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Alia. IND. HYG. ASSOC. J. 53(8):531-532 (1992) SC-1 Fiber Levels during Removal and Installation of Valve Gaskets and Packing . William JV. Jr. Rex W. Moore .. Turnkey Environmental Consultants, Inc., 500 W. Central Road, Mt. Prospect, IL 60056-2380 This project was designed to evaluate airborne asbestos fiber levels generated during dry installation and removal of asbestoscontaining 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 conductedtinder aset of controlled condi tions. "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 negativepressure was maintained in the work area for protecting adjacent areas of thebuilding. All personnel entered and exited the work area through a decontamination unit. Ail personnel in the work, area wore supplied-air respirators. Ah 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. Work Practices Every effort was made to make these experiments representative ofpast work practices involving gasket and packing material instal lation and removal. Work practices were utilized that simulated those normally used by trained pipefitters when there was little concern about asbestos exposure. An experienced pipefitter was on siteduring ail testing to provide consultation and advice on how to perform specific tasks necessary to complete an operation. Tools of the trade and other tools normally available to maintenance person 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 of operation 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 of 46 min; and packing installation, ah 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 prior to the packing operations. Air monitoring (under aggressive conditions with a leaf blower) was completed prior to initiation of packing experiments to ensure work area fiber levels were reduced to background values and no cross-contamination would occur between experiments. Air-Sampling Techniques Materials Researched Old valves with asbestos-containing gaskets and packing materials were obtained from a scrapyard that bought materials from industrial facilities. New asbestos-containing sheet gasket and packing materials were obtained directly from distributors. All researched materials were sampled and analyzed by polar ized light microscopy (PLM) forasbestos content by the Chem-Bio Corporation, which is accredited by the National Voluntary Laboratoiy Accreditation Program (NVLAP) and by the National Insti tute for Occupational Safety arid Health's (NIOSH's) Proficiency Analytical Testing (PAT) program. PLM results showed an asbestos content of 50% to 60% chiysotiie.in the gasketing materials and 30% to 50% chiysotile in the packing materials. A high-volume vacuum pump was used, to collect air sam ples. The pump was connected via Tygon tubirig (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. . . v; : - Two to three of the filter cassettes were positioned on the workerVIeft lapel for evaluating breathing zone fiber levels. 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 of the room approximately 4 ft from the work being performed. All area samples were collected approximately 5 ft from the floor and 18 in. above the worktable used to hold Copyright 1992. American industrial Hygiene Association 531 AM, INO. HYG. ASSOC. 4. (53) / August 1992 TABLE !. Gasket and Valve Packing Removal and Installation Location Personals Center Corners Flow Rates (L/min) 0.6-3.6 1.4-2.8 2.0-4.0 Volume (L) 20, 70,120 40, 80 60, 120 the valve that was being evaluated. 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. Table 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. General LABORATORY ANALYSIS All air samples were analyzed by using phase contrast mi croscopy (PCM) by the Chem-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. All samples were further analyzed by using TEM by the same laboratory. TABLE II. PCM and TEM Data for Gasket Removal and Installation PCM Data Fibers/cc Location Center-Rc Center-1 ND Personal-R Personal-iN Northeast-R Northeast-1 N Southwest-R Southwest-IN No. 23 12 23 12 13 6 13 6 Location Center-R Center-1 N Personal-R Personal-IN Northeast-R Northeast-IN Southwest-R Southwest-IN No. 23 12 26 12 13 6 6 6 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 Structures/cc min. max. 0.29 28.22 0.86 3.52 0.86 18.45 0.40 0.69 74.32 15.36 0.93 3.23 0.52 12.74 0.91 3.53 0.19 0.19 0.16 0.20 0.08 0.16 0.05 0.14 GM 3.32 1.05 4.58 2.97 3.92 1.73 2.74 1.66 aGM = geometric mean. BGSD k geometric standard deviation. CR removal. IN ~ installation. < 3 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 of air samples collected during gasket removal and installation showed personal fiber levels ranging from 0.049 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. Table II shows specific sample locations and results. Packing Materials Operations PCM analysis of air samples collected during packing mate rials removal and installation showed fiber levels ranging from 0.04 to 1.01 fibers/cc for removal and 0.03 to 0.75 fibers/cc for installation. TEM analysis of air samples collected during packing mate rials removal and installation showed asbestos fiber levels rang ing from 0.39 to 19.57 structures/cc for removal and 0.03 to 10.88 structures/cc for installation. Table III shows specific sample locations and results. PRELIMINARY CONCLUSIONS Comparison ofPCM 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 higher than the current permissible exposure limit (0.2 fibers/cc). Further data analysis is being conducted. TABLE III. PCM and TEM Data for Packing Removal and Installation Location Center-Rc Center-1 ND Personal-R Personal-IN Northeast-R Northeast-IN Southwest-R Southwest-IN No. 14 12 21 18 14 12 14 12 Location Center-R Center-1 N Personal-R Personal-IN No. 7 6 7 6 PCM Data Fibers/cc min. max. 0.05 0.60 0.03 0.75 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 Structures/cc min. max. 0.39 18.86 0.03 10.88 0.52 0.07 19.57 . 4.05 G/WA 0.25 0.09 0.29 0.10 0.22 0.09 0.19 0.09 GM 5.38 0.38 4.37 0.42 *GM geometric mean. 0GSD ~ geometric standard deviation. CR = removal. dIN = installation. GSDb 2.05 2.73 2.28 2.21 1.94 2.48 1.87 2.25 GSD 3.49 7.81 3.09 5.80 AM. 1ND. HYG. ASSOC. J. (53) / Augusl 1992 532