1

MEMORANDUM

DATE: January 21, 2015

SUBJECT: Technology Review for Primer and Topcoat Application Ope rations in the

Aerospace Source Category

FROM: EC/R Incorporated and Eastern Research Group, Inc.

TO: Kim Teal, U.S. EPA/OAQPS/SPPD/MMG

1.0 INTRODUCTION

Section 112 of the Clean Air Act (CAA) requires the U.S . Environmental Protection Agency (EPA) to establish technology-based standards for listed source categories. These technologybased standards are often referred to as maximum achievable control technology (MACT) standards. The Aerospace MACT (40 CFR part 63, subpart GG) r egulates HAP emissions from facilities that are major sources and are engaged, eithe r in part or in whole, in the manufacture or rework of commercial, civil, or military aerospace ve hicles or components. The rule requires the use of MACT to reduce HAP emissions from the following o perations: cleaning; primer, topcoat and chemical milling maskant application; depainting; and wa ste storage and handling.

Section 112 also contains provisions requiring the EPA to peri odically revisit these standards. Specifically, section 112(d)(6) states:

(6) REVIEW AND REVISION. – The Administrator shall r eview, and revise as necessary (taking into account developments in practices , processes, and control technologies), emissions standards promulgated under this se ction no less often than every 8 years.

To comply with this CAA requirement, the EPA conducted a technology review for the Aerospace MACT standard for major sources. This memoran dum addresses the portion of the technology review for primer and topcoat application opera tions.

For the purposes of reviewing a MACT standard, the EPA con siders a “development” in practices, processes, and control technologies to be:

• Any add-on control technology or other equipment that was not identified and considered during MACT development;

• Any improvements in add-on control technology or other e quipment (that was identified and considered during MACT development) that could result in significant additional emission reduction;2

• Any work practice or operational procedure that was not i dentified and considered during MACT development; and

• Any process change or pollution prevention alternative t hat could be broadly applied that was not identified and considered during MACT development.

Section 2 of this memorandum presents a summary of the sources of data that were used to conduct the technology review and Section 3 presents the t echnology review for primer and topcoat application operations.

2.0 SOURCES OF AVAILABLE CONTROL TECHNOLOGY INFORMAT ION

To identify any developments in practices, processes, or c ontrol technologies that could be applicable to topcoat and primer application operations in the Aerospace industry, we consulted the following sources of data: RACT/BACT/LAER Clearingho use, the California Statewide Best Available Control Technology (BACT) Clearinghouse, regulat ory actions promulgated subsequent to the Aerospace MACT, regional and state regulati ons, and correspondence with state agencies and industry.

In addition, in order to assess developments in practic es, processes and control technologies that have occurred in the aerospace manufacturing and rework i ndustry since promulgation of the MACT standards, the EPA sent out a comprehensive informa tion collection request (ICR) to all known facilities in February 2011. The ICR requested informat ion on material usage and control techniques used on all of the regulated and unregulated emissi on sources. Responses were received from 100 major source facilities and 145 synthetic m inor facilities with adequate information to determine the current level of control of HAP emissions, as well as to calculate HAP emissions.

2.1 RACT/BACT/LAER Clearinghouse Database

Under the EPA's New Source Review (NSR) program, if a co mpany is planning to build a new plant or modify an existing plant such that criteria ai r pollution emissions will increase by a certain amount, then the company must obtain an NSR pe rmit. The NSR permit is a construction permit which generally requires the company to minimize air pollution emissions by changing the process to prevent air pollution and/or installing air pollution control equipment.

The terms "RACT," "BACT," and "LAER" are acronyms for different program requirements relevant to the NSR program. RACT, or Reasonably Avai lable Control Technology, is required on sources in areas that are not meeting national ambien t air quality standards (non-attainment areas). BACT, or Best Available Control Technology, is required on new or modified major sources in clean areas (attainment areas). LAER, or Lo west Achievable Emission Rate, is required on new or modified major sources in non-attainm ent areas.

