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FILE NAME Power Generation POW DATE 1975 Feb DOC POW007 DOCUMENT DESCRIPTION Published Journal Article Asbestos Control in Electric Generating Plants JACK II FONTAINE and DAVID M. TRAYER Valley Authority Muscle Shoals Alabama 35660 The Tennesser control industrial work work exposures to airborne asbestos fibers is pre- A program to consistent with OSHA standards and with current good sented The program is consistent includes methods of problem evaluation industrial hygiene practice The program corporate standards and provisions for environmental the establishment of effective control measures and techniques are discussed and medical surveillance Huzard and their merits related IntroSdBucEtSiTonOS HAS BEEN USED EXTEN-EXTEENX-TEN- thermal SIVELY for many years as a insulator When new asbestos insulation is applied or when old insulation is removed considerable quantities of fiber may become lead airborne and unless controlled may to the to excessive inhalation exposures workers Asbestos is known to cause a pulmonary fibrosis known as asbestosis and may cause carcinoma of the lung and mesothe- lium The Tennessee Valley Authority TVA has been engaged in efforts to pre- vent excessive workers exposure to airborne asbestos for about 30 years The Tennessee Valley Authority operates 12 fired electric generating plants in three states Alabama Kentucky and Ten- powered nessee By 1978 three electric generating plants will be added and several more are in the planning stages These facilities require substanbtoitahl amounts of thermal insulating materials for initial construction and for replacement be Each generating unit is scheduled to out of service at approximately month inas tervals for maintenance of such systems and steam lines boiler feed pumps valves turbines During these outages old insula- tion is routinely removed from the systems scheduled for maintenance and new insula- tion is applied when the systems are rein- stalled Small insulating tasks may be completed as needed between outages The insulating materials originally installed in the fired plants contained large amounts of asbestos primarily amosite Most of the insulation was preformed pipes and blocks of hydrous calcium silicate in- sulation reinforced with asbestos fibers Oth- er insulation included boards blankets felts cloths tapes sleeves and cements that contained various quantities of asbestos Evaluation of Exposure At each electric generating plant TVA employs as many as six time insulators including a foreman These men are classified as asbestos workers Usually one or two time laborers are assigned to this group During maintenance outages temporary insulators are employed also time insulators and laborers are mon- itored for exposure to asbestos twice yearly during unit outages.2,3 time insulators are also monitored at these times but because of the temporary nature of their employment these insulators may not be individually monitored every six months In addition to individual exposure,evalu- exposure,evaluations area samples are taken to determine the airborne fiber concentrations in the gen- cral work environment Sampling and anamethods are those recommended by 126 American Indi } the National | and Health | survey of a maintenance | should be c counting no bestos fibers indicated pe engaged at i i cation Asbestos : worker Asbestos worker Asbestos worker Asbestos worker Laborer -. Laborer All in 1973 TWAC E borne concent is 5 fibers g length per cul cm PSC Peak : ceiling limit v crometers each air 10 fibers ae) e | American Industrial Hygiene Association Journal 127 e the National Institute for Occupational Safety installing or building up insulation mixing and Health NIOSH Typical data from a insulation cement or cutting insulation with survey of a steam plant during a routine a shop band saw The laborers were engaged maintenance outage are given in Table I. It primarily in cleaning up scrap insulation should be emphasized that during particle counting no distinction is made between as- Control Methods bestos fibers and other fibers During the indicated periods the asbestos workers were engaged at tearing out insulation sawing Hazard Control Standard To begin a new effort to achieve better control of airborne asbestos fibers within TABLE I TVA a hazard control standard on