Document 5kQGGKgKrxvMMbpwMZN0RKD7J

Y-Bep 86-2 Tests of Asbestos-Free Mi . ji _ m _ a_____ mi I #1 t By E.A. Bake, Research Manager and R.J. Gradle, Senior Research Engineer Measurement and Flow Control Division Rockwell International August 1986 ABSTRACT INTRODUCTION Atest program was conducted to evaluate asbestos-free valve stem packing materials proposed for high, temperature ; service. Backing gland holt loads, stem frictional loads, and packing compression Practically everyone is aware of the publicized problems that'have been associated with asbestos. It is not necessary to detail alt of the regulatory impacts that have been felt by construction and other industries. However, by the iate 1970's, secondary effects of U.S. regulations took the form of "asbestos-free'' clauses in were measured. Tests were performed specifications written by a few customers and architect/ with roomtemperature water at pressures to 6250 psig (431 bar) and with steam at pressures to 8200 psig (152 bar). Valve stem diameters from 1.000 to 4.000 inches (25.4 to 101.6 nun), engineers for industrial valves. The growth in demand for asbestos-free valves was not as fast as was initially expected. While the elimination of asbestos was not a difficult technical problem in some moderate temperature applications, it still required signifi cant time to identify and prove the performance of cost- and strokes from 1.68 to 20 inches (42.7 to 508 mm) were included inthe testing. Live loading ofthe packing was evaluated. In all, approximately 100 packing sets were cycle tested over effective substitutes. In the area of stem packings for valves for elevated temperature service, asbestos-base packings had been the industry standard for generations, and the technical qualification of substitutes was a major challenge. User interest in asbestos-free valves showed a moderate but steady increase through the early 1980's. a 12 month period. In addition, In some parts of the world, particularly Australia and effectiveness of several corrosion inhibitors was evaluated in corrosion tests with 24 packing sets. Several successful packing material combinations are identified. Scandanavia, the determination was particularly strong to avoid asbestos-containing equipment; while some nations still have no. clear policy to eliminate asbestos, it is likely that this will come in time. It was known that some U.S. suppliers of packings had discontinued sale of asbestos packings earlier, but early in 1985 JohnCrane1 {John Crane-Houdaille, Inc.) announced that it would discontinue its asbestos packings. JohnCrane asbestos packings, particularly 187!, had been used in many Rockwell high temperature valves for many years and were specified in some customer specifications. * Rockwell International NIBCO001314 Partial Cross-Sectional View of the Univalve, \j FIGURE 2 _ 3RAIDED ASBESTOS^- , AMTVEXTRUSIONfllNGS: -. v.,' s> eN r4"1 ^ . T -V.'-r i DIE FO R MCO'FUEXfB t GRAPHITE RINGS \ <: , T1* , -' if J "! `i - y 1 t h iAi i' ,** f* v > TA r , M' > * '1 M i"'" ' S.VI v`. ' wjiL i*An ' ' s VJll't* I,' i' Rockwell Univalve Packing Configuration.(1979) ' Note: Antl-Rxtrusfon Rings are Now BraidedCarbon- .Wit- ..j Aftera careful review of the developments overthe past five to ten years, the Flow Control Division of Rockwell International concluded that the best approach would be lo discontinue use of asbestos in the manufacture of valves. Test programs already in progress were expanded in 1985 :o assure that use of asbestos could be curtailed, and these Drag rams have been continued to provide qualifications >f alternate sources and studies of more cost effective naterials. This program has been costly, but it was consid ered necessary so that Rockwell could stand behind its jommitment to assure excellent overall performance of isbestos-free valves. "- . BACKGROUND It is perhaps fortunate that other problems with isbestos-base packings had emerged earlier and had itimulated research and testing. Specifically, the perfornance of asbestos-base packings had never been outtanding, but requirements for periodic retightening and epacking had been accepted as routine in many fossil uef power plants. When the same packings were applied 1 nuclear power plants in the 1960's, serious problems /ere encountered due to (1) inaccessibility of many valves jr packing adjustment for prolonged periods, (2) loss of azaii i or precious (e.g. heavy water) fluids, (3) valve amag^sfrom packing leakage, and (4) radiation exposure f maintenance people, These problems were well . ocumented in studies in the U.S., Canada, and France. tohnCrane is a registered trademark of John Crane-Houdaille, Inc. One successful approach to the leakage problem in-, nuclear power plants was to use `"ive loading--a means \ for compensating for packing wedrandfbrihkagdby use ` H of springs. Atomic Energy of Canada,. Ltd/,(AECL);per- > formed major work in this area; One probie mwas that ' /Jj1, -4M available asbestos packings^djsplayetffDipmichQjjnpac* ,"-3 tion that very large beileville spring packages wereke- ' quiredto maintain the _ over a significant period of. tirneirVvhi!e;'Speelal-valves' " could be designed to meet AECt criterfaipariy standard valves did not allow enough space for springs. v:'' age in nuclear power piant.valyes:.i.tiyplv0d:appiica.ti0rt of a; new material which had made alimel^appearanceiin the scene. Flexible graphite,, initialisin'thdform of Grafoil* from Union Carbide Corporation, was found to offer;SU- , perior sealing-properties ihafi^ J ink program in 1971 [1j3, and use of this material was:brpad in U.S. nuclear power plants by the mid-I^TCj^HbvyeVe r; ` * to a broad range of high temperature, highpfeSsup valves ? for nuclear power, fossil power, and other applications re quired more research and development::Rockwell and . others did considerable testing resuStingin development of superior combinations of flexjbliegj-apbits and other , materials. In the case of Rocta^&^'^li'^ffccorttriBiited to an improved stem seai.fn a hewlfrte of-forgpd steefj Univalves [2]. These valves (illustrated In Figure 1) have rotating/translating stems:with,di ameters u p to -.1-.125T (28.6 mm) and are madein accordance with ANSI B16.34 2Grafcsil is a registered trademark of Union Carbide Corporation ^Numbers in brackAte rtassinnafn rAterannfccj HctaW at nri nf r%onr if V NIBCO001315 FIGURE 3 / Hof Functional Tost ofSize 30 (DN 760) Rockwell Fquiwedge Main Steam Isolation Valve at CETIM Laboratory(Nantes, France). Classes 1690,2680, and 4500. They incorporate smaller packing chambers than used in earlier valves to provide more efficient packing loading. Anti-extrusion rings were found necessary to prevent extrusion of flexible graphite rings at the high pressures these valves could encounter in fossil plant applications, but excellent sealing perfor mance was achieved with two JohnCrane 1871 end rings combined with two Grafoil sealing rings in Class 1690 and 2680 valves. The new Univalve packing arrangement is shown in Figure 2. in addition to the excellent test results achieved in the Rockwell laboratory before these valves were released, firsthand experience has been developed with 28 such valves In a^high temperature steam test facil ity in the same laboratory; after four years of frequent pres sure/temperature cycling at up to 2500 psi {172 bar) and 1050F (565C), none of these valves has required repack ing and only two required tightening of gland bolts to stop minor leakage. While that stem seal still contained asbestos, it used less asbestos and provided improved performance. Through work with the Rockwell Valve S.A. (RVSA) plant in France, it was learned that cooperative work be tween Latty International and Electricite de France (EdF) had led to a solution of the stem leakage problem in EdF Pressurized Water Reactor (PWR) plants. This solution ^S^nvolved some of the same elements that had been so suc(liilsessfuf in the Rockwell tests, namely asbestos-base antf- ^"'extrusion rings combined with flexible graphite interior sealing rings. This combination of Lattytex4 117 and Lattygraf4 El has been applied successfully in Rockwell valves built in France--in sizes up through size 30 (DN 750) quick-closing Main Steam Isolation Valves (MSIV's). A major qualification program [3] on the first French-built Rockwell MSIVinciuded ahot functional test on steam at 1040 psi (71.7 bar) and 547F (286C); this test provided an excelient.demonstration of the iive-ioaded stem packing. Through 600 full stroke cycles, 400 partial stroke "exercise" cycles, and several thermal cycles, there was no observed stem packing leakage. Considering that this valve had a stem diameter of 3.000 inches (76.2 mm) and a travel of 19 inches (483 mm), these test results were considered very good. The MSIV is shown in the steam test facility in Figure3. When requirements started to deveiop for high- temperature asbestos-free valves, most of the demand was for smaller valves which already incorporated flexible graphite sealing rings. While some new proprietary braided asbestos-free materials were evaluated in a Rockwell packing test program [4] in 1980, test results indi cated need for frequent readjustments and marginal pack ing life, particularly at high pressures. That test program therefore concentrated on retention of the flexible graphite sealing rings and finding an acceptable replacement for the asbestos anti-extrusion rings. Others had reported good results with braided graphite "wiper" rings, such as JohnCrane 1625 GF. Rockwell tests showed that these rings prevented.extrusion of flexible graphite sealing rings and provided good performance at low and moderate pres sures; however, testing at over 4000 psi (275 bar) required frequent packing adjustments and revealed a moderate seepage condition that could not be controlled. Since Rockwell Class 1690,2680 and 4500 Univalves a!! have room temperature working pressure ratings above 4000 psi, this combination of available braided graphite end rings with flexible graphite sealing rings was judged inade quate. However, excellent results were obtained when flex ible graphite was combined with braided carbon filament top and bottom anti-extrusion rings. Specifically, . Garlock5 98 end rings provided good sealing with minimum readjustment in tests with stems 1.000 inch (25,4 mm) in diameter in room temperature watertests at up to 11,000 psi (759 bar). Backup testing at high tem peratures revealed no degradation with line fluids at ternperatures typical of the highest seen in power plants. The asbestos-free packing research related to high pressure, high.temperature vaives paid off an unexpected dividend, A new Rockwell high performance butterfly valve (Classes 150 and 300) was required to meet the fire test requirements of American Petroleum Institute (API), British Standard Institute (BSi), and other user specifications. The same combination of packing materials selected for high pressure valves was adopted for use in the new Rockwell McCannalok Bidirectional Fire-Seal butterfly valves. An extensive development and qualifica tion test program [5] demonstrated that this packing com bination provided excellent sealing in quarter-turn service at normal pressures and temperatures, and it also met the fire test requirements of API 607 (1980 and 1985), API Spec 6FA (1985), Exxon BP3-14-4 (I960), and British Standard 5146 (1974) in tests witnessed by a third-party inspector. " ; j j i3 5( 4Laitytex and lattygraf are registered trademarks of Latty international 5Garlock is a registered trademark of Garlock, Inc. 3 ; ! 1 NIBCO001316 TABLE 1 Packing Sets Tested Braided End Rings/Fiexible Graphite Center Rings Manu: it aarlock, Inc. Jnion Carbide- iarlock, Inc. Material * j Combination ! Material Description . Garlock98/ Grafoil Braided carbon fibers Corrugated flexible graphite ribbon GarlockSB/ Graph-Lock Braided carbon fibers Diamond texturized flexible graphite Graphite Ring Stem Size Packing Gross : Recom mendedGiand: Density, g/ec Tested Section, In. Bolt Torque, Ft-Lbtt . 2.375 0.38 1.6 '4.000 , " 0.50 175 475 '1 ` / 4.000 1.4- , 0-50 414' 7 ^ ' IV "J v, W, Chesterton Company L W. Chesteron lompany /tartln Merkel 3mbH &Co. KG .atty nternational Style 1-Ci/ GTPI Style 1-CI/ GPP Carbosteam/ Grafiflex Lattygraf6000/ LaitygrafEl 3tty nternational LattygrafTSP/ Lattygraf El Sarlock, Inc. 1200-PB1 3arfcerSeaJ afoup >ohn CraneHoudaille, Inc. Kt W, Chesterton Company 028** 2371** Style 1800 Braided graphite yarn Corrugated flexible graphite ribbon 1.2 . 2.375 >- 03S-r x. * - 330 ` ,i j'' ' ' ' Braided graphite yarn Compressed graphite powder 1.4 \ 1>( 0.25 , 1 , ,1 , ,, `41, *i. j** l * * ,c Braided carbon yarn Diamond texturized flexible graphite 1.3/1.4 Braided carbon liber Corrugated flexible graphite ribbon with zinc " 1-7 Braided carbon fiber Corrugated flexible graphite ribbon with zinc 1.7 Other Packing Materials Tested: 1,,000 2.375, " 0.25 , 1 0,38: 1.000 . 0,2^ , 2.375 , , Q.3B`< ' 40 , ,n/ 200\ 4 f 61 . ' fT n>'1< - lOfl ; n} ^ M ,VVI ' ,-> ^ ,r \ _ 1.000- ; [i i ' 0.25,; /: ' 1 ` `k ' v' ' 6i.5i ,) J. jfr< ' w'jL'J* i ,, i ty 1 i , t1< " '* ' s>{ - 4't1,* >$ 'rsfW^emd,( Braided polybenzimldizole fiber Braided construction-- no other description available Braided construction--. /' no other description available Inconel reinforced carbon yarn j j { N.A. . NiA. N.A. N.A. t- 1.000 . \ .1 0.25; f: 2.37S , ,,,. 