BACT and LAER (and sometimes RACT) are determined on a c ase-by-case basis, usually by State or local permitting agencies. The EPA established th e RACT/BACT/LAER Clearinghouse, or RBLC, to provide a central data base of air pollution t echnology information (including past BACT and LAER decisions contained in NSR permits) to pro mote the sharing of information3

among permitting agencies and to aid in future case-by-case determinations. However, data in the RBLC are not limited to sources subject to RACT, BA CT, and LAER requirements. Noteworthy prevention and control technology decisions and information may be included even if they are not related to past RACT, BACT, or LAER dec isions.

The RBLC contains over 5,000 air pollution control permit de terminations that can help identify appropriate technologies to mitigate most air pollutant emission streams. It was designed to help permit applicants and reviewers make pollution prevention a nd control technology decisions for stationary air pollution sources, and includes data submitte d by several U.S. territories and all 50 States on over 200 different air pollutants and 1,000 industria l processes.

The RBLC provides several options for searching the permit database on-line to locate applicable control technologies. On October 21, 2013, we c onducted a search of the RBLC. Our search specified processes in the Aerospace surface coat ing category, with permits dating back to 1995. The search results included the following data fields:

• RBLC ID; • Facility Name, and State; • Permit Date; • Process name; • Throughput; • Pollutant; • Control technology; and • Percent efficiency of control.

The results of the search are presented in Appendix 1 fo r the Aerospace source category.

Finally, a search of Washington State’s records of permit s for aerospace facilities identified a Final Prevention of Significant Deterioration (PSD) pe rmit dated September 10, 2014 for the Boeing Everett facility. 1 In this, the PSD permit considers BACT for VOC coati ng operations as complying with all applicable VOC emission standards of t he Aerospace NESHAP. The accompanying technical support document identified add-on contro l technologies, including RTO, but these were not considered BACT after taking in to account energy, environmental, and economic impacts. 2

2.2 Subsequent Regulatory Actions

1 Department Of Ecology, State Of Washington: Preventi on Of Significant Deterioration (PSD) Permit. Issued To: The Boeing Company, Boeing Commercial Airplan es, Everett Facility. Facility Location: 3003 West Casino Road, Everett, Washington 98203, Permit Number: PSD -14-01, Date of Original Permit Issuance: September 10, 2014. Effective Date of Permit: September 10, 2014. 2 Department Of Ecology, State Of Washington: Technical Support Document For The Boeing Company, Boeing Everett 777X Project. Prepared by Air Quality Program, W ashington State Department of Ecology, Olympia, Washington, September 9, 20144

Regulatory actions promulgated subsequent to the 1995 Aerospace MACT have been identified for sources similar to Aerospace coating operations. The se regulatory actions, listed in Table 1, were reviewed for developments in practices, processes a nd control technologies.

Table 1. Subsequent Regulatory Actions for Sources Similar to

Aerospace Coating Operations

MACT Standards Subpart Date Practices, Processes, and Control Technologies Evaluated

Surface Coating of Metal Furniture RRRR 5/23/2003 Emission limit as mass HAP per volume solids used, add-on control devices, low-HAP coatings (powder, non/low-HAP solvents, UV-curable, autophoretic) Surface Coating of Wood Building Products QQQQ 5/28/2003 Emission limit as mass HAP per volume solids used, add-on control devices, low-HAP coatings

Surface Coating of Large Appliances NNNN 7/23/2002 Emission limit as mass HAP per volume solids used, add-on control devices, low-HAP coatings (powder, non/low-HAP solvents, UV-curable, autophoretic) Surface Coating of Automobiles and Light-Duty Trucks IIII 4/26/2004 Emission limit as mass HAP per volume solids used, low-hap coatings (low/ non-HAP solvents), powder coatings, improved capture and control systems

Surface Coating of Plastic Parts and Products PPPP 4/19/2004 Emission limit as mass HAP per volume solids used, add-on control devices, low-HAP coatings (waterborne, UV-curable), high solids coatings,

vacuum metalizing Surface Coating of Miscellaneous Metal Parts and Products MMMM 01/02/2004 Emission limit as mass HAP per volume solids used,add-on control devices, low-HAP coatings (UVcurable, electron beam-curable), powder coatings

Area Source Standards Subpart Date Practices, Processes, and Control Technologies Evaluated Paint Stripping and Miscellaneous Surface Coating Operations HHHHHH 1/9/2008 Confining all coating operations to a spray booth, high transfer efficiency spray guns, training and certification of spray equipment operator to optimize transfer efficiency, spray booth filters

