DEPARTMENT OF LABOR OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION DocketNo. H054A



### =============================== OSHA'S PROPOSEDRULE CONCERNING "OCCUPATIONALEXPOSURE TO HEXAVALENT CHROMIUM" 69 FED. REG. 59305 (OCTOBER4, 2004) 

### =============================== TESTIMONY OF KENNETH GOULD, REGULATORY COUNSEL OWENS CORNING 

### ===============================

February 9, 2005INTRODUCTION TESTIMONY OF KENNETH GOULD, REGULATORY COUNSEL OWENS CORNING

I am Kenneth Gould, Regulatory Counsel for Owens Corning (OC). Among the various products produced by Owens Corning are fiber glass insulation, continuous strand glass fibers for reinforcement and textile applications and cement based stone veneer products which are marketed under the brand name of Cultured Stone. OC appreciates the opportunity to present testimony that augments its previously submitted written comments concerning OSHA's Proposed Rule on Occupational Exposure to Hexavalent Chromium and its potential impact on those products andtheir production. Owens Corning supports and incorporates the positions expressed by the North American Insulation Manufacturers Association (NAIMA) specifically withrespectto fiber glass insulation and generally regarding the glass manufacturing industry and the proposed rule. I amhere today to briefly address issues relating to the effect of OSHA's Proposed Rule on Occupational Exposure to Hexavalent Chromium and Owens Corning'scontinuous strand glass fiber and stone
veneerbusinesses. CONTINUOUS STRAND GLASS FIBERS Owens Corning incorporates the concerns and positions expressed by NAIMA regarding OSHA's failure to analyze all segments of the glass manufacturing industry in its feasibility analysis, especially all portions ofthe glass industry using chromium-rich refractory. One such segment ofthe glass manufacturing industry is continuous strand glass fibers. Owens Corning appreciatesthe opportunityto provide OSHAwith informationrelatingto thatproduct. However, even given that opportunity, the lack ofavailable exposure data, the timing limitations for gathering additional data andthe unique instances ofexposure associated withthe production ofcontinuous strand glass fibers, create uncertainty withrespectto the effect ofthe proposedrule
on Owens Corning's continuous strand business. This lack of data includes the absence of information onthe continuous strand industry inOSHA's feasibility analysis. Manufacturing Continuous Strand Glass Fibers Continuous strand glass fibers are produced by melting raw materials consisting primarily of Silica, Clay, Limestone, Dolomite and Soda Ash. Chromates or materials containing chromates
are not used in the production of continuous strand glass fibers. The furnace is a direct melt operation, meaning that the raw materials are mixed, pneumatically transferred to and melted in the refractory-lined furnace. The temperature ofthe molten glass in the furnace is approximately 2900 Deg. F. As with the production of glass fiber insulation, the molten glass is kept at a constant level by feeding the raw material into one end of the furnace at the same rate that molten glass flows out of the other end. The attached schematic generally shows the manufacturingprocess.

1Typical Continuous Strand Glass FiberManufacturing Line

The molten glass flows out the furnace through refractory lined channels where the temperature ofthe molten glass is adjusted to obtain the proper viscosity. The molten glass then flows into the fore hearths where the bushings are located. A furnace may supply a number ofbushings based onfurnace size, pull rate (i.e., the rate at which glass comes out ofthe furnace), product(s) and bushing design. The number ofbushingpositions onatypical furnace range from 20 to 112. Attached is a schematic ofatypical bushing.



### 2Direct MeltBushing

End Wall 

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The furnace, channels and fore hearths used to produce continuous strand glass fibers are different than those usedto produce glass fiber insulation. The refractory lining is multi-layered, and each layer contains a varying percentage of chromium. Fugitive emissions in the furnace area generally are low. The attached schematic shows in greater detail the construction ofthe furnace, channel and fore hearth.

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CutawayofTypical Continuous Strand Furnace, Channeland Forehearth SourcesofHexavalentChromium The principal source ofpotential hexavalent chromium exposure is from the chrome refractory used in critical high-wear areas ofthe furnace, channels and fore hearths for glass contact. The refractory used for glass contact is a high purity, dense chromic oxide (>90% Crz03) material. Trace levels of impurities in the refractory, such as sodium, in combination with operating conditionscanlead to the conversionoftrivalent chromium to hexavalent chromium. Chrome refractory is used in continuous strand glass fiber production because ofthe extreme temperatures experienced during manufacturing. At those temperatures, the raw materials and moltenglass are highlycorrosive. High chromicoxide refractory is the most suitable material for the temperatures necessary to produce these products. The chrome refractory is corrosion resistant and has a low stoning potential. 1 Typically there is little exposure to these refractory exceptduringfurnace demolition, rebuild and repairs. At the end of a furnace's life and during the subsequent furnace rebuild, chrome containing refractory are removed and replaced. Certain repairs during a furnace campaign may also necessitate the removal and/orreplacement ofsome chrome refractory. The persons involved in the demolition and construction during a rebuild or a repair may be exposed to hexavalent

1 Stoning occurs when extremely small pieces ofthe refractory break offor are dissolved in the molten glass, reforming when the glass cools, and travel through the channels, the fore hearth and then pass through a bushingtip. Because ofthe different viscosity ofthe stone versus the glass, the strand ofglass breaks eventually causing all of the strands flowing from the bushing to break and interrupting production until the bushing can be restarted manually.