0.38/,- j;' . 2.375 ' , ' ' ; 2.375 0.38-.,', f 1.000 |. ' 2.375 0,25,'' ' 0.38r ojyy fir-, y Ar 1 .* . *si5omMiWp'Uiiij sT 1iiil^ BecommendyitianL,' V'<8 ./J.' No-v ' .'iyj-ff-">$ * U'~it 'Recommendation//,1;1 ' J '* 'f/-I "r&\ J, , 4ff ',/ .,i, .-v 242'"' 7 'JK f "K i jtA * Where applicable, material combinations list braided end rings first, followed by flexible graphite center rings,' .. . . ' The material tested In this program is no longer available, A revised material uaingthe same Identiftcatlonds-currantly-avaifable:. tRecommendatlon by manufacturer ' . 1 ' i" AO* " jr 1 '<$ W, While the earlier laboratory tests of the braided car)n/flexibie graphite packing combination had-been conted to fairly small valve stem sizes, this combination was jplied selectively in valves with larger stems over the ist few years with no field problems, in some severe jplications, the combination was applied successfully to place asbestos packings that had given leakage probms. While field performance results were very good, it as decided early in 1985 to establish a laboratory data, ise through testing of braided carbon and flexible graphi with larger valve stems. Shortly after this program was iderway, the Rockwell decision curtail use of asbestos suited in expansion of the test program to permit evaluion of other promising asbestos-free packings. A survey as made of packings available in the U.S., Europe and ipan, and meetings were held with technical represenlives from a number of key packing manufacturers. While there was a general concensus (not necesirily total agreement) that combinations of flexible graphi sealing rings with either braided graphite or braided' irbon end rings offered the best in asbestos-free packing srformance, other asbestos-free high-temperature packgs were available. Manufacturers reported that these takings were either new developments or had been im- ovedsignificantly over the past five years. Most of these Her i" ;ngs were proprietary braided materia! combiitions&iiAvhich some laboratory and/or field performance iccess was reported. Generally, the data available from ' - 4 ^| L , V* u ! I'T i / >* the manufacturers on these proprietary packings were' not v * sufficiently convincing to permit use ofthese materials )n ^ ^ ^ Nevertheless,, sinee suchproprietary braided packings^ "....r; offered potential cost savings in comparison.with'carboripi,;..' ,,; ^ ( and graphite pact mgs, those wh,ch seemed most^promis- ing were obtained for testing in theexpdrtdbd Rockweit - * - ' program. ' x1 ^ Within:Iess.thanaye:ar:afte.r.thecbfrentprgiiam.,`; -J rSjti, was started, a U.S. regulatory announcement provided - ' theJustification (ifanyvyas;needed).and.Sdtadeadltne.!iv. 'i.'t, . ,r^|i On January 23,1986, the,U.S. Environmental Protection^ ' Agency (E.RA>) proppsedapianjeiinvoKr-mg immediate^ ^ ' "T ' r prohibition.obuse of asbestos in certain products and: phase-oufof.-dbmestfcrminingand importationofa'sbestos""'. \ * over.aten-year period?. * / , j iw fell TEST PROGRAM 1 /v ' Pre^oiis.develq^mentworJcperformed within( asbestos-frad paekingimaterials showed that the resiL- - ` | - 1 ience of flexible' graphite packing rriateridlfcouid be taken ' - advantage of to reduce the size of packing;chambers.This- .. earlier work centered on smaller forged steel vaives;:with , little laboratory work on larger valves. Large valves have . historically had very.deep packing chambers using, aJargei/'., V'. number of asbestos packing rings. A major goal of the pro- `W NIBCO001317 Stem Dfanieter d, inches (mm) 1.000(25.4)2.375(60.3) 4.000(101.6) Sizes of Packing Tested* Packing Cross Section A,.inches (mm) Number of Flings N 0.25(6.4) 0.38(9.5) 0.50(12.7) 4 4,5 5 packing required to seal the stem could be substantially reduced by both decreasing the packing cross section and reducing-the required number of rings. The revised pack ing chamber designs would then have to be evaluated through sealabiiity and wear cycle tests. A test program was devised to evaluate performance of asbestos-free packing using the revised packing chamber design. The program was designed to expose the packing to all of the loading conditions that it would encounter from the time it is installed in the valve manufacturer's plant through end use. This involved exposing the packing to valve hydrostatic shell tpst and seat leakage test pressures (with associated ieakagebriteria), followed by cycling a valve stem through the packing under high pressure and room temperature or high temperature operating conditions. Results of earlier tests [4] demonstrated that the packing material combination of Garlock 98 braided car bon end rings and Grafoil flexible graphite center rings would successfully seal valve stems up to Class 4500 opeating,conditions-The Grafoil rings used in those tests were formed from Grafoit ribbon by Rockwell so that the density of the rings could be closely controlled. Similarly, Grafoil rings used in the current test program were also formed by Rockwell. Flexible Graphite rings from other manufacturers were obtained preformed (with density per standard practice), Rockwell specifications fbr.generalyiMvice flexible graphite die-formed packing rings call for a density of 1,4 to 1.9 grams/cm3 (87 to 118 lb/ft3), although tighter controls are specified for some special applications. This range has been found to be successfuf in new valves with good stem and packing chamber finish. Accordingly, Grafoil rings formed by Rockwell for the current program.- were made to provide a nominal density of 1.6 grams/cm3 (100 ib/ft3). Several packing manufacturers normally sup ply lower density flexible graphite rings on the grounds that they are more suitable for repacking worn yafves. At least one manufacturer [7] offers both "low density" and "high density" flexible graphite rings. , . - Although the majority of cycle tests performed uti lized conventional packing gland bolting to compress the-, packing into the packing chamber, tests using live loading were also performed. These tests were performed primar ily to evaluate live loading in comparison to conventional packing gfand bolting. Gland spring sets were designed to accommodate the wear and compaction characteristics of braided carbon/flexible graphite packing combinations observed in previous tests. The presence of carbon or graphite in many " , asbestos-free packing materials can cause galvanic . corrosion of some valve stem materials. This test program , included testing to determine the effective ness of several corrosion inhibitors currently being used or proposed for use with carbon or graphitic packing materials, . Packings Tested Packings tested in this program include carbon and graphite braided packing, die-formed flexible graphite packing, and other proprietary braided packings. Individual packing materials tested are listed in Table:! Die formed flexible graphite packing was always tested in conjunction with carbon or graphite braided end ringswhibh served as anti-extrusion rings. An exception to this was testing of one of the proprietary braided packing materials as .an anti extrusion ring for flexible graphite packing; Otherwise, proprietary braided packing rings were normally tested by themselves. Materials to be tested were normally obtained from manufacturers in sets to accommodate the-test fixture packing chambers. The only exception is Grafoil rings, which were formed by Rockwell. ,. Three sizes of packingwere tested, as described.;: in Table 2. Manufacturers were advised of the temperature and pressure conditions that the packing would ba exposed to before the packing was supplied. They were asked to supply recommendations for loading the packinginto the test fixtures, especially the packing gland bolt loading to be used to compress the packing into the.packirig cham ber. It was considered particularly importantthat manu facturers supply this information for the new materials.for. which there was no Rockwell experience base. . \ I 5 NIBCO001318 NIBCO001319 FIGURE 4C Photograph of 1.000 Inch (25.4 mm) DiameterStem Test Fixture. Test Equipment and Facilities Three-test fixtures were used in the course of cycle ' | testing the packing materiais. These are shown in Fig lire "y, ' ! 4:.Each fixture consisted otafubular pressure vessel withy' , a packing chamber at each-end. A simulated valve stem , ' * j extended completely, through both packing chambers ancT^j, .. vvps-.conne'bted' to an actuator on one end-This design ( , . >4 .'. allowed,twp-tests of-any particular,packing,material;.to- vbeiibrmel'at-p itrpfovided a pressure bai~yy^v) ' anced stem design, so that the-actuator-had to workagainst ',y " stem pack;ng friction onty (noistem.blowoufeload^Steros^C^ were made from heatifeated'AISt^-l Ostainie'ss Steei-with^^Jj'f ahardness;of.Rockwelll;C21tO!35:and;asurface;,finfsh.ofi''j'i>^^4 very close to 32:microinches'{p:80 micrometer),.,v/hich.;:i ' represents co hseb/atwltupppipboUpd-on-allowablei'Ste surfacefinishes.Thls.'!JSthe:n,0riT)al:Rockwe!t'standard:fG,i valve stems,.although'ithe 'map^factur.!pg:.proeessds,nor mally produce ^smoother finish on smaiier stemsv.Som ' ' ' i'fin ishes, particuiarlyforimodulatragtcant-rpitvaivesiwitch.^ari exp.osed;tQ;continuo.uscycling;ibut,thisJfiriishhasrberenf;4i found satisfactory in.riormaj-.b^fdffisjalveiservicefFaekirig-1 chamber bo res. were^achine'ditoibrowdea'ifi nish?pfj1 aSjf, microinches (3.1 promote smoother packing ch^Ribebtoshe^bulthrsihair not been found necessary in Rockwelktests, AJffisdureV'fi weredesigned to operate at22Q0psig (132 bar) atlOQOF (538PC) or 6250 psig (431 bar)'at room temperature.=Thes designeonditionswere chosemtdiipfermibsimulationof \ valve service conditions.forupfeljiass 25do:vatyes per ANSIB16.34. ; /'>' *" y<ij Jj The smallest fixture wa?cdnstruetedilorreprese:r"* duced the helical motion ty'preaPofsrtall^brged'ist&el^ valves Stem travel was 1 68 inches (427 mm) and one complete cycle was;compfetetiin 30 sebandSkThe"paejp ing chamber was designed tp'hbid,4 packing nngs'of v , OsSSJqcb^^nfwi^squge-^^^oii^ThetWo packing* FIGURE 4D Photograph of2.375 inch (60.3 mm) Diameter Stem Test Fixture FIGURE 4E Photograph oi 4.000 inch (101.6 mm) DiameterStem Test Fixture. " - onejaireadyhn use.-i-KuRockivat : - :1 The next largest fixture-was buiitto^epresi ^-*.^^urotSl^yalvesi'|n<k)r{^'i5|^'s^i^&^c^'$g9^rniTt)^ ' stem with translational stem ^trorijpqljfc^teii^fywel^as'" 10''ihches'(254,mm),:and one|^n^|l|fix|pJe(exiebsion ' ' an'dlretradtion); vya8a4bmpli^e^p^^^pd,d*;S^e@(f&:d.|jj{i the stem size and travel represented a size: 10 Class 250b ` Rockwell Eauiwedge gate valve;.,The;packlngLchamber,lnjj this fixture was designed to hold'ajunk. ringandS'packing rtngsof0.38 inch (9.5 mm) squarebrbss:section.''(f!!acking, ( gland bolting,was 1.00. inch.(25';4;m;m). diameter,.Mh-readsfe'^l inch (312 mm/thread). Twodp(ts^eTesusSd;:fqreact[''packV ing gland; Stem actu&ionvki^&i^i^^fctvISri^rcd^^^; pled to the stem. Strain gages on the coupling allowed y * pi: stem frictional load measprementsto be made. Strain _ `` ' gages on. the packing gland bolting; allowed toads,to be " monitored during ambient temperature tests (these were ; removed to avoid damage duringhottests)): Hydraulic; \ : cylinder pressures were aIso:monitored.as a baek'upto * ,* *y// the stem load measurements obtained from the coupling/1 The largest fixture was built to represant large cast < steel valves, and had- a 4:000 inch (101.6 mm) diameter stem; 11 -J also with translationai stem-motion only: Stem travel .was r ^ / T NIBCO001320 STEAM EXHAUST -SUPERHEATER/TESTAREA BYPASS 11X1 THROTTLE VALVES --[X]--i--1X3--: TESTAREA SIZEZXXH XX .'DRAIN- SUPERHEATER: , .swsihmnpw-icgAO'.u'-'i K .. AT7B0F(4-C| ' . HXF1-. 2000IWhr(907Ttg/hr) 1 r- ' : AT1050F(555"Cp ' -.SDO-27!)O|Hl3!34^-t08ljar) " : V?$ DRAIN 4------------------ TEST AREA BYPASS XX DRA1N-' r -# 11 i V|V :V;i; 'F.a -'`nr XX vVSlaTi7E5AASWNJ^t|Qi'hHfte5((2M233E447B7(ACTQ0Dr^tirRiJg`j,./V; FEEDWATER^TJ: ^ F6S8A0TPUFR,fA3BTE0?DCS)T'MEAAXMTEMVPi. LAT227M00QMpsMlg (J86 bar) r* ?500&7Bagiug{:M;1B6 bar); ' 1 < X-4 r ~t ' * '* ? , 4i t , t-v -l / xX'C!f flfiw&L'VtjWX.X? GURE5 JjV. i" BV-V^fc ickwoll Steam Generator Test Loop. 3 incK; ;08 mm). The packing chamber in this fixture as deigned to hold a junk ring and 5 packing rings of SO inch (12.7 mm) square cross section. Packing gtand siting was 1.25 inch (31.8 mm) diameter, 12 threads/inch .1 mm/thread). Two bolts were used for each packing gland, acking gland bolting was not instrumented on this fixture, gain, stem actuation was by a hydraulic cylinder coupled the stem. This permitted one complete cycle to be perrmed within 90 seconds. Hydraulic cylinder pressures are monitored to determine stem packing frictional loads. Packing rings of square cross sections were used in i cases. In the case of braided rings, this shape is normal icause the ring is cut from a "rope" that is'square or round id die formed to be a square.