Document 65Yo9oD8aLnnwg8nwLEVM4yYE

FILE NAME: Asbestos Cement Pipe and Sheet (ACPS) DATE: D DOC#: ACPS0 KhMENT DESCRIPTION:hZZ - Technological Feasibility and Economic Impact of OSHA Proposed Revision to the Asbestos Standard J J J ]-: _. J - -~;_ ::~,r .. ~ J. ~. -: . . . Technologic.al Feasibility and Econ_omic Impact of OSHA Proposed Reyision _- :- __ to the-Asbe_stos Standard -_- ~ . ..... . .. . . Prepared for. . . . . Asbestos information Associaiion /North America ~ _ . r . - : Washi~gton, D.C. ' . > .... ..... : ", .;. . "' .. _. ... ... ~ ~ B - 1 . =n . <f J; . .~, vilwn,V"IAI r w~ j . ENVIRONMENTAL .. . '. ~ - f t : , j ~r=F1i50D:a:!IMZ'S"" CONSULTANTS-DESIGNERS D- ., . J ] ] J J J J J J J J Asbestos Cement Sheet Technological Feasibi.J..!.lt Asbestos cement sheet is a flat or corrugated cement product using asbestos fiber as a reinforcing agent. The material is durable, strong, fireproof, and has excellent weathering resistance. It is widely used in construction applications such as roofing and siding for both industrial and residential buildings. It is also used in the manufacture of heaters, boilers, vaults and safes, electrical equipment rrounting panels, welding shields, and many other applications re- quiring a non-combustible or heat-resistant sheet. This industry segment also includes other asbestos-containing products, bound with cementatious materials other than portland cement. These sheet materials are generally thicker than the sheets described above, ranging from" to 411 in thickness._- The products are used in specialty applications such as laboratory furniture and firedoor construction. Process Description The raw materials and manufacturing processes used to make asbestos cement sheet are similar to those used for asbestos cement pipe. Asbestos fiber is combined with cement~ sand and water; the sheet is formed, cured, and finished. Bags of fiber are manually opened and dumped at the fiber introduction step. The fiber is either dumped directly into the dry mixer or conveyed to the mixer by bucket elevator and screw conveyor. The first mixer breaks the compressed fiber lumps, thereby opening the fiber structure and obtaining maximum use of its reinforcing properties. Sand and cement are added at this point, and the solids are mixed until uniform. The dry raw materials are con.-eyed to a second mixer, where water is added. After water is.added, the mortar must be used within a short time, .before the cement starts to set; therefore, the two mixing steps are required. Once the water is added, the sheet is formed in large presses. After the sheet has obtained preliminary set, it is removed from the press, allowed to cure further in the air, and is then cured with steam. J .... J J J J J _] ~] :] ~] ~] ~] ,-] ] ] ] 1 '.] Although sheet-forming casts a nearly uniform size, some trirrmlng of the edges and ends is generally necessary after curing. Cut-off saws using diamond or carborundum wheels are used to trim the sheet to standard size. Even rrore important than edge trim is uniform sheet thickness. In the final manufacturing step, the cured and trimmed sheet is sanded to a uniform thickness. In applications such as residential siding, the formation press is grooved to form the siding pattern. Several applications of paint are applied to the sheet between the curing and finishing steps, and the final product is ovendried to cure the thermal-setting paint. No sanding is used in this application, but sheets are stamped to size before packaging. Corrugated roofing and siding are also produced without the. final sanding step. The thicker specialty products generally start by dry-mixing asbestos with lime and fine silica. The sheet is formed by pressing at high temperature and high pressure. While In the press, the lime and