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FILE NAME Brakes BRK DATE 1999 DOC BRK195 DOCUMENT DESCRIPTION Journal Article - Asbestos Fiber Release from the Brake Pads of Overhead Industrial Cranes Appried Occupational and Environmental Hygiene Volume 14 397 4012999 Copyright '1999 Applied Industrial Hygiene 1047-322X 12.00 + .00 ' Asbestos Fiber Release from the Brake Pads of Overhead Industrial Cranes John W. Spencer Marc J. Plisko and J. LeRoy Balzer Environmental Profiles Inc. Baltimore Maryland The purpose of this evaluation was to determine the ac- tual contribution of airborne asbestos fibers to the work environment from the operation of overhead cranes and hoists that use asbestos composition brake pads The evaluation was conducted in a working manufacturing facility Other potential sources of asbestos were accounted for by visual inspection and background air monitoring An overhead crane assembly comprised of a trolley and two hoists was employed for this study The crane was oper- of ated for two consecutive eight shifts representative a heavy cycle Forty personal and area air samples were collected during the assessment Asbestos fibers were analyzed for by phase contrast NIOSH 7400 and transmission electron NIOSH 7402 microscopy methods Eighthour weighted average TWA asbestos fiber concen- trations ranged from 0.005 to 0.011 fibers PCM and 0.0026 to 0.0094 cc TEM There were no asbestos fibers detected by the TEM method from air samples samples collected during the operation of the cranes chemical corrosion and frictional wear high tensile strength and flexibility composition friction products have been utilized for many years in friction applications including auto- mobile and truck brakes elevator brakes and clutch assem- blies Traditionally friction products have contained blends of asbestos cellulose synthetic fibers and fibrous binding materials 7 In July 1989 the Environmental Protection Agency EPA issued a final rule under the Toxic Substances Control Act TSCA to prohibit the manufacture importation processing and distribution of asbestos in almost all products This final rule sought to eliminate the use of asbestos in most commercial products in three stages over seven years beginning in 1990 In October 1991 the Fifth Circuit Court of Appeals vacated and remanded most of the ban and phase rule As a result composition brake pads are still manufactured on limited basis t a BACKGROUND Keywords Asbestos Brake Pads Cranes Hoists Asbestos has been used in thermal insulation building ma- terials gaskets and packings friction products and many other user goods for decades Several containing prod- ucts such as gaskets packing materials and equipment brake pads remain in use as integral parts of industrial machinery systems Previous studies have reported that asbestos fibers released from brake linings tend to be in the microscope size range The purpose of this study was to determine the actual contribution of optically phase contrast microscopy PCM visible airborne asbestos fibers to the work environment from the operation of overhead cranes and hoists which use asbestos- composition brake pads The term asbestos refers to fibrous naturally occurring silicate minerals that exhibit properties rendering them useful in commerce Such properties include resistance to heat Overhead are utilized for a variety of material han- dling needs and other industrial applications They are available in a range of capacities typically from 1 to 250 tons and may be found in thousands of plants and facilities nationwide Indus- trial uses include shipbuilding automotive and heavy equipment assembly and other industrial operations where heavy material loads have to be moved . Overhead or bridge cranes are supported above the working surface by a movable bridge The bridge travels horizontally along parallel girders which may be either supported or supported by the structure housing the crane The bridge contains the essential working elements of the crane including the bridge motor and bridge drive systems electrical controls an operator's cab and the trolley supporting the hoist The trolley is supported by wheels which move along a track perpendicular to the directional movement of the bridge The trolley contains a motor and drive machinery that allow its movement to be controlled independently from the bridge The movement of the bridge and perpendicular movement of the