-Each-ring naturally had one ip when installed in the packing'dhamber, and rings were acked in the chamber so that the gaps in upper rings ere all rotated 90 from the gap in the next lowerring, exibfe graphite rings are die formed as short tubes and e not limited to a square cross section. It is probable that, ithin limits, shorter washers or taller tubes of flexible aphite would also function similarly providing they have e same volume and density as the assemblies of square oss section rings tested. Square cross sections were sed far this program because of successful prior expesnce with this form. The die formed rings were cut agonaliy at two locations to facilitate installation in lives, and the split locations were staggered at 90 at iserf^The gap in adjacent braided anti-extrusion , igs fejy^.hstalled 90 from the splits in the flexible aphite ring. Room temperature tests were performed by filling e fixture with water and pressurizing it to the test pres ire using a pneumatically driven hydraulic pump. High ` < ^' Ml *3. temperature tests were'.performed.in.theHci.ckweltsteam. .:.^:.1, generator loop (see Figure 5).The stearn/generatoris f capable of prbvidihg.saturated sfeam upto;680oF,(360oC)'.i1: ' A superheateronginally installed with the steam generator * ... was-not available for this test,.so highertetnperatures were - , ' produced SriTan,electrically. heated test loop. This loop (see . Figure.6) hasaeapabiiity of90Q"F (482C) at.2500`psig , (172bar). /(.*' 'C'X X~- ' ` * '' ' `VX,, At feast two-tests of.eacfi packing material'were [' ' % planned and.performed unless.the first test was unsuc- cessfui. These were, a room temperaturestest using-water -' h X as the test medium, and a high.temperature test;using saturated steam. Braided.carbon (or graphite)/flexible s.. graphite packing combination$.were tested at 6250 psig . it , ,c,"l vji (431 bar) during room temperature tests, and 650F (343C) * sM at2200psig;(1S2.bar);featuratod'steam)dutlngihotjests. X, While valves ussd in high temperatureservice areihot nor- - - ' H | I IUI | y Wrt I^WWvl'.kM' A I' Kfc* " * ' n " . IT .' . r . I .. w . . i^S'- they are fated for such pressures by ANSLB16l34. Since manufacturers pHpwthe Bie.S^ratings^egl'SSSO'psi ' [431 barl at;tip;tpi10QFi38C]ifor'Class 2500 valves) in'- ,, A . catalogs;.it.iyas\riecess;ai7toverifylhatthe packings can. t, withstand tildfatedmonditions'' ' -`T ", " --F Proprietary braided packings were in general tested-:,- -. at 2250 psig(155'bar) (Class 900-1,00oF/38(,C rating);during room temperature tests. This lower pressure testing condi-. tion was decided upon after early,tests indicated that such, materials might'not meet requirementsdonhighest'pressure' T;: valves but might be cost effective for Ciass 900 and,lower,; Hot test conditions were generallythe sameasforthe braided carbon/flexible graphite packing material combinations. ' ' Test conditions used in-this prdgrarnwere.chdsen-: ^ . based on earlier packing tests performed by Rockwell , vm .,,va, ` NIBCO001321 tures) were completed. These wear cycle limits;were selected to provide a conservative upper boundary on. . expectedpperation of on-off valves. Normally, larger ,, valves are not operated as frequently as smaller valves. KSj Packing gland bolt loads an date m frictional loads were S> recorded.periodically throughout each test. , , rt, . -.. Fof.high temperature tests, after completion ofsheilV testing arid.seat:leakage pressure testing, the test fixture *- generator.loop'{Figure 5). Atthe"'* beginning of each day, the packing was hydrostatically . tested with room temperature water at 2500 psfg (.172 bar)',_;,v. and checked for leakage Leakage was measured and - L packing gland bolts retorqued, if required Then the steam j ) i, ^ ' '' ' 4 fc! 11 TABLE 3, ; ACGU 4ULATDR` : ; it - .Test PiS&sure*^. * - ^ ?;;Sheil'Test ^ Seat Test ",'Cycle Test: ' '/. ''1 j'kv V-' Pressure .PressUm,.'' Pressure, V, mA . PressureClass- '. pslg (bar);?,1 ' Psig(bar)V "!.r,psig(bar);',' ; k ,i'* . f.' p-' ' 600': -V' ' v.~22&o (tssytr^"- ''IBSOtilXjiV '-11500(103)4; .900;',/ ,y3375;(233)f^ 1 '24.75-(!l7a)i. -. 2250(155) v- wCt't : . 150Qi i ' i:;S5635(3Sa)'i( ; 3750 (259) /' ..25oav.-V... ': ...9375 (647)>;' ,6275(474).' 6250(431),';' J I FIGURE 6 Electrically Heated Test Loop Schematic Diagram. V. : ; 1]. Results of those tests demonstrated that the braided ^rbon/fiexibie graphite packing material combinations are not adversely affected by higher temperatures typical of normal steam valve applications. Therefore, 650F (343C) was considered adequate to demonstrate accept able performance in applications involving larger stem sizes than previously tested, and also for proving the per formance of other packing materials considered to be "equivalent" to the materials previously tested. Because the high temperature performance of the proprietary braided materials was unknown, most of those that were reasonably successfuly at 650F (343C) were subse quently tested at9Q0F (452C).using the electrically heated test loop. J- At the beginning ofeach test, the packing was assembled Into the test fixture according to the manu facturers' instructions (when provided). The amount of packing compression at installation was measured and recorded. The packing was first exposed to the shell test pressure and then to the seat leakage test pressure (ANSI B16.34) for the pressure class conditions being tested. Packing leakage was allowed at shell test pressure (1.5 x 100F rating) butwas not allowed at seat leakage test pressure (1.1 x 100F rating), ` For room temperature tests, the pressure was then reduced to the appropriate 100F (38C) rating (see Table 3), and stem cycling was started. Packing was checked if^odlcally for leakage. When leakage occurred, the llpjre was depressurized and packing gland bolt torque either restored to its original value, or, if that was not effec tive, increased above its original value until the leakage was stopped. Testing was completed when 2500 cycles (1.000 inch [25.4 mmJ fixture) or 1000 cycles (larger fix- TheTirst two completaeycles ea,ch day were per-;,Jjj, ykj formed tib^i'mbl^^airelatlve^'dptd. st^hi moving,into rela^T^' tively hotpacl<ipgi;a(conditi4p;^ncbunt'eredf fotexample,,*; when valves in steam service stand open foira long period 'h; J ( of time and are closed to sh utoff ffow. In the test; the end aS*; the stem furthestp.ut'of.the::fp:bre was.allayved ttrcool approximately 100:?F (38C),:'and then?stroked.into the packing. Packing temperaturpswere approximately 540FTk; (282C). These-"thermal equilibrium" tests were designed'^'.'* to evaluate effects bf'thermaMapei'f of valve stems, si nee,' > the cool,.extended portion of the.stemjs significantly _ , smaller in. diameterthan the portion intha packing cham-'i*; \< ber. In the case of a stem witha nominal diameterof4.000 ''' - inches (101.6 mm), the diameter difference,is about 0.01 (0.30 mm), Following the first,two complete cycles; wearJ iv' cycling resumed at the same rate as in the ambient tem ri~r r perature tests. The test.was complete when 1000 cycles^ [ tbeltwp large-rdix-, /IS* .'hires'dniMwe^ dbring the-hottests.'/ m ` Packing: [nitHesnr^ normally underwent two ther- ; malcycles:'' ., . !: -, ' ' jl ' Throughout.ail tests,^'stem-frictional load was moni-1 1 tored peripdibajly-qn:astripphart recordptlStem frictional , load is the force necessary to.move the stem through the '(1C ' packing, and is a result of the packing being squeezed against thestem to provide aseal. lrJ,,3' \ ,`i;,, TfeTjL' Atthe end of all tests, final packing compression was measured arid recorded..Packing compression was /, ^, |i[ determined by measuring the axial position.pf the packing; "rT|J gland before any boltingjoads were applied, and-then x1; measuring the axial position ofthe gland atthe endofthe.' test (or other point of interest): The difference between, >.': these two measurements is the amount ofcompression . and when divided by the nominal packing stack height yields the percentage compression of the packmg set > * At the end'of the.test,; the torque remainingonthe.' i- packing gland bolts was measured-and-recorded. In " selected tests, gland- bolt loads andstem friction-loads : -.. : were logged over a.range oftest pressures at-room tem peratures. Test flxturesweretoen'disassem and the packing examined. ' ;;T, (f. NIBCO001322 SURE? osion TostFixture, FIGURES Photograph Showing Corrosion Test Fixtures in Test Oven: . erosion Tests The corrosion tests were performed to determine effectiveness of the various corrosion inhibitors being td or recommended for use with carbon or graphitic iking materials. Itwasthe intent of this study to examine h corrosion of vafve stems and of packing chambers. i test fixtures used in the corrosion test program are iwn in Figure 7.. . These fixtures were constructed to represent actual ye packing chambers with a valve stem extending )ugh them. The "stems" were madq from.typicai valve ti materials, heat treated andlinished similarly to actual ye stems. The fixture, bodies were made from ASTM 16 Grade WCB, a material from which many large cast ei valves are typically made. Before starting the test, all surfaces were cleaned emove any machining oil. The packing to be tested was ded into the fixtures and slightly compressed. Tap water ipproximately 600 psi (41 bar) was then infected into the iking through the holes in the center of the fixture body, issure was maintained until the packing leaked and the iking was wet. Then, the fixtures were placed into a ar plastic container, and the container placed into a iperature controlled oven forthe period of the test {see ure {^approximately two quarts (2 liters) of distilled :er v(. > ;aced in the bottom of the container Once :h da^,' the ove n was heated to approxi mateiy 100F C) and held there for one hour. This was done to ;ure a 100% humidity environment around the test ures. Each test was completed when the required test e had elapsed. Two tests were completed after 650 hours (27 days). One test was extended to,2000 hours,- (83 days). Upon compietion'.ofthetest; the fixtures were y removed from the oven and'disassembledi Stem and- ,. . , i ^ packing chamber surfaces were,inspectedTo determine j, theextentof'thecorrosi0ni;if;anys.i'rv. ` , ,s RESULTS " ro Table 4 presents cycle test^esuits for all packings- ,r tested to date in this program. Results for flexible graphite ' y packings and other proprietary braided packings are dis- ' cussed individually below. < ' -- . Flexible Graphite With Braided Carbom and Graphite End Rings 2.375 Inch Stem Tests: . vV Earliertests had included extensive,room temper-",\ ature and high temperature verification of braided carbon/7 flexible graphite packingmaterial combinations in.valves . with a stem diameter of 1.000 ineh(25.4 mm); the first part, of the current program emphasized testing,with larger stems ;. Testing of flexible graphite packingmaterials began, with two room temperature tests of Preference material combination, Gariock 98 end rings with Grafoil center' . rings, in the 2.375-ineh (60.3 mm) stem test fixture: This testi ng, as well as most other roo tntemperatiiretebtihg' , of flexible graphite packing, materials, was performed at 6250 psig (431 bar). Packing gland bolt torques of 175 ft-!bf (237 N.m) were used in these tests, corresponding to:a pressure loading on the packing.of approximately 6500psr (448 bar), slightly higherthanthetestpressure, . if:., NIBCO001323 j ....\ ufaefurer Martin Merkel GmbH & Co. KG Latty International Uatty International Garlock, Inc. Material Combination Carbosteam/. Grafiflex LattygrafSOOD/ LattygrafEI LattygrafTBP/ LattygrafEI 1Z00-PBI A. W. Chesterton Style 1-CI/GPP Company A. W. CJiQBterton Style 1800 Company . Garlock, !na Union Carbide GariOcK 120O-PBI/ Grafoil TABLE 4 Cycle TestResults 1.00 Inch (25.4 mm) DiameterStem Test Results Test Number 1-K 1-H 1-J Bolt 1 Packing. . Test j; Test, Torque Pressure' Temp Press., Ft-Lbf ! Load.pslJ- . F psig. Stem Torque Ft-Lbf 40 7B00 .. . ro 6250 ' 37.5 :v-v':-v, - 40 7800'.: " 70' 6250:-' ;; 30" 40' 7600. = 1650-.. ; 2200' :35 I Packing. . Compression % Packing. Adjustments Required HA 1 `K> 2/8 \^ ' ,27 * J, " '. i/i : 1 -> , -.28 , - - ., -. ,0/0 ? Number, of - Cycles, Notes/', [' Completed- Comments-: , 1361 .< - , 1 1 , * ( ' b` f., ' 2500, i.,1'' k-HvTOOO'.yi.i-V^ 1,2 ' , 1 ` \ ,i /r ''i,V i'7< . r'r1. K' '1 < 1-B 1-D 62 62 lecoo:-.. .. 70 , 2250 16000." ; 650!" 2200. ' ' -25 102' '20 , 'Oft... 0/0 - V V 2500'..* 796/ i"! V."' 3, n't 1 r - 1-C 1-E 41 41' sooo: ' 70.- 2250 - ' '40... 8000" . 650 2200 55' . NA NA. 2/1.. 1 1/0 , ' 2500, \ 110001.., U` J1- ' *, i^i 1-L 46' 9000 70 2250'' '33 27' ' 0/2 . 2500" ,-t / J 'jfj, ' 3*- i ` 1-M 46 9000 goo 2000 28' ",41 r , - 2/2 ' *'*' 1000' v* ';fV , ve 'i.'. i* 1-F 41 8000 650 2200 '55, , '33 ,.3/3 , .' '",1000,*/ 1-G 41 8000 650 2200 18 / ':37' ' . - y M/i ' yn TOODSTdr. 