Residual Risk Standards Subpart Date Practices, Processes, and Control Technologies Identified as Developments Magnetic Tape EE 04/07/2006 No developments Printing and Publishing KK 4/21/2011 Permanent total enclosures installed on controlled

presses Shipbuilding and Ship Repair II 11/21/2011 Concentrator/RTO installed on spray booths to achieve 95% control efficiency; lower VOC coating limits based on California regional rules

Wood Furniture Manufacturing JJ 11/21/2011 RTO; Lower VOC coating limits based on California regional rules, more efficient spray guns, limit formaldehyde emission to 400 lb per 12 months5

Developments identified in the regulatory actions liste d in Table 1 will be discussed in Section 3 (Technology Review for Primer and Topcoat Application Ope rations).

2.3 State and Regional Regulations

In the original Aerospace MACT proposal 3 , the EPA considered numerous regional regulations, including the following California regional rules:

• San Diego Air Pollution Control District Rule 67.9 – Aero space Coating Operations, VOC limits;

• South Coast Air Quality Management District Rule 1124 – Aer ospace Assembly and Component Manufacturing Operations;

• Bay Area Air Quality Management District Regulation 8, Organic Compounds, Rule 29 – Aerospace Assembly and Component Coating Operations.

Clean Air Act (CAA) section 172(c)(1) requires that state implementation plans (SIPs) for nonattainment areas must provide for the implementation of “reasonably available control measures” (RACM), including “reasonably available control technology” (RACT), for sources of emissions. The Control Techniques Guidelines (CTG) for A erospace Manufacturing and Rework Operations 4 and Miscellaneous Metal and Plastic Parts Coatings 5 were developed to provide State and local air pollution control authorities inform ation to assist them in determining RACT for VOCs from surface coating operations. The CTG includes detailed information on practices, processes and control technologies for the reduction of VOC and HAP.

3.0 TECHNOLOGY REVIEW FOR PRIMER AND TOPCOAT APPLICAT ION OPERATIONS

As defined in the Aerospace MACT, a coating is a materia l that is applied to the surface of an aerospace vehicle or component to form a decorative or functional solid film, or the solid film itself. A primer is the first layer and any subsequent la yers of coating prior to the topcoat and is typically used for corrosion prevention, protection from the environment, functional fluid resistance, and adhesion of subsequent coatings. A topco at is a coating that is applied over one or more layers of a primer for appearance, identification, camouflage, or protection. Specialty coatings are not included under the definition of primers or topcoats.

3 59 FR 29216. June 6, 1994. 4 Guideline Series: Control of Volatile Organic Compound E missions from Coating Operations at Aerospace Manufacturing and Rework Operations, EPA-453/R-97-004. Decem ber 1997. 5 Control Techniques Guidelines for Miscellaneous Metal and Plastic Parts Coatings, US EPA/OAR/OAQPS. September 2008.6

Most aerospace coatings contain a mixture of organic sol vents and/or inorganic HAP. The organic HAP emissions from the application of primers a nd topcoats occurs from the evaporation of organic solvents during mixing, application, and drying. Em issions of inorganic HAP from coating operations, typically metal compounds (e.g., chro mium, cadmium compounds), occur when particles do not adhere to the surface being coated (i .e., overspray). The organic and inorganic emissions from coating application occur in la rge open areas, such as hangars, or partially or fully enclosed spaces, such as within spray bo oths.

3.1 Summary of Existing MACT Level of Control

The Aerospace MACT standard (subpart GG) promulgated in 1995 requ ires the following organic HAP and VOC content limits for uncontrolled primer s and topcoats:

• Primers: 2.9 lb/gal (less water) as applied; or 4.5 lb/gal (less water) as applied for general aviation rework facilities, or 5.4 lb/gal (less water) a s applied, to large commercial aircraft components (parts or assemblies) or fully ass embled, large commercial aircraft;

• Topcoats: 3.5 lb/gal (less water) as applied; or 4.5 lb/gal (less water) as applied for general aviation rework facilities.

Alternatively, a control system can be used to capture and control emissions from the primer or topcoat application operation. The system must achieve an overall control efficiency of 81 percent.