trolley 397 398 . J. W. SPENCER ET AL s enable operation of the crane in all directions with respect to an y Cartesian coordinate system . The trolley also contains the hoists the hoist motors and the hoist gear assemblies Many overhead cranes operate with two hoists the main hoist hit perfom the majority of the work and the auxiliary hoist which often has a lift capacity less than that of the main hoist The operation of overhead cranes is usually controlled in one of three ways operator's control cab attached to the crane a pendant button control operated from the floor or a wireless radio control The inertia generated during the movement of the bridge trolley and hoists is controlled using friction brake products The typical overhead industrial crane may contain four sets or pairs of brake shoes One pair each may be found attached to the bridge drive gearing the trolley auxiliary drive gearing the main hoist drive system and the hoist drive system The brake shoes consist of friction materials bonded or riveted to metal brake shoes which are in turn attached to brake calipers GENERAL PROCESS DESCRIPTION This evaluation was performed in building utilized for product subassembly and light welding at a mining equipment manufacturing plant No manufacturing activities were in progress during the evaluation The building size was approximately 107 ^ 270 x 30 The building contained a total of six overhead cranes and two light jib cranes The main runway situated along the center of the building contained two overhead cranes each with a ton main hoist and a ton auxiliary hoist Two additional runways each situated on either side of the main runway contained two ton overhead cranes One of the two ton cranes which plant personnel reported as being manufactured and installed in 1941 was used for this evaluation As reported by the plant's test engineer the brake shoes on the bridge trolley and auxiliary hoist were original i.e. installed in 1941 The brake shoes on the main hoist were replaced in the mid- to late 1960s Prior to our arrival at the site the unused ton crane was parked one end of the ru^ vy crane main ru^ vyoppose the where the work was performed With only a few exceptions an foot portion of the approx- imate long runway was used during the study See Figure 1 i The evaluation was performed over two consecutive eighthour shifts Based on normal plant operations a test duty cycle was prepared by a crane engineer The duty cycle analysis was prepared to reflect a representative worst scenario of a duty cycle for cranes in manufacturing facilities operating at a Crane Manufacturer's Association of America CMAA Class C rat- ing The test loads included a 6.75 weight for the main hoist and a 1.98 weight for the auxiliary hoist The first shift duty cycle included eight steps with a total cycle time of approximately six minutes per cycle This resulted in a frequency of 10 duty cycles per hour The first shift duty cycle included the following steps 1. main hoist lowering 15 feet unloaded 2. main hoist raising 15 feet under load with 2 jogs engage brakes 3.3. trolley motion span 20 feet 4.4. bridge motion of 80 feet 4. } 5.5. trolley motion span 20 feet 6.6. main hoist lowering 15 feet under load with 2-3 jogs 7. reverse above 5 steps unloaded 8. crane remained stationary for 3 minutes i.e. During the first shift duty cycle the auxiliary hoist was in- termittently raised and lowered though no load was attached The second shift duty cycle was similar to the first shift duty cycle however operation of the auxiliary hoist with a weighted load attached was added during the second shift Operation of | 270 @ ak + OAM i, 107 " Locations of Area Air Samples FIGURE 1 Facility layout N ASBESTOS FIBER RELEASE FROM OVERHEAD CRANES BRAKES f 399 the auxiliary hoist with its attached load was performed during Step 1. Atmospheric the reverse steps of the main hoist duty cycle Screening Test The performance of repetitive duty cycles during the first and The atmospheric screening test was conducted to determine dieued shifts result the brakes whether ambient atmospheric contaminants would adversely ; 39 times per minute cycle This being applied on average affect the analyst's ability to evaluate sample filters at low fiber resulted in approximately 390 concentrations The applications of the brakes per hour In terms of | brake screening was performed using different average usage per duty cycle