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MEMORANDUM

TO : Kim Teal and Keith Barnett, U.S. Environmental Prote ction Agency

FROM : Eastern Research Group, Inc. (ERG)

DATE : January 12, 2015

SUBJECT : Methodology for Estimating Emission Reductions from Spe cialty Coating

Application Operations for Proposed Amendments to 40 CFR 63, Subpart GG, National Emission Standards for Aerospace Manufacturing and Rework Facilities

1.0 INTRODUCTION AND SUMMARY OF RESULTS

This memorandum describes the methodology and summarizes the results of estimating the potential emission reductions from specialty coating operati ons for the proposed amendments to the Aerospace NESHAP. Potential emission reductions wer e calculated as a result of complying with the requirements to meet VOC and HAP emission li mits for specialty coating operations, and for complying with requirements to use high-efficiency a pplication methods for spray applied specialty coatings.

The EPA estimated that annual HAP emissions from speci alty coatings are about 360 tpy; inorganic HAP emissions are about 5 tpy and the remainder is organic HAP emissions. These baseline emission estimates are based on the specialty coating emissions estimate used in the final residual risk modeling file, which was developed from the 2011 information collection request for 2008 emissions data, and supplemented with data fr om the 2011 National Emission Inventory (NEI) and 2005 National Air Toxics Assessment (NA TA).

The estimated emission reductions are 58 tons of HAP from the proposed regulation of specialty coatings.

2.0 ESTIMATED EMISSION REDUCTIONS FROM COMPLIANCE WIT H

PROPOSED VOC AND HAP EMISSION LIMITS

The EPA estimated that compliance with the proposed VOC and HAP emission limits would achieve a HAP emission reduction of 14.3 tons per year of o rganic HAP.

To determine emission reductions from compliance with the proposed VOC and organic HAP emission limits, the EPA compared the calculated HAP c ontent of each specialty coating, in units of grams of HAP per liter of coating (g/liter), to the proposed VOC and organic HAP content limits. However, it is important to note that the propose d VOC limits are in units of VOC g/liter (less water and exempt solvents), and the HAP limits a re in units of HAP g/liter (less water). www.erg.com2

The EPA did not have sufficient information from the I CR data on water content to convert the HAP content in g/liter to g/liter (less water), or to calculate the VOC content as VOC g/liter (less water and exempt solvents). If water is present in any of the coatings, then correcting for the

water content would increase the calculated HAP content relative to the proposed HAP limit for that coating category, and could possibly increase the numbe r of coatings that would not be in compliance, and this may increase the estimated HAP reduc tions.

It is also important to note that these reductions are ba sed on the assumption that facilities will

not use averaging of specialty coatings to demonstrate compl iance. The use of averaging would reduce the potential emission reductions.

These reductions are also based on the assumption that a non-compliant coating would be replaced with a coating with a HAP content exactly equa l to the limit for that specialty coating category, instead of with another coating that would ha ve a HAP content lower than the limit. The latter would lead to greater emission reductions than e stimated.

3.0 ESTIMATED EMISSION REDUCTIONS FROM COMPLIANCE WIT H PROPOSED REQUIREMENTS FOR HIGH EFFICIENCY COATING A PPLICATION

METHODS

The EPA estimated that compliance with the proposed requ irements for high-efficiency coating application methods would achieve an estimated HAP emissio n reduction of 43.4 tons per year. The high-efficiency application methods would affect both organic and inorganic HAP emissions equally, but the reductions would be almost entirely of o rganic HAP emissions because organic HAP represent over 98 percent of the HAP emissions from specialty coatings.

The EPA assumed a 20 percent reduction in emissions for e ach spray applied specialty coating used at a facility outside California. The 20 percent reductio n in emissions would be due to a 20 percent reduction in coating consumption when switching to hi gh-efficiency coating application methods. The 20 percent reduction in consumption and emissio ns would be equivalent to an increase in transfer efficiency from 40 percent efficien cy to 50 percent efficiency.

For example, at 40 percent transfer efficiency, a coa ting applicator needs to spray 2.5 gallons of coating to achieve 1.0 gallon of coating on the part’s surfac e. At 50 percent transfer efficiency, a coating applicator needs to spray only 2.0 gallons of coati ng to achieve 1.0 gallon of coating on the part’s surface. The reduction from 2.5 gallons to 2.0 gall ons represents a 20 percent reduction in coating consumption and emissions.

The EPA did not apply these reductions to specialty coatings used at facilities in California because many of the California aerospace surface coating rules require the use of high efficiency application methods for all coatings, with no exceptio ns for specialty coating application operations. State rules outside California, based on the Aerospace CTG, 1 often allow an

1 Guideline Series: Control of Volatile Organic Comp ound Emissions from Coating Operations at Aerospace Manufacturing and Rework Operations. Emission Stand ards Division, U. S. Environmental Protection Agenc y, Office of Air and Radiation, Office of Air Quality Plannin g and Standards, Research Triangle Park, NC 27711, December 1997. Publication No. EPA-453/R-97-004.3

exemption from the application equipment requirements f or specialty coatings, as found on the Aerospace CTG model rule.

In addition, the EPA applied this reduction only to special ty coating categories that were assumed to be spray applied. The following specialty coatin g categories were assumed to be applied with non-spray application methods, and no reductions were not applied to these specialty coating categories:

• Adhesive – Nonstructural

• Adhesive - Structural Autoclavable

• Adhesive - Structural Nonautoclavable

• Caulking and Smoothing Compound

• Critical use and line sealer maskant

• Cyanoacrylate Adhesive

• Dry lubricative material

• Fuel Tank Adhesive

• Rocket motor bonding adhesive

• Rubber-Based Adhesive

• Screen Print Ink

• Seal coat maskant

• Sealant - Extrudable / Rollable / Brushable