1-1 40 j 7800 900 2200 2e: ' ' : .'"22" - "ty-o/i ! jM*. Manufacturer Garlock, Inc. Union Carbide Material Combination Garlock 98/ Grafail A. W, Chesterton Style 1-CI/GTPl ' Company Martin Merkel f;*J;:?H&Co.KG v ,-j f*i2i;hatlonal Garlock, Inc. Carbosteam/ Grafiflex Lattygrafeooo/ LattygrafEI 1200-PBI Parker Seal Group John Crons' Houdallle, Inc. A> W. Chesterton Company Parker 2028 Crane 2871 Style 1800 2.375 Inch (60.33 mm) Diameter StemTest Hesu Its. Test Number 5 24 2 3 4 26 19 20 21 14 15 16 27 26 23 31 6 7 8 9 10 17 ii 12 13. Bolt Torque Ft-U>f Packing Pressure Load, psf 125 4600 125 4600 175 6500 175 6500 175 6500' 175 6500 r~ 3100/4400 175 y esoo SO 1850 SO 1850 330 12200 330 12200 330 12200- 200 7400 200 7400 200 7400 200 7400 150 5600 150 5600 150 5600 150 5800 ISO 5800 5800 ISO 5600 ISO 5600' 175 6500. Test Temp. F 70 650 70 70 650 650 850 70 70 572 70 70 650 70 650 70 650 70 70 70 650 650 650 70 650: 70 Test Press. psig StemFriction. tbf 6250 2200 6250 6250 2200- 2200 2200 1200 2300 2500` 1500 3000', 1500' 2500 6250 3200 ' 1500 1500 1248 ' -1200' 6250 4000 6250 4000 2200 3800.1 6250 2200 2700 2700 . 0250 " 3500 2200 3900 2250 3750 6250 2200 2200 2200 2500 3400 '.NA'.. .900" 750 ' ' 1500' 2250 1800 2200'.'' 4 , 600 2250 5700 Packing-... Racking [irNumberot/ h' 4. -k yi Compression Adjustments1 f(< Cycles .IV'cbmm^ts . -m . . Required Completed" 2a 0/0 /.V-tli-L.TOOOfA, ii>. .** M 30v T ' ' . 2It\ ICuir* t-'M NA ' , 010- 4 f--: 1000% 20* , 29r 010 1 Jfr IbOOWP sir,1* V- o/o,1. wi'ltxwJ/M n \ If*'/* 23. > ,,< NA -k $ 1B47''45i r&sdi' 20 ,, . 0/0:, '33V V' ` 1/T, 4 v if>oo;fM 7t p;2500*! 'a*'; 16 * O/O \{ i'l j;r)'1UOO0f ' 3/3 . 5,J uiooa!if};f NA" NA NA. < :> -,3362?':.. .;.-,.-.- , '2/3 2/1 . , 010 1 1000'jj (L .7 'A, 1000^ hu,, 0/0 1/1 , ft* f ; lOoot .A .1000/% 'km. 23 ,1 0/0 * 24 , 1/1 ' 3G'-!' \V ` o/o - , 100b,i 27 . 1/1 . 11001 If ,28, \, "212!-, b , 1-0007-.^ V* - 11 J , 26 1/1 1 1'- 376 25 , "i 11/1 /m t.y 327/31': 27`." ' , 3/2 700 V' '<13,7' )?" n 32, i',,-., 1/1 , ( 1, '43200 lit "38 1 ,y{S 4/4, ~V 1 29 \ Hr A JScJt 2^?,,{* xwt il k 29 240 8900' 70... -2250', 2600 , , ,35 , r,',-2'2 v , 1000*. ,,. 30. 240 8900 . , 650 '2200 r, WA v*; 1,^*1? k 4,' t O.Swffl, ,11 i*t\ LkA Manufacturer Garlock, IncUnion Carbide Material' Combination Garlock 98/ Gmfoii Gatlockjnc. Garlock 98/ Graph-Lock 4.000 Inch (101.6 mm) Diameter Stem Test Results^ I W/ ' \ ^f ` Test Bolt Tomue Packing Test . Test Stem Packing ' , Packing Number of ' Pressure Temp, 'Press, Friction Compression,, Adjustments J, Cycles,'<(- Number Ft-Lbf Load, psl F psig .Lbf 54 ' " Required. ; 'Completed!' t k* rfy \;' ^ 4-A 475. 6500 70 6250. ' . 4000.''' " Aasi' 0/0 j / 1000 v i 14-B 350 4750 650 2200 ' '59001. . 3 i/r ,J 1 1000 '& 44D 31004400 650 2200 7100 : N/A . 1/1 J 1000 Uvelotidrxik 4-D 414 5600' 650 2200 0,166. 26f - - *',j 1/1, >, 641V mm< [ Ft T %,r t'yi `t , fi General Notes: Where two material* are listed together, the firet is the anB-extrualon ring material and the second Is the center ring material. \ v, .< .. a^i. Pecking adjustments required bKowb the number of adjustments required tor teetendl followed by number ofadjustments required tor.teatenda; Stemfrictfonloadslstedarelargestmeasureddudngeachtest. * <' 1 <t5v' Notes/Oommente: .. . .- w v' s 1. Extra braided end ring requiredto prevent packing gland from bottoming out. 15. Gland boJttCfquw Increased toTS.WW during seat leakage; f^ 2. Test stopped dub to excessIve ambient temperature leakage. 16. Packing did not leak after glandbalMorquas atone endwere redudto6AHW;/:^;v;:{j;i.;.;pi ;j 3. Could not pass ambient temperature ftydrotest at 2QOO pelg after cooldown from hot testing. 17. Three ratorques required to seal against seat leakage test pressure , 4. ExtrabraldedemJ rings required torsealing. 16. Gland bcrittorques were decreased toSfiOft-lbf at Ocyclesbecaueestem toctionai.lpacPwaa^. ; 5. RecommendedboIttorquBB too lowtopnovide sealing, rargeenoughthailhehydmullccyltedercculdextendbutnotretreict. ; fl. Tbrquelncreaeedtol/BFt-LbfafterfiOOcydes. 19. Test 46 wasa continuation ofTbst'4A,.with the test fixture not being repacked beforethe;;;. :?.- *. 7. Torque established at 300 ftHbf to maintain desired packing pressure loading alter relaxation. start ofthe test. Gland boittorques ware restored to 350 (Wbf before the start of the test; ^St^st stopped dueto excessive ambient temperature leakage. . ' '.' ^v'sCkkiinngn ngllallnMd hbrotJltt Itonrmquiieasi IInncnrweaasaeivdl ftpoi ^177R6 tfWtJhbtf atffhteirr I1BB/10 ncy.cles. U i .and botttorquMlncreasecI to 50 tt-lbfet 248cycles. , 20. Compression represents additional compression after.retofqylng.to 35afUbfin^repgratton^jv, forthlatest . ' . ' .'j:--':' 21. Tbstwas.stopped after severe leakage developed during first'''thermal aqiJlllbriMmu cyclfc.-:?^v.. thriInatsd normally stSOOcycies. 22. PaoklngadjuBtedafterfirsUhermEdequillbriljmcycletost,opleakag& >,` > 12. Gland bolttorquas Increased to I75ft*lbfafwr6 cycles. - 23. Flret 100cycle9comptete<l'atioomtenfip*aJure,'625trpsig;1^; : < ,* 13. Gland bolttorques Increased to 176 ft-lbfafterheatupbulbefore firststem cycle. 24. Test stepped after 641 totalcydeeformaintenenceonstearngenerator , 14. Retorqire at 1000 eyries success^] at stopping minor leakage. Extra 200 cydes completed esverificatioTL J \v ti NIBCO001324 ' Results of this testing were very good. Two 1000 cycle tests were completed with no adjustments of the ` packing required at all. Compression of the packing at the conclusion of testing {but with bolt loads still applied) was apf "/Ornately 29%, with most of the compression occur ring^ i result of initial bolt preloading and hydrostatic testing. Normally, very little additional compression of the;... packing was observed during the subsequent cycle test ing. Stem frictional loads averaged approximately 3000 Ibf (13,300 N) per 5-ring packing set. Probably the most interesting observation made during these first two tests was that during the cycle test ing, while the test fixture was at test pressure, the meas ured packing gland bolt load quickly approached a load equal (within experimental accuracy) to the hydrostatic end. / load on the packing due to test pressure.. That the force ' , measured at one end of the packing set is approximately equal to the force being applied at the other end suggests the axial pressure within the packing is, to a reasonable extent, evenly distributed, and additionally suggests that the packing is to a great extent pressure energized. This result was unexpected. Results of hot testing of the reference material design were equally as good. The initial test setup was the same as forthe room temperature tests described above. As noted previously, the first two complete cycles of the, stem each day were thermal equilibrium cycles,,.which involved cycling a relatively cold stem into a hot'packing FIGURE 9 chamber. During this part of the testing, minor visible steam leakage through the packing was observed; it Packing GlandBcItLoadvs. TestPressure, Bedeck 98/Gmtoll Combination Test 5-F}oom Temp-End of Test. . . started part,way during stem motion and stopped when stem motion stopped or within a few seconds thereafter. equilibrium cycles, there was no leak age ]e opposite end of the fixture where the hot stem came but of the packing chamber and a hotter section of in a further consideration of the previous results, stem entered the chamber (simulating opening of a valve Test No. 5 was performed. In this test, packing gland bolt that was already hot). preload torques of 125 ft-lbf (169 N.m) were used to deter Leakage through the packing was not visually ob mine if reduced initial bolt loading would adversely affect served during normal continuous wear cycling. Stem fric packing performance. This torque produced a gland pres tional loads during this test were approximately the same sure of just.4600 psi (317 bar) orjust74% of the test as had been observed during room temperature testing. pressure. At this point in the testing, it was observed that after Results from Test No. 5 indicated that although depressurization at the end of 1000 cycles, packing gland retorquing to 125 ft-lbf was required after hydrotest to seal bolt torques had decreased to provide a pressure loading at the seat leakage test pressure (6875 psi or474 bar); no on the packing of approximately 3270 psi (225 bar), a 50% retorquing was required during this 1000 cycle room tem reduction from the initial preload value of 6500 psi (448 perature test. High temperature testing (Test 24) using this bar). This result suggested tha|it may be possible to lose same packing gland bolt torque yielded slightly degraded a significant amount of packing gland bolt preload during (but acceptable),performance, with one packing set refer- normal operation. Therefore,. Test No. 4 was performed to qued twice and'fhe other end once to control packing leak find out what would happen during high temperature oper age during the 1000 cycle test. ation if practically all packing gland bolt preload was lost. . Results of measurements made at the end of Test Results of Test No. 4 were surprising. After initial No. 5to determine the effectof test pressure on packing test setup, hydrotesting and 570 hot wear cycles, gland gland bolt load are shown in Figure 9. Test pressure was bolt torques on one packing gland were intentionally re gradually reduced from 6250 psig (431 bar)toOpsigand moved completely, then retightened to reduced levels of then back again; At each data point; the stem wad cycled 15 ft-ibf (20 N.m), and then to 5 ft-lbf (7 N.m) torque to de- a few times to eliminate residual effects from the,last pres terminethe impact on packing leakage during high tem sure tested. Bolt loads were summed to determine total perature operation. Leakage In this test was virtually the gland load, which is plotted in the figure. These data are same as in the previous hot test. These results indicate compared to the hydrostatic force on the packing. The that^^ie otherphenomenon is occurring which helps the gland pressure at zero test pressure had declined from the paOTjto seal. This supports previous test results show 4600 psi (317 bar) pretest value to just 680 psi (47 bar), yet ing f^Mhis packing combination tends to be pressure, the packings continued to seal at all pressures to 6250 psig energized after it is initially compressed at installation. (431 bar). It is clear that as the hydrostatic end load on the 12 NIBCO001325  All previous tests of the reference material design in , this test program had a test duration.of 1.000.cycles. In order, to demonstrate a reasonable amountaf performance:;mar^;;i gin, TestNd, 19was performed. Thiswas an ambtenttem-,>.i>/ . perature test at 6250. psig (431 bar), but with a duration.of;' , ' -, 2500 cycles. During the course of tljjstest, adjustmentipf,^ - `v*` each'packing set was required onlyonce. These results^).' ind icate that the reference packing material combination _; n has,an;adequate performance margin. 'Additionaliy.'-be;; . valve stems,at1eastas,;a,worstc.as.e;;,ln:'atl,Woio|lj ,graphite packing|and. braided e.h.d;.r!ingsr.stems?were'|p^i to polish tea finish'of ab'oOt 20 njicrbinches (KSO.mfqrer eters) during cycle testerstems were removediframte= tore arid "roughened" to 32 microinches between test; Asa result otthese.test.resuitsr.testsi'todeterroifiepacts performance with stems having smoother surface fimshps^ were not performed. While ftner^stem finish r^ightjQffej^;,^ someadvantagB;|hbbntrat.vafveawhfch;cycle^nbnudu^"|5S^ FIGURE 10 y Stem Friction Load vs. Pressure, GarJock-98/GrafolTComblnation Tests- Room Temp -End of Test \v packing increases above that resulting from total gland bolt preload on the packing, total gland bolt load and ihe hydrostatic load on the packing are very nearly equal. Figure 10 shows measurements made at the end of Test No. 5 to determine the impactof test pressure on stem packing friction load. These data were taken in the same manner as the data shown in Figure 9. These results indi cate that for the reference material design, stem packing; friction loads are essentially independent oftest pressure, This was unexpected. '' These results have some very interesting implica- tions with respectto effect of loadings on this packing;ma- terial combination, it is reasonable to assume, although, not proven here, that.there is a minimum initial amount of axial compression.(l.e., gland bolt load) ofthe packing re quired to make it seal properly. This is due primarily to the radial flow ofthe packing required to take up clearances between thepacking and the stem and packing chamber sidewall, Then, if the hydrostatic end load on the packing is greater than this mimimum load, packing performance would be expected to be good, although not necessarily perfect. This is not to say that total loss of packing giand bolt preload is acceptable. However, this does mean that, assuming the packing was Installed properly to begin with, live ioadingof the packing (using belleviile spring washers, Tests No. 20 and^werep'ej^prined.tp'detgrplfl it packihgsetswfth'.just 4 rings dfthe^reference'material combmationicould be. usiSdiWith valve stomsas large as1; 2.375 inpb'fSO^ifnmJ'diameter^tiQpefatjngiC^uditioh^i.^ to those'of Clas&SOO valves; Ambient temperature perfor mance of the packing setswas very1 pood, with no adjustv ments bfthepackfng required'during the 1000 cycle testiHf duration., Performance during hbttestingat 572Fand; 1246 psig.