NAIMA 


NORTH AMERICAN INSULATION 


MANUFACTURERS ASSOCIATION 


VIA E-MAIL AND OVERNIGHT MAIL 

January 28, 2013 

Ms. Susan Fairchild 

Sector Policies and Programs Division 

Metals and Minerals Group (D243-02) 

Office ofAir Quality Planning and Standards 

U.S. Environmental Protection Agency 

4930 Old Page Road 

Durham, NC 27703 

RE: Follow-Up To Manufacturing Facility Tours 

Dear Ms. Fairchild: 

INTRODUCTION 

The North American Insulation Manufacturers Association ("NAIMA") and its members 

appreciate the ongoing dialogue with the Environmental Protection Agency ("EPA") and the 

opportunity to provide EPA representatives with tours of various manufacturing facilities. The 

meetings and facility tours helped explain the differences among the various types of furnaces 

used in the manufacture of fiber glass insulation. These distinctions are particularly relevant 

because the different designs of those furnaces can directly impact the level of hex chrome 

emissions. 

As you know, hex chrome emissions are the primary reason NAIMA and its members have had 

an extended dialogue with EPA in recent months. In fact, EPA has acknowledged that, but for 

one particular outlier test result from the CertainTeed Kansas City facility, chromium emissions 

from the fiber glass industry would not be a concern for EPA. 

During the facility tours, EPA representatives were shown operating oxy fuel, air gas, cold top 

electric, and steel shell furnaces. NAIMA and its members also provided graphic presentations 

ofthese different furnace types and the refractory bricks typically used in each. The presentation 

effectively demonstrated that refractories play a critical role in containing molten glass and 

protecting facilities and workers. Images of heavily scored and corroded refractory brick 

dramatically illustrated the necessity of high chrome content bricks. The presentation also 

demonstrated that chrome emissions do not correlate to the level of chrome content in the 

refractories. Those graphics are enclosed herewith. 

44 CANAL CENTER PLAZA. SUITE 310 • ALEXANDRIA, VA 22314 • TEL 703/684-0084 • FAX 703/684-0427 
Ms. Susan Fairchild 

January 28, 2013 

Page 2 

DIFFERENCES AMONG FURNACE TYPES 

As the furnace graphics demonstrate, differences in furnace types and design attributes, far more 

significantly than simply the level of chrome content in a furnace's refractories, impact chrome 

emissions. Many facilities' furnaces use high chrome refractories yet have low chromium 

emissions. Rather, the specific design attributes of the individual furnace the chrome content 

in the above-glass refractory, temperature, water vapor concentration, and other possible factors 

-are relevant to the level ofhex chrome emissions. 

In all gas furnaces - both oxy fuel and air gas the burners are located above the glass line. But 

even between oxy fuel and air gas furnaces, there is a significant difference in the peak flame 

temperatures, and thus the temperature in the furnace above the glass line. This temperature is 

significantly higher in an oxy fuel furnace than in an air gas furnace. In oxy fuel furnaces, flame 

temperatures peak above 5,000 degrees Fahrenheit, whereas in air gas furnaces, flame 

temperatures peak at about 3,560 degrees Fahrenheit. The bulk wall temperature will be lower, 

driven by the heat transfer within the furnace. 

In further contrast, cold top electric melters have no heat source input (absolutely no combustion 

of natural gas) and virtually no chrome refractory above the glass line. Instead, the glass is 

heated by electrodes located below the glass line. The temperature above the glass line in these 

furnaces is driven only by the heat transfer from the molten glass through the batch cover which 

acts as an insulator, and thus is substantially lower than the above-glass temperature in either 

type of gas furnace. 

Steel shell melters similarly have very low temperatures and no significant chrome refractories 

above the glass line. Their heat input is below the glass line as well; therefore, heat transfer from 

the molten glass through the batch cover drives the temperature above the glass line. 

The significantly higher temperatures exhibited in the oxy fuel furnaces, along with an oxidizing 

atmosphere from the use of pure oxygen for combustion, are conditions that increase the 

potential for chromium emissions from the refractory above the glass line, and, more 

importantly, to the conversion to hex chrome (Cr206). The higher temperature of the oxy fuel 

burners can volatize the glass batch components more readily than in other furnaces. These glass 

volatiles that contain alkaline earth oxides reduce the temperatures that chrome can be vaporized 

to as low as 1,832 degrees Fahrenheit. While the chrome must still reach temperatures of at least 

2,700 degree Fahrenheit to oxidize the Cr203 to Cr206, the potentially increased volatiles can 

contribute to higher chrome emissions. The 40 percent higher peak flame temperature of oxy 

fuel burners compared to air gas furnaces also raise the probability that available chrome will 

encounter the conditions that will convert it to Cr206. 