asbestos Asbestos Sampling Data was developed and is being instituted as part Classifi- cation Asbestos worker Monitoring Date 4/24 4/25 5/23 5/29 TWAC PSC Fibers Fibers 3.1 8.2 1.0 3.6 4.7 18.1 0.7 0.9 of the overall TVA hazard control plan This standard is based primarily upon the asbestos dust standard promulgated by the Occupational Safety and Health Administration OSHA originally in 1972 and up- 5/30 0.3 0.5 dated in 1974. The TVA requirements 5/31 0,6 1.1 concerning permissible exposure limits mon- Waku Asbestos 4/24 3.3 7.2 itoring medical surveillance and control are, worker 4/25 1.1 2.7 methods are identical to the OSHA standard Ns 4/30 3.5 17.0 merc: 5/23 2.2 - 13.8 In addition the TVA standard includes 5/24 0.0 0.0 other requirements applicable to TVA's spe- 5/25 0.1 0.3 cific operations e / 5/29 1.1 4.1 ee Asbestos 4/24 5.9 14.8 Exhaust Ventilation Are worker 4/25 5/29 1.5 2.4 0.6 3.0 Local exhaust ventilation is used con- men 3g Asbestos worker 5/30 5/31 4/24 4/25 5/23 5/25 0.6 0.1 1,6 0.2 0.1 0.1 1.5 0.2 24.6 1.S 1.1 0.3 trol airborne asbestos dust produced by cutting block and pipe insulation with a band saw in the steam plant insulation shops Atmospheric sampling before and after such ventilation was installed has shown the ef- ually 2 gned 3m Lages mon- 4 early 4 Laborer Laborer 4/24 4/25 4/30 5/25 5/31 4/24 4/25 1.7 0.4 3.6 0.0 0.1 3.7 1.6 17.6 2.9 21.5 0.0 0.4 6.4 2.4 ficiency of this type of control Also downdraft tables are used in some of the shops to control dusts from cutting with hand saws and from other shop work Wetting Hators4 t be- -em- -em-& e in- i cvalu- am mine gen- ana-i d by 4 5/24 5/25 0.0 0.0 0.0 0.0 All in 1973 TWAC Eight weighted average air- borne concentration Present threshold limit value is 5 fibers greater than 5 micrometers each in length per cubic centimeter of air 5 fibers > 5 cm PSC Peak sample concentration Present ceiling limit value is 10 fibers greater than 5 micrometers each in length per cubic centimeter of air 10 fibers > cm Wetting has been shown to be an effective method of dust control particularly in the cleanup of insulation scrap.6 Table II shows the effectiveness of wetting reflected in the exposures of two laborers sweeping with brooms to clean up insulation scrap Wetting of insulation scrap before cleanup is being instituted throughout TVA steam plants Wetting is also an effective method of suppressing dust when wall boards that contain 128 TABLE II Wet Method Effectiveness of Controlling Airborne Asbestos Fibers Task No. of Samples Fibers > 5 cm . Removing dry scrap insulation 13 0.3-13.8 Removing wet scrap insulation 6 0.0-0.3 February 1975 less of the concentrations of airborne asbestos that may be present during this process TVA expects that for many years to come insulation that contains asbestos will be removed in TVA steam plants Therefore TVA is implementing more stringent requirements concerning protective clothing and respiratory protection during removal of this insulation American Industrial i i iy Company Amtex Corp. Amspec Atlas Textile Calsilite Carborundum Celotex Certain P asbestos are cut with speed radial saws This method has reduced airborne asbestos Medical Control Picher Forty In fibers by 85 Control of Waste Another method of controlling asbestos The TVA Division of Medical Services examines workers before employment and periodically thereafter Asbestos workers are given an annual respiratory health evaluation Manvill Kenne Corp. Cornin Pabco Pittsburgh . fibers during cleanup of scrap is to use plastic sheeting to catch the scrap This is especially effective where insulation work is that includes respiratory history physical examination chest ray and pulmonary function testing Rock Wool M. U.S. Gypsum performed over grating floors Scrap material falling through grating floors may spread fiber contamination over several levels of a plant thus potentially exposing employees in other areas Training Training is a factor too often overlooked in industrial hygiene control efforts In- formed and trained workers are much less prone to overexposure than those who are tain asbestos Tal types of thermal i tain asbestos and such insulation . TVA is workin Respiratory Protection At the present time the type of respiratory protection used most often by TVA insula- left ignorant of the nature and control of the hazards