Document QXqVxEGe1QLxGaZzOOBvaJLrR

;-*r .fin tabbies* AM. MO. HYO. ASSOC. X 53(a):M1-W2 (1992) ______ _____ _SC-1 Evaluation of Airborne Asbestos Fiber Levels during Removal and Installation of Valve Gaskets and Packing William JV. McKinnery, Jr. Rex W. Moore TUmkey Environmental CoosultMU, Inc., 300 W. Central Road, Ml. Prospect, IL 60056-23*0 This project was designed to evaluate airborne asbestosfiber levels generated during dry installation and removal ofasbestoscontaining gaskets and packing materials. Every effort was made to simulate work practices commonly utilized by pipefit ters and maintenance personnel in the past when asbestos exposures were not a concern. he study was conducted under a set of controlled condi tions. All work was conducted in an isolated room constructed in a manner similar to an asbestos abate ment project. Construction was conducted by an Illinois-licensed asbestos abatement firm. BACKGROUND Research Conditions A slight negative pressure was maintained in the work area for protecting adjacent areasofthe building. All personnel entered and exited (he work area through a decontamination unit. All personnel in the work area wore supplied-air respirators. An Illinois-licensed asbestos worker conducted the removal and installation of the asbestos-containing materials. Removal/installation work was con ducted under the supervision of an experienced union pipefitter familiar with asbestos removal work practices. Materials Researched Old valves with asbestos-containing gaskets and packing materials were obtained from a scrapyard that bought materials from industrial facilities. New asbestos-containiag sheet gasket and packing materials were obtained directly from distributors. All researched materials were sampled and analyzed by polarwed tight microscopy (PLM) for asbestos content by the Chem-Bio Corporation, which is accredited by the NationalVoluntary Labo ratory Accreditation Program (NVLAP) and by the National Insti tute for Occupational Safety and Health's (NIOSH's) Proficiency Analytical Thsting (PAT) program. PLM results showed an asbestos content of 50% to 60% chrysotile in the gasketing materials and 30% to 50% chrysotile in the packing materials. Work Practices Every effort was made to make theseexperiments representative ofpast work practices involving gasketandpackingmaterial instal lation and removal. Work practices were utilized that simulated those normally used by trained pipefitters when them was little concern about asbestosexposure. An experienced pipefitter wason ate during aR testing to provide consultation and advice on bow to perform specific tasks necessary to completean operation.Ibols of the trade and other tools normally available to maintenanceperson nel performing these tasks were utilized. Operations of a similar type were conducted in sequence without cleaning the work area between operations except to maintain a satisfactory work space. Each type ofoperation was repeated five or more times. The gasket removal operations had an average duration of 32 min; gasket installation, an average duration of 31 min; packing removal, an average duration of46 min; and packing installation, an average duration of 26 min. The work area was wet-wiped or vacuumed free of debris and dirt following the gasket removal and installation phase and priorto the packing operations. Airmonitoricg^underaggressive conditions with a leafblower) was completed prior to initiation of packing experiments to ensure work area fiber levels were reduced to background values and nocross-contamination would occur between experiments. , Air-Sampling Techniques A high-volume vacuum pump was used to collect air sam ples. The pump was connected via "iygon* tubing (6-mm ID) to a manifold connected to six to nine filter cassettes placed at various locations inside the work area. Each cassette's flow was controlled with a needle valve. Airflow through each cassette was measured at the beginning and end of each run with a precision rotameter that was calibrated daily. T\vo to three of foe filter cassettes were positioned on the worker's left lapel for evaluating breathing zone fiberlevels. One to two filter cassettes were positioned within 18 in. of the work being performed. Two to four filter cassettes were positioned in the opposite comer offoe room