(30DC and 86 bkr^was.also su.ccpsdfuli!.'t.e;a age of steam through the packingduring hottesting.was^' minimal. Thre8adjustmeptS:ofga,df){packing'iaet1werai:ey%| quired during.th'e;teist;:wh'[ehwas mo^e thannQrmaikut,r; acceptable for.rndstappiicatidhsiTheseadjustrnentswkirel ___ i. hottest ing. These results indicate that;the,^nng packmgaetsdfe the reference packing material combination can po usr'r successfully m Glass 6O0;applic.atians;,with;stems;as, a'2.375mch (60 3imm) diameterr^'f?,;' C ^ ' ' TestNo; 26was performed,tb-aksess'ibejmpact ofliveloading onlthe pafckingmaterial. Live loading wf .accomplished byapplyingjbellevjlle.washerptacks in place. bfithe staqdard.gi|p|'bglfing'.The washer, sta< were designed^d^rs^|pi6K^a!dcord ing to the AECL proposed;kesigrf:Criiki ia 8] 'Using 2500 psig,; (172 bar).as.the,design oper|iting, pressure.Tbp 250 * design pressu rkwasch'pail^becfaSkKthe.1 ture teste coulcfonlybe pk$ormed at 2200 psig (152,ba and it was:desired to designthespriiiig stacks.pased'oi the aetuaftest pressure-.iThe>stackswore designed tor; deliver i .25 to 1::75 times tnekydrostatic ibadipgldn'the packing over a spring travel of 0.116 inches(2;95':mm);. Spring travel requirement was derived basedkk.resultsi.bfer' previous tests. The spring-stacks are shown ih Figure tljj % performance, since the packing is already "live' Jed'-by line pressure; !^'lt \> * .> ' A, \j " f\( ` 13 NIBCO001326 Live LoadingArrangement. In preparation fortesting, the packing was installed two rings at a time and compressed using a gland pressure load of 6500 psi (448 bar) before the next two rings were installed. The fifth ring was installed individually in the same manner. This procedure was used for consistency with that previously used in assembling Rockwell nuclear power plant valves with live-loaded packings. The standard bolting apparatus was then replaced with the live loading apparatus. Lines were previously scribed on the spring, stack plunger (see Figure 11) to indicate the 125% and 175% load positions and were used to establish the con figuration of the spring stack^p'rior to thestart of testing. The first 500 cycles, df this test were performed at room temperature and 2250 psig (155 bar). Room tem perature performance was very good, with no leakage observed. The stem began '`groaning" at approximately 19 cycles and stopped at approximately 170 cycles. This was not observed in previous tests without live loading. The last 500 cycles of this test were performed at 650F (343C) and 2200 psig (152 bar). On the first day of testing, thermal equilibrium cycles exhibited no leakage (an im provement), and no leakage was noted during normal wear cycles. On the second day of testing, however, the packing leaked steam during thermal equilibrium cycling tr^Tiroximatelythe same transient degree as packing ^ ^ tandard gland bolting. Wear cycling was without incident. These results indicate that live loading improves packing performance, but not as significantly as might have been expected. During testing, gland travel for test ends 1 and 2 was ,081 (2.1 mm) and .064 inches (1.6 mm) respectively (well within the 0.116 inch (2.95 mm) design spring travel). Stem frictional loads observed during this test are compared to loads observed in earliertests in Figure 12, Data in curves 1 and 2 were taken from tests performed at 6250 psig (431 bar) using standard bolting, with the differ ence being the initial gland bolt torque. Curves 1 and 2 show a definite increase in stem frictionaf load with increas ing initial gland bolt torque. Data from the live loaded pack ing test show higher stem packing friction occurring for a lower test pressure and lower unit pressure loading on the packing. The step increase in the magnitude of the stem frictional load with the live loaded packing at 500 cycles occurred after the test fixture had been reconfigured for the hot portion of the test, and,has no specific explanation; since several days were required for the reconfiguration, a simple "time set" effect may have been involved. 4.000 Inch Stem Tests; ' Testing of braided carbon/flexible graphitic packing material combinations was also conducted in the 4.000 inch (101.6 mm)diameterstehi test fixture. Testing in this fixture was performed in the same manner as in the 2.375 inch (60.33 mm) test fixture. Packing was loaded into the fixture and the giand bolts torquedto 475 ft-lbf(644 N.m), sufficient.to provide 6500 psi (448 bar) pressure loading on the packing. This is the same value used in most tests in the 2.375 inch fixture. u NIBCO001327 PT`3" CURVES I 'I 1t`l f t-%wi'i'-i twuv 'y s CURVE 1 --CURVE 2 --" CURVES ** 500 700 600 BOO STEM CYCLES fMbl,- 175 62S0 psig, ROOM TEMR - 125 Ft'Lirf, 6250psig, ROOM TEMP. * LIV LOAD?NG2250 psig 0-500 CYCLES - ROOM TEMR 600-1000 CYCLES 650<,Ff343BCj 1000 'J! TM i FIGURE 12 NStoermaFlrBicotilolinnLgovas.dLvisv.eCLyocaledsin, gG.arfoeir98/G.rafol!Conmabtinoen,, t n*k firct two tests performed In this fixture were a "SmSsSs frictional load caused by the packing. ~ retractagain ^ _ torques were reduced to 350 ft-lbf wSmUo reduce the stem friction load. While this pro- (475 N-.m) to^reou. ^ q{jugt4800 pgf (330 barJj jt auced a gian . P ceecJ. Tests 5 and 24 (Tabie 4) with the 2o.3^7c5^iMnvctuhref^haWd producedTshuecfcixetsusrefuwl raesstuhletsnwpitrhesa- SSdiotX leakage'test P^sure (6875 psig/474 bar) hunzeu iu ui 0f the packing. When proper seal- to verify Pt0J> jfi0C| cycling of the stem was started. Re- inlha Sirst test were good, with just 2 adjustments to e",Soao ngSTMrJUIduriUaTM00Retest. " ^Aftflralf measurements had been made at the end although the results demonstrate considerable perfor- . Hichtemperature tests in the 4.000 inch (101.6 mm) 1 - ^ure were performed in the same manner as those in the $ ^375 inch (60 33 mm) fixture. The only change was in then nialequHibrium cycling. Because of the size and mass of the stem and the time required to heat and cool it, only one thermal equilibrium cycle was performed at the beginning of each test day, as opposed to two in previous tests. . Performance during this second test was also good. No leakage was observed during the first thermal cycle. During the second through the fourth thermal cycie,. minor leakage was noted during thermal equilibrium cycles. Minor leakage during hydrostatic testing at 2500 psig (172 bar) at the end of the second thermal cycle prompted an . adjustment of both packing sets to stop the leakage. No additional adjustments to the packing.were required. . Upon disassembly following Test 4B, full-stroke scoring of the stem was observed at test end 1, Foreign, material found in the test fixture (resulting from manufac ture and heat treatment) was the probable cause. Even with this scoring, however, test end 1 sealed leak tight against a hydrostatic test pressure of 2500 psig (172 bar) at the end of the test. While certainly not intentional, this test demonstrated the ability of this packing combination to "heal" the effects of a valve stem damaged in this manner. The Gariock 98/Graph-!ock material combination was also testedjn the 4,000-inch (101.6 mm) test fixture. Only one test of the material: was performed. The first 100 cycles of the test were performed at room temperature/ 6250 psig (431 bar)..The remaining 541 cycles were per formed at 650F/2200 psig (343C/152 bar). Testing was . stopped at 641 cycles due to maintenance requirements on the steam generator. Room temperature performance wasgood. Additionally, no leakage was observed during wear cycling at high temperature. Performance during "thermal equilibrium" cycling was good at the beginning, but the amount of leakage and time before it stopped increased with each thermal*1 cycle; higher initial gland bolt torques (i.e., gland pressure loading on the packing) might have solved this problem. 4.000 inch Stem Test---Live Loaded: Testing of the live-loaded packing (Test 4-C in Table , 4) in the 4.000 inch (101.6 mm) test fixture was conducted in a slightly different manner than in previous tests. Test end 2 (see Figure4B) was fitted with belleville washer stacks while test end 1 remained with conventional gland bolting. This arrangement allowed the full 20 inch (508 mm) stem stroke to be maintained, while at the same time providing a repeat test with conventional gland bolting. " in this test, as. in the previous five-loaded packing test, the first two rings of packing were loaded into the test fixture and-compressed to 6500 psi (448 bar) gland pres sure. These first two rings were then followed by the sec ond two, and finally the last ring in the same manner Both test ends were packed this way. Belleville washer stacks were then fitted on test end 2, while the gland bolttorques on test end 1 were adjusted to 350 ft-lbf (475 N .m). The spring stacks used in this test were designed to provide 125 to 175% of the hydrostatic end load on the packing at 2500 psig (172 bar) over atravel of 0.112 inches (2.84 mm). Results from the previous two tests in this test fixture indicated that for tests 4-A and 4-B combined, total gland motion due to gland Readjustments was approxi mately 0.102 inches (2.58 mm), so that the design should be adequate. The first 500 cycles were performed at room tem perature, 2250 psig (155 bar). Significant motion of the five-loaded gland (0.050 inch/1.27 mm) was observed dur ing the first 100 cycles of the test. Gland motion continued at a much reduced rate until at the end of 500 cycles, total live-loaded gland travel had reached 0.082 inch (2.16 mm). \\\\ HIS Vi, NIBCO001328 tal gland motion with conventional bolting was approxiately 0.004 inch (0.10 mm). Neither end was exhibiting ly sign ""akage during these first 500cycles. Tv .... ,'st fixture was next installed into the,steam jneratoriest loop in preparation for high temperature 50F, 2200 psig) (343C, 152 bar) testing. A total of three ermal cycles was completed during this test. At the beginng of each thermal cycle, one "thermal equilibrium" cycle as conducted. During the first thermal equilibrium cycle, ;e live-loaded packing did not leak, while slight leakage as observed from the conventionally loaded packing, uring the second thermal cycle, leakage of approximately le same magnitude was observed from both packing seats. At the end of the second thermal cycle and after the ist fixture had cooled to room temperature, it was observed lat the live-loaded gland travel had exceeded that for hich the belleville spring stacks were designed. There>re, the spring stacks were restored to the 175% load conition prior to the heatup for the third thermal cycle. At this ame time, the conventional gland bolt torque was restored 3 350 ft-lbf (4/5 N.m). No leakage was observed from either packing hamber during thermal equilibrium cycling at the beginiing of the third thermal cycle. Throughout the wear cycling iortion ofthe hot test, no leakage was observed coming rom either packing set. Also, no leakage was observed hrough either packing set during room temperature lydrostatic testing of the packing following cooldown after sach thermal cycle. The maximum stem packing friction oad of 7100 Ibf (31.5 KN) was observed at the beginning )f the - " i temperature portion of the test. !, \' Alternate Carbon and Graphite Packing Materials: Material combinations with braided carbon or graphite end rings and flexible graphite central rings from either manufacturers were tasted variously in two of the cycle test fixtures, in general, assuming that proper gland boit preloads were specified, pe rformance of these pack ings was comparable to that of the reference material com bination. Short discussions of each material combination tested follow. Chesterton6 Style 1-Ct/GTPI packing material com bination was tested in the 2.375 inch (60.3 mm) stem test fix ture. The packing gland boit torque recommendation from Chesterton for this material combination was the highest of all materials tested and resulted in the highest stem fric tion loads measured during testing of the graphitic mate rials. in spite of this, however, the first room temperature test performed using this materia! (Test 14) showed poor results because of minor uncontrollable leakage from both packing chambers. It was noted that the Chesterton Style 1-CI and ring is of braided graphite (not carbon) construc tion, and a similar problem was encountered with different braided graphite end rings at high pressures in earlier Rockwell tests [4]. Nevertheless, this problem was solved in a subsequent ambient temperature test by Installing an additional Style t end ring next to the packing gland In eacfestacking chamber after hydrostatic test. With this chi , ,j both room temperature and high temperature sealing performance was good, but packing friction was quite high. However, this change made the 5 ring packing chamber into a 6 ring packing chamber, and it requires additional manufacturing assembly steps (adding a packing ring after initial compression). . . Martin Merkei Carbostearn7/Grafiflex7packing . material combination was tested in both the.