Document 7pQ4a68noRLrXyV4My93p5RV

Feature Article PLAINTIFFS EXHIBIT |1 e>5CMG.C0 PLAINTIFF'S EXHIBIT Exposure to Asbestos from Asbestos Gaskets .Hobart T. Cheng and Henry 4 MeDermett Chevron Corporation, P.O. Box 78*4, Bon Francisco, OoMomlo 841*0 for mn dun SO yoors, Mbrtiot gosksti bm boon v*d in piping. voh-oo, pumpt, and odwr tqutptntnt to prtrenr Mup* or fluids between Kitd iurforo*. Although wxpotun deu an oefltblt for workers In dw gaaluM nuuuifoctwriAg Muttry, dm* ara no published report* oo utmtoi iwpniinai for potm mttt. This etticfo picacna data oo asbestos expoaurtt during use and handling of aibettoa gaskets In tha od and ehomkal Mdustritt, Diets' Umettelghted avarapa exposure* to aabaatoa during w placement of aftaraeavka gaskets, owahe fabrication (cutting) of ahMt gaafcoti, and handling of ntw and afW-servict gstfcatt inaidc Catitat Traitara war# all within tha Occupational Safety and Health Adminittration (OSHA) PiraiaiBW Exposer* Limit. Tha practice of dry removal of aftar-aarvka ibaat ftakMi M* lowed by dry poilahiog of tha tauttag aurfocet aritb a power render, could ctaato a ihort-acrw aabaatoa exposwe lover in aacaw of tha 08HA Bncuralon UnWt. Thla typo ofpotential, thon-tarm, high eapoaura. however, con bo eUnrfaoied aimpty by watting tha gotten and rooting aurfoco* prior aagaihtt aapiaaaaaant. In July ISN. cha UJ. InritunOMatri heutiloa AgancytfPA) prohibited tha manufocturo, Importation, procattlng. and dlatributiaa in commeroa of moat aabawoa ftritm by UK WTA't dacWon to bm oaboatua gathata woe baaad latriy on oqwouto data obtained from tha gaakat ntowuftctutdra. However, tabtatoi gaskets win continue to be used fee aaony yean In the woritpfcco aa io-ayrtca gotten* ara removed and entering auppflaa ora laatadoSTUnta Bom dal* Invcadgailon wggait that atbaawagathata can ba aafely handled If ptopaa ptocafcnoi aaa foUowad. Bug nt* MoConUOtt HJj hgaon h MMllM M MMN iMMh AppL Oooup. Environ. Hyg. MM-Nli INI. II^mAfaMfltrUiiiOflj^UfjPtana Asbestos gaskets ore used extensively in piping (ftangcsx vah*, pumps, and other equipment to prevent leakage of fluids between solid wrfooea. hi high phptal atronglh, hesi snd chemical resistance, and reasonable cost make asbestos a good choice whew these features are important In July >989, die U.S. Environmental Protection Agency (ERS) issued a final rule banning, In stages, the manufocture, importation, processing, and distribution In com* merce of ememlally all asbestos products.'1* EM placed asbestos gaskets under a Stage 2 ban. Hie effective deles for the Stage 2 ban are August 25,1995,. for manufacture, importation and processing and August 25,1994, for dlatrfoutlon in commerce. BRA'tidecbkxi to ban aSbcatoogaakata was baaed solely on exposure data the asbestos gasket manufacturing facilities. A search of the literature showed no published studies reporting gasket user*' asbeatos exposures. Despite the EflA's reoenr action, aabestoa gaskets will continue to be handled for many years in (he workplace as in-service gaskets are replaced and inven tories of the remaining asbestos gasket material are used. This article presents data on asbestos exposures during use and handling of asbestos gaskets in the oil and chem ical industries. Some pumps contain asbestos In die packkig material used to seal routing shafts; these are not included in this study. Type* of Asbestos Gaskets The following three types ofgaskets are commonly used in the oil and dtemical process plant*: Sheet gaskets, which are typically vu<x Vk inch thick compreused asbestos sheets (containing-at least 70* chryaotile asbestos) with Nitrile ortSoprene hinder. Spiral wound gaskets, which consist of asbestos filler anurial compcemed between Type 304 Stainless Steel spiral windings. The windings are held In place be tween an outside carbon steel compression centering ring and s Type 504 Stainless Steel inner ring. Spiral wound gaskets con much more than shoot gasket* bm provide greater testability and better blow-out prevention. o Metal-jacketed gaskets, which consist of compressed/, asbestos filler material held within or between metal Jacketing. Metal-lacketed gaskets ate primarily used In large heat exchangers or vessel manway*. Because the asbestos filler material In a metal-jacketed gasket is virtually enclosed by the metal Jacket, asbestos exposure is nor a problem for users of meial-jacketed gas kets. Therefore, the