sand react to form a calcium silicate binder reinforced with asbestos. These products I do not require the extensive curing of the portland cement sheets, but still require edge and end trim and surface sanding. In addition to sheet formation 7 some large consumers have forced the sheet producer to do some initial fabrication, to reduce fiber exposure at the consumer's plant. Initial .fabrication takes the form of cutting or punching standard sizes or shapes and drilling or punching holes. Work Practices/Controls Figure 4-6 illustrates the processes involved In sheet pro- duction. At the fiber introduction step 7 hoods and local exhaust are the control equipment in general use. Exhausted air is vented to the atmosphere through dust collectors. Bags are manually placed in the hooded area. The bags are slit and dumped; the empty bag is removed and placed in a large plastic bag for disposal. The A/C sheet segment uses paper bags. Raw material make-up is a batch operation~ The batch make-up rate depends on sheet thickness; fiber introduction occurs for 2 to 6 hours per shift. 4-ss LJ LJ LJ LJ LJ u w u i l l I ~ \.-I \.-I L.....J ---..... ------ LJ LJ i::} /;::,},: LJ ,', I ,,'?, ,':r '~ ' LJ w l-J ;~ .'.,, . ~ t; r:,, ''"" '''"' IXISflHG (X)tl:U.OL lOUl"'4tNf Fta.fll RE.C(IVIMO A.NO ITO~ACll O,y h.w""11-wctl Glut\.Kktd. P,.i1,11nd $hp,T'ffll, Ol,ll'Wll9' RC'p.,.t 81<.tlttn lQt. Vao,11,1,nS,p,11,. $N,n~-W,wo,df1IWtt 2 w3 flU(R ORV lt,TRODUCnON Mil( h~4 wn ..I)( ' I Hood '11//LOCM hr,-.,,,10 O~tColl.CIOI I o,. I w., - - . (nclOI lq1.11111Nnt . - , .,,,hh,,'-,m hi Diiu CollKIOI w 1-:i.: SHUT fOIIMATIOH Oft'f/ CUlll : . I Wt1 I Wd,'Oty I I Sorn. Lac,I 1 ' hhi6UH ' .. , . - 7 CUT/ TRIM 1 O.v 8 SAND 1. llry I Ra,np ot EQUlp,n.nl lrOfll e,-.fN\OHQOd\111/(ahat.114, --i00w1&CoU.1or I 9 f UIIICA TIOH . I -'' ~c.,_,. .._ I ., Cnc'""9, tor $ow(q,.,,,,,...., ~(1,Nr.10- K..-.STcao11. &AT C:OUTROL --- f.OU1'"'ENT IJI of IOO,t. olus Otd"'hd c,,,. lmp,o.cdP~J9'nt C.,tl1,1I P1IWI nd h9H,l,l'\dhng Sunci.rd I~ S,,r, lfftO,O'f.c.\ Hood Dn,v,\#HTOP 8440,~I .,.._,...,...,. ADVAAC(O -=:=~: TIC><M>LOC.V Ptllflt1td F,tw, ~p,n\ld81o<:k,bff. AutOffl.shC 8,tg 0PfR"9 J,A,l(h,,,W UI 81o1Nr. f1tw1 10-,---,---------,-------------::-:-:-----r-------------------,-----I-----,---------.-......r. --- 010111 Th., ,_. c.,.,.., .r.,,Rb.....e.,o..v,,, 2!i t - .,..,..,..,..,..,..,..,. f',o,tttNI --- --------- --.................~ ....--------------------------- .,..,. ~ ""\'"f"o''l 1 1s ~,r -e lmpra'ttll Endow,, Oni9' - - w,1'tig111irE1'hAl\!R41 T.gi,1irn Hu~ll,n,a E&,11,,1,1p,wr,,I ... f,&w, 11 Ttww St.a11on1 U.y fl11wh fro,n l-_d1.,i.t111 0li,rtuur1. ,. ' e- lo-,td hl\Ntt 'Sv111l\1 _ . lln1uiw1, O,yt.111 '' filu Cloi,.101 Wt1 Cwlh"I ' 'S&n..lu '!. ,;., ,\ 1~0tm.il10fl - - f@UIIW AulOtNltd (Qlllp,ftrfnl -~: ,.-s..... 0..,... T..._. MH-~,tiat 01.11tConloul. A..,i:Qffl,t111 . . . . . . , ' _,,:,owd S,d P1oUnSlrp FIGURE 4-6 DIAGRAM OF PROCESS FLOW AND FIBER COUNT ' ASBESTOS CEMENT SHEET : : ; :-: . \/, I , ~ ', ,l, ~-] . _] ~] ~] ~] --].'_:. --_J ] ~],.. ,.., .] ~-] ~] ~] ] ] ] ] ,. J local exhaust of enclosed m1x1ng equipment is the control technology used at both the dry and wet mix processing steps. Exhausted air is vented to the atmosphere through fabric fiber (bag) dust collectors. Dry mortar conveying equipment between the fiber introduction step, dry mixing, and wet mixing steps also results in an area dust source. Some exhaust of the materials-handling equipment is obtained through exhaust of the mixing equipment. Although the wetmortar is not expected to be a significant fiber source, some exhaust equipment is in use at the sheet formation press. Good housrkeeping controls are also necessary when handling the wet mortar. While the wet material does not release fiber, abrasion from