d irection,

,

H!Cd + 403 1300 HR

',-•

~' . . . ~ :, .. "

/, l'

, '

"

6

SERMETEL 15380 2 100 HR

Figure 7. Results or acid salt immersion tesl. Tesl conditions: pH . 4.5 sulfurous acid, 5% NaO, 170 of , immersion.

humidity, and what chemicals an: I)resent :u par­ticulate or ~s.l..ocal condilions are imponarll. It has been shown thaI minute amOllillS of ([lain chemicals can Tl:sult in very acidic conditions and signifICantly compromise the life orthe compressor blading.

A way 10 dctennine if a site will Imvc (om:)5,ol1 problems is to consider first Ihe humidity. As we have ~n, if humidities an: above 50% fo r sub­$tamial periods, Ihe n moiswre willl>e romled ;u the

8

I>cllmouth and corrosion is possible. Nexl. olle should consider if the cnvirollnlC!n! will be acidic ' 11;s can be de te rmined by noting the acidity of the dews and the r ... ins in the areas. A knowledge of what add-fonnin g gases are present in the air is also useful. Inform3tion about their concenumion can give some idea o f their acidity as shown in TlIllle 2. l.oeal conditio ns, in temll o f emi:l5iolls o r ehemic:al storage, should TlOI be O\'Criooked in dctennining the suitability ofa site. Corrosion experience 31lhe

<.

c PGP3601·8

Figure 8. Fine black spots are corrosion pits which developed during 3000 he of exposure. (Scratches were present prior 10 testing.)

PGP3601-9

Figure 9. Corrosion pits under cadmium-depleted NiCd coating (300X).

9

eorr()llon Pili

PGP3601-10

Figure 10. Corrosio n pits underSermetel 5380 coating (500X).

Sile, if a .... ilable, should be collsidered. If lime penniu, corrosion specimens should be placed where Ihe lurbine will be siled and given a year's exposure.

We have JCCn that wme Ir.lses are greatly concen­traled in moisture (iU shown by the examples in Table 2), causing quile acidic conditions for very low concentr.lIioll5 in the .... por phase. Ifall environ­ment conl:lim such If.ues, then Ihe mOSI corrosion­resistant materials should be se lected. However, il should be appr~iated Ih:1I ifp Hs drop bclow about ".0 for the condensing moisture. a colT05ion prob­lem will exist. AI; mentioned previously, fihration d~s nOt hal'e mueh efTecl on reducing corrosion. Watcr·wLuble salIS are If"dnsllOncd through filters

" nd gases are nOi. Slopped by them. The results of corrosion les\s were TC\'iewcd. An

acid s;oh cO'Tosion teM representing a worst-case cOlnpressor e ' lVironmetlt was shown to cause scvere piuingofNiCdlAISI <l03 and bliste ring of St:mletel 5380/ AISI 403.

Examples from the field for severe environments werc cited ill this repan and showed similar results. GTl).450 showed minor pitting a!lack in the acid $lIlt te51 and has shown superior IlCrfonmlllce in Ihe field.

To assist those involved in choosing compressor b lade materials, a guide is prc5Cnted in T able <I which shows what materi:.ls could be used IInder what envirolunenl:ll condilions.

Table' COMPRESSOR BlADE RAINBOW RESULTS

l!<I,OOO·HR TFST IN MS7001 (SEVERE El'o.'VIRONMENT)

MateriaVCoating AISI <103" NiCd AISI <l0~" AI Sluny CTI>450

Max. Pit Dia. (Mil) 50 ,. 2Q

10

Erosion PreS$ul"e Side I'ressure Side None

"ok , 2 1

(

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Table 4

MATERIAL SELECTION GUIDE

Recommended II Relative Is Moisture Is High-Mate rial' H umidily>5O% Acidi ty' Efficiency

(Minimum M05l ohhe pH>5? FIltration corr~on/e~on Time? Present?

resistance required) NiCd/AISI 403 ITS vrs vrs GTl}.450 vrs YES NO Senneld 5380/AIS1403 vrs NO ITS GID<50 ITS NO NO NiO:VAISI 403 NO "'~ YfS GTD-450 NO YfS NO NiCdJAISJ 403 NO NO YfS (;T045O NO NO NO

.om 'Corn>oIonruiow>< •• C1'f1.4.'.,O>_)3IIO>~!Cd.~"" ___ ,,",~_"'Sl401

Anr ......".u,j in .... 1»1< rnooId ... ~od ... h "'" ......rn.I 01,...- «>m>Iion ....nw-. dq><n<Ii", .... -. _" M«>m>Iion ~ ~...".."., Ioodi"l" -....i_..,. fikr>lioft..,........ and_ ~<Ita"'n.-..kIio><l""' n""""'l~n .. l n 'h<l>D<r<aO<.C'ftl..4~hlh<~-nalun<l<f 011",,_ ..

'Co,up,,,,,,,, cIq>ooit 'h<mill'}';' ;m,_.'" In ....... iI_r. .. I~ .. 1< """".'" d .... ;....,. I, may<"'''r< """.ri .. «qui"" .. ,, .... No loCI mdOOd j, .... il..,.. fu< delermi"'"1 romf"l''''''- """ .. ,,,. _1'T.lonol pli ........ faJI<" .. of "'I" ...... ,. 'kw. nlt<Hompa'UII<", pudd ..... ,ot! bb ... dq>osit ..... "oro to eotlm ...... 10 ... o.pooiI pi' ;, ,.I.e" .. 'Il< I,ll of do.,..l,odW>lt,,,,,,,ihln<<<' wh ........... ror8 hr ... c""".nu'.oo., ofl pn old<pooitper looccol -,. REFERENCFS

Henthorne, M .. llebold, T" and Vingt:r, It, "CuStom 4!)(). A New High-Strcligth Sice!." Corrosirm172, NACF~

Kolkmall, HJ .. and Mom, AJ A., 1984. "Corrosion and Corrosion Co,llIol in Gas T urbines Pall I: T he Compressor Section," AS ME 84-GT·255.

Schmid" N.S. and He",honle, M., "Precil'ita'ion­Hardening Stainless Stttb, An E ..... lluation ofThcir ltesi5lance to SU"ess-Corrosion Cracking, H C;uventer Technology-Corp.

II

Tatge. R.S .. 1983, "Gas Turbine Inlet Air Treat­mene. Cf. Company, CER-34 19.

Uhlig, 1-1 .. 1948, (,.orT(Uio .. HamibooJl, John Wiley and Sons.

Uhlig, H ., 1963, CornlSio"",,dConwiofi (;o"I.-oI, J ohn Wiley and Sons..

Zerkle. R.D. et al .. 1982, '"Analysis of Moi$lure Condensation in Engine Inlet Duel$. H l'roceedings of the SymllOsiUln of Paniculate-Laden How in Turbomachinel)', edited by W. Tabakoff et al., ASME, New Yor!r.. pp. 101 -111.

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