emphasis of this article Is on Spiral wound gaskets and sheet gaskets. m wtf-tnwiMmMMasM mt am /W OCCUf. iiww. nro. ten . swvwst FSOf. NIEHJ I ta.ar.ian id h ho. 3 Zi p. 3 TMUit Warturt* Sabaatot lipeawat Owhfl Shaat Ottkat flMcittxi Dasoirfidn of Qashst FtMcsties TmMqum LoA0-ten toed* (Ming aSh pa* Shew and tumor punch MS* wMi sawn Owe aid Caskg at* Mb** a M twketUbli vwm^ mi pmp anmr vn wwim pwm GvIVflQ iMh Anf md mImou (Wltoo (pvv itiMr pmch CuSks Sh akail auBit isd twaww puAth Shoit-feflti Stnein QuMag aM i Mb* m MfaQrttstSktrue OA*^ou^A^^SwaNrS aai*k maawust atA^h^awm^swt ^asran^rdd ^aeJrt^taaa^rdRi waassusJdlwatstr SamsIt Duration (mid) no sot s*0 144 4N MS 4S5 to u so so CancMtiaSoi (Sten/OO (LOIS anir aotr turn 0001 ooos 0001 o. (Ltt tu* 0.$s Spiral Wound Qaakata Spin! wound gaskets come prefabricated Pom the man* ufscturen Therefore, there are no asbestos exposures re lated to the on-site gasket Mxkauion or ahcratlou During gasket replacement, an after-service spiral wound gasket cun be easily lifted Pom the seating surface*. in fact. (Ur a vcnicaiiy installed spiral wound gasket, the old gasket would tell off by Its own weight ss soon as the seating surface* are separated ifthegasket was not held m place (Figure 1). Before installing the newgaakeia, workers may wipe the seating surfaces clean with a rag or may remove any cor* rusion with a whe brush. Consequently, asbestos fibers retraining on the seating surfaces are disturbed, resulting In a brief exposure to atffaome asbestos. Two shon<iursrion sir samples were collected during replacement of two typ ical spiral wound gaskets in a piping system. The moni toring period covered the lifting and disposal of the old gaskets, wire brushing (lie surfaces of tlie flange*, and installing the new gaskets, ftmuks show nondetectable sir* borne fiber levels (detection limit 0.U6 flhci/cc), indl* rating no worker exposure problem during the use and handling of spiral wound gaskets. Fabrication of Sheet Qaekete At oil refineries and larger chemical plants, asbestos sheetgasket materials ate usually purchased in bulk sheets. These are later fabricated rui) into gaskets of various sixes and shapes at die facility's machine shop, Various types of equipment and touts, Including power shears, hammer punch, whed cutier, knife, and saber sow, may be used in the fabricadon process (Figure 2). Workers' asbemus ex posures during fabrication of street gaskets are sumraortxed tn Table t. Seven (Ull-shift, personal air sample* col lected during the data of sheet gasket fabrication showed that rime-weighted average (TMWV) exposure concentra tions ranged (font 0.00i to 0.017 itberfec, well wkhin the 0.2 Abcnfcc Permlimlble Exposure Limit (FB.) act by the Occupational Safety and Health Administration (OSl-tA).*1' ROMS 1. (tapkdnQ spM wound gssM. r- *m occur, emvmon. mat am , auur imi i noun i. Mitcswif t thsti ftakM. ;'ROM HttHt i* ,6r.1**1 1**19 NO, 3 WMiM. Mtertwn1 Short-Twi* feDMM Ctpasurw During ReplacwraM of MUr- Mrihod sl dsatOHi aaa tortr* tote* Ctowdng tty fVKMfc 1 IMMi Diy mrnm. 1 psma p*m, wvphsfcMSto ujf IWME PfHmi N^p^VIIPVI (X|r MMNt ft me laip aNMs Msar Mnte we wMea a ysao peat impiiwkaaMiia a PPHi $*mpt OsraVos t9 46 SS 25 10 If Cosecntiallw (totfd Ml an 043 M <0 <006 P. Pour short-term air samples collected during the peak m> don period of gasket fabrication dtowed that xhon-duruUon exposures ranged from 0.J3 to 0A9 Ifoet/ee. which were within (he IX) fiber/cc OSHA Excursion Although respiratory protection la not required at these exposure level* by the OSliA Asbestos Standard, writers are m- atructed to wear a hatf-maik HUH respirator as a precau tionary measure during fabrication of sheet gasket*. Replacing Sheet Qtakets lhe Job of replacing sheet garfocta is generaliy a abortduration task, lasting from several minute* for replacing a small pipe fbu*e gasket In the held to-slightly under one hour for replacing a largeoteed pump gasket in the shop lhe sheet gaafceu are under tremendous seating stress <e, 10,000 psi) during service, and they may be in contact with oxKibting or corrosive fluida. At the aealtng auifacaa are separated, sometimes the after-service sheet gasket tears, and pieces of the broken gasket material stick tightly to one or hath of the seating surfaces. A flat screw driver, putty knife, or scraper Is used to lift the broken gasket off the metal, followed by