local traffic will result in.significant airborne fiber concentrations if a spill is allowed to dry. No control equipment is used at the drying or curing steps. Good housekeeping is again required to minimize fiber release. A broad range of dust control equipment and work practices were reported for the cutting, trimming, and sanding operations. The level of control technology ranged from area ventilation using exhaust fans to extensive equipment enclosures, exhausted to a dust collector. Some wet sanding was reported by an asbestos cement sheet manufacturer to be in use at one of his customers' plants; however, no wet sanding is currently practiced at any asbestos cement sheet manufacturer responding to our survey. r local exhaust with hoods or enclosures is generally used for major pieces of finishing or fabricating equipment. local exhaust is generally used on hand and small tools. Existing Fiber Counts Tvoical TWA fiber counts in the A/C sheet segment vary from 1.0 to 3.0 fibers/cc through all processing steps. (See Table 4-6). Fiber introduction into the process results in a range of counts from 0.3 to greater than 3 fibers/cc, with a typical value of 2.3. The adjacent dry mixing operation has a TWA fiber count range of 1.1 to greater than 3, with a typical value of 2.5 fibers/cc. The TWA fiber counts at the fiber 4-57 ] ., ~] ~] -- ~] Process Stee ~] _-,,. :J..,- _J 1 Receiving & Storage 2 Fiber Introduction 3 Dry Mix 4 Wet Mix Table 4-6 Time-Weighted Average Fiber Counts Asbestos Cement Sheet Fiber Count with Existing Control Technologl Typical Range Fibers/cc Fibers/cc 1.0 0.25 - 2.5 2.3 0.3 8.7 2.5 1.1 8.4 1.25 Fiber Count wi!h Best Available Technolo9yO) Fibers/cc 0. 5 or 1. 0 1.0 1.5 0.9 ~] 5 Sheet Formation 6 Dry/cure 2.0 1.6 - 3.5 1.25 1.9 1.3 - 2.5 1.25 7 Cut/Trim ~]T"' 8 Sand rJ 9 Finishing & Fabrication 2.5 0.6 6.7 3.0 .. . 0.9 - 8.0 1.8 0.9 - 3.6 ------- 1.0 2.0 1.0 j Data Base: Data collected from plants consuming 48,000 tons of asbestos, or r1I 89 percent of the A~bestos Cement Sheet Segment. I ' (l) Projected fiber counts are estimates of average exposure after implementing r1I BAT. Variations of these values are expected depending upon individual -1 installations. 1 ] ] 4-58 l :1 .. ] . J J ] ]. .. ] ., : ('~. 1 J .] ,-] "] ] -1 1 -1 ] ] ] '] introduction and dry mix steps of the A/C sheet process are higher than at the same steps in its sister process, A/C pipe. The reason for higher counts may be found in the fact that at some instaJlations the fiber is introduced directly into the first mixer, with a resulting higher fiber emission rate and TWA exposure. A typical TWA fiber count for the wet mixing_operation is 1.25 fibers/cc. This fiber count is approximately the same as in the A/C pipe segment. Airborne asbestos fiber results from ijgitation in the mixer before the solids are thoroughly wetted. Conveying equipment in the area also adds to the background fiber count. TWA fiber count in the sheet formation step and the drying and curing step is 2.0 and 1.9 fibers/cc. respectively . .Counts at these two steps ranged from 1.3 to greater than 3 fibers/cc. This number is unexpectedly high for a wet pro- cessing step, and the only explanation seems to be background fiber levels from adjacent operations. . 