they face TVA is organizing a training program for insulators and insulator 1 contains asbestos not contain asbest . the TVA Office ( + tors is an air purifying respirator with a replaceable filter which is approved by the Bureau of Mines and NIOSH for use as pro- laborers to explain the nature of the potential asbestos hazard Protective systems and devices and the reasons for their use will be Construction the and each individi. ing plant have bea bea tection against the dusts that produce pneumoconiosis TVA has not approved the single type of air purifying respirator for protection against airborne asbestos fibers primarily because of concern for the effectiveness of the face seal In order to comply described Good work practices will be encouraged and the reasoning behind them will be explained to the workers Instructors will demonstrate respirators and the workers will be drilled in their proper use and care Hazard control requirements for ability of insulati contain asbestos : such materials sho { sible Pure asbest : the design and c ; Superintendents - with the TVA Hazard Control Standard on Asbestos powered purifying respirators or supplied respirators must be worn ' when the ceiling or the weighed aver- age concentrations are reasonably expected to exceed 10 times but not more than 100 respirator use will be explained and respira- tor limitations will be delineated Substitution One of the most effective control measures is substitution of a less hazardous material ing out pure asb nance insulation stitutes for asbes wool mineral w These appear to bestos although times the prescribed limits Our monitoring Manufacturers have over the past several program has not yet indicated a need for this years developed a complete line of thermal type of respiratory protection protection However the insulation materials that do not contain as- standard requires the use of supplied res- bestos For all practical purposes the ther- pirators and special clothing during removal mal insulating properties of these materials r^gard- of insulation that contains asbestos are as good as those of materials that con- 1 only with detailed and industrial e # borosilicate glas are basically cal fibers are alumin constituents of th , nN American Industrial Hygiene Association Journal 129 Company TABLE III Manufacturers of Asbestos Thermal Insulation Pipe Covering Blocks Boards Blankets Felts Tapes& Cements Sleeves Cloth Amtex Corp. Amspec X X Atlas Textile Calsilite x x Carborundum X Celotex Certain Products XX XXXXXXXX XXXXXXXX OK XXXXXXXX Picher X Forty Insulators Manville Kenne Corp. X Corning X Pabco Pittsburgh Rock Wool Mfg U.S. Gypsum X XXXXXXX XXXXXXX XXXXXXX XXXXXXXX X X XX ~ ~ XXXX XXXX XX XX XXXX XXXX 4 X X x tain asbestos Table III shows the available types of thermal insulation that do not con- tain asbestos and the companies that supply such insulation TVA is working to replace insulation that contains asbestos with compositions that do not contain asbestos Responsible persons in the TVA Office of Engineering Design and Construction the Division of Purchasing and each individual electric generating plant have been informed of the availability of insulating materials that do not contain asbestos and have been advised that such materials should be used whenever pos- sible Pure asbestos is no longer specified in the design and construction of new plants Superintendents of operating plants are phas- ing out pure asbestos insulation in mainte- nance insulation The most common substitutes for asbestos are fibrous glass rock wool mineral wool and ceramic fibers.2,3 These appear to be less hazardous than asbestos although confirmation may come only with detailed toxicological investigations and industrial experience Fiber glass is a borosilicate glass mineral and rock wool are basically calcium silicates and ceramic fibers are aluminum silicate The nonfibrous constituents of thermal insulation are usual- ly considered to be inert or nuisance particulates even when they are airborne and respirable These materials primarily are composed of various types of silicates usually calcium silicate or magnesium silicate The substitution of materials that do not contain asbestos for those that do does not necessarily eliminate all health hazards In some formulations that do not contain as- bestos the physiological effect