DEPARTMENT OF LABOR 

OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION 

Docket No. H054A 

=============================== 

OSHA'S PROPOSED RULE CONCERNING 

"OCCUPATIONAL EXPOSURE TO HEXAVALENT CHROMIUM" 

69 FED. REG. 59305 (OCTOBER 4, 2004) 

=============================== 

TESTIMONY OF 

KENNETH GOULD, REGULATORY COUNSEL 

OWENS CORNING 

=============================== 

February 9, 2005 
INTRODUCTION 

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 and their production. 

Owens Corning supports and incorporates the positions expressed by the North American 

Insulation Manufacturers Association (NAIMA) specifically with respect to fiber glass insulation 

and generally regarding the glass manufacturing industry and the proposed rule. I am here today 

to briefly address issues relating to the effect of OSHA's Proposed Rule on Occupational 

Exposure to Hexavalent Chromium and Owens Corning's continuous strand glass fiber and stone 

veneer businesses. 

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 of the glass industry using chromium-rich refractory. One such 

segment of the glass manufacturing industry is continuous strand glass fibers. Owens Corning 

appreciates the opportunity to provide OSHA with information relating to that product. 

However, even given that opportunity, the lack of available exposure data, the timing limitations 

for gathering additional data and the unique instances of exposure associated with the production 

of continuous strand glass fibers, create uncertainty with respect to the effect of the proposed rule 

on Owens Corning's continuous strand business. This lack of data includes the absence of 

information on the continuous strand industry in OSHA'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 of the 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 

manufacturing process. 

1 
Typical Continuous Strand Glass Fiber Manufacturing Line 

The molten glass flows out the furnace through refractory lined channels where the temperature 

of the molten glass is adjusted to obtain the proper viscosity. The molten glass then flows into 

the 

based 

fore hearths where the bushings are located. A furnace may supply a number of bushings 

on furnace size, pull rate (i.e., the rate at which glass comes out of the furnace), product(s) 

Attached 

and bushing design. The number of bushing positions on a typical furnace range from 20 to 112. 

is a schematic of a typical bushing. 

2 
Direct Melt Bushing 

End Wall 

' Ear 

The furnace, channels and fore hearths used to produce continuous strand glass fibers are 

different than those used to 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 of the 

furnace, channel and fore hearth. 

3 
SAC~ WJ.llCHMGIIiC EHO 

HlVl 

M[JtftUIG 

CHAHH~I. 

Cutaway of Typical Continuous Strand Furnace, Channel and Fore hearth 

Sources of Hexavalent Chromium 

The 

used 

principal source of potential hexavalent chromium exposure is from the chrome refractory 

refractory 

in critical 

used 

high-wear areas of the furnace, channels and fore hearths for glass contact. The 

Trace 

for glass contact is a high purity, dense chromic oxide (>90% Crz03) material. 

levels of impurities 

conditions 

in the refractory, such as sodium, in combination with operating 

can lead to the conversion of trivalent chromium to hexavalent chromium. 

temperatures 

Chrome refractory is used in continuous strand glass fiber production because of the extreme 

experienced during manufacturing. At those temperatures, 

molten glass are highly 

the raw materials and 

the temperatures 

corrosive. High chromic oxide refractory is the most suitable material for 

necessary to produce these products. The chrome refractory 

resistant and 

is corrosion 

has a low stoning potential. 1 

except during 

Typically there is little exposure to these refractory 

furnace demolition, rebuild and repairs. 

refractory 

At the end of a furnace's life and during the subsequent furnace rebuild, chrome containing 

necessitate 

are removed and replaced. Certain repairs during a furnace campaign may also 

the demolition 

the removal 

and 

and/or replacement of some chrome refractory. The persons involved in 

construction during a rebuild or a repair may be exposed to hexavalent 

1 Stoning occurs when extremely small pieces of the refractory break off or are dissolved in the molten glass, 

Because 

reforming 

of 

when 

the different 

the glass 

viscosity 

cools, and 

of 

travel through the channels, the fore hearth and then pass through a bushing tip. 

the stone versus the glass, the strand of glass breaks eventually causing all of 

manually. 

the strands flowing from the bushing to break and interrupting production until the bushing can be restarted 

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

_.:» furnace repair during the life ofthe furnace. 

Continuous strand glass fibers are drawn through platinum alloy bushings. The bushings are set 

in a cas table refractory with a flat top surface. Each bushing nests to a piece of refractory 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. A typical bushing lifetime is on the order of 200 days after which it needs to be replaced. 

It takes 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 of the block surface to remove glass is performed to provide a flat 

surface for the installation of the new bushing. Flowblocks are not changed, but may be ground 

during a bushing block change, again to 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 which has formed on the chromium bearing refractory. 

Exposures to 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 of Owens 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 of the 

replacement of a bushing. Owens Corning was not able to collect exposure data during 

demolition of a continuous strand furnace, channel and fore hearth during the comment period 

for the proposed rule because no furnaces were scheduled to be replaced. 

Owens Corning has collected a small amount of data during normal bushing changes. 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 of the exposure to hexavalent chrome would be less 

than two hours during the work day. 

Controlling Exposure to Hexavalent Chrome 

Typical Rebuild Operation 

Owens Corning already takes steps to mmJmJze potential exposures to dust during furnace, 

channel and fore hearth rebuilds. Considering the nature of these demolition jobs, 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 

in closed containers. The used refractory is sent to a recycler. The demolition operation typically 

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

worn during the demolition process, including respiratory protection. 