In addition, subpart GG requires the use of one of the f ollowing coating application techniques:

• Flow/curtain coat application;

• Dip coat application;

• Roll coating;

• Brush coating;

• Cotton-tipped swab application;

• Electrodeposition (dip) coating;

• High volume low pressure (HVLP) spraying;

• Electrostatic spray application; or

• Other coating application methods that achieve emission reductions equivalent to HVLP or electrostatic spray application methods.

Subpart GG also provides operating requirements for the appl ication of primers or topcoats that contain inorganic HAP, including control of spray booth exh aust streams with either particulate filters or waterwash.

3.2 Identified Control Measures for Primer and Topcoat Appl ication Operations

3.2.1 Add-On Control Technology or Other Equipment Not Identified and Considere d During MACT Development

Add-on control technologies considered during MACT developme nt for the reduction of organic HAP include carbon adsorbers, thermal oxidizers, ultravi olet oxidation, and activated carbon fiber adsorbents frequently used in conjunction with ther mal oxidizers. Equipment considered7

during MACT development includes the use of high transfer e fficiency spray guns, enclosed spray gun cleaners, and proportional paint mixers. Partic ulate filters, including HEPA filters, and waterwash were considered during MACT development for th e control of inorganic HAP.

The technology review conducted for the Printing and Publis hing Industry identified the retrofit of permanent total enclosures onto controlled presses as a development. Total enclosures were considered during development of the Aerospace MACT and are widely used on paint spray booths in the industry – in the 2011 ICR data, sources report ed the booth type of permanent total enclosure more frequently than any other booth type.

The Wood Furniture Manufacturing technology review identifi ed the use of a regenerative thermal oxidizer (RTO) on a spray booth as a developmen t and the Shipbuilding and Ship Repair technology review identified the use of a concentrator/ RTO to achieve a 95 percent control efficiency for HAP as a development. The use of an RTO was considered during development of the Aerospace MACT as a control technology capable of a achieving an efficiency up to 98 percent. In addition, the Aerospace MACT standard provides f or the use of an add-on control device in the form of a compliance alternative to the po und HAP/VOC per gallon coating limits. No new equipment or control technologies were identif ied that were not considered during MACT development.

3.2.2 Improvements in Add-On Control Technology or Other Equipment (That Was Identified and Considered During MACT Development)

The BACT determinations in the RBLC database that were made subsequent to promulgation of the Aerospace MACT specify the use of add-on controls, in cluding zeolite concentrators, thermal oxidizers, and zeolite concentrators with thermal oxidi zers. All of these control technologies were in use during development of the Aerospace MACT.

The technology review conducted for the Wood Furniture Man ufacturing Industry identified the use of more efficient spray guns as a development, and adop ted regulations preventing the use of conventional spray guns. The Wood Furniture Manufacturing MA CT identified the use of air assisted airless spraying as a more efficient coating application technology. Th e Surface Coating of Plastic Parts and Products identified the use of the v acuum metalizing application process which is similar to electrodeposition and involves the ev aporation of metals inside a vacuum chamber which then bonds to the substrate. Although the Aer ospace MACT standard does not specifically prohibit the use of conventional spray methods , it does specify that only spray application methods that are equivalent to HVLP or elec trostatic spray application methods may be used.

High efficiency particulate arrestors (HEPA filters) , rated at 99.97 percent efficiency, were known and considered in the development of the Aerospace M ACT for the control of inorganic HAP. No other particulate control technology having a hig her control efficiency has been identified.

In addition to the regulatory actions promulgated subsequent to the Aerospace MACT, numerous other data sources were considered, including the RBLC, regi onal and state rules and databases,8

and industry correspondence, and no improvements in add-on co ntrol technology or other equipment were identified.

3.2.3 Work Practices and Procedures Not Identified and Considered During MACT Development

No additional work practices or procedures were identified t hat were not already identified and considered during MACT development. The current MACT standa rds require that the handling and transfer of primers and topcoats be done in a manner that minimizes spills.

3.2.4 Any process change or pollution prevention alternative that could be broadly applied that was not identified and considered during MACT development.

