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FILE NAME Packings and Gaskets PAG DATE 1993 DOC PAG019 DOCUMENT DESCRIPTION Journal Article - A Study Determining Asbestos Fiber Release During the Removal of Valve Packing A Study Determining Asbestos Fiber Release During the Removal of Valve Packing James R. Millette and Michael D. Mount MVA Inc. 5500 Oakbrook Parkway Suite 200 Norcross Georgia 30093 Asbestos packing material used in valves is generally considered to be nonfriable material unless cut or torn In a controlled contained area within a steam power plant personal and area air samples were collected be- fore and during removal of asbestos packing material from valves that had been used at the plant The results of this study show asbestos fibers can be released into the air during the generally used procedures for the removal of asbestos packing material Air concentrations were measured by phase contrast microscopy in the range of 0.2 to 1.3 fibers and by transmission electron micros- copy in the range of 1.5 to 4.2 fibers for all diameter fibers greater than 5 ...min length Millette J.R Mount M.D A Study Determining Asbestos Fiber Release During the Removal of Valve Packing Appl Occup Environ Hyg 790 7913993 Introduction Most piping systems use valves to regulate the flow of fluids or gases within them The valves especially in industrial facilities may contain asbestos packing material that acts as a seal to prevent fluid or gas leakage as the valve is turned Periodically the values must be repaired or routinely maintained by removing the packing and replacing it with new packing In some steam plants it is common practice to perform the removal and repacking of number of valves at one time This effort may involve several workers and take a number of days to complete A literature search showed only one published study reporting on the release of asbestos fibers from packing material. Asbestos Packing Material According to the U.S. Environmental Protection Agency EPA asbestos packing means an containing product intended for use as a mechanical seal in circumstances involving rotary reciprocating and helical motions and which are intending to restrict fluid or gas leakage between moving and stationary surfaces In a valve the packing is compressed against the bore of the box by a gland that is tightened down on the packing Figure 1 The packing is forced against the throat of the valve box and packing conforms to the valve shaft surface forming tight seal Compression packings are manufactured from various types of fibers such as vegetable animal mineral asbestos or synthetic and twisted or braided with binders and lubricants One of the most commonly used types of compression packing in valves is a graphite impregnated packing material that has the appearance of shiny stiff rope Packings are not considered friable containing materials ACM because they are not easily crumbled into fine or dusty material by hand pressure However the EPA states that products such as packing may release asbestos dust if cut or torn Study Design containing materials are common in industrial steam plants and because a maintenance activity often involves the disturbance of more than one material it is difficult to assess the contribution any of particular ACM to the overall airborne asbestos concentration Valve packing removal for instance may involve the removal or at least disturbance of containing pipe insulation or fitting mud Therefore to determine the possible contribution of valve packing only special precautions were taken to isolate this material from other activities that might have contributed airborne asbestos from other sources Study Site The study was conducted in an unused steam power plant in Manchester New Hampshire The study team conducted the valve packing removal tests after an asbestos abatement contractor had prepared a double containment area around two valves attached to the main power plant turbine Prior to the studies the abatement contractor prepared the valves by removing all pipe insulation from the valve area and thoroughly cleaning each valve In separate area of the plant the abatement contractor also prepared a third valve that had been disconnected from the steam plant piping system by similarly removing all the pipe insu- 790 1047-322X '1993 AIH APPL OCCUP ENVIRON HYG 9 SEPTEMBER 1993 VALVE SHAFT RINGS OF PACKING IN BORE OF VALVE BOX / GLAND NUT AND BOLT TIGHTENS THE GLAND AGAINST THE PACKING THROAT OF THE VALVE BOX PIPE FLOW AREA FIGURE 1. Diagram of steam pipe valve containing packing lation and cleaning the valve thoroughly This valve was later moved into the containment for packing removal The containment barriers in the area consisted of layers of polyethylene plastic sheets on a wooden frame and 2 layers of polyethylene plastic on the floor A containment area ^ 7 ft around the valves was completely contained within a larger containment area 7^ 11 ft Figure 2 The