OAR Box 1313 

Prepped by LaTeia Shed 

Document Number: 

73) ll-B-47 

Docket Number: 

A-88-02 

Printed 6/12/2008 9:03:30 AM Sheet 73 of 99 

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A-88-02 

MIDWEST RESEARCH INSTITUT! 

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•-Ol Harrison Oaks Bowevat 

Carv, N C "5 1 

Date: May 20, 1988 

(Finalized June 30, 1988) \ \ , \\\l\ 

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Subject: Site Visit—Lufkin® \\f*\ «—rr^-'I ..i.}, 

Chromium Electroplating NESHAP \\\\\\...--• 

EPA Contract 68-02-3817; ESD Project 85/02a \V^- \ 

MRI Project 7717-K 

From: Robin Barker 

To: Andrew M. Smith 

ESD/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 

on the use of the trivalent chromium process as a replacement for the 

hexavalent chromium process for decorative electroplating applications. 

II. Place and Date 

Lufkin® 

Post Office Box 728 

Apex, North Carolina 27502 

(919) 362-7511 

November 9, 1987 

III . Attendees 

Lufkin® 

Matt Caton, Environmental Engineer 

Midwest Research Institut e 

Robin Barker 

U. S. Environmental Protection Aqency 

Gail Lacy, SDB 

Andrew M. Smith, ISB 

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IV. Discussion 

The visit consisted of a tour of the plating shop followed by a 

discussion on the trivalent chromium electroplating (plating) process. 

A. General 

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

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

decorative chromium electroplating lines. One line utilizes a hexavalent 

chromium plating bath to plate high-quality steel surveyor tapes. The 

other line is an automated trivalent chromium process line used to plate 

plastic tape cases. The plating lines operate 10 to 12 hours/day, 

5 days/week, and 48 weeks/yr. A previous visit to the plant in December 

1985 was conducted to obtain information on the electroplating of plastics 

and the use of a trivalent rather than a hexavalent chromium bath. This 

site visit was conducted to gather more detailed process information on 

the trivalent chromium operation at Lufkin3-. (For more information on the 

hexavalent chromium process at Lufkin®, please refer to the previous trip 

report dated March 28, 1986.) 

B. Process Description 

Figure 1 is a flow diagram of the trivalent chromium process line. 

The plastic tapes are loaded onto racks that are automatically transferred 

through the process line. The process line consists of a series of tanks 

used to etch, activate, electroplate, and then dry the plastic cases. The 

tape cases are undercoated with layers of copper and nickel before 

chromium plating. 

The trivalent chromium plating tank is 1.4 meters (m) (4.6 feet 

[ft]) long, 1.17 m (3.85 ft) wide, and 1.7 m (5.5 ft) deep and holds 

approximately 2,380 liters (a) (630 gallons [gal]) of plating solution. 

The typical plating time is 4.0 minutes at 12 volts and 1,600 amperes. 

The trivalent chromium plating solution is a single-cell process, 

TricrolyteTM III, manufactured by OMI/Udlylite International Corporation. 

The concentration of trivalent chromium is about 30 grams per liter 

(4.0 ounces per gallon). The bath operating temperature is approximately 

42°C (75°F). The plating solution is cooled by TeflonTM cooling coils. 

The plating solution is continuously filtered; and the filters are changed 

three times per week. 

The trivalent chromium plating bath was installed in 1984 to reduce 

scrap (rejected parts) due to "mischromes." "Mischromes" is a term used 

to describe an area of a part that did not receive a chromium plate due to 

the poor throwing power of a hexavalent chromium bath. At first, however, 

scrap increased because of black streaks in the chromium plate caused by 

plating bath contaminants (mainly copper). Lufkin® and OMI/Udylite'" 

personnel spent a great deal of time correcting the startup problems. The 

plant finally sold the original bath back to OMI/Udylite and purchased a 

newer generation trivalent chromium solution. The new bath has been 

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operating satisfactorily, and scrap has been reduced from 6 percent with 

the hexavalent chromium bath to less than 2 percent with the trivalent 

chromium bath. However, because of the bath's sensitivity to 

contaminants, such as brass and copper, tight laboratory control is needed 

to maintain the bath within the normal operating range. An atomic 

absorption unit is used to determine the level of contamination in the 

plating bath. Laboratory analysis time has increased from 30 minutes a 

day with hexavalent chromium to 2 hours a day with trivalent chromium. 

C. Emission Control 

The trivalent chromium tank is equipped with side draft hoods ducted 

to an evaporator manufactured by Headie. The evaporator operates at room 

temperature and was installed to recover plating solution lost by 

evaporation. Plating bath chemical costs have been reduced 50 percent 

since the evaporator was installed. Exhaust air from the evaporator goes 

into a single packed-bed scrubber manufactured by Viron International. A 

demister was installed downstream of the scrubber. The airflow rate of 

this system is 79 standard cubic meters per minute (2,800 standard cubic 

feet per minute). 

During the visit, no misting was observed at the surface of the 

plating tank. The current emission control system, except for the 

evaporator, was installed to control mist from the hexavalent chromium 

plating tank before the process was converted. However, the plant chose 

to keep the scrubber and demister in place and operational to control any 

misting that may occur. 

D. Costs 

The capital cost of conversion from hexavalent chromium to trivalent 

chromium was $25,500. Table 1 lists the components of the capital 

costs. The major component of the capital cost was the purchased cost of 

the two new rectifiers. 

The net annual cost reduction associated with the use of trivalent 

chromium is $28,000. As stated above, the number of rejects decreased 

from 6.0 percent to less than 2.0 percent, and the cost of each reject 

decreased from 2.5 cents per case with hexavalent chromium to 1.7 cents 

per case with trivalent chromium for a total cost savings of $47,000 per 

year. The chemical cost of trivalent chromium averages approximately 

$29,250 per year, a substantial increase over the chemical cost of 

hexavalent chromium, which averaged $6,400 per year before the conversion 

to trivalent chromium. The plant did not experience any savings in 

wastewater treatment costs after converting to trivalent chromium. The 

volume of sludge generated was not reduced significantly because the plant 

still operates with hexavalent chromium in the etch baths. The plant was 

able to reduce the amount of sulfur dioxide used for reduction of 

hexavalent chromium; however, the cost savings associated with this 

reduction was offset by the increased chlorine usage to treat the high 

ammonia content in the trivalent chromium bath. Ammonia is used in the 

trivalent chromium bath to regulate the pH. 

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TABLE 1. CAPITAL COST FOR TRIVALENT CHROMIUM CONVERSION AT 

LUFKIN®, APEX, NORTH CAROLINA 

Components Cost, $ 

Equipment costs 

1. Rectifiers (2) 15,000 

2. Anodes and hangers 1,800 

3. Cooling coils 4,200 

4. Filter system3 5,000 

Modification costs 

Trivalent chromium makeup solution 4,500 

Total 30,500!* 

25,500° 

aThe plant had an existing filter that was used on another 

process tank. The cost data presented are for a new filter 

.system. 

Represents the total capital cost minus the filter system 

cost. 

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E. Conclusions 

The trivalent chromium process was installed at Lufkin® in 1984 to 

reduce scrap from mischromes. At first, the plant had major problems with 

the bath because of contamination and had to dispose of one bath and 

replace it with another. After 4 years of operation, the trivalent 

chromium bath achieved a reject rate below 2.0 percent. The trivalent 

chromium process has not reduced the costs as much as anticipated because 

wastewater treatment costs have remained essentially the same as they were 

before conversion. However, the plant currently is satisfied with the 

trivalent chromium process and would not go back to using a hexavalent 

chromium bath.