scraping, brushing, polishing, or even sanding to dean the sewing surfaces before installing tlve new gasket (Figures). When this deanli* is done in dry conditions, asbestos flben can become airborne to create a potential inhalation hatard. TO guard against ex* eeedlng die OSHA I'W. or excursion Limit, or simply as a precautionary measure, workers should be required 10 wear a lulf-face HE1H respirator during dry rwnovel of afler*ecrvke sheet gaskets. Workers' abort-term asbestos exposures were moni tored at four different refinertea and chemical plants dur? Mg removal of after-service aheet gaskets. Tablet! tummariMCs the manhurtng results under two methods ofgMkct removal and seating surface cleaning, Ia, the old method ofdiy removal and diy surfiice cleaning and a new method of wet removal end wet surface cleaning. Short-term-ex posures during the old way ofdry removal varled bctween 0.11 and 0.3S ftbcr/Ct when surface cleaning wtb done with a aersper amkor with a wire brudt. One air sample, coiiccted during dry polishing ofpipe flangeswith a power fender, showed \A fiberate for a iaak that lasted for 2$ minutes. Although that particular air sample was ooQecied in 1966 and was in compliance with the than applicable OSHA PEL of 0.2 fiberta (8-hour Tm),* would no longer meet the current 1.0 Rbcr/cc OSHA Excursion Lknk. A wet-work method was inter established for the removal of after-service sheet gaskets. Typically, the wet-wotk pro cedure calls for (lie spraying of a solvent-based wetting agent (eg,. Chesterton 723 Sprasolvo Knetratfog Oft) to wat tire gasket and the seating surfaces before removing and cleaning (Figure 4). Monitoring results Indicate that, when die wet method Is employed, workers* shon-term asbestos exposures were all below detection (detection limit - 0.06 ftbet/cc). Because very little time and labor are involved, and a spray can of wetting agent is all die material that is required, the wet-work method for gasket replacement fat well received by workers and by plant management. mums. itttiMmtoetftatfNlflOartei*' Gasket Trader Worker Expoeure At some ofthe larger petroleum refineries and chemical plants, gaskets of all types are kept In a special storage facility called the Casket Trailer. The trailer Is staffed by an attendant whose duties are to maintain an Muentofy of gaskets, to collect and dispose of used gaskets, and to distribute new gaskets to other workers. During unk shut down and turnaround time, the attendant can be very busy as gaskets in many fiicccs of equipment aro replaced Six personal air samples ware collected from Gasket Trailer attendants during two major shutdowns an oil refinery. m *m.oeeup.atmoM.Hvo.tm . Jwvmt ** `t r*Q.< N I CHS 1 1 &3 2 tdfc !.?.1991 16tr HO. 0 f. 0 practice of dry removal of after-service siiect gaskets, fol lowed by dry polishing ofdie netting suf&ccs with power Mflder, could create a short-term exposure In excess of the OSHA Excursion Umk. This potential exposure, how* ever, can be controlled by wetting the gasket and the seat ing surfaces prior to gasket replacement. Recommendations Asbestos gasketing material* play an important role *bere their special features are needed. Their uae remains ac ceptable aa long as they are Mill commercially available. Replacing after-acivice shut* gaskets and cleaning the seat ing surface* under wet condiuoni mintmtxe* fiber release. In addition, regardlea* of the exposure level, a half-fore HEM respirator should lie provided as a precautionary measure when the seating surface cleaning Involve* brush ing, polWiing, or sanding, or when handling friable asbestoscontaining wa*te gasket material*. . i Reference* I 1 Bowks show the trailer attendants' 8-hour nth exposure* ranged from 0037 to 0,0$8 fibet/cc, *ed within the OS! (A 1. UJ. fttvinaouciiud lkuh-akiaAaMKp40Cmr*rtNS,ArfMNe*Miin. uteture, kitporutkm, ProorMlng md Dtarlbution to Commerce ProMbMorn; nnal IWo. K*A Ncg.Vol S4. Ho. 1SS (My I2,JM*X PEL 2. (Uk OspanawM of labor, Oceupatonal Sfftsy and iteakb AdmM * Gondualona mataiii n Cnt nut iStt.)S: AdMMOt, Trcmotki, AmhuphyUm; and ARMutat. Ked. Mg. vut. t, No IIS 0un M, Wt*X intended tn ML 1, Haa> tML S). No. I7H <ibqmmtbr li MMX r Exposures to aabeatot during on-eite fitbrication, han S dling, and replacement of fastens can be maintained well d beiow the OSHA n& wuh good wodc practices. 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