-2.375 inch (60.3 mm) and 1.000 inch (25.4 mm) stem test fixtures Performance in the 2.375 inch fixture during both-room temperature and hightemperature testing-was.very good. Room temperature testing of this material-.irvthe T.000 inch test fixture was troubled by.leakage whicfTC.ould.not be controlled. Martin Merkel has been consulted about this problem. A high temperature testjcvthe 1000 inchfixture-' was not performed. : The Lattygraf 6000/ETp;adicigg-:matenal-cbrnbina-- xb tion was tested in both the 100 inch (25 4mm)1 and 2.375 . inch (60.3 mm) test fixtures; RooSiemperature-,and:liigh-. temperature performance in the li'pOO-inch test fixture was ,. very good. A problem with obtaiifjjrjg the correctpacking gland bolt torques from the supplier hindered the testing in 7 j the 2.375 inch test fixture. The first torque- recommendation ^' received appeared to be too low;.although,recommended , gland pressure loading (500 bar:br,7200^|f|appB(aipd to v ^ be approximately correct. A revised torquelydiuegeceived-sy, -f from the Latty U.S. representative was too high and the- - t,-f packing friction caused theacte(isiioc-toj^[ife^i.ir4cBcom- mendation was low, and the pac^dng|e|ii^?A|th||^point, \'M>' Rockwell gradually increased the torque;jtd;200.ft-|ii)'f,{271 1 1 N.m) and achieved an effective seal. Performance in the rW room temperature test then was very good, although pack-' ing friction was still somewhat high. Pertofmance-in the ,, ^ high temperature test was also good, with onry.orie'ad]ust- ' ij'14 ment of each packing set required during the.1.000 cycle test. Stem frictional load was slightly higher than imthe " room temperature test. . / ; -T" J v'Un Proprietary Braided Packing Materials 4 4- . f Proprietary braided packing materials from several - 4 "a manufacturers were tested. ALf of these packmg materials ^ were rated by the manufacturers for high temperature, high pressure service atthe time theywere submitted for rl'*, i ^ j tests. During this test program, all of these packing mate- ,, t rials were tested at 2250 psig (155 bar) dbnng room tern-. - >1$ perature testing, and at 650F (343aC), 2200 psig (152 bar)' ' during high temperature testing. Thetfightemperature , . condition. Packing compression for all .materiaistested ( averaged around 30/o. Generally, butwith one notable. 1' exception, materials which performedrbesf.tendedipi y * II maintain packinggland bolt preload,wejkjhis.ji%b8cause^ during heatup, usually related tovoiatizatiori; of substances. ' i A' kU\ acontalnad.in the packing.. Thatvolume,redLfctidn.translates, - directly into loss of gland preload; With one exception, petformahediafthese proprie tary materials during ambient temperature testing was v very good. One specifically was tested.atup to 6250 psig (431 bar) and performed very well. However, with two - -. exceptions, most proprietary braided.packings failed to . perform satisfactorily during, high temperature testing. Discussions of the Individual materials testedare presented below. ' ' 6Ches!erton is a registered trademark of the A. W. Chesterton Co. 7Carbostaam and GrafIflex are registered trademarks of Martin Merkel - - .- Gmtofi & Co. , -.5 NIBCO001329  Several tests of Garlock 1200-PBI were performed temperature performance was good. At the beginning of during the test program. This material performed very well high temperature testing, melted packing material was at room temperature, with no adjustments of the packing noted coming out ofthe packing chambers. However, high ^required in 1000 cycles at 2250 psig (155 bar). Room tem- temperature performance started off good but gradually ;v:' -.-lerature testing was carried to 6250 psig (341 bar) with degraded until, during the fourth thermal cycfe, the testing '... very good results. Three high temperature tests of this was stopped due to excessive steam leakage, Rockwell material were performed. The first two tests showed simi has not tested the new 2028 material. lar results, those being significant leakage during thermal . JohnCrane 2871 was the only packing tested which equilibrium cycling, followed by a gradual increase in could not pass the room temperature screening test. A steam leakage during normal wear cycling. In addition, high temperature test was not attempted. This packi ng is the packing could not be made to seal ambient temper no longer available from JohnCrane. A new JohnCrane ature water at 2500 psi (172 bar) following cooldown after material, EX-363, was received fortesting but not in time only one thermal cycle, indicating that it had hardened and for inclusion of results in this paper. lost its resilience. Increases in gland bolt loading produced Two Chesterton packings were tested in this part of no measurable packing compression, and post-test exam the test program, these being the Style 1-CI/GPP (graphite ination disclosed that packing rings had fused into a single, powder packing) combination and the Style 1800 packing rigid tubular form. -- material. The Style 1-CI/GPP material combination was These results were reveiwed with Garlock repre tested only in the 1.000 inch (25.4 mm) stem test fixture. sentatives who offered specific recommendations to im Both room temperature and high temperalure performance prove packing performance. These changes substantially were good. Again, however, an extra Style 1 end ring had improved performance with the final high temperature test to be added.to the top of each packing chamber, because lasting 700 cycles, almost twice as long as previous tests. packing compression caused the glands to bottom out, Steam leakage through the packing was also substantially leaving no further adjustment. This made the original 4 ring reduced, but the packing could not be made to seal against packing chamber a 5 ring packing chamber and involves room temperature water at 2500 psi (172 bar) after cooldown use of additional assembly labor to add the fifth ring. following the second thermal cycle. Testing was stopped at The Chesterton Style 1800 packing was tested in that point. " both the 2.375 inch (60.3 mm) and the 1.000 inch (25.4 mm) Although high temperature test results for Garlock stem test fixtures. Testing in the larger fixture was performed 1200-PBI by itself were not encouraging, some potential first. Room temperature performance was good, although was seen for this material as an anti-extrusion ring for use, initial cycling caused extrusion of an alarming amount of with flexible graphite packing material. The hardening of wear debris from the gland. During the first cycle of the the rings (which prevented successful test results with high temperature test, however, the packing started leak {')se rings alone) made the material a good candidate ing steam severely, so the test was stopped. After cool ' San anti-extrusion ring. down, a room temperature hydrotest at 2500 psi (172 bar) Three tests (1-F, 1-G, 1-1) of a Garlock 1200-PBI/ showed significant leakage. While this leakage could be Grafoil material combination were performed in the 1.000 controlled through tightening the gland bolting, the test inch (25.4 mm) diameter stem test fixture to determine the . was curtailed and Chesterton was consulted. performance of this material combination. Testing con About this same time, room temperature testing of sisted of two tests at 650F (343C) and one test at 900F this material was being completed in the smaller (1.000 (483C), both at 2200 psig (152 bar). No room temperature inch/25.4 mm stem) test fixture, it was decided to omit the testing was performed, as previous results indicated that 650F (343C) test and proceed to test the material in the room temperature performance of both materials should electrically heated loop at 900F (482DC) and 2200 psig be satisfactory. . (152 bar). Initial results during this test were the same as Results of the first two tests were good, with perfor- in the previous hot test--significant steam leakage during manceduring the second test being Somewhat better than the first stem cycle. However, at this point the test fixture the first. The presence ofthe flexible graphite in the pack was depressurized and the gland bolt torques, which had ing set gave it the resilience required to provide adjust dropped to a very low value, were restored to their original ability to control leakage, and the Gariock 1200-PBI value. This solved the leakage problem, and subsequent functioned well as an anti-extrusion devise. The third test high temperature performance of this packing was very at 900F (482C) again showed good performance of this good. Chesterton was consulted, and their representative materia! combination. Over the 500 cycle duration of the claimed that because this packing is a "jam" packing, it test, one packing set was adjusted once and the other set should be retorqued after initial heatup and prior to stem not atall. The test was terminated at 500 cycles as an cycling. These results indicate that performance of this adequate demonstration. packing in the larger fixture woufd probably have been Parker 2028 material was tested in the 2.375 inch acceptable if it had been retightened after heatup, but (60.3 mm)stem test fixture. After this test was completed, an additional high temperature test ofthe material in Parker stopped production of the material tested and later the larger fixture has not beers performed. The need for introduced a new packing material carrying the same retightening when hot before cycling is a significant identification number. Since the material tested is no . disadvantage. e|er produced, discussion ofthe results of thetesting 'pe brief. Compression of this packing was high at the que required to effect a seal, 32 to 38 percent. Room . 17 NIBCO001330 Corrosion Test Results The test fixtures were removed from the test overs and dissembled after the specified testperiods. Stem surf/ and the surfaces inside the stuffing boxes were examined for corrosion. A description of the packings tested is presented in Table 5. . None of the 17-4PH (H-1100) stems showed any evidence of corrosion. Even the control (no corrosion inhibitor) packing set did not corrode the 17-4PH stem. This is consistent with previous results obtained for stems made from 17-4PH. The 410 SS stem material next to the control (no corrosion inhibitor) packing set exhibited pitting .001 to .003 inches (0.03 to 0.08 mm) deep (see.Figure 13). The 410 SS stems protected from corrosion by the zinc washers, the aluminum washers, and the non-metallic corrosion inhibitor exhibited some discoloration but no pitting. Results with the zinc washers were subsequently confirmed in a 2000 hour test (see Table 5). After 2000 hours, however, a stem protected by aluminum washers showed significant pitting, and a stem protected by the non-metallic corrosion inhibitor displayed minor pitting. Results of corrosion tests with zinc and aluminum "dusted" graphite rings were mixed. In a previous Rock- we!! test program [4J, flexible graphite rings were "dusted" by applying thedust between the layers of the graphite rib bon and then forming the ring, and thus trapping the dust .; inside the ring. However, a survey of several major packing manufacturers indicated that dusted rings are usually made by applying a tackifying agent and then the metallic , dus*:>the external surfaces of the packing ring. The tack- ifyi, . jent is required because the dust will normally not adHeid to the flexible graphite rings. When the test stems were removed from the fixtures in Tests 1 and 2, it was observed that every stem surface which had been adja cent to dusted Grafoil packing had an adherent buildup of Grafoil, the metallic dust, and the tackifying agent. At the conclusion of the first test, it was thought that an insuffi cient curing time for the tackifying agent was the cause of this problem. However, similar results were observed at the end of the second test, even with factory-supplied dusted rings. Effects of this adhesion, of materials to the stem are stili under evaluation. No corrosion of the 410 SS stem surfaces which had been adjacent to zinc-dusted rings was observed. However, significant corrosion under the aluminum- dusted graphite rings was observed in both tests 1 and 2, with pits as bad as those observed for the control packing set (see Figure 14). Corrosion protection using interleaved zinc foil was found to be good in Test 2. However, corrosion protection from the interleaved aluminum foil was found to be poorer, with pitting observed on the 410 SS stem under the Grafoil rings, However, pitting was less severe than that observed with the aluminum dust. The Garlock 1200-PBI included in Test2 exhibited behavior similar to the aluminum-dusted graphite rings. Uppn removal from the test fixture, the stem which had C; .adjacent to the 1200-PBI was found to have packing niiWial adhered to it. When this material was removed from the stem, significant pitting of the stem was observed. Because 1200-PBI reportedly uses aluminum dust on the outside of the ring as a corrosion inhibitor (some zinc pow der is included in the core material for corrosion protection FIGURE 13 Close-up Photograph Showing Pitting of410 SS Stem Causedby ControlPacking Set In Test 1. also), this result is consistent with results obtained with aluminum dusted graphite rings in both Tests 1 and 2. Garlock has been consulted regarding these observations. Results with the Lattygraf 6000/El and the Chester ton Style 1-CI/GTPI material combinations were very good, with no corrosion observed on the 410 SS stems adjacent to these materials. Corrosion was noted on all of the carbon steel stuffing box inside surfaces and was most severe under braided end rings. The corrosion under these