approximately 4 ft from foe work being performed. All area samples were collected approximately 5 ft from the floor and 18 in. above the worktable used to hold 'I i I Copyright 1992, American Industrial Hyglane Association t lOd 900 531 AM. IND. HYO. ASSOC. X (S3) / August 19S2 01? : l l 20-80-266 I X+ TABLE I. Gasket and Valve Packing Removal and Installation Location How Rates (L/min) Volume (L) Personals 0.6-3.6 20,78,120 Center 1.4-2.8 40,80 Comers 2.0-4.0 80,120 the valve that was beingevaluated. Afibrous aerosol monitor was also used to obtain real-time information on fiber levels. Airflow rates and volumes were adjusted according to the type of work being conducted and the anticipated fiber levels. Multiple samples (each with a different volume) were collected at each location to minimize the impact of filter overloading and underloading. TfcNe I lists typical airflow rates and sampling durations associated with these operations. All samples were collected on 0.45-p cellulose ester filters loaded in 25-mm cassettes with 50-mm nonconductive cowls. LABORATORY ANALYSIS General All air samples were analyzed by using phase contrast mi croscopy (PCM) by the Cbem-Bio Corporation, which is accred ited by the American Industrial Hygiene Association (AIHA), NVLAP (for both transmission electron microscopy (TEM] and PCM analysis), and NIOSH's PAT program. Ail samples were further analyzed by using TEM by the same laboratory. TABLE IL PCM and TEM Data for Gasket Removal and Installation Location Center-R Center-IN0 Personel-R PersonaMN Noctheast-R Northeast-IN Southwest-R SouthwesMN No. 23 12 23 12 13 6 13 e Location Center-R Center-IN Pensonat-R PersonaMN Northeast-R NortheasMN Southwest-R SouthwesMN NO. 23 12 26 12 13 8 8 6 PCM Data Fibers/cc min. max. 0.09 0.59 0.11 0.35 0.05 0.44 0.13 0.29 0.03 0.32 0.13 0.19 0.00 0.17 0.11 0.18 TEM Data Stmctures/cc mtn. max. 0.29 28.22 0.86 3.52 0.86 16.45 0.40 74.32 0.69 15.36 0.93 3.23 0.52 12.74 0.91 3.53 GM* 0.19 0.19 0.16 0.20 0.06 0.16 0.05 0.14 GM 3.32 1.05 4.58 2.97 3.92 1.73 2.74 1.66 *GM > geometric mean. *080 - geometric standard deviation. R- removal. IN - installation. gsdb 1.62 1.35 1.91 1.28 1.95 1.16 4.62 1.21 GSD 3.44 1.83 2.73 3.40 3.53 1.56 3.48 2.00 Gasketing Operations PCM analysis ofair samples collectedduringgasket removal and installation showed personal fiber levels ranging from 0.019 to 0.44 fibers/cc for removal and 0.131 to 0.29 fibers/cc for installation. TEM analysis ofair samples collected during gasket removal and installation showed asbestos fiber levels ranging from 0.86 to 18.44 structures/cc for removal and 0.40 to 74.32 structures/ cc for installation. Ihbte II shows specific sample locations and results. Packing Materials Operations PCM analysis ofair samples collected during packing mate rials removal and installation showed fiber levels ranging from 0.04 to 1.01 fibersAx for removal and 0.03 to 0.73 fibers/tc for installation. TEM analysis ofairsamples collected during packing mate rials removal and installation showed asbestos fiber levels rang ing from 039 to 19.57 structuree/cc for rtsmOval and 0.03 to in10.88 structureaAx for Installation. Tbbic shows specific sample locations and results. PRELIMINARY CONCLUSIONS Comparison of PCM results with TEM results suggest that under these simulated working conditions, airborne asbestos levels reported by TEM analysis are 5 to 10 times higher than those reported by PCM analysis. Numerous times. PCM levels were observed to be higherthan the current permissible exposurelimit (0.2 fibers/cc). Further data analysis is being conducted. TABLE HI. PCM and TEM Data for Packing Removal and Installation Location Center-R Center-1bP Personal-R PersonaHN Northeaet-R Northeast-IN Southwest-R SouthwesMN No. 14 12 21 18 14 12 14 12 Location Center-R Center-IN Personal-R PersonaMN No. 7 6 7 6 PCM Data Fibers/cc mtn. mar, 0.06 0.60 0.03 0.76 0.05 1.01 0.04 0.52 0.04 0.48 0.03 0.43 0.04 0.34 0.03 0.46 TEM Data Structursa/cc min. max. 030 18-88 0.03 10.88 0.52 19.57 0.07 4.05 GMA 036 0.09 0.29 0.10 0.22 0.09 0.19 0.09 GM 5.38 0.38 4.37 0.42 *QM - geometric mean. GSO - geometric standard deviation. removal. IN - Installation. GSD9 Z05 2.73 2.28 Z21 1.94 2.46 1.87 236 GSD 3.49 7.81 3.09 5.80 AM. IN0. HYG. ASSOC. J. (S3) / Auguu 1992 532 ;od 900 Gtcll Z 0~8 0-2 6 6 l