### 4chromium that may have been formed. A typical furnace lifetime is 12+ years with one major

_.:» furnace repair during the life ofthefurnace. Continuous strand glass fibers are drawn through platinum alloy bushings. The bushings are set in a castable refractory with a flat top surface. Eachbushing nests to apiece ofrefractory called

a bushing block that is in contact with the fore hearth flow block. High purity dense chromic oxide refractory is used in flow block and bushing block applications. A bushing has a limited lifetime. Atypical bushing lifetime is onthe order of200 days after which itneeds to bereplaced. Ittakes about 45

- 60 minutes total to replace a bushing. During a bushing change, the bushing block may need to be either ground to remove glass penetration that has occurred between the bushing and the bushing block, or replaced. Bushing blocks typically remain in place for 3 bushing changes. Grinding ofthe block surface to remove glass is performed to provide a flat surface for the installation ofthe newbushing. Flowblocks are not changed, but may be ground during abushingblockchange, againto provide a flat surface. These grinding operations, which typically take approximately 20 minutes of the total replacement time, may be a source for exposure to hexavalent chromium whichhas formed onthe chromiumbearingrefractory. Exposuresto Hexavalent Chrome Because the furnace, channels and fore hearths are sealed and fugitive emissions from these
sources are low, exposures to hexavalent chrome during routine production ofOwens Corning's continuous strand glass fibers are expected to be low but insufficient industrial hygiene data is available to sufficiently quantify those potential exposures. Exposures might also occur during demolition of the furnace, channels and fore hearths and the grinding that can be part ofthe replacement of a bushing. Owens Corning was not able to collect exposure data during demolition ofa continuous strand furnace, channel and fore hearth during the comment period for the proposedrule because no furnaces were scheduled to be replaced. Owens Corninghas collected a small amount ofdata during normal bushingchanges. Task-based samples collected during the grinding operation showed exposures during that task ranged from 0.94

- 1.1 flg/m3 During a typical workday, no more than 4 bushings are replaced by a maintenance crew. Thus the total duration ofthe exposure to hexavalent chrome would be less thantwo hours during the work day. Controlling Exposure to Hexavalent Chrome TypicalRebuild Operation Owens Corning already takes steps to mmJmJze potential exposures to dust during furnace, channel and fore hearth rebuilds. Considering the nature ofthese demolitionjobs, it is virtually impossible to install enclosures, ventilators or similar engineering controls to minimize the employee exposure. The furnace is demolished by specialized, skilled personnel. Owens Corning's employees may be in the area performing related tasks. All refractory is removed to minimize potential damage to the refractory bricks. The refractory is then segregated and stored inclosed containers. The used refractory is sent to arecycler. The demolition operation typically

_:= lasts for two weeks. The refractory removal is completed within a week. Appropriate PPE are
wornduringthe demolitionprocess, includingrespiratoryprotection.

5Bushing Change Operation It is extremely difficult to employ effective local dust collection during the replacement of a bushing because the working space is very crowded. Each bushing is a plate approximately 8 inches by 4 inches and the bushings are set I - 2 feet apart. There are numerous bushings attached to eachfore hearth. The space is further crowded as a result ofthe presence ofelectrical connections and coolingwaterloops. PossibleReplacement ofthe Chrome ContainingRefractory Owens Corning has tried to identify potential replacements for chrome containing refractory. Considering the operating conditions andhighly corrosive nature ofmolten glass, we have been unable to do so. All replacement refactories, including zircon, greatly reduce the life ofthe furnace and result in significantcostpenaltiesto Owens Corning. In the U.S., Owens Corning operates 6 continuous strand glass furnaces, at 3 different plants all ofwhich could be impacted by the proposed Rule. These are some ofthe largest continuous strandglassfurnaces inthe world. The current operating life ofone ofthese furnaces is approximately 12 years. Replacing the dense chrome refractory withanalternate material, like a zircon, wouldreduce furnace life by 35 to 50% and reduce Conversion Efficiency (CE) between 2 and 3%, primarily as a result of increased stoning. InConclusion Owens Corning requests that OSHA include furnace rebuilds w1der the construction standard. When the furnace, channels and fore hearths are being rebuilt there is no industrial activity takingplace in that part oftheplant. The only activities involve the demolition and construction ofthe newequipment. Contractors hired by Owens Comingto do the demolition andrebuild will be covered bythe construction standard. Owens Coming'semployees, workinginthe same area, will otherwise have to comply with the general industry standard. The application ofthe two standards, with their different requirements, to the same immediate working area will create confusion and conflict. Owens Corning requests that OSHA modify the compliance deadline for the installation of engineering control devices in recognition of the potential need for manufacturers to obtain environmental permits to undertake the required modifications. There is a significant likelihood thatthe normal delays associated withobtainingthose pern1its will make it impossible for Owens Coming to implement any required changes within the time permitted by the proposed rule. Additionally, the timing requirements must also take into consideration the rebuild schedules for some of the equipment employed in this industry and the ability to turn off some of this equipment. It is entirely possible that some engineering controls, if needed, could only be installed whenthe furnace was shutdown. Finally, Owens Coming supports NAIMA's position on the applicable PEL for Hexavalent Chrome and joins NAIMA in requesting that OSHA establish a PEL similar to that recommendedbythe ACGIH andmostmajorU.S. tradingpartners.