5 
Bushing Change Operation 

It 

bushing 

is extremely 

because 

difficult to employ effective local dust collection during the replacement of a 

inches by 4 inches 

the 

and 

working space is very crowded. Each bushing is a plate approximately 8 

attached 

the bushings are set I - 2 feet apart. There are numerous bushings 

connections 

to each 

and 

fore hearth. The space is further crowded as a result of the presence of electrical 

cooling water loops. 

Possible Replacement of the Chrome Containing Refractory 

Owens Corning has tried to identify potential replacements 

Considering 

for chrome containing refractory. 

unable to do 

the 

so. 

operating 

All 

conditions and highly corrosive nature of molten glass, we have been 

replacement refactories, 

furnace and result 

including zircon, greatly reduce the life of the 

in significant cost penalties to Owens Corning. 

of 

In the 

which 

U.S., 

could 

Owens 

be 

Corning operates 6 continuous strand glass furnaces, at 3 different plants all 

strand glass 

impacted by the proposed Rule. These are some of the largest continuous 

furnaces in the world. 

The current operating life of one of these furnaces is approximately 12 years. Replacing 

dense chrome 

the 

to 50% and reduce 

refractory with 

Conversion 

an alternate material, like a zircon, would reduce furnace life by 35 

increased stoning. 

Efficiency (CE) between 2 and 3%, primarily as a result of 

In Conclusion 

Owens 

When the 

Corning requests that OSHA include furnace rebuilds w1der the construction standard. 

taking place 

furnace, channels and fore hearths are being rebuilt there is no industrial activity 

of the new 

in that part of the plant. The only activities involve the demolition and construction 

be covered 

equipment. 

by 

Contractors hired by Owens Coming to do the demolition and rebuild will 

will otherwise 

the 

have 

construction standard. Owens Coming's employees, working in the same area, 

standards, with 

to comply with the general industry standard. The application of the two 

their different requirements, 

confusion and conflict. 

to the same immediate working area will create 

engineering 

Owens Corning 

control 

requests 

devices 

that OSHA modify the compliance deadline for the installation of 

in recognition of the potential need for manufacturers 

environmental permits 

to obtain 

to undertake the required modifications. There is a significant 

that the normal delays 

likelihood 

Coming 

associated with obtaining those pern1its will make it impossible for Owens 

Additionally, 

to implement any required changes within the time permitted by the proposed rule. 

the timing requirements must also take into consideration 

some of the equipment 

the rebuild schedules for 

employed 

equipment. It 

in this industry and the ability to turn off some of this 

installed when the 

is entirely possible that some engineering controls, if needed, could only be 

furnace was shut down. 

Chrome 

Finally, Owens 

and 

Coming supports NAIMA' s position on the applicable PEL for Hexavalent 

joins NAIMA in requesting 

recommended by 

that OSHA establish a PEL similar to that 

the ACGIH and most major U.S. trading partners. 

6 
CULTURED 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 

proposed to do in the 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 of natural stone. Cultured Stone products are cast in molds 

taken from carefully-selected natural 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 Portland cement arrives at the plants in closed tanker trucks. It is 

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 of Portland 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 secondary enclosed collection hopper. 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 

of batch is placed into a mold that has been prepared by applying the appropriate coloring to the 

surface of the 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 shipped to customers. The attached flow chart depicts this 

production process. 

7 
Flow Chart Showing Production Process for Cultured Stone 

_,---,-----------------~-----, ;;::: 1!"',---1\~-----T _____ I I I 

~,~· .• _. I I 

Raw Materials Suppliers t I I 

/\ /' J, J, J 

Curing 

Molds 

/\ /\ /\ 1\ ;/\ / \ / \. ~~ \ ~~ ,, I \ / \ ,Aggregate& / Cement \

1 ;. . 1 1 

Water \ &FI A h 1 ;AdmrxtureS1 Color \ / \ 1 &Sand 1

\ 1 y s \ \ 

!_____ ___ _.'::,'~ ~-T--' ·--~-·-· L __ -- '--~ -· 

·~ I I ~-, -.. ,".~-~---~-----L _____ ~ I 

iv--"-~ ~ 

(\ 

/ 

Mixer \ ) 

fwet 

1

\ Station c:Jr~ . I ~ 

~,~/ l __ __j ...._ 

/-~~ V~l i 1

1 } Colonng 1 Pounng f.oll-- --~ Molds 

I I 

~~ __ _..../ ~~/J 

Empty~ 

~91~·1 ,------ -"' --· -. // / 

, ______ ./.ioio.::===; / \ '/ 

( Demordiog 

1

I 1 

) Stones 

R~auck~s 

into 

___ ~.YDryer 

~ )

1

~~-/_;--- 1 I 

~~ ~--, iA.,CJ -" Pack~ng /\) 

Re ack 

_.,,-1 • 

l)-CJ:J ---;:y_;; 

'--, iff! 

~ '-1 

• 

Distribution Center 

& Dealers Cure time 

& FG Inventory 

8 
Sources of Hexavalent Chromium 

The apparent source of hexavalent 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 

December 23, 2004. The PCA stated in pertinent part: 

... 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 in the production process. 

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 of the batch mixing is to reduce the already low levels of hexavalent 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 

specifically prohibit the use of such processing equipment. 

Exposures to Hexavalent Chromium 

A limited number of industrial hygiene samples, measuring exposures to hexavalent chromium 

have been taken at Cultured Stones manufacturing facilities. In each case the level of Hexavalent 

Cluomium was less than the detection limit of the 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 

9