study area had two high efficiency particulate absolute air filtration devices AFD used to clean the air of particulate including asbestos before each valve packing removal activity The inner area AFD was turned off during each phase of testing The outer area AFD operated throughout the tests Study Procedures The study consisted of the collection of air samples before and during valve packing removal activities A retired steam plant maintenance supervisor using his own tools performed the valve packing removal in the same way that he had in his previous years of work on industrial valves and as is often done in power plants today Although some lubricating oil was used to loosen the packing the work was generally done in a dry manner Three packing removal tests were performed The first two packing re- moval activities consisted of opening valves connected to inch diameter pipes and reaching in with varietoyf tools to pull out three to four rings of the old packing The third test utilized the same valve that had been opened in the second test and duplicated the packing removal activity More packing was removed under the same conditions as the second test Pieces of the removed packing were placed inplastic bags and stored for analysis The packing removed from both valves appeared to be graphite impregnated packing material that had a shiny black appearance Each packing removal activity occurred for approximately 30 minutes The study site was cleaned between activities Prior to starting each part of the study four area air samples were collected to determine the background level of asbestos in the air of the study area The sampling cassettes were located on the walls at the breathing zone 5 feet from the floor A volume of 720 to 840 L of air was passed through each cassette at a flow rate of 15 min Two area samples ) HEPA FILTER ] ' 2 . 4 xX 7 AREA AIR SAMPLE 2 , 5 Le HEPA FILTER \ @) VALVES i] oO ra T AREA AIR SAMPLE 2 x FIGURE 2. Diagram of enclosure for valve packing removal study APPL OCCUP ENVIRON HYG 8 SEPTEMBER 1993 3 STAGE DECON 4 791 were collected during the valve packing removal in the same locations as two of the background air samples ap- TABLE 1. Results of Air Monitoring Prior to and During Asbestos Packing Removal proximately 5 feet from the gasket removal activity One was collected at 7.5 min the other at 15 min The person Sample Duration Air Volume Concentration ber doing the packing removal was fitted with two personal air sampling devices as was a person observing and photo- Sample Description Test 1 min L fibers graphing the activity These personal air samples were collected at rates from 2 to 3.5 min All personnel inside the study area were protected by air purifying respirators and complete head and body coverings The decontamination system consisted of a changing room outside the testing area a shower room and a clean suit room The decontamination system was used each Area before packing removal Area before packing removal Area before packing removal Area before packing removal Personal packing remover Personal packing remover Personal observer Personal observer 54 810 56 840 56 840 56 840 25 50 Pump failure 25 87.5 25 50 0.006A 0.006 0.006A 0.006A 0.2 NA 0.1 0.1 0.2 a time person exited the study area and the overall contain- Area during packing removal 26 390 0.06 ment area Area during packing removal Filter damage NA Analytical Methods Air samples were analyzed by the standard phase contrast microscopy PCM method using the A counting rules Although the phase contrast microscope enhances the analyst's ability to see fibers over other types types of light microscopes the standard procedure does not involve identification steps that specifically determine how many of the fibers counted are actually asbestos Because packing material is known to contain other types of fibers some of the samples were analyzed by transmission electron microscopy TEM following the NIOSH 7402 preparation procedure The TEM analysis method identifies asbestos fibers on the basis of morphology crystal structure and ray elemental analysis Although many shorter fibers were seen only asbestos fibers longer than 5 ...mwere counted Polarized light microscopy was used to determine the type of asbestos in the samples of packing material re- moved from the valves A friability test was performed on samples of packing material that had been removed from valves as well as on some unused asbestos packing material found in a storeroom at the steam plant The friability test to determine whether or asbescontaining material will potentially field test in which an attempt is made to crumble the ACM by hand If the material can be crumbled by hand it is considered friable The EPA distinguishes friable from nonfriable ACM in their regulations on handling asbestos products Friable ACM is considered more of a potential hazard than nonfriable material Results The results of the air monitoring are shown in Table