Pollution prevention measures that are currently used by the industry and were considered during MACT development include product reformulations for coati ngs, including waterborne, higher solids, powder, and self-priming topcoats. For the purposes o f this analysis, product reformulations will be divided into two categories – lo w-HAP liquid coatings and high solids coatings. A review of regulatory actions promulgated subseque nt to the Aerospace MACT has revealed potential developments in the control of emiss ions from coating operations, including lower VOC content and formaldehyde limits. These potentia l developments are discussed further in the sections below.

Advancements in the Use of Low-HAP Liquid Primers and Topcoats

The most common type of low HAP liquid coatings are th ose that have been reformulated with solvents that are not organic HAP, such as waterborne coat ings. A secondary category of low HAP liquid coatings was identified in several subsequent r egulatory actions (see Section 2.2) and includes coatings that result from alternate technologie s, such as Ultraviolet (UV)-curable, electron beam (EB)-curable, and autophoretic. Liquid UV a nd EB curable coatings are converted into a solid, cured film using alternate forms of energy t hat interact with the components of the coating as a catalyst. 6 As described in the Surface Coating of Large Appliances M ACT proposal 7 , autophoretic coatings are applied using a dip application m ethod in which a chemical reaction deposits the coating on the surface of the part . However, this process is best suited for long runs of relatively small parts, such as in the man ufacture of appliances and some automotive parts, but is not suitable for the painting of large struct ures with components and sub-assemblies that cannot be submerged in the coating process.

In the development of the MACT floor, the EPA assume d that facilities would replace their conventional primers and topcoats with reduced HAP conten t, high solids primers and topcoats to meet the MACT floor limits rather than controlling emissions through abatement. This was verified in the 2011 ICR data where only 5 percent of facil ities reported the use of a control device for a coating operation.

6 UV/EB Curing. Fast. Tough. Easy on the environment, PPG Industries. 8/27/2009. Available at: http://www.ppg.com/coatings/industrial/technologiesproducts/ele ctrocoat/Pages/default.aspx 7 65 FR 81133. December 22, 2000.9

Advancements in the use of primers and topcoats with si gnificantly lower HAP content than the current MACT limits could constitute a development as a p ollution prevention alternative. To determine if advancements have been made in the use of low-HAP primers and topcoats, the 2011 ICR data were compared with the Aerospace MACT HAP/VOC content limits. The same procedure that was used to determine the MACT floor limits, as outlined in the Background Information Document (BID) for the Aerospace MACT propo sed rule 8 , was applied to the ICR data. This procedure involves finding the volume weighted ave rage HAP content of all primers or topcoats used at each facility. For the purposes of thi s analysis, the weighted average HAP content values were then averaged across all facilitie s for comparison with the MACT limits. The average HAP content from the ICR data are presente d in Table 2.

There are three differences between the MACT floor limits and the ICR data that must be addressed.

First, the coating usage volumes in the denominator of th e MACT floor limits are “less water,” while the coating usage volumes reported in the ICR include water. Table 2 provides a theoretical HAP content less water that was calcula ted from the average HAP content from the ICR data, assuming 10 percent water content and a coating de nsity of 10 pounds per gallon.

The second difference involves the derivation of the MA CT floor organic HAP content limit. When the MACT floors were originally determined for subpa rt GG, the EPA could not determine an organic HAP content limit due to the limited data that were available at the time of proposal. Therefore, the EPA set the organic HAP limit s at the same level as the VOC limits. Consequently, the ICR data, which include information on a ll HAP and VOC that are also HAP, cannot be directly compared to the VOC based content limi ts of the MACT floor.

The third difference is that the ICR only required facilities to report coatings as either primers or topcoats. It did not require them to report by the three di fferent types of primers and four different types of topcoats that are in the current r ule. These different types distinguish among military, general aviation, and large commercial aircraf t, between original equipment manufacturing and rework, and between self priming topcoats and standard topcoats.

Based on data obtained from the section 114 responses coll ected as part of the 1995 Aerospace rule development, the EPA concluded that approximately 50 perc ent of the VOC reported were also organic HAP, on average, but the EPA did not calculat e the ratio by coating type or document the variability in the ratio. Therefore, the t heoretical VOC content presented in Table 2 was calculated based on a HAP-to-VOC ratio of 0.5 for a ll coating types, and is provided only for comparison with the current MACT VOC content limi ts.