of exposure is apparently not well defined Some formulations may for example prove to be less toxic but may be more dusty in use in these cases the hazard potential of the substitute may equal or even exceed that of the asbestos formulation The crystalline form of some mineral fibers has not yet been well defined and the absence of hazardous quantities of trace constituents has not yet been confirmed Nor does the substitution of less hazard- ous materials for those that contain asbestos eliminate the need for dust suppression In many instances concentrations of nuisance materials may exceed the Threshold Limit Value of 10 mg and therefore must be controlled by dust suppression Further research is needed to find sub- stitutes for asbestos that are both acceptable 130 in terms of hazard control and that meet the important considerations in selecting insulating materials such as cost engineering per- formance in reducing heat loss or gain ease of application durability and ease of maintenance Summary The Tennessee Valley Authority has im- plemented an asbestos control program in its electric generating plants that will eventually result in minimal exposure to airborne asbestos fibers The program is based primarily upon the substitution of thermal insulation materials that do not contain as- bestos fibers for those that do Insulating materials that contain no asbestos are able avail- commercially and appear to be accept- able substitutes However research is needed to assure that these materials meet both en- gineering and hazard control requirements Other control methods such as local exhaust ventilation wetting respiratory protection and training are also used and will continue to be required in the future to control nuis- ance dusts even when apparently less hazard- ous materials are substituted for those that contain asbestos February 1975 References 1. National Institute of Occupational Safety and Health Criteria for a Recommended Standard -Occupational Exposure to Asbestos HSM 72-10267 National Institute of Occupational Safety and Health Washington D.C. 1972 2. Balzer J. L. and W. C. Cooper The Work Environment of Insulating Workers Amer Cooper Ind Hyg Assoc J. 222 1968 - 3. Fowler D. P. J. L. Balzer and W. C. Exposure of Insulation Workers to Airborne Fibrous Glass Amer Ind Hyg Assoc J. 32 86 1971 4. Occupational Safety and Health Administra- tion Standard for Exposure to Asbestos Dust Part 1910.93a Chapter XVII Title 29 Federal Register 23543 June 27 1974 5. Committee on Industrial Ventilation Industrial Ventilation Manual of Recommended Practice 13th Ed Amer Conf of Govern Ind Hyg P.O. Box 453 Lansing Mich 1973 - 6. Mangold C. A. R. R. Beckett and D. J. Bessmer Asbestos Exposure and Control at Puget Sound Naval Shipyard Puget Sound Naval Shipyard Ind Hyg Div Bremerton Wash 1970 7. Kloos E. J. and R. H. Schultz Respirators Approved by the Bureau of Mines as of May 24 1972 A Revision of Information Circular 8436. U.S. Dept. of the Interior Bureau of Mines Washington D.C. 1972 NIH Biohazards Safety Guide The Division of Research Services of the National has prepared a manual of Institutes of Health safety procedures and guidelines to protect employees working with biological agents tissue cultures and The NIH Biohazards Safety Guide contains animals ment of safety programs the information on the develop- identification and classification of hazardous microorganisms procedures for the control of biohazards and the ing of laboratories monitor- Single copies can be obtained without without mental Services Branch DRS charge from the Chief Environ- Building 13 Room 3K04 National Institutes , Bethesda Maryland 20014. Multiple copies be from the Superintendent of Documents , GPO can purchased Washington D.C. for each The GPO Stock Number is 1740-00383 3.85 . Depa In a parti Eight samp Introduction THE REDI pe iron in the pe the use of a re tae The most pop toy making in the is produced by peratures near During this ba is emitted fron sions are colle 4E: manifold but . volatiles j volatiles leaks oven charging | ing and throu | port seals Th tery workers t variety of com nuclear aroma " some of which ' ' studies as carci Because of of the PNA e coke oven wor mortaliy of the mortality conducted by found that co * 2.5 to 5 times cer than the th Mention of com eas constitute endorseni cupational Safety