These facts are further verified in the analysis provided by Dr. Denis Brosnan of Clemson 

University and attached to NAIMA's earlier comments. After thoroughly analyzing the role of 

temperature in the volatilization of chromium from pure chromic oxide, Dr. Brosnan found that 

"[i]n mineral fiberglass furnaces, the local temperature at the surface of chrome alumina 
Ms. Susan Fairchild 

January 28, 2013 

Page 3 

refractories [above the glass line] is the single most influential variable influencing hexavalent 

chromium emissions."l 

The emissions data submitted to EPA by NAIMA and NAIMA companies corroborate the 

correlation between differences among furnace types and the respective furnaces' chrome 

emissions. 

Therefore, with respect to chrome emissions, oxy fuel furnaces are distinctively unique from 

other furnaces used in the manufacture of wool fiber glass. They have: 1) a higher flame 

temperature; 2) more chrome refractories above the glass line; 3) higher water vapor 

concentration due to the absence of diluting nitrogen; and 4) an oxidizing atmosphere with 

increased concentration of oxides. These distinctive characteristics directly affect the amount of 

hex chrome emissions that can be emitted. Thus, NAIMA asks EPA to address the oxy fuel 

furnaces differently and separately from the other glass furnaces and to consider that oxy fuel 

furnaces may be the only furnace type that may need to be identified for potential regulation in 

developing an area source standard. Specifically, the other glass furnaces air gas, cold top 

electric, and steel shell - should not be considered as appropriate candidates for an area source 

standard. 

Despite their potential for increased chrome emissions, oxy fuel furnaces will continue to be 

used for a number of important reasons, including environmental benefits: 1) oxy fuel furnaces 

reduce NOx and CO emissions because they emit less of these pollutants than does combustion 

with air; 2) oxy fuel firing reduces NOx emissions because it does not introduce nitrogen from 

combustion air into the furnace; 3) oxy fuel furnaces use less energy than air gas furnaces by 

obviating the need to heat nitrogen contained in ambient air and thus produce less greenhouse 

gas emissions; and 4) oxy fuel firing also produces a reduced volume of flue gases which lowers 

the gas velocity in the furnace combustion zone and lowers the potential to entrain particulate 

matter. Moreover, oxy and air gas furnaces produce less direct C02 per ton of glass than the 

indirect C02 from an electric furnace; this is particularly true in the Midwest and Southeast 

regions ofthe United States. 

STARTUP AND SHUTDOWN PROVISIONS 

NAIMA would support EPA's proposed approach to startup and shutdown as described by Keith 

Barnett at the December 6, 2012 meeting in Kansas City, Kansas, following the facility tours. 

This approach recognized that work practices, rather than emission standards, were appropriate 

during startup and shutdown periods. For gas furnaces, this would mean having the control 

devices in use while batch was being charged. The Rule would need to make an exception for 

cold top electric and steel shell furnaces, which need a batch cover established before the 

temperature is cool enough to allow safe operation of the control device. For those furnaces, 

NAIMA proposes that the Rule require the control device to be started expeditiously after a 

I Denis A. Brosnan, Ph.D., PE, "Technology Review, Chromium Emissions in Wool Fiberglass Melting Furnaces," 

December 10,2011, p. 9. 
Ms. Susan Fairchild 

January 28,2013 

Page 4 

batch cover is established sufficient to reduce the exhaust temperature to a safe level established 

by the recommendations ofthe control device manufacturer. 

FLAME ATTENUATION 

EPA's original proposal merged heavy density and pipe produced on flame attenuation lines 

together into one Standard. NAIMA urges EPA to take no further action on flame attenuation. 

RISK MODELING 

NAIMA's request that any area source standard be limited to the consideration of only oxy fuel 

furnaces is also supported by both EPA and NAIMA companies' risk calculations. 

Based on EPA's Detailed Risk Modeling Results (Appendix 6), the following facilities are below 

a cumulative one-in-one-million excess cancer risk: 

Knauf- Lanett, Alabama Johns Manville - Richmond, Indiana 

Guardian - Kingman, Arizona Guardian - Albion, Michigan 

Owens Coming - Eloy, Arizona Johns Manville - Berlin, New Jersey 

Johns Manville - Willows, California Owens Coming - Mount Vernon, Ohio 

Knauf - Shasta Lake, California Guardian - Winnsboro, South Carolina 

Owens Corning - Lakeland, Florida Owens Corning - Salt Lake City, Utah 

Knauf - Shelbyville, Indiana Guardian - Inwood, West Virginia 

Based on additional modeling conducted by Owens Corning and Guardian, pursuant to EPA's 

methods, the following facilities are below a one-in-one-million excess cancer risk for hex 

chrome: 

