PERMIT MEMORANDUM No. 2002-469-O 18
OKLAHOMA DEPARTMENT OF ENVIRONMENTAL QUALITY
AIR QUALITY DIVISION
MEMORANDUM June 9, 2005
TO: Dawson Lasseter, P.E., Chief Engineer
THROUGH: Ing Yang, P.E., New Source Permits Section
Grover Campbell, P.E., Existing Source Permits Section
THROUGH: Peer Review
FROM: Ellis Fischer, P.E., New Source Permits Section
SUBJECT: Evaluation of Permit Application No. 2002-469-O
Texoma Truck Bodies, Inc.
Utility Truck Body Fabrication Facility (SIC D3713)
Section 19, T8S, R8E, Bryan County, Oklahoma
Take State Highway 91 exit off State Highway 69. Then east to Franklin Street. Then south approximately 4 blocks. Plant sits on the right.
350 S. Franklin Street
Colbert, Oklahoma
INTRODUCTION
Texoma Truck Bodies, Inc. (Texoma) has requested an operating permit for their existing utility truck body fabrication and painting facility (SIC 3713). The applicant has been manufacturing truck bodies since July 1995. Applicability Determination No. 2002-146-AD, issued July 19, 2002, determined that the facility’s potential to emit (“PTE”) xylene (a HAP), exceeded the 10 TPY major source threshold and the facility’s combined PTE for all HAPs exceeded the 25 TPY major source threshold. Applicant submitted a Title V permit application on October 21, 2002. Consent Order No. 03-151, issued July 29, 2003 indicates that the applicant had not submitted a timely Title V operating permit application and was operating without a permit. As of the date of this memorandum, the applicant is current in submission of emission inventories and payment of emission inventory fees. Issuance of this permit will not interfere with enforcement of the consent order. The applicant has requested that federally enforceable limitations of emissions be included in the permit to allow the facility to operate as a “synthetic minor” source facility. This permit will be processed as a Tier II application with issuance of a “synthetic minor” operating permit contingent on public and EPA review.
PROCESS DESCRIPTION
Since 1995 the facility has specialized in manufacturing and painting utility truck bodies. The facility’s “2001 Air Emissions Inventory Turn-Around Document” indicated operations are 9 hours per day, 5 days per week, 50 weeks per year (2,250 hr/yr). The flow of work process is performed in approximately 16,800 square feet of attached contiguous buildings. Production is approximately 12 utility truck bodies per day (3,000 per year) depending on the size and type produced. The production includes conducting the fabrication and assembling, cleaning, coating (priming and painting), drying (inside and outside), and washing the utility truck bodies.
Truck body manufacturing involves the following process:
Utility Truck Body Fabrication
Utility Truck Body parts are fabricated from raw steel plate and steel stock. The assembly occurs in the shop building where the truck bodies are manufactured. The A-36 raw steel is shaped using various methods with various tools including shearing, sawing, torching, breaking, plasma cutting and drilling. These steel parts are then welded together using the GMAW process to form the truck body or its various components. After assembly, portions of the metal are touched up with abrasive wheel grinders and sandblasted prior to applying a primer coat to the assembled parts. No solvents are used to wipe the parts clean prior to applying the prime coat to the assembled parts.
Prime Coat Application
Once the truck bodies are clean and dry, they are brought into the paint booth for application of the prime coat. Texoma currently uses a single brand of primer, Gillespie Coatings’ gray primer. The primer is applied using high volume low pressure (HVLP) spray guns. A synthetic enamel reducer is mixed with the primer to improve the primer flow characteristics (approximately ¼ gallon of T414 per 2 gallons of primer). Acrylic lacquer thinner is used to clean the spray guns and other equipment. The primed parts are then allowed to dry to the touch and are left in place to dry or moved out of the way of the next unit to be primed.
Surface Coat Application
Once the truck bodies are clean and dry, they are brought into the paint booth for application of the surface coat. Texoma currently uses a single brand of paint, Gillespie raven black and green. The paint is applied using high volume low pressure (HVLP) spray guns. Acrylic enamel reducer is mixed with the paint to improve the paint flow characteristics (approximately 1/2 gallon of T535 per 1 gallon of paint). Acrylic lacquer thinner is used to clean the spray guns and other equipment. The painted parts are then allowed to dry to the touch inside the paint booth and then moved outside for storage.
Minor Touch-up
Other paint usage involves the use of aerosol spray cans to perform touch-up and complete detailing. Touch-up and detailing is performed in the shop area during the completion of the utility truck body assembly.
Drying
After painting, parts are allowed to air-dry prior to moving to outside storage. Depending on the production requirements, the painted unit may be moved outdoors for storage.
Final Production
The final production step involves application of any decals, cleaning of the truck body, inspection, and detailing specified for each truck body that is requested by the purchaser.