the brakes on the bridge were applied sampling collection durations and air flow rates The informa- tion obtained from the 9 times on the trolley 11 times on the main hoist 9 times and analysis of the screening samples e.g. on the auxiliary hoist 10 times estimated dust loading fiber density fiber concentration was Prior to initiating the process evaluation all heating and ven- used to develop the final sampling strategy for the baseline and process evaluation tilation within the building was deactivated All doors and win- samples Sampling parameters and sample dows were closed in an effort to minimize air currents in the results for the atmospheric screening test may be found in the Results section in Table I. uildingAir flow within the building was qualitatively assessed by observing smoke flow patterns in the air current Air currents were determined to be relatively stable with no significant air low detected Temperature measurements averaged 75.5 at ground level and 85.5 at crane level approximately 25 feet bove the finished floor The outdoor temperature averaged 19 ; Step 2. Baseline Samples Baseline air samples were collected indoors and outside the building The purpose of the baseline sampling was to determine the existing background or ambient asbestos fiber level absent the hoisting operations A total of five indoor samples and five outdoor samples were collected Two sample blanks were also obtained The results from the baseline samples were com- METHOD NIOSH Method 7400 2 Fibers by Phase Contrast Microscopy PCM August 15 1994 was selected for this pared to the results of the exposure samples obtained during the study to determine the actual contribution of airborne asbestos fibers from the activities monitored tgs te ene: are EN I NTE Sen aad etnn, Ser are Et, Ut TIN. TNR Ne om mts work given its use by the Occupational Safety and Health Ad- Step 3. Monitoring of the Subject Process rene og inistration OSHA as the standard for evaluating personal Bulk samples of the brake xposure to asbestos and other fibers NIOSH Method 7402 pad material were obtained and analyzed prior to initiating the duty cycle evaluation One bulk Fe AelsebcetsetdosasbyaTransmission Electron Microscopy TEM was sample each was obtained from the bridge trolley and the main ee verification if interference were experi- bre nced during sample analysis The 7402 method is prescribed by and auxiliary hoist brake pads Samples were extracted from the existing brake pads using a knife IOSH for confirmation of results obtained by NIOSH method the surface of the to scrape material from me 400. Accordingly the 7402 method specifies that only as- an pads The selected pad surfaces consisted of TI estos fibers meeting the size requirement specified in the 7400 exposed edge where the brake pad material fits into the ethod be counted This brake shoe an area that does not come into contact with the means that only asbestos fibers greater an 5 ...min length and 0.25 ...mwide were measured and brake wheel during brake use The objective was to collect Jantified a sample without altering the existing contact surface or the Following the review and selection of sampling and analyt- al methods a standard operating procedure was developed he procedure included an atmospheric screening test baseline mple collection and the sampling protocol for the process aluation performance specification of the brake pads Analysis was per- formed using Polarized Light Microscopy PLM with disper- sion staining The results of laboratory analysis indicated that each brake shoe material contained 12 percent chrysotile as- bestos by weight The laboratory which performed the analy- sis was accredited by the National Institute for Standards and ; TABLE I Air sample results summary table for atmospheric screening test Sample no SS SS SS SS SS Description Center of crane bay Crane working area Crane working area Blank Blank Flow rate min 4.0 4.0 3.0 n n Duration min 482 242 247 n -- Volume liters = PCM result cc 1928 968 741 n n 0.005 0.010 0.010 O fibers fields 0 fibers fields 6 J. W. SPENCER ET AL TABLE II Sample distribution for first shift and second shift sampling Location Floor level Crane control Crane level Outdoors Personal operator Personal bystanders Blank Total No. of first samples , 8 0 2 1 1 0 2 14 No. of second shift samples 8 I 2 1 0 3 3 18 Total 16 1 4 2 2 2 5 32 Technology NIST and the American Industrial Hygiene