p.1 

OAR Box 1313 

Preppedby LaTeiaShed 

Document Number: 

17) l-B-10 

Docket Number: 

A-88-02 

Printed 6/12/2008 9:03:27AM Sheet 17 of 99 
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® MIDWEST RESEARCH INSTITUTE 

-;-r.~>; ii. UBS H

 450 5

 Creedmoor Road 

Raleigh, N.C. 27612 

Telephone (919) 781-5750 

A-88-02 

x-fe-io FILE COPY 

Date: February 21, 1986 

(Finalized March 28, 1986) 

Subject: Site Visit—Lufkin® 

Chromium Electroplating NESHAP 

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

MRI Project 7717-K 

From: Randy Stra iW 

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 information about the 

electroplating of plastics and the use of a trivalent rather than a 

hexavalent chromium electroplating bath. 

II. Place and Date 

Lufkin® 

Post Office Box 728 

Apex, North Carolina 27502 

(919) 362-7511 

December 19, 1985 •i\]\) 

III . Attendees 

JAN I 8199| 

LM^M^ l^E^l^ociirf j 

Ray Blakely, Engineering Manager 

Matt Caton, Environmental Engineer 

George Whitesell, Chief Chemist 

Midwest Research Institute 

Charles Hester 

Randy Strait 

U. S. Environmental Protection Agency 

Cynthia Dowd-Monroe, SDB 

Al Vervaert, ISB 

/ 

Principal Laboratories 425 Volker Boulevard, Kansas City, Missouri 64110 
P.3 

IV. Discussion 

We arrived at the plant at 9:00 a.m. The visit consisted of a 

discussion about electroplating processes operated at the plant and the 

basis for their selection. The discussion was followed by a complete tour 

of the plant. 

A. General 

Lufkin® is a division of Cooper Industries and produces a variety of 

cloth, wood, and steel measuring tapes. Lufkin® operates two decorative 

chromium electroplating lines. One line contains one hexavalent chromium 

bath and is used to chromium electroplate high-quality steel surveyor 

tapes. The other line contains two chromic acid etch baths and a 

trivalent chromium bath and is used to chromium electroplate 

acrylonitrile-butadiene-styrene (ABS) plastic cases for 10-foot steel tape 

rules. 

About 2 years ago, Lufkin® replaced their hexavalent chromium bath 

with a trivalent chromium bath on the ABS plastic case line both to reduce 

wastewater treatment costs and the number of rejected parts (scrap). The 

conversion was accomplished at a cost of approximately $100,000. The 

trivalent chromium bath is a proprietary solution sold by Udylite® under 

the name TricrolyteTM. The plastic plating line averaged 3.9 percent scrap 

when using the hexavalent chromium bath and now averages about 2 percent 

with trivalent chromium bath. 

Plant personnel stated that they have encountered significant 

problems with operating the trivalent chromium bath due to its complex 

chemistry and sensitivity to contaminants. Discoloration of the cases 

occurs when the copper content in the bath reaches 8 to 10 parts per 

million (ppm). When Lufkin® began operating the trivalent chromium bath, 

the scrap rate ranged from 10 to 12 percent because of copper contamination. The copper content in the bath is now maintained at well below 

10 ppm. In addition, frequent additions of ammonia to the trivalent bath 

(~2 gallons/day) also are needed to regulate the pH. Although the 

wastewater treatment cost for trivalent chromium is somewhat less than for 

hexavalent chromium, the required addition of ammonia to the trivalent 

bath has offset some of the cost savings. Hexavalent chromium in the bath 

also is considered a contaminant. Its presence in the bath, even in 

negligible amounts, causes discoloration of the plated parts. Although 

hexavalent chromium is formed in the plating process, its presence in the 

bath is controlled by the addition of a reducing agent. 

B. Process 

Figure 1 is a flow diagram of the ABS plastic case plating line. 

The cases are loaded manually onto racks at the first work station. Parts 

are placed into .two chromic acid etch baths where the surfaces of the 

plastic cases are etched to increase adhesion characteristics. The first 

etch tank contains a solution of 58 ounces of chromic acid per gallon 

(oz/gal) of water, and the second tank contains 54 oz/gal. Both tanks are 

J?. 
Figure 1. ABS plastic case plating line. 

3 
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maintained at a temperature of 150°F. Side draft hoods are used to 

provide ventilation around the tanks, and Udylite® fume suppressant is 

used to reduce dragout and misting at the surface of the tanks. After 

etching, the parts go through a series of seven countercurrent flow rinse 

tanks filled with water. 

After rinsing, the parts are placed in an "activator" tank that 

contains a combination of palladium and tin in solution. The activator 

solution is used to fill cracks and voids in the surface of the ABS 

plastic cases and to provide a conductive surface. Two countercurrent 

flow rinse tanks follow the activator, and then the parts are placed into 

an accelerator tank where excess tin is removed in a dilute hydrochloric 

acid solution. This process is followed by two more countercurrent flow 

rinse tanks. 