Equipment Clean Up
The spray guns are cleaned with acrylic lacquer thinner. Approximately 4 gals/month are used. Used paints and cleaners are disposed of by a third-party vendor.
The current hours of operation are 16 hours per day, 5 days per week, 50 weeks per year (4,160 hr/yr). The flow of work process is performed in attached contiguous buildings.
EQUIPMENT
The facility building consists of three contiguous buildings totaling 16,800 square feet. There are two paint booths. The westerly booth is 24’ by 14’ and can be fully enclosed during spray application. The booth exhausts to the atmosphere from a 26’h x 36” diameter stack in the roof that operates at a temperature of 70 °F with a flowrate of 12,600 acfm. The easterly booth is 26’ by 17’ and can be fully enclosed during spray application. The booth exhausts to the atmosphere from a 21’h x 42” diameter stack in the north end that operates at a temperature of 70 °F with a flowrate of 12,600 acfm. The specifications for the exhaust fans used to ventilate the paint booth are shown in the table below. The paint booth design features filter grille on each hood including dry particulate filters in each hood inlet. The filter collectors are a glass fiber. The filter material has an estimated 95% efficiency to collect particulates formed in the priming and painting process. Filters are changed per manufacturer’s recommendations or at least twice per month, which ever is more frequent.
Exhaust FansLocation / Make / Model / Number / Motor H.P. / Fan Speed
RPM / Duct Size / CFS
Average
Westerly Paint Booth / GE / 5KC184AD2120 / SFK1A028814 / 3 / 1730 / 21”x42” / 210
Easterly Paint Booth / Ind. Motors / 3XX04 / T985A-A98A323R014M / 5 / 1745 / 26”x36” / 210
The high volume, low pressure (HVLP) spray guns have a spraying efficiency in excess of 85% due to painting large, flat surfaces. The spray guns have a maximum application rate of 16 ounces per minute each. Emission calculations for the maximum lb/hr emission rates are based on all four spray guns operating at their maximum capacity simultaneously. This results in a maximum application rate of each material at 30 gallons per hour. Even though there are two spray booths, the emissions were assumed to originate from one stack to allow for SCREEN3 modeling. Spray gun data is shown in the table below.
Paint Spray Gun EquipmentMake / Number of Units / Model / Model No. / Coating / Fluid Output
Oz/Min / Transfer Efficiency
10psi
DeVilbiss / 1 / GTI-546P-14 / 170165 / General Purpose / 16 / 85%
DeVilbiss / 3 / JGA-635G-14 / 110269 / General Purpose / 16 / 85%
Two tanks are located at the facility. A 250-gal propane tank and a 560-gal diesel tank. Both tanks store fuel for vehicles.
EMISSIONS
Emission Calculation Assumptions
Texoma provided emission estimates for the facility. Emissions summarized in the tables at the end of this section provide maximum estimated usage of the various products based on the maximum amount purchased for material inventory between the years of 2002 and 2004 and operating 4,160 hours/year. To provide for variance in usage of the materials a safety factor was applied to each solvent used in the priming and painting process. For modeling purposes, maximum hourly Toxic Air Contaminant (TAC) emissions were determined by multiplying the worst-case material usage (highest hourly application rate) in gallons/hour of coating used times the TAC ingredient content of the coating (pounds/gallon). Emissions calculations are based on each corresponding Material Safety Data Sheets (MSDS) for all the various products used at the facility. When a weight percent range of a TAC ingredient was given, the maximum percentage was used and therefore a worst-case emissions calculation resulted. Emissions from the coating operations are also based on the following assumptions:
1) Priming and painting will take place in consecutive operations in the same paint booth.
2) Five 16-hour days per workweek, 52 weeks per year, or 4,160 hrs/yr. Actual painting occurs for approximately two-to-three hours per day. The facility’s current work hours are 10 hours per day, 4 days per week, 52 weeks per year, 2,080 hours per year. Actual painting occurs five to six hours per day.
3) 85% transfer efficiency, 50% overspray, and 95% filter collection efficiency. This efficiency is conservative since all overspray is assumed to reach the filter.
4) The TAC emissions maximum ambient air impact was based on estimating the worst-case rate of application of a product material and the maximum material ingredient weight percentage listed in the MSDS. The maximum emissions in lb/hr are listed in the Toxic Air Contaminants table.
5) Fast or slow catalyst is mixed with the paint at ratio of 1:4 or less (i.e. 7.5 gallons of catalyst to 30 gallons of paint)
Welding and Fabrication
The welding operations generate fumes from the heat and combustion of wire welding operations. These fumes dissipate within the building and drift out the doorways and other building openings as fugitive emissions. Estimated total dusts as metal oxides were established from welding rods and wire usage. The plasma cutting exhaust emissions are intermittent and produce primarily particulate matter and metal fumes. Emission estimates are based on using 13 tons per year of welding wire and AP-42 (1/95), Tables 12.19-1 and 2. The worst case estimated emissions of PM-10 is 0.07 TPY, TAC is 0.004 TPY, and HAP is 0.004 TPY. Emissions for each constituent of the welding process are less than the de minimis threshold level for the respective constituent and no modeling is required. Worst-case levels of TAC are listed in the Toxic Air Contaminants table for welding.