As- sociation AIHA for PLM analysis Visual inspection of the installed brake shoes indicated mod- erate wear Plant personnel reported that the brake shoes on the bridge trolley and auxiliary hoist were installed when the crane was manufactured The brake shoes on the main hoist were re- portedly replaced in the mid- to late 1960s Air sample collection focused on two levels within the build- the trolley level and the main floor Sample collection at the trolley level was conducted using portable operated air sampling pumps The portable pumps were used to collect air samples on and around the trolley and in the area formerly occupied by the operator's cab The sample col- lected from the operator cab area was intended to represent fiber exposed concentrations to which an operator may have been were the cab still present exposed Sampling locations at the main floor level were evenly distributed within and adjacent to the crane areaway also referred to as the hoisting area and were obtained using flow air sampling pumps The collection of samples within and adjacent to the crane areaway hoisting area was intended to represent fiber concentrations to which both floor crane operators and bystanders may be exposed Representative personal sam- ples were also collected using portable air sampling pumps Thirty air samples were collected during the process shifts evaluation The sample distribution for the first and second is described in Table II Four locations were selected for the col- lection of the floor five to six feet above the floor samples The sample filter cassettes were changed halfway through each shift resulting in eight floor samples per shift The floor- level sample locations remained constant from the first to the second shift During the second shift a personal sampling pump was attached to the cranc's pendant control to represent the operator's exposure Three personal samples were also collected , during the second shift The personal samples were obtained from the breathing zones of the investigators who were eval- uating the duty cycles while observing from the hoisting and adjacent areas . . RESULTS AND DISCUSSION The results of air sampling and analysis are presented in the I following tables Each table gives the sample descrip- tion flow rate duration volume and result Table lists sam- ple data and test results for the Atmospheric Screening Test The sample data and test results for the Baseline Samples are presented in Table III The sample data and test results for the Process Evaluation are presented in Table IV All sample results reported in Table I are based on sample analysis by PCM using NIOSH Method 7400. Sample results reported in Tables III and IV are based on analysis by PCM using NIOSH Method 7400 and confirmatory analysis by TEM using NIOSH Method 7402 TABLE III Air sample results summary table for baseline sample collection Sample no Description 111596 111596 111596 Baseline Outdoors B_aseline Outdoors Baseline Outdoors 111596 Baseline Outdoors 111596 111596 111596 111596 _ Baseline Outdoors B_aseline Indoors _ Baseline Indoors Baseline Indoors 111596 Baseline Indoors 111596 Baseline Indoors } 111596 Blank 111596 Blank Flow rate min 2.7 2.9 2.75 2.6 2.45 12.0 12.0 12.0 12.0 12.0 a n Duration min 240 240 240 240 240 180 180 180 180 180 a -- Volume liters PCM result cc 648 696 660 624 588 2160 2160 2160 . 2160 2160 a a 0.010 0.010 0.010 0.010 0.010 0.005 0.005 0.006 0.005 0.005 1 fiber fields 1 fiber fields TEM result cc 0.0054 0.0050 0.0053 0.0056 0.0060 0.0016 0.0016 * 0.0016 20.0016 0.0016 - 401 ef ASBESTOS FIBER RELEASE FROM OVERHEAD CRANES BRAKES PCM Results All PCM results reported in Table I were below the limit of quantitation LOQ With one exception all Baseline Sam- LOQs tion Table IV Fifteen of the 27 samples were reported by the laboratory as being below the respective - ple results Tabic ) were also cow me respective LOQs The one exception was marginally above its respective LOQ PCM analysis indicated one fiber each on the blank samples A total of 27 samples were collected during the Process Evalua- Results TEM analysis was performed on the baseline and process evaluation samples to determine whether fibers detected by PCM analysis were asbestos fibers The analysis was performed using . TABLE IV Air sample results summary table for Process Evaluation Samples Sample location No. samples Sample period min PCM result cc Hr TWA . PCM cc TEM result cc NE corner of hoisting 2 225 area shift 225 0.006 , 0.006 0.0026 NE corner of hoisting 2 225 0.005 0.0026 area shift 0.005 0.006 0.0026 225 0.006 0.0026 NW corner of hoisting 2 225 0.005 area shift 0.005 0.0026 NW corner of hoisting 2 225 225 0.005 . 