The first plating bath is an electroless nickel bath. The nickel 

binds to the palladium and provides a hard, durable, and conductive 

surface. Following two countercurrent flow rinse tanks, the parts are 

placed in a copper sulfate tank that adds a thin layer of copper to the 

surface of the cases. After further rinsing in five tanks, the cases are 

placed in a long acid-copper electroplating tank. The copper-plated parts 

then go through three countercurrent flow rinse tanks, another activator 

tank containing a hydrogen peroxide and sulfuric acid solution, and two 

more countercurrent flow rinse tanks. The bright nickel electroplating 

tank then provides a durable nickel surface. After three countercurrent 

flow rinse tanks, the cases go into the trivalent chromium electroplating 

tank. Following the trivalent chromium electroplating, parts are rinsed, 

dried, and unracked. The racks then go through a chromium strip (caustic 

soda solution) and a nickel strip (nitric acid solution) for cleaning 

prior to starting the cycle again. 

Steel surveyor tapes are plated on a continuous plating line 

(Figure 2) using a conventional chromic acid plating solution. The 

hexavalent line is much smaller than the trivalent line. Eight steel 

tapes are unwound in parallel from eight large spools at the beginning of 

the process, are pulled through a series of rinse tanks, a nickel 

electroplating tank and the hexavalent chromium electroplating tank, are 

rinsed again, dried in an oven, and rewound onto spools at the end of the 

plating line. The hexavalent chromium plating bath contains 33 ounces of 

chromic acid per gallon of water and is operated at 6 volts and 

425 amperes of direct current. The bath temperature is 112°F. 

C. Emission Control 

The trivalent chromium tank is ducted by side draft hoods to an 

evaporator (manufactured by Headie) that is used to reduce the volume of 

the liquid before it is recirculated to the tank. Exhaust air from the 

evaporator goes into a single packed-bed wet scrubber (manufactured by 

Viron International). The airflow rate of this system is 2,800 standard 

cubic feet per minute (scfm). An additional demister (manufactured by 

Kimre) was installed after the scrubber to improve mist elimination. 

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Figure 2. Steel surveyor tape plating line. 

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The hexavalent chromium electroplating tank on the strip plating 

line is vented (8,000 scfm) to a single packed-bed wet scrubber 

(manufactured by Viron International). 

Air from the plating shops and all tanks other than the trivalent 

chromium plating and hexavalent chromium etch tanks is ducted to a common 

exhaust system. The airflow rate of this system is 38,000 scfm. 

D. ConclusionsThe trivalent chromium electroplating line at Lufkin® is 

well-designed and -operated. Plant personnel expressed some 

dissatisfaction that the trivalent system has not resulted in the 

magnitude of cost savings they had anticipated. After an extensive 

startup period, the scrap rate has been reduced; however, wastewater 

treatment costs have not decreased. 

Chromium emissions from the plating operations are controlled by 

single packed-bed wet scrubbers. Udylite® fume suppressant is used to 

control emissions from the chromic acid etch tanks. The etch tanks are 

ducted through an exhaust system that also handles exhaust air from 

several other operations. Although emission testing is possible, it is 

not recommended at this time because of the low hexavalent chromium usage 

rate and the dilution of the exhausts from the chromic acid etch tanks. 

However, plant personnel are cooperative, and further exchange of 

information may be beneficial. Plant personnel agreed to provide the 

information requested in the attachment. 

Attachment 

£ 
For each chromium plating tank, please provide the following infonnation (cite typical values rather than ranges for operating and production parameters). 

1. Dimensions of tank 

2. Concentration of chromic acid, oz/gal 

3. Catalyst(s) used 

Plastic plater 

Plastic etch 

Tank 1 

55-1/4" x 22-1/2" x 6S-1/2" 

58 

Udique 857 

Tank 2 

55-1/2" x 94-3/8" x 65-1/2" 

54 

Udique 857 

Plastic plater 

trivalent chromium 

55-5/8" x 46-1/4* x 65-5/8" 

Tricrolyte catalyst 

Strip plater 

hexavalent 

chromium 

36" x 48" x 66" 

33 

Hone 

20-25 dynes /cm 

150 

4. Concentration of catalyst(s), 

measured by surface tension 

5. Temperature of plating solution, °F 

6. Operating voltage, volts 

7. Operating current, amperes 

8. Thickness of chromium deposited, in. 

9. Plating time, min/rack 

10. Hours of operation, h/d; d/wk; and wk/yr 8; 5; 48 

11. Percent of operating time electrodes are 

energized 

12. Production rate,* 

cases/yr 

feet of tape/yr 

3,250,369 cases 

342,000 other parts 

20-25 dnyes/cm 

150 

Same 

<32 dnyes/cm 

75 

12 

1,600 (depends on size of 

case) 

Unknown 

4 minutes 

80 percent 

Same 

112 

550 

10 millionths 

8; 6; 48 

100 percent 

15,697.839 feet 

*1985 production rate. 

Nl