'Sheet trimming and sanding represent the highest exposure levels in the A/C sheet process, at 2.5 and 3.0 fibers/cc. The very nature of these operationsgenerates airborne asbestos fiber. Although control equipment has proven effective, it is difficult to control fiber Joss from the large surface area of a sheet during sanding. In addition, loose fiber remaining on the sheet tends to become airborne as the material is handled. The finishing and fabricating operation has a typical TWA fiber coun~ of 1.8 fibers/cc, with a range of 0.9 to greater than 3. Actual employee exposure at this processing step is highly variable, because of variations in schedule and ~he extent of fabricating required. Best Available Techn~?ogy (BAT) BAT for the fiber introduction step in an A/C sheet plant requires a well-designed hood or enclosure and adequate ventilation. Proper bag handling, both befor~ and after the bag is emptied, is also required to achieve the lowest level of exposure. Improved hood design should provide for empty bag disposal through the rear of the hood to minimize bag handling. 4-59 J .. _] :J _] -7___, ~3 . - . ' . .,- __ j ~]i' I'~ 1 l- -~ i-] 1-- ' i ;-] t .- ] ] ~ i ,, 1 V -1: 1, , I I ! l ] ; l ] !... ] As in the A/C pipe segment, hydropulpers cannot be used to eliminate the bag slitting and dumping steps because they .could contaminate the product with cellulose. Adequate enclosure of the dry and wet mixing operations, with adequate exhaust rate~ will be considered BAT at the two mixing steps. Where screw conveyors are involved, they should be tightened and maintained to minimize fiber escape. lt is highly unlikely that BAT fiber levels could be achieved in a process where the asbestos is charged directly to the mixer. The large opening in the mixer, with such an arrangement, tends to result in considerable fiber loss. If improvements elsewhere in the sheet manufacturing oper~ ations do not reduce the background fiber levels at the sheet formation~ drying, and curing steps, hoods and local exhaust. should be installed to control fiber exposure. Improved exhaust systems should be considered BAT control for the trimming and sanding steps. Wet sawing and sanding should be seriously considered, in addition to enclosure and ventilation~- to provide minimum employee exposure. Since wet sanding in such a process has not yet been dempnstrated, it cannot be truly defined as BAT; however, it appears that only minor development work would be necessary to adapt wet pro- I cessing to these steps. In addition to reducing the fiber losses during the actual cutting and sanding, wet.proces- I sing will tend to flush loose.fibers from the sheet surface. Improved hood and exhaust system design is considered BAT for the finishing and fabrication operations. Projected Fiber Counts (with BAT) If Best Available Technology is applied to the fiber infroduction step, the projected exposure is estimated at 1.0 fiber/cc. The estimate at this processing step is based primarily on the projected exp~jure levels for the A/C pipe ~P9ment fiber introduction step. Centralized fiber introduction should also be adopted where production rates warrant, to reduce background fiber concentrations. nJA fiber levels at the dry mixing and wet mixing steps, with BAT equipment installed, are estimated at 1.5 and Oo9 fibers/cc, respectively. The sheet formation and curing steps have projected TWA exposures of 1.25 fibers/cc. As noted above, the fiber count at these two work statlons is raost likely not attributable to the il'Mlediate operation, but rather a background fiber level from adjacent processing steps. 4-60 J I >.. ) j :J ---] -, _J ~] .. ] ;:~--. -] ] -] J 1 J l 1 l 1 Improved exhaust systems applied to the cutting and trimming operations should reduce TWA fiber levels to 1.0 fibers/cc. Exposure at the sanding operation is estimated at 2.0 fibers/ cc, even after the app.lication of BAT systems. A NA fiber count of 1.0 fibers/cc is projected if wet sanding techniques are employed. A TWA exposure of 1.0 fiber/cc is projected for BAT installed at the finishing step. This Is a higher exposure level than projected for the cement pipe fjnishing operations, but the more extensive use of small, powered tools with less efficient exhaust enclosures will result in higher fiber emissions. Advanced Technology