rings was characterized as being extensive with deep pitting. Cor rosion was most severe under the rings at the bottom of packing chambers. This was true regardless of whether the braided rings had corrosion inhibitor in them or not. Corrosion underthe center rings was reasonably uniform but much less severe than that observed underthe end rings. These results indicate that the observed corrosion of the stuffing box surfaces was due primarily to the pres ence of water next to the surface; that is, there would have seen similar results if the stuffing boxes had simply been immersed in water by themselves. The fact that the cor rosion was observed to be worse underthe braided end rings is probably due to the f&ct that they are somewhat porous and retain more water than the flexible graphite rings. CONCLUSIONS In a technical field which had seen only slow changes over several generations, developments over the past 15 years in valve stem packings seem remarkably accelerated. The pace has been accelerated even more over the past NIBCO001331 TABLES Corrosion Test Description Test Run No. f--650 Hour Duration Stem Packing Material Set No. Packing Material Description w -MOSS 1A Garlock 98 end rings--no corrosion inh i bitor Grafoil canter rings--no corrosion inhibitor (control packing set) 4-10SS. IB Gariock 98 end rings--no corrosion i nhibitor Grafoil center rings--Union Carbide phosphorus based corrosion inhibitor (GTK) 410 SS 410 SS 2A Gariock 98 end rings--no corrosion inhibitor Grafoil center rings--no corrosion inhibitor Zinc washers between packing layers 2B Gariock 98 end .rings--zinc impregnated Grafoil center rings--zinc dusted ' 410SS 3A Gariock 98 end rings--no corrosion inhibitor Grafoil center rings--no corrosion in hibitor Aluminum washers between packing Sayers 410 SS 3B Gariock 98 end rings--aluminum dusted Grafoil center rings--aluminum dusted 17-4PH 4A Gariock 98 end rings--no corrosion inhibitor Grafoil center rings--no corrosion inhibitor (control) 17-4PH 4B Gariock 98 end.rings--no corrosion inhibitor Grafoil center rings--Union Carbide phosphorus based corrosion inhibitor (GTTK) FIGURE 14 Close-up Photograph Showing Pitting of410 SS Stem Causedby Aluminum Dusted GrafollRings In Test 1, 17-4PH 17-4PH 17-4PH 5A Gariock 98 end rings--no corrosion inhibitor Grafolt center rings--no corrosion inhibitor Zlnc washers between packing layers SB Gariock 98 and rings--zinc impregnated Grafoil center rings--zinc dusted 6A Gariock 98 end rings--no corrosion inhibitor Grafoil center rings--no corrosion inhibitor Aluminum washers between packing layers y^ar or two. In a period of such acceleration, it is a major challenge to draw "conclusions"; the conclusions could change within 3 months if someone invents a really new material. Barring the invention of a new material, such as one combining the merits of polytetrafluoroethylene (PTFE), carbon fibers, and flexible graphite, the tests conducted by Rockwell suggest some important conclusions that should permit major improvements in stem sealing in valves for elevated temperature service.. It is recognized that others (e.g. Electric Power Research Institute) are conducting independent research work that may produce somewhat different results, but it is, believed that results of the Rockwel! test program anesignificant. Elimination of use of asbestos is the goal addressed most in this paper, but improvement in stem sealing performance is aiso an important result of the program. While sealing performance results are emphasized in this paper, cost effectiveness was not overlooked. Most," if not all, asbestos-free packing materials are more costly today than the asbestos-base products they may have to replace. Note that asbestos-base packings were not tested as a "control" in the experiments; this was deliberate, be cause asbestos is not an alternative and because its per formance was marginal in many past applications. The hazards of packing leakage in valves for nuclear power p||||ts stimulated the first modern research on packings, 'kspfhe costs of packing leakage (energy loss, product loss) have been recognized in fossil power plants, refiner ies, and other installations. Thus, replacement of asbestos packings with materials offering equivalent performance was not a realistic option. A new "state of the art" had to be recognized as a requirement. 17-4PH Stem Material 410 SS 410 SS 410 SS 410 SS 410 SS 410 SS 410 SS 410 SS 1 Stem Material 410 SS' 410 SS 410 SS 410 SS 6B Gariock98 end rings--aluminum dusted. Grafoil center rings--aluminum dusted Test Run No. 2--650 Hour Duration Packing Set No, Packing Material Description 9A Gariock 98 end rings--Aluminum dusted Grafoil center rings--Aluminum dusted 9B Gariock 98 end rings--Zinc impregnated Grafoil center rings--Zinc dusted 10A Gariock 98 end rings--Zinc impregnated Grafoil center rings--layered Zi nc foil 10B Gariock 98 end rings--Aluminum dusted Grafoil center rings--layered Aluminum loll 11A. ' Gariock 1200-PBI 11B Lattygraf 6000 end rings Lattygraf 61 centerrings 12A Chesterton Style 1-Ci end rings Chesterton GTPI center rings 12B Gariock 98 end rings--Zinc impregnated Graph-lock center rings--Zinc dusted Factory prepared packing set Test Run No. 3--2000 Hour Duration Packing SetNo. Packing Material Description 7A Gariock 98 end rings--no corrosion inhibitor Grafoil center rings--no corrosion inhibitor (control packing set) 7B Gariock 98 end rings--zinc impregnated Grafoil center rings--Union Carbide phosphorus based corrosion inhibitor (GTK) 8A Gariock 98 end rings--no corrosion inhibitor Grafoli center rings--no corrosion inhibitor Zlrtc washers between packing layers SB Gariock 98 end rings--no corrosion inhibitor Grafoil centerrings--no corrosion inhibitor Aluminum washers between packing layers in 3 (? ! .. . v NIBCO001332 Best Packing Material Combinations ..^^ults of the current program show no fundamen tal chi in comparison to earlier Rockwell reports. Good stem seating performance requires a combination of packing materials in high-pressure, high-temperatureapplications. The Pest sealing, results were achieved with combinations of flexible graphite internal sealing rings and anti-extrusion, rings of braided carbon or graphite. Among the various TABLE 6 Relative Grading of Corrosion Protection Systems Grade Material- A Zinc washers between packing rings . Impregnated zinc dust . " Externa) zinc dust with tackifying agent.' ' . . Non-metallic inhibitors . ; Interleaved zinc foil in flexible graphite. ' combinations of these materials tested, the reference B Aluminum washers between packing rings material design of Garlock 98 end rings with Grafoil seal ing rings gave the best results overall. Perhaps this is C Interleaved aluminum foil in flexible graphite Externa] aluminum dust with tacklfying agent1 related to greater Rockwell experience in applying these D No corrosion inhibitor . materials, which have been tested and applied for over five 1 Adherent buildup of packing material on stem OD currently being evaluated; years. All combinations of these basic materials, supplied by several manufacturers, exhibited performancethatwas Other materials tested in this program cannot be "graded". * significantly better than that produced by proprietary because they had such different strengths and weaknesses. ' braided asbestos-free packings. individual users may find some of these materials quite , One constituent of the packing material combi acceptable in their own specific applications. However, : nation often overlooked is the corrosion inhibitor. While. despite the cost advantages offered by,some of these . these and prior Rockwell tests suggest that this may not materials, none can yet be recommended as a general:. :' ; be an issue with AISI316 or 17-4 PH stainless steel stems service replacement for asbestos-base gackinglnvalves . as used in some valves in nuclear power and chemical rated for the full pressure/temperature ranges shojwn.ih / \ processing applications, it is difficult to base long-term current catalogs. .. . V;,.' ; ' confidence on results of short-term tests. Certainly, history One-reservation must be expressed,iwith.respe.ctto .' '. shows that stems of 400-series stainless steels ..require all of the n ew asbestos-free pack) ngs for high tb.hipe ratu re . . protection when used with packings having high concen service. This relates to the long-term service life to be ex- ' . trations of carbon or graphite. Even heavily graphited pected with these materialsatvery high temperatures , ; . packings of braided asbestos have used zinc powder for (950 to 1100F [510 to 593C] or higher) with various flow V 1 years as a sacrificial anode. Previous Rockwell tests had media. As noted previously, Rockwell tests of braided car- sh<" that zinc powder and zinc washers can also offer bon/fiexible graphite packing combinations has shown prt, on when properly applied with braided carbon and no degradation with line fluid temperatures through the flexjDie graphite packing rings. This was reaffirmed in this highest normally encountered in power plants. Neverthe program, except that a question remains to be answered less, laboratory tests are necessarily of limited duration. relative to an adhesion effect noted when "dusted" flexible While there are no known problems from field applications' graphite rings were tested. This program also showed of these packings, published data on the various packing promising results with flexible graphite rings with newer rings and materials are less than complete in providing ' non-metailicinhibitors(ag. Grafoil GTK, Chesterton GTP1). valve manufacturers and end users with the confidence . However, use of aluminum as a sacrificial anode gave desired for. all applications. It is considered that the pack-. mixed results. The position of aluminum in the electro ing and material manufacturers should take the lead in, motive series suggests that it should be befferthan zinc, developing such application engineering data, and it but test results did not support this; one theory is that alu is clear that several manufacturers are active in such minum forms a tenacious oxide on the surface and then research; Ofcourse,valve manufacturers shouidjatsp; becomes "unavailable" for anodic protection. While evalu cooperate, advising the fluid sealing industry wellabout. y ation of corrosion pitting tests isrinherently somewhat sub the conditions that packings will encounter in valves; for jective, a quantitative ranking method was devised based example, the relationship between packing temperature on depth of pits, number of pits per unit area, and time of and line fluid temperature is more likely to be known by the testing. Table 6 provides a coarse "grading" of corrosion valve manufacturer (the temperature differenee.may be- ' . protection systems based on this method, with some bias less than 100F f56C] in a high temperature gate valve ' from results of prior Rockwell tests. Generally, itis consid but as much as 500F [278C] in a globe valve with an ered that a corrosion protection system with an "A" grade internal thermal barrier). ,T should be at least as effective as prior zinc-impregnated Since the current program is ongoing, some results asbestos packings in protecting 400-series stainless steel are incomplete. Preliminary results suggest that combi- . stems. Lower-rated systems may be satisfactory with more nations of available proprietary braided asbestos-free . corrosion-resistant stems, depending on the fluids and packings and flexible graphite ringswill give acceptable . , service conditions involved. performance in some valves. Specifically, Gariock 1200 ' As a group, the proprietary braided asbestos-free PBI anti-extrusion rings seem to be effective combined; .