I During the second valve packing removal activity which lasted approximately half hour the asbestos fiber level for the person removing the packing was in the range of 1 fiber the Occupational Safety and Health Administration excursion level Personal samples on the person nearby the packing remover collected over periods from 25 to 40 minutes were over 0.1 fiber The area samples collected Test 2 Area before packing removal 5656 Area before packing removal 5656 Area before packing removal 5656 Area before packing removal 5656 Personal packing remover 5656 Personal packing remover 5656 Personal observer 31 Personal observer 31 Area during packing removal 24 Area during packing removal 25 Test 3 Area before packing removal 0000 Area before packing removal 0000 Area before packing removal 0000 Area before packing removal 0000 Personal packing remover 3333 Personal packing remover 3333 Personal observer 3333 Personal observer 3333 Area during packing removal 33 Area during packing removal 33 At detection limit Quality control by second analyst NA = not available 855 840 840 840 93 62 62 93 180 375 2222 2222 2222 2222 66 27 117 78 525 262.5 0.006A 0.009 0.006A 0.006 1.0 1.3 0.9 0.6 0.5 0.4 0.3 0.007A 0.007A 0.007A 0.007A 0.4 0.5 0.7 0.7 0.2 0.2 0.4 0.2 0.2 in the vicinitoyf the packing removal activity were elevated over the background levels in all three tests The TEM analysis results are shown in Table II Only as- bestos fibers longer than 5.0 ...mwere recorded Chrysotile fibers were identified as the primary type of fiber It is generally considered that fibers thinner than 0.25 ...mwould not be resolved by the light microscope used in the PCM method Therefore two TEM asbestos concentrations are listed One of all asbestos fibers greater than 5 and one which includes only those fibers over 5 ...min length and also greater than 0.25 ...min width The latter value is con- sidered a PCM equivalent count because these fibers counted in the TEM should be roughly equivalent to what would be counted under the PCM The used packing removed from the valve was friable Polarized light microscopic analysis showed it to be approximately 85 percent chrysotile while the bulk of the re- 792 APPL OCCUP ENVIRON HYG 9 SEPTEMBER 1993 TABLE II Transmission Electron Microscopy Results on Personal Air Monitoring Samples During Packing Removal Asbestos Concentration fibers Sample Description All > 5...m PCM Equivalent Test 2 Personal packing remover 22 Personal packing remover 4.2 fifi 2.6 Test 3 Personal packing remover 1.5 1.2 Personal packing remover 2.1 1.5 Phase contrast microscopy equivalent by transmission electron microscopy counting Asbestos fpers or bundles greater than or equal to 5...min length and at least 0.25 ...min width 3 1 aspect ratio maining material was carbon Similar looking unused asbestos packing found in the storeroom of the power plant was not friable In an additional test a piece of the unused packing was subjected to heating at 400 for 1 hour in a muffle furnace The packing became friable after the treatment by heat Conclusions Asbestos packing although not friable in original unused condition can become friable after use in valves and can release asbestos fibers into the air during valve packing removal operations The levels of asbestos detected in the air were similar to the levels reported previously for valve packing activities and in some instances involving gasket removal activities Recommendations The results of these tests suggest that asbestos packing material although not identified a friable ACM should considered as such during packing removal activities If possible the packing should be wetted with water or oil before it is cut and torn with packing tools such as hooks during the procedures for removing old packing References 1. McKinnery W.N Moore R.W Evaluation of Airborne Asbestos Fiber Levels During Removal and Installation of Valve Gaskets and Packing Am Ind Hyg AssocJ. 531-532 1992 2. 2. U.S. Environmental Protection Agency Title 40 Code of Federal Regulations Part 763. Asbestos Manufacture Importation Processing and Distribution in Commerce Prohibitions Final Rule Fed Reg 132 July 12 1989 3. Nelson C.A Millwrights and Mechanics Guide p 236. McMillan Publishing Co. London 1986 4. U.S. Environmental Protection Agency Asbestos Waste Management Guidance 85-007 Office of Solid Waste Washington DC May 1985 5. Carter J.W Taylor D.G Baron P.A Method 7400. In NIOSH Manual of Analytical Methods p 7400-1-7400-8 National Institute for Occupational Safety and Health Cincinnati OH 1984 6. Carter J.W Baron P.A Taylor D.G Method 7402. In NIOSH Manual of Analytical Methods p 7402-1 7402-7 National Institute for Occupational Safety and Health Cincinnati OH 1987 7. Cheng R.T McDermott H.J H.J Exposure to Asbestos from Asbestos Gaskets Appl Occup Environ Hyg 588-591 1991 Received 8/27/92 review decision 12/3/92 revision 11/19/92 accepted 01/28/93 APPL OCCUP ENVIRON HYG 9 SEPTEMBER 1993 793