The data collected in 2011 from the industry indicates that most of the aerospace manufacturing and rework facilities perform original equipment manufac turing and rework of large commercial aircraft, general aviation aircraft, and military airc raft. The only sources that do not perform original equipment manufacturing of aerospace vehicles ar e the military facilities and the National Aeronautics and Space Administration (NASA).

8 National Emission Standard for Hazardous Air Pollutant s (NESHAP) for the Aerospace Industry - Background Information for Proposed Standards, US EPA/OAR/OAQPS. A pril 1994.10

Table 2. Comparison of the Average 2011 ICR HAP Content to the MAC T Floor

Coating Category Average HAP

Content from ICR data (lb/gal) Theoretical HAP

Content (lb/gal less water) Theoretical VOC

Content (lb/gal less water) Current MACT

HAP/VOC Limit (lb/gal less water)

Primers 1.36 1.55 3.10 2.90

Topcoats 1.38 1.57 3.14 3.50

* The procedure used to calculate the theoretical HAP co ntent less water and the theoretical VOC content are provided in Appendix 2.

This analysis suggests that significant advancements in t he use of low-HAP primers and topcoats have not been broadly achieved in the facilities that perform original equipment manufacturing of aerospace vehicles. Although the theoretical VOC con tent of topcoats is below the current MACT HAP/VOC limit, the assumptions made for the wate r content and HAP to VOC ratio are likely conservative (e.g., not every coating is going to c ontain water), resulting in lower theoretical VOC content values. The ICR data show a wi de variation in the HAP content and a difference in HAP content between the best performer s (i.e., facilities with the lowest HAP content) and the least performers. Because of this vari ability, it would be difficult for many affected sources to comply with an emission limit esta blished lower than the current MACT standards.

While there are a number of facilities that have wei ghted-average HAP content values in the 2011 ICR data that are well below the current limits, it is unlikely that all of the affected sources in the source category could achieve HAP content values equal to the lower emitting facilities.

Any emission limit established lower than the MACT floo r as part of EPA’s technology review process must be achievable throughout the aerospace industr y. However, as outlined in the Aerospace CTG, the types of coatings used in the aerospa ce industry will vary significantly as each coating must meet individual performance standards part icular to a specific design. Many of the currently used coatings have already been reformula ted to meet the current MACT HAP content limits. Manufacturers of aerospace vehicles ar e constrained to using certain types of primers and topcoats based on the market segment for whic h the coating is intended (i.e., military OEM, military rework, commercial OEM, or co mmercial rework) and the unique circumstances and design considerations within each marke t segment. For example, certain aerospace manufactures must consider the corrosive resis tance of a primer or topcoat for flights overseas, or for various military applications, such a s primers and topcoats that are chemical agent resistant 9 . Other considerations that differ between and within m arket segments include the weight of the aircraft, aesthetics, the level of ai rworthiness and safety of the final product, and many others.

9 The SERDP, the Department of Defense’s environmental science and technology program, highlights numerous projects involving the development and demonstration of a lternative military coatings that do not require toxic materials to provide corrosion protection. Available at: http://www.serdp.org/Program-Areas/Weapons-Systemsand-Platforms/Surface-Engineering-and-Structural-Material s/Coatings

.11

In addition to the Aerospace MACT, aerospace vehicle ma nufacturing is also regulated by the Federal Aviation Administration, the Department of Def ense, and specific customer requirements. As outlined in EPA’s 1998 promulgation of ame ndments to the Aerospace MACT 10 , affected sources must comply with FAA Airworthiness Directives (AD) that can potentially require the use of chemicals containing HAP, an d affected sources may have to obtain alternative means of compliance for ADs to all ow for the substitution of non-HAP materials. These multiple regulations can result in lengthy processes of qualifying new paint systems. The 1998 amendments also describe concerns from industry representatives that the long-term impact of alternative chemical usage on var ious aircraft structures is not consistent across various products and manufacturers.

For these reasons, it is unlikely that revised emissio n limits lower than the current MACT limits could adequately represent the full range of variability in t he source category.