Guardian - Mineral Wells, Mississippi 


Owens Corning - Santa Clara, California 


Owens Corning - Kansas City, Kansas 


Owens Coming - Fairburn, Georgia 


These company-specific modeling results have been or will be provided to EPA. If additional 

companies conducted individual facility modeling, it would likely show results similar to those 

from Owens Coming and Guardian given the commonalities of the furnace design 

characteristics, the manufacturing processes, and the use of raw materials. The fact that many 

other facilities were very close to a cumulative one-in-one-million excess cancer risk in EPA's 

Detailed Risk Modeling Results, they quite likely would be below a one-in-one-million excess 

cancer risk for hex chrome. 
Ms. Susan Fairchild 

January 28,2013 

Page 5 

CONSIDERATION FOR AN AREA SOURCE STANDARD 

Based on EPA and company modeling results and different furnace type characteristics that 

affect each fumace's potential to create hex chrome emissions, NAIMA asks that EPA consider 

the following for any area source standard EPA determines is needed for the Wool Fiberglass 

industry. 

1. 	 Applicability ofthe Wool Fiberglass Area Source Standard 

• 	 The Area Source Standard applies only to each oxy fuel furnace that: 

- Melts a mixture of raw materials to produce molten glass that is used to produce 

wool fiberglass building insulation, and 

- Is located at an area source ofhazardous air pollutant ("HAP") emissions, and 

- Has a potential to emit hex chrome at a rate equal to or greater than 25 lbs. of hex 

chrome per year. 

2. 	 Furnaces That Are Exempt From the Rule 

• 	 Furnaces that are located at an area source that has a cancer maximum risk less than 

one-in-one million based on the geographic centroids of any census block, or 

• 	 Furnaces that emit hex chrome at a rate less than 25 lbs. of hex chrome per year. 

3. 	 Covered HAPs 

• 	 The Area Source Rule will apply only to hex chrome emissions. 

4. 	 Area Source Requirements 

• 	 Emission limit for hex chrome: 4.6 x 10-4 lbs/ton 

5. 	 Compliance Date 

• 	 Existing sources must comply with applicable emission limits within a specified period of 

time (no less than three years from the effective date of the applicable rule) that 

recognizes the time needed for manufacturers to implement necessary controls and/or 

other changes to a glass furnace to avoid applicability ofthe Ru1e or specific language in 

the Rule that recognizes that if changes are made after the effective date of the Rule but 

before the first substantive compliance date that a furnace wou1d be excluded from 

coverage under the Ru1e; the concept of once in always in would not apply. An extension 

may be requested allowing up to one additional year to comply with applicable emission 

limits. 

• 	 New sources must comply with emission limits upon initial startup ofthe source. 
Ms. Susan Fairchild 

January 28, 2013 

Page 6 

• 	 Define affected source to embody the concept that modification to the furnace!source 

could facilitate non-applicability to the Rule (e.g., change an oxy fuel furnace to a cold 

top electric). 

6. 	 Performance Tests 

• 	 Only one test is required for identical furnaces. 

• 	 EPA and NAIMA would work together to define what constitutes identical furnaces. 

• 	 Emission testing conducted as part of the National Emissions Standards For Hazardous 

Air Pollutants: Wool Fiberglass Manufacturing (Docket: EPA-HQ-OAR-2010-1042) will 

be allowed to show non-applicability ofthe Area Source Standard. 

7. Testing Method 

• 	 Sources should select the preferred testing method. 

• 	 The test methods used for major sources would be appropriate. 

• 	 The test method used for the NESHAP: Wool Fiberglass Manufacturing (Docket: EP AHQ-OAR-201O-1042) testing is an acceptable test method. 

8. Compliance Requirements 

• 	 The Area Source Standard should recognize as acceptable any control devices! 

mechanisms that have been accepted by MACT or Residual Risk Rule as valid control 

devices for the Area Source Standard. 

9. Monitoring and Recordkeeping Requirements 

• 	 There should be no additional monitoring requirements above or beyond the MACT 

Standard. 

• 	 The area source monitoring, recordkeeping, and reporting requirements should not be as 

onerous as the MACT Standard requirements. 

• 	 Area sources should conduct only stack testing, with no interim monitoring, once every 

five years or one time every campaign. 

Sincerely, 

~~<&. Angus E. Crane 


Executive Vice President, General Counsel 


Enclosure 
Ms. Susan Fairchild 

January 28,2013 

Page 7 

cc: 	 (With Enclosure) 

Mr. Keith W. Barnett 

Group Leader, Office of Air Quality and Planning Standards 

Sector Policies and Programs Division, Mineral and Manufacturing Group 

U.S. Environmental Protection Agency 


4930 Old Page Road 


Durham, NC 27703 


Mr. Dave Reeves 


RTI International 


P.O. Box 12194 


3040 East Cornwallis Road 


Research Triangle Park, NC 27709-2194 

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