Advanced technoiogy in the fiber introduction step should be considered as either automatic bag-opening or bu1k fiber ship-. ment and introduction. Automatic bag-opening will be_the first of these technologies developed, and its use in other to industry segments indicates automatic bag-openers should be . available for use in the A/C sheet segment within one two years. Bulk fiber shipments will take considerably longer . to develop and implement. Elimination of the dry mixing operation has been suggested as an advanced technology, based on comments received from the A/C pipe segments. Considerable development will be required to establish the feasibility of such a process modification. Wet cutting and sanding lies somewhere between advanced tech- / I nology and BAT control equipment. A totally automated dry-end handling system should be investigated, to eliminate or sub- l. stantially reduce operator exposure at these typically high- emission-level operations. Wet finishing and fabricating techniques should also be developed for use not only at the sheet plant but also at the secondary fabricator. Automated equipment should_be developed and installed where applicable. Economic Impact Data and information supplied to Weston represents 89 percent of the segment (Table 2-1); however, only 37 percent of this segment supplied usable data to generate cost informationc The size of firms supplying usable data range from 4,000 to 6,000 tons of asbestos used annually. 4-61 -] .. r ., _] .] __'] _] :J., J ] ] ~ ] ] -- ] ] ] ] ] ] ~ J The capital costs to achieve BAT for this segment are $3,300,000. Operating costs are projected to be $130,000. This segment has 64 percent of its employees exposed. In- dustrial hygiene and medical costs will be $1,120,000 for this segment; this represents 54 percent of the total annual costs {$2,070,000 ). The total annual costs to comply with the proposed standard represent 3.0 percent of this segment's average annual sales. The toal annual costs versus average annual sales range from 1.2 to 3.5 percent. The expected capital costs estimated by industry to comply with the proposed standard represent 256 percent of this segment's typical total annual capital expenditures. Asbestos_Usage Summary of Impact Asbestos Cement Sheet Segment 54,000 tons/year Increased Cost of BAT to Industry Seg~ent: Capital Cost to Achieve BAT . Annual Costs: $3,300,000 Capital Operating Costs Industrial Hygiene and Medical Program $ 820,000 130,000 1,120,000 Total Annual Costs $2,070,000 Total Annual Costs versus Average Annual Sales J.O percent Expected Capital Costs versus Typical Total Annual Capita 1 Expenditures 25q percent Conclusions The A/C sheet industry is currently in compliance with existing regulations. All processing steps are below the 5.0 fiber/cc TWA standard. However, four of nine processtng steps currently exceed 2 fibers/cc. ' ~] ,.,,. ,, . ' ~] ~] ~] --] - __ ] :.] I ] 1 -] 1 11 I ] ] ] ] J ] '] lmple~ntatfon of ~est Iechnology ~vailable will be re- quired to w~et the 1 July 1976 TWA exposure standard. Even with the Implementation of BAT, no processing step in the asbestos cement sheet Industry will be below the proposed 0.5 fibers/cc TWA exposure level. Implementation of.BAT control equipment will require three to five years, based on industry estimates. I ~ :...;,:.~~: - The economic impact of implementing BAT requirements..-:.::~ . for this segment~ while not as severe as for other segments on a percentage of sales volume, ls signifi~ cant because of the availability of substitutes for asbestos cement sheet. Manufacturers will have to absorb much of the anticipated production cost in- crease or risk a reduction in the market for their asbestos products if they pass all of the cost in- creases on to the customers. 4-63