Advancements in the Use of High Solids Primers and To pcoats

During MACT development, the EPA identified high solids prim ers and topcoats as a likely product substitution that affected sources would use to comply with the emission limits. To determine if significant advancements have been made in t he use of high solids primers and topcoats, the average solids volume fraction (gallon s olids/gallon coating) was determined for values reported in the 2011 ICR; calculated as 0.42 for prime rs and 0.48 for topcoats. These values are lower than what was considered “high solids c oatings” in the 1994 Aerospace proposal, which specifies 50 to 65 percent solids by volume. In addition, the solid volume fraction of primers and topcoats remains relatively con stant for the lowest and highest average HAP content values for each facility in the ICR data; as shown in Chart 1 for primers and Chart 2 for topcoats. Based on this information, we found no direc t evidence of significant advancements in the use of high solids primers or topcoat s.

Chart 1. Solid Volume Fraction Plotted as a Function of

Increasing HAP Content – Primers

10 63 FR 46525, September 1, 1998.12 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80.000.080.110.220.340.410.430.490.640.680.820.850.991.091.341.431.541.611.852.022.483.99Facility Weighted Average Solid VolumeFraction (gal solids/gal coating)

Facility Weighted Average HAP Content (lb HAP/gal C oating)13 Chart 2. Solid Volume Fraction Plotted as a Function of

Increasing HAP Content – Topcoats

Lower VOC Content Limits

Both the Shipbuilding and Ship Repair and Wood Furniture Manufa cturing technology reviews identified more stringent VOC content limits establishe d in California regional rules as a development. These regional limits are also lower th an the limits established in the Aerospace MACT; however, they are unique to their specific industries . The current versions of the three California regional rules identified in section 2.3 that specifically regulate aerospace coating operations provide VOC content limits for primers and to pcoats that are identical to the VOC limits for general primers and topcoats in the Aerospace MACT. However, the California air district rules include exemptions for certain coating oper ations that are subject to HAP and VOC limits under the Aerospace MACT. One example of an ex empt operation is the surface coating of assembled aircraft at rework facilities when the ori ginal coating formulation is used. Under the Aerospace MACT, rework operations are subject to HAP and V OC content limits that are not found in the California air district rules. Therefore, these district rules cannot be considered more stringent than the current Aerospace MACT when these e xemptions are taken into account. In addition, any limit established lower than the MACT floo r would likely not be achievable throughout the aerospace industry for the reasons detaile d in the section above (Advancements in the Use of Low-HAP Liquid Primers and Topcoats). 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.90.040.130.170.220.280.320.450.520.580.650.690.760.820.860.881.031.131.291.411.581.862.693.293.63Facility Weighted Average Solid VolumeFraction (gal solids/gal coating)

Facility Weighted Average HAP Content (lb HAP/gal C oating)14

Appendix 1. Practices, Processes and Control Technologies Id entified for Aerospace Coating Operations in the October 21, 2013, Query of the RBLC D atabase

RBLCID Facility Name State Process Name POLLUTAN T Control Method Emission Reduction (%) CA

- 0685 T.B.M. INC. CA AIRCRAFT REFINISHING OPERATION VOC LOW

- VOC COATINGS AND HERCULES GW/R ENCLOSED GUN 0

CA

- 0685 T.B.M. INC. CA AIRCRAFT REFINISHING OPERATION PM HVLP SPRAY GUN 0

CA

- 0771 CA AIR

NATIONAL GUARD, FRESNO CA HVLP APPLICATOR USED TO COAT AEROSPACE PARTS VOC LOWEST AVAILABLE VOC CONTENT WHICH MEETS MILITARY SPECIFICATIONS 0

CA

- 0771 CA AIR

NATIONAL GUARD, FRESNO CA HVLP APPLICATOR USED TO COAT AEROSPACE PARTS PM HVLP GUN APPLICATOR, DRY FILTERS AND 10 BHP EXHAUST FAN 0

CA

- 0881 HUCK INT.