^pkings (tested as sets without other materials) were a with Grafoil sealing rings. This combination provided good, jppointment. Some earlierexampiestested in 19B0 sealing performance in tests simulating asmail vaive . Tmowed marginal performance, but better results were (1.000 inch or 25.4 mm stern) at pressures andtempera- . expected when this program was undertaken in 1985. Two tures representative of typical Class 900 valve service. manufacturers withdrew packings or changed them after Stem corrosion test results with this material produced .. ., Rockwell tests (not necessarily because of these results). some adverse results that require further evaluation. NIBCO001333 ezz API 600 99B * CURRENT ROCKWEU. GATE AND <3LOBE VALVE m ** PROPOSED DESJGN * VALVESTEW PACKING TEST F1GURE15 . Packing Cross Suction Comparisons. Packing Chamber Design With one major exception, standards for design of valves for elevated temperature se rvice do not specify packing chamber design or packing materials. The excep tion is the American Petroleum Institute API Standard 600, Steel Gate Valves, Flanged and Buttwelding Ends. The eighth edition (January 1981) specifies braided asbestos packing and specifies packing width {cross section) and numbers of packing, rings for valve stem diameters from 0.62 to 3.00 inches (15.7 to 76.2 mm). While many high tem perature valves, particularly those used in power plant ser vice, do not have to comply With API Standard 600, some valve manufacturers tendfo follow some parts of this stan dard but not others. For example, most larger Rockwell globe and gate valves designed in the past used the cross sectional packing widths from this standard (extrapolating upward for stems larger than 3.000 inches [76.2 mm] diameter) but notthe requirement for number of rings-- which was considered unreasonable for normal service. Aside from partial guidance from API Standard 600, packing chamber design was largely based on individual manufacturers' experience, engineering folklore, and ruies-of-thumb (e.g, packing chamber depth of 1.5 times stem diameter). Particularly in small valves, packing chambers were often disproportionately large--sometimes i?p$ause of a general feeling that "more packing means pilfer sealing". So long as large packing chambers could, be filled with inexpensive asbestos packing, and so long as users did not complain too much about the need for occasional retightening of glands and periodic repacking, it was found that packing chambers of widely different designs ail gave "acceptable" sealing. The demand for better sealing performance, which developed first in nuclear power applications in the early 1970's, led to some serious questions concerning packing chamber design. Flexible graphite packings demonstrated clearly improved sealing, but such.packings were very expensive at first. Early packing rings of laminated con struction required interference fits and very "delicate" assembly work. The cost of filling a packing chamber designed for inexpensive asbestos packing became a major issue. Further, it was sometimes found necessary to compress flexible graphite packing rings one or two at a time when they were used in deep packing chambers; this procedure added even more cost to a valve due to increased assembly labor. in earlier Rockwell work with flexible graphite pack ings, it was found that even one continuous ring provided excellent sealing performance. Further research and de velopment on valves with smaller stems [2,4] led to the use of two flexible graphite seailng.rings to allow repacking with split rings with the splits offset, When used with either asbestos or braided carbon top and bottom rings, excel lent performance was achieved without sequential load ing; the four-ring set could be loaded simpiy as one set. Additionally, tn the earlier program, it was shown that a 1.125 inch (28.6 mm) diameter stem could be sealed effec tively with a packing cross-sectional width of 0.25-inch (6.4 mm), although API Standard 600 called for a step-up to 0,31-inch (7.9 mm) cross section at this diameter. This was a small increment but it gave some confidence that smaller cross sections could be applied effectively with even larger stem diameters. In early work in 1985 on the current program, plans were made to allow for testing of 5-ring packing sels with larger stems, strictly for conservatism. Also, it was decided to use packing cross-sectional widths smaiferthan shown in the AP! Standard 600 tables. Thedimensions shown in Table 2 for the two larger sternsresuit in packing,widths 0.12 inches (0,3 mm) smaller than listings orextrapofations of API dimensions, but testresults showed excellent per formance with the better packing material combinations. In discussions with representatives of packing manufac turers early in the current program, it was found that several agreed with the Rockwell approach and some would have gone even further in reducing packing widths. Thus, it is not claimed that this approach was original with Rockwell, but it is believed that the current program is first to provide confirmatory test data. Figure 15 provides a plot of packing cross-sectional width vs. stem diameter, showing (1) API Standard 600 di mensions, (2) the prior experience base with Rockwell globe and gate valves, and (3) the tentative proposed basis for new Rockwell valve designs. The dimensional combinations proven by these and prior tests are shown on the graph. ! i i I j i I NIBCO001334 XIST1N0 PA<iiAMQER DESIGN 7/t -ASBESTOS *>CKING WIDTH OfNCH (12.7 MM) ACKING VOLUME L55 IN(23?CM>) JNKR1HO' r CpHrAoMpoBsEeRdDpEaScIGkiNmg - BRAIDED CARBO/J El- FLEXIBLE GRAPHITE PACKING WIDTH .30 INCH (9.7 MM) PACKING VOLUME * 8&iN{9!6CM*) i VOLUME REDUCTION"- IGURE16 ' taking Chamber Designs, Size 10 Class 2500 Rockwell Equiwodge ate Valve, As a further Illustration, Figure 16 illustrates a size ) Class 2500 Rockwell Equiwedge gate valve packing i amber as designed for asbestos-base packing and as oposed for modem carbon and graphite packing. The 3W dimensionsal configuration represents one of those sted in this program. The 55% reduction in packing tamber volume not only makes premium packing _ laterials more affordable but also assures better sealing erformance. Note also that tests of a similar packing lamber with just four rings (as used with smaller stems) ere successful at conditions rep/espntative of Class 600 nd lower valves with a 2.375-irictl,{|>0.3 mm) diameter stem. Some users of valves in particularly hazardous ser es have insisted on double packing chambers with a lantern gland" and a "teak off" connection between lem, permitting the leakage from the first packing set to e piped off to a "safe" location. This construction has die ted even deeper packing chambers in past designs. Uniss these packing chambers were packed carefully, lower acking rings were lightly loaded and the "double packing" ffered no better seating than a single set. While not reuired in most services, the modern packings do permit double packing with a chamber depth little greater than squired with single packings sized for asbestos rings. IguraAXjilustrates such a design with a lower packing omtf pn similarto that in Figure 16, precompressed rith the iantem gland before installation of the upper acking combination. Packing Chamber with Lantern Gland Proportions shown are typical for a 1.500 inch (38.1 mm) stem in Class900orhigher valve if , ; - , L'/.fvAf, A kf .. 1" * ^ t/ ' ' 4' 1. r'-i ' j' While practical realities prevent instantaneous - ", changes in all high-temperature valves to apply optimized,;., packing chamber dimensions, the results of this program^,, will be applied to new designs and to redesign of existing {.:. valves as opportunitiesdevelop. In the mterim'jpartial, results can be applied by reduction of the numberof pack-"1 ' ing rings, using metal spacers where appropriate Similar, steps can be taken.in repacking installed valvea p the( , ,, field, but this also Ihvolves cansideratlon of valve stem and packing chamber condition (wear* corrosion,: pitting,-, etc.).;.;- ? The tatter factors are outside the scope of this paper., > Vi Advantages and Disadvantages of , '' Live-Loaded Packings X i V >K `,ACH^'(/ There is no reason to dispute the success,ofAECL - - and EdF in applying.live loading to critical service yalves in nuclear power plants.;A recent reportby the Electric,Power, Research Institute (EPR1) [9J documents the AECL expe rience well and proposes design criteria for applying live- ^ loading to new packing.materials, Rockwell/hassupplied* valves meeting AECL specifications [8], and live-loaded valves have also been buiifand tested to. satisfyEdF. requirements [3]. There is no rea?on to suspeefthe. . reliability of any of these designs............. .......................... !2 NIBCO001335 ' One problem arising from trying to apply live load ing to general service valves is that "System Pressure" is a necessary input number for design calculations for ^spring assemblies for live-loaded packing glands [9J. This put is usually available in Design Specifications for speal valves for nuclear plants. For many general service valves, however, users' orders show only an ANSI B16.34 cfass or some similar rating; with only this input, a manu facturer might have to design all valve gland springs for the 100F (38C) ratings of such valves; this pressure could be from two to three times higher than any service pressure that the valves would actually encounter in hightemperature service. A design practice meeting such a worst-case criterion would obviously not be cost-effective. At best, two or three different spring sets would have to be available for each valve to be selected based on individual users' operating pressures. However, the present state of the art involves custom design of live loading assemblies for specific valve operating pressures. The special design work, extra parts, larger yoke to allow space for springs,, and additional assembly labor combine to make a proper live loading system a quite expensive accessory; while it is apparent that this expense has "paid" off well in live-loaded valves with asbestos packing in nuclear service, it is not dear that live loading is attractive or necessary in general sen/ice valves (fossil fuel power, typical refinery valves, etc.) that probably represent over 99% ofall applications. While Rockwell laboratory tests of live-loaded pack ings have been limited, tests of current braided carbon end rings with flexible graphite sealing rings and live load ing show little improvement over results of tests of the same packings without live loading. Even with conven$&f|nal gland bolting, the best current packing material Hiii^mbinatlons sealed well in both room temperature water and saturated steam tests; in many tests, 1000 stem cycles and several thermal cycles were completed with no re quirements for readjustment. Generally, with the best materials, the worst performance noted was transient steam leakage during a portion of the stem travel with the larger valve stems during "thermal equilibrium" cydes. This is attributable to "thermal taper", the difference in diameter between the hot stem initially in the packing and the cooler extended stem. This condition is maximized with large valves, simply because the stem diameter is large and the long extended stem is cooler. The transient leakages witnessed duringThfs program were never severe or unsafe, but it W&s expected that live loading would stop them'; while there was some improvement with live loading, it did not meet expectations even though the loadings were slightly higher than listed in the recent EPRI report for simitar materials and pressures [9J. Neverthiess, live loading does offer an additional degree of insurance for valves in very critical services. Summary Elimination of asbestos in the stem seals in valves for elevated temperature service was not an easy task, and several major programs have been required to prove the adequacy of asbestos-free replacements. However, in all Rockwell valves where asbestos stem seals have been replaced, the test programs have proven that the new seals provide improved performance. The material which has made this improvement possible is flexible graphite, but mere replacement of asbestos packings with flexible graphite did not solve alt probfems. Combinations of materials and innovations in stem seal design were required in a numberof cases to achieve the required per formance and to apply new materials cost effectively. In addition to the programs described in this paper and in .,, listed Rockwell references, major programs were involved in developing stem seals for improved tapered plug valves. While these plug valves are not normally used at the Very high temperatures that globe and gate valves encounter, ! these valves provided excellent laboratory, manufacturing, and field service experience with carbon and graphite stem seals. Counting all valve types, hundreds of thousands of Rockwell valves have been shipped using stem seals con taining modern braided carbon and/or flexible graphitic materials, and overallperformance has been excellent. The present.program gives confidence that the same suc cess can be expected with the material combinations and packing chamber designs evolved through the present program for large high-temperature valves. Rcfcroftcss 1. R. D. Norden; "ROCKWELL-EDWARD UNIVALVE BORATED WATER STEM PACKING TESTS", Rockwell Technical Article V-Rep 72-1. 2. E. A. Bake and R. L. Schweitzer; "UNIVALVE EVOLUTION - ANOTHER ADVANCE", Rockwell Technical Article V-Rep 80-1. . 3. E. A. Bake and DidierThevenet; "QUICK-CLOSING EQUIWEDGE ISOLATION VALVES - GLOBAL QUALIFICATION", Rockwell Technical Article V-Rep 85-2. 4. R. L. Schweitzer and D. A. Goodman; "ASBESTOSFREESTEM PACKING FOR HIGH TEMPERATURE VALVES" Rockwell Technical Article V-Rep 82-1. 5. E. A. Bake, L. J. Stephens and S. P. Turcsanyi; ROCKWELL McCANNALOK BIDIRECTIONAL FIRE- SEAL BUTTERFLY VALVES-DEVELOPMENT AND QUALIFICATION", Rockwell Technical Article V-Rep 86-1. 6. EPA Environmental News; Press Release January 23,1986. 7. S. F. Thomas (Ftexitallic Gasket Company, Inc.) and G. R. McKillop (John Crane-Houdaille, Inc.); "ASBESTOS SUBSTITUTION IN PACKING AND GASKETS FOR REFINERY SERVICE",, API 51st Year Refining Meeting, May 14,1986. 8. Technical SpecificatlonYS-00-30830-3, "LIVE LOADING OF STEM PACKING FOR VALVES, REV. 0", Atomic Energy of Canada, Ltd., 1977. 9. Foster-Miller, Inc., "VALVE STEM PACKING IMPROVEMENTS", Electric Power Research institute Report NP-4255, February 1986 = j fJ | t; | I | | I | | is | ^ ;; !j 1 ! f I f t Jf | NIBCO001336 R cJ. Gradle Senior Research. Engineer . Aj- 1 V, 1 a '1 j 3 `l i 4 y`i Rockwell International NIBCO001337