6CULTURED STONE Owens Coming agrees with the positions expressed by the Portland Cement Association (PCA), the American Concrete Pipe Association (ACPA), the National Concrete Masonry Association (NCMA) and the Colorado Ready Mix Concrete Association (CRMCA) in the comments they submitted earlier in this proceeding. The purpose of this testimony is to supplement Owens Coming's earlier comments and support the recommendation by those trade groups that OSHA exclude Portland cement from the general industry standard of the proposed rule as it has proposedto do inthe construction standard. Cultured Stone's Manufacturing Process Owens Coming's, Cultured Stone Division manufactures stone and brick veneer used in residential and commercial construction. The Cultured Stone product line includes hundreds of pre-cast stone veneers and architectural trim products that replicate an extensive variety of textures, sizes, shapes and colors ofnatural stone. Cultured Stone products are cast in molds takenfrom carefully-selectednatural stone. Cultured Stone products are produced at three manufacturing plants in the U.S. The primary materials used to manufacture the stone and brick veneers are Portland cement, fly ash, aggregates, sand and water. The Portlandcement arrives at the plantsin closed tanker trucks. Itis pneumatically offloaded into enclosed storage silos. The production process begins by weighing aggregates and sand in weight hoppers and transferring them to the batch mixer. Water is immediately added to the batch mixer which reduces or eliminates further airborne dust. The appropriate proportions ofPortland cement and fly ash are acquired through enclosed cement weigh hoppers that utilize dust collection systems and are pneumatically conveyed through a dense phase piping system into a secondaryenclosed collectionhopper. The Portland cement and fly ash constituents are then introduced into the aggregate and water slurry in the concrete batch mixer. Additional water, coloring agents and admixtures are then added to the mixer to produce the desired batch. The wet batch material is fed to the pouring station and the required quantity ofbatchis placed into a mold that has been preparedby applying the appropriate coloring to the surface ofthe mold. The newly formed stone and brick veneers are allowed to cure in the mold. When sufficiently cured, they are removed and no further finishing is required. The stone and brick veneers are then packaged and shippedto customers. The attached flow chart depicts this productionprocess.

7Flow Chart ShowingProduction Process forCultured Stone**_,---,-----------------~-----,** 

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/ \ ,Aggregate& / Cement\1 ;. . 1 1 Water \ &FI A h 1 ;AdmrxtureS1 Color \ / \ 1 &Sand 1 \ 1 y s \ \ !_____

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8Sources ofHexavalent Chromium The apparent source ofhexavalent chromium in Cultured Stone's manufacturing process is the cement. The Portland Cement Association characterized the amount of hexavalent chromium typically reported in Portland cement at page 2 of its comments on the proposed rule, dated December23, 2004. The PCA stated inpertinentpart:

...This study concludes that the water soluble hexavalent cluomium content in Portland cement manufactured in the United States and Canada ranges from zero to seven parts per million. Another study cited in the German table puts U.S. cement concentrations at zero to 5.2 ppm. This number has declined in recent years as fewer cement plants utilize refractory materials and grinding balls containing chromium intheproductionprocess. The batch used by Cultured Stone, to produce these stone and brick veneers, consist of approximately 8- 8.5 %Portland cement. As was pointed out in comments already received by OSHA, the effect ofthe batchmixing is to reducethe already low levels ofhexavalent chromium
even further. Owens Corning has discussed, with its current Portland cement suppliers, the amount of hexavalent cluome present in the material they provide. They have indicated that they no longer
use any processing equipment, such as grinding balls, that contains Hexavalent Cluomium. Owens Corning intends to discuss with its suppliers, modifying its product specifications to specificallyprohibitthe use ofsuchprocessingequipment. Exposuresto Hexavalent Chromium A limited number ofindustrial hygiene samples, measuring exposures to hexavalent chromium have been taken at Cultured Stones manufacturing facilities. In each case the level ofHexavalent Cluomiumwas less than the detection limit ofthe test (0.5 ug/m3). Because the measured levels
were so low, in comparison to the existing Permissible Exposure Level (PEL) for Hexavalent Cluomium, Cultured Stone has not conducted additional sampling as part of its regularly scheduled workplace exposure assessments. In Conclusion Owens Corning requests that OSHA extend its proposal for excluding Portland cement from the construction standard to the general industry standard.

Thank You

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