Sand Blasting
Particle matter emissions are generated from sand blasting truck body components. Texoma has limited sandblasting activities, which are conducted in a covered area, where the remaining sand is routinely cleaned up from around and within the covered area. Particulate matter emissions dissipate during sand blasting and drift as fugitive emissions. Estimated emissions are based on using 810,000 pounds per year of sand and an estimated emission factor of 55 lb/1,000 lb of sand from AP-42 (9/97), Table 13.2.6-1 with an average wind speed of 10 mph and 1% quartz in the sand. The worst case estimated emissions of Total PM is 22.28 TPY and HAP is 0.23 TPY. Since the Air Quality Division (AQD) is in the process of reviewing and proposing significant changes to Subchapter 41, the permit will be issued without the BACT review and without MAAC compliance. However, the permit may be re-opened to address compliance with the finalized rule.
Natural Gas Heating
Natural gas is used to assist drying by heating the booth. Less than 5 TPY NOx and other pollutants formed during combustion are associated with the painting process. Several minor sources of fugitive emissions at the facility include LP gas space heaters, central natural gas heating in the office areas, fuel storage and dispensing, use of propane forklifts and other insignificant sources shown in the permit application.
Facility-wide Fugitive Emissions
The fugitive sources include the facility-wide emissions that cannot be attributed to the emissions from the paint booth exhausts. They include emissions from welding and metal cutting processes; assembly and painting of trailers; washing down metal components; dispensing and mixing of primers, paint and solvents; storage of solvents; detailing and touch-up painting; and fugitive dusts on roads within the property line and sand blasting.
VOC Emissions
The following table shows the estimated VOC emissions based on the anticipated coating and application rates discussed above.
Process / Maximum Density / Max Hourly / Annual Usage / VOC Emissions // lbs/gal / gal/hr / gals/yr / TPY / Wt % / lbs/gal / lbs/hr / TPY /
Primer & Painting Process
Gillespie 75-995 LFD Raven Black / 8.09 / 30 / 3200 / 12.94 / 56.00 / 4.53 / 135.91 / 7.25
PR-112 Gray Primer W / 10.28 / 30 / 1,050 / 5.40 / 44.80 / 4.61 / 138.30 / 2.42
UH320SP-Uni. Topcoat Catalyst Slow / 8.07 / 15 / 500 / 2.02 / 60.35 / 4.87 / 36.53 / 1.22
Tem-Tex Solvents T-414 Synthetic Enamel Reducer / 6.80 / 30 / 687.5 / 2.34 / 100.00 / 6.80 / 204.00 / 2.34
Tem-Tex Solvents T-424 Synthetic Enamel Reducer / 6.91 / 30 / 1300 / 4.49 / 94.79 / 6.55 / 196.50 / 4.26
Tem-Tex Solvents T-805 Acriylic Lacquer Thinner / 6.71 / 30 / 825 / 2.77 / 100.00 / 6.71 / 201.30 / 2.77
Self Etching HiSolid WashPrimer AE-1003 / 8.7 / 30 / 62.5 / 0.27 / 65.00 / 5.66 / 169.65 / 0.18
HiSolid Wash Primer Catalyst AE-1003C / 7.0 / 30 / 62.5 / 0.22 / 96.00 / 6.72 / 201.90 / 0.29
Uni-Topcoat Catalyst Fast UH310SP / 8.07 / 15 / 150 / 0.61 / 48.00 / 3.87 / 29.03 / 0.29
11-382 LFD Green / 7.75 / 30 / 30 / 0.12 / 55.50 / 4.30 / 129.04 / 0.10
Tem Tex T-434 Synthetic Enamel Reducer / 7.02 / 30 / 900 / 3.16 / 100.00 / 7.02 / 210.60 / 3.16
Tem-Tex Solvents T-535 Synthetic Enamel Reducer / 7.28 / 30 / 12.5 / 0.10 / 100.00 / 7.28 / 218.40 / 0.10
UTech 360 Epoxy Primer / 10.61 / 30 / 82.5 / 0.44 / 40.25 / 4.27 / 128.10 / 0.18
UTech 375 Hardner / 7.46 / 30 / 60 / 0.22 / 75.74 / 5.65 / 169.5 / 0.17
Tem-Tex Solvents T-525 Acrylic Enamel Reducer / 6.77 / 30 / 1413 / 4.78 / 100.00 / 6.77 / 203.10 / 4.78
Tem-Tex Solvents T-959 Universal Retarder / 7.63 / 30 / 12.5 / 0.10 / 100.00 / 7.63 / 228.90 / 0.10
Totals / 30.1129.61
Toxic Air Contaminants