0.011 ; 0.0026 area shift 0,008 0.0026 225 SE corner of hoisting 2 225 0.005 0.0026 area shift 0.005 0.005 0.0026 225 0.005 SEacor rne era of hsohiifstting 2 225 0.005 0.006 00..00002266 ne SW 225 0.006 0.0026 corner of hoisting 2 225 area shift 0.005 0.006 0.0026 225 0.006 0.0026 SW comer of hoisting 2 225 i area shift 0.005 0.005 0.0026 Center of 225 0.005 0.0026 crane bridge 1 435 0.005 0.005 0.0031 on guard rail shift . Center of crane bridge 1 401 0.005 0.004 0.0036 on guard 2nd shift ~ Beneath bridge at former I operator cab1st shift 435 0.005 0.005 0.0031 Beneath bridge at former 1 operator 2nd shift 470 0.005 0.005 0.0030 Beneath crane on pendant 1 control shift 435 0.006 ~ 0.005 0.0032 Personal bystander 1 1st shift 417 0.008 0.007 0.0034 Personal bystander 1 149 2nd shift 0.035 0.011 0.0094 Personal bystande-r- 1 2nd shift Personal bystander i 2nd shift Outdoors shift 1 Outdoors shift l Blanks 5 225 0.011 206 . 465 435 0.010 0.005 0.005 0.2 fibers flds 0.005 0.004 0.005 0.005 0.0066 0.0069 0.0025 0.0027 Fibers were determined by TEM to be asbestiform average  402 J. W. SPENCER ET AL TEM in conjunction with NIOSH Method 7402 which is recom- mended by NIOSH as a verification for PCM analysis The samples generated during the atmospheric screening test were not analyzed by TEM because the PCM results did not indicate interference due to particulate matter or other obstructive material The TEM analysis indicated the presence of asbestos fibers on only two of the 44 samples analyzed one asbestos fiber each was reported on two of the baseline samples No asbestos fibers were reported on any of the process evaluation samples including the personal samples and the blanks All samples collected during this evaluation yielded analytical results below the OSHA hour weighted average TWA permissible exposure limit PEL for asbestos of 0.1 cc With the exception of the personal air samples all but one of the area samples were reported to be less than 0.01 cc 10 times below the OSHA PEL as measured by PCM The sample reported to be greater than 0.01 cc was only marginally above this value The sample was further evaluated by NIOSH Method 7402 which revealed that the fibers were asbestiform CONCLUSIONS The purpose of this evaluation was to determine the contribution of airborne asbestos fibers to the work environment containing from the operation of overhead cranes with brake shoes The air monitoring results revealed that airborne asbestos fiber concentrations were in all cases below the OSHA that eight TWA exposure limit of 0.1 cc Further analysis of air samples by the TEM method determined no asbestos fibers were detected in the size range determined by the NIOSH 7402 method during the operation of the crane and hoists The operation of cranes and hoists fitted with asbestos- containing brakes did not contribute measurable optically visi- he airborne asbeste berconcentrations to the crane operators or bystanders REFERENCES 1. Nicholson W.J Pundsack FL Asbestos in the Environment LARC Sci Pub 126 1312973 2. Asbestos in Public and Commercial Buildings Literature Re- view and Synthesis of Current Knowledge pp 1-2 Health Effects Asbestos Research Cambridge MA 1991 3. National Institute for Occupational Safety and Health Method 7400-1-7400-14 In NIOSH Manual of Analytical Methods 4th ed NIOSH Publ No. 84-100 Government Printing , Office Washington DC 1995 4. Occupational Exposure to Asbestos Code of Federal Regulations Title 29 Pt Appendix A 1994 5. National Institute for Occupational Safety and Health Method 7402. In NIOSH Manual of Analytical Methods 4th ed National Institute for Occupational Safety and Health Cincinnati OH 1995 ? 6. National Institute for Occupational Safety and Health Method 7402. In NIOSH Manual of Analytical Methods 4th ed National Institute for Occupational Safety and Health Cincinnati OH 1995 7. National Institute for Occupational Safety and Health Method 7402. In NIOSH Manual of Analytical Methods 4th ed Na- tional Institute for Occupational Safety and Health Cincinnati OH 1995 8. U.S. Department of Labor Occupational Safety and Health Ad" ministration Federal Register 59FR 40964 August 10 1994