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OAR Box 1313 

Prepped by LaTeia Shed 

Document Number: 

45) ll-B-19 

Docket Number: 

A-88-02 

Printed 6/12/2008 9:03:29 AM Sheet 45 of 99 
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(§) 

A-88-02 

MIDWEST RESEARCH INSTITUTE 

4505 Creedmoor Road 

Raleigh. N.C. 27612 

Telephone (919) 781-5750 

Date: March 16, 1987 

(Finalized April 13, 1987) 

Subject: Site Visit—Hamilton Standard 

Chromium Electroplating NESHAP 

EPA Contract 68-02-3817; ESED Project 85/02a 

MRI Project 7717-K 

From: Robin Barker fe 

To: Al Vervaert 

ESED/ISB/SSS (MD-13) 

U. S. Environmental Protection Agency 

Research Triangle Park, N.C. 27711 

I. Purpose 

The purpose of this site visit was to gather background Information 

about the chromic acid anodizing operations at this plant and to assess 

visually the amount of chromic acid emissions generated by chromic ad d 

anodizing operations. 

II. Place and Date 

Hamilton Standard 

Mail Stop I-B-3A 

Bradley Field Road 

Windsor Locks, Connecticut 06096 

(203) 654-6000 

December 17, 1986 

III. Attendees 

Hamilton Standard 

Paul LaQuerre, Manager-Facilities Compliance 

George Tompsett, Process Engineer 

U. S. Environmental Protection Aqency (EPA) 

Al Vervaert, ISB 

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Midwest Research Institute 

Robin Barker 

IV. Discussion 

We arrived at the plant at 11:00 a.m. The visit consisted of a tour 

of the anodizing and plating shop followed by a discussion about the 

chromic ad d anodizing process. 

A. General 

Hamilton Standard 1s a captive shop primarily engaged 1n chromic 

a dd anodizing of aircraft parts such as propeller bulbs, gears, and 

miscellaneous small parts. The facility also performs sulfuric add 

anodizing and hard chromium, nickel, copper, and cadmium electroplating. 

The facility employs 8,000 people and operates 3 shifts/day, 

6 days/week. 

B. Process Description 

There are two chromic ad d anodizing tanks at this facility, 

arranged as shown 1n Figure 1. Both tanks are 3.6 meters (m) (12 feet 

[ftl) long, 1.1 m (3.5 ft) wide, and 0.76 m (2.5 ft) deep. The tanks both 

have a capacity of 2,972 liters (a) (785 gallons (gall). The chromic acid 

anodizing process Involves the following steps: 

1. Degrease; 

2. Alkaline cleaning; 

3. Hot water rinse; 

4. Cold water rinse; 

5. Chromic add anodizing; 

6. Cold water rinse; 

7. Nickel acetate seal; 

8. Cold water rinse; 

9. Hot water rinse; and 

10. Blow dry. 

The anodizing bath is a water and chromic ad d solution. Plant 

personnel monitor the baths to maintain the hexavalent chromium 

concentration at 41.6 to 57.2 grams per liter (g/a) (12.2 to 16.8 ounces 

per gallon [oz/gal]) of anodizing solution. Sulfate and chloride 

concentrations are checked periodically to ensure that these parameters 

are within the normal operating range for the bath. If these parameters 

exceed the normal operating range, contamination of the bath 1s 

indicated. The maximum allowable values for the sulfate concentration and 

chloride concentration are 0.5 g/a (0.07 oz/gal) and 0.2 g/a 

(0.03 oz/gal), respectively. Both tanks are a1r-agitated to produce a 

uniform solution. The operating temperature 1s 20°C (69°F), 23°C (74°F), 

or 34°C (94°F) depending upon the amount of alloys present 1n the 

aluminum. The higher the amount of alloys, the lower the operating 

temperature. 

2 
LEGEND 

AIRFLOW -> 

VENTILATION HOODS 

VENTILATION HOODS 

<* 

Figure 1. Schematic of chromic acid anodizing tanks. 

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The tanks are equipped with 1,000-ampere rectifiers that have 

automatic controls to step the voltage from 0 to 40 volts 1n 10 minutes 

and then maintain the voltage at 40 volts for 30 minutes. The aluminum 

oxide layer that 1s formed on the aluminum during the process 1s very thin 

(about 0.05 micrometers [0.002 mils]). 

C. Emission Control 

Both tanks are equipped with double-sided lateral hoods that are 

ducted outside the plant. At the time of the visit only one of the tanks 

was 1n operation. No misting was visible around the anode (workpiece) or 

cathode (tank). The air agitation caused a small amount of the solution 

to be splashed up Into the hood's slots. Neither chemical fume suppressants nor emission control devices are used to control chromic add 

emissions from the chromic acid anodizing tanks. 

V. Observations 

Hamilton Standard 1s representative of a captive shop that performs 

chromic ad d anodizing of aircraft parts. At the time of the visit, no 

visible misting was observed at the sides of the tank (cathode) or around 

the workpiece (anode) while the tanks were 1n operation. There was no 

chromic add visible on a piece of clean white paper that was held over 

one of the baths for a short period of time. 

f