-

DEUTSCH OPERATIONS CA FOUR SPRAY BOOTHS VOC TELLKAMP SYSTEMS REGENERATIVE THERMAL OXIDIZER WITH A 1.6 MMBTU/H NAT GAS BURNER 0

CA

- 0889 KAL

- GARD

COATING & MFG., E/M CORP. CA SPRAY BOOTHS, NINE BRINKS, DEVILBISS & BLEKKER VOC BACT DETERMINATIO N IS USE OF ZEOLITE CONCENTRATO R AND THERMAL OXIDIZER. PERMIT LIMIT IS LB VOC/DAY FACILITY LIMIT. 0

CA

- 0901 TIME AVIATION

SERVICES, INC. CA SPRAY BOOTHS, TWO DRY FILTER VOC PERMIT LIMIT IS USAGE LIMIT AND USE OF SCAQMD REGULATION XI COMPLIANT MATERIALS. 0

CA

- 0977 KAL

- GUARD

COATINGS & MANUFACTURIN G CA AEROSPACE METAL PART COATING OPERATION VOC ZEOLITE CONCENTRATO R AND THERMAL 9715 OXIDIZER

CA

- 1045 KAL

- GARD

COATING & MFG. E/M CA SPRAY BOOTH VOC A ZEOLITE CONCENTRATO R AND THERMAL OXIDIZER 0

IN

- 0126 DEAN BALDWIN

PAINTING LP IN REFINISH OPERATION VOC MANGAMENT AND WORK PRACTICES 0

UT

- 0058 HILL AIR FORCE

BASE UT SURFACE COATING, MILITARY AIRCRAFT OPERATIONS HAP ZEOLITE ADSORPTION SYSTEM - M&W CONDESORB FOB - 26ZEOLITE ADSORPTION CELLS 90

UT

- 0058 HILL AIR FORCE

BASE UT SURFACE COATING, MILITARY AIRCRAFT OPERATIONS VOC ZEOLITE ADSORPTION SYSTEM - M&W CONDESORB FOB - 26 ZEOLITE ADSORPTION CELLS 95

WA

0344 RENTON WA PAINT BOOTH/HANGA R VOC LOW VOC VAPOR PRESSURE CLEANING SOLVENTS AND STRIPPERS WITH LOW PRESSURE APPLICATORS OR MANUAL APPLICATION FOR DEPAINTING. 0

*WA

0347 BOEING RENTON WA Floor Activities VOC Compliance with VOC emission standards of Aerospace NESHAP 0

*WA

0347 BOEING RENTON WA New Vertical Wing Booth (PB5) VOC Compliance with VOC emission standards of Aerospace NESHAP 0

*WA

0347 BOEING RENTON WA New Vertical Wing Booth (PB6) VOC Compliance with VOC emission standards of Aerospace NESHAP 0

*WA

0347 BOEING RENTON WA New Vertical Wing Booth (PB7) VOC Compliance with VOC emission 016 stand a rds of Aerospace NESHAP *WA

0347 BOEING RENTON WA New Corrosion Inhibitor Compound Booth (CB1) VOC Compliance with VOC emission standards of Aerospace NESHAP 0

*WA

0347 BOEING RENTON WA New Corrosion Inhibitor Compound Booth (CB2) VOC Compliance with VOC emission standards of Aerospace NESHAP 0

*WA

0347 BOEING RENTON WA New Corrosion Inhibitor Compound Booth (CB3) VOC Compliance with VOC emission standards of Aerospace NESHAP 0

*WA

0347 BOEING RENTON WA New Paint Hangar (P-7/P-8) VOC Compliance with VOC emission standards of Aerospace NESHAP 0

*WA

0348 BOEING RENTON WA Final exterior coating Building 5-50 VOC low VOC primers, coatings, and solvents. Application requirements. composite vapor pressure of 45 mm Hg @ 20 degree C 017

Appendix 2

Calculation of Theoretical HAP Content Less Water

To determine the mass of organic HAP per volume of coatin g (lb/gal) less water, the volume of water in one gallon of coating was first determined usin g an assumed coating density of 10 pounds per gallon with the following equation:

=   ∗ 

  where: V W = volume of water in one gallon of coating (gal); D C = density of coating (lb/gal); W WC = weight fraction of water in coating; D W = density of water (8.33 lb/gal).

The volume of water was then subtracted from the tota l coating volume as shown in the following equation:

= 1 − where: H = mass of organic HAP emitted per volume of coating (l b/gal) less water as applied; M H = mass (lb) of organic HAP in one gal of coating; V W = volume (gal) of water in one gal of coating.

Calculation of Theoretical VOC Content

The theoretical VOC content was calculated by dividing the theoretical HAP content less water by an assumed HAP/VOC ratio of 0.5.