The intent of this article is to provide information about what one plating company experienced as the result of an audit by OSHA.

A client of mine that plated cadmium (cyanide) onto various substrates using a return-type automatic plating machine received an OSHA inspection. The client was cited for insufficient diking, a "serious" violation.

Precautions Are Necessary

OSHA regulations require special precautions for cyanide used around open surface tanks. Section 29 of CFR 1910.94(d)(10) says: "Dikes or other arrangements shall be provided to prevent the possibility of intermixing of cyanide and acid in the event of tank rupture." OSHA personnel calculated that insufficient volume was provided in the diked area just under the plating tank. Although their requirement was not defined, I assumed that the volume provided in the existing diked area was less than 110 percent of the plating tank maximum operating volume.

To complicate matters, OSHA officials were informed that the cited company would be using an alternative chemistry (most likely to be an alloy of zinc) within one year.

Double-Wall Tank Used

During the inspection, OSHA representatives did not recognize that the company used a double-wall cyanide plating tank. The existing plating tank consisted of a polypropylene inner layer tank that was wrapped on the outside with a fiberglass outer tank. The regulations state clearly that dikes or "other arrangements shall be provided" to prevent the intermixing of cyanide and acids. The double tank was purchased with that regulation ("other arrangements") in mind. This information will be presented to OSHA in an appeal. Results of the appeal will be reported in a future article.

The original U-shaped plating tank had been replaced by a modified tank at one end of the elevator conveyor machine about five years earlier. Following the OSHA audit, my client requested that a tank supplier provide a proposal to furnish a "drop-in liner." This option was eliminated because of the close tolerance that would be produced. OSHA requested that the existing dike be upgraded and that the plating tank be reviewed by a professional engineer.

Professional Assessment Required

The company was required to hire a Registered Professional Engineer (P.E.) to certify the integrity of the tank for use until a new non-cyanide chemistry was used for the process. To accomplish this I directed the company to completely drain, scrub-clean and dry the inside of the tank before inspection. The procedures used to drain, store and refill the cadmium cyanide electroplating tank were documented with photographs.

The inspection of the inner layer white polypropylene tank was both visual and physical. As polypropylene is somewhat transparent, one can visually detect if any liquid has entered the outer fiberglass tank and also inspect the condition of the tank sides and bottom.

Confined Space Rule

Because we required access to the inside of the tank (a confined space), the company followed the procedures defined by OSHA (the final rules were published in the Federal Register dated January 14, 1993, Part 2) to ensure that we were not exposed to hazardous conditions such as oxygen deficiency. The atmosphere in the tank was tested and arrangements were made for supplying ventilation, adequate lighting and a method to remove the technician quickly should he become disabled. All appurtenances that would inhibit movement within, entering or exiting the tank were removed before our arrival for inspection.

Tank Inspection

The supplier used aluminum tape in between the inner tank and the outer tank, behind the welds of the inner tank, in a double-wall tank. If the tape has not been dissolved or destroyed, the tank should be intact. To check all the polypropylene welds, we used a Ground Fault Detector. The "probe" of the detector is placed within the tank and the power is activated. If a spark occurs, a hole in the weld is located.

In this case, we did not observe a spark or a leak. The certification included a description of the procedure used and the results of the inspection. Cost of removing the bath, inspecting the tank, and replacing the bath was about $4,000.

The objective for filing an appeal is to eliminate the fine of about $20,000 for this "serious" violation.

About the Columnist

Peter Moleux is president and owner of Peter Moleux, P. E. and Associates, Newton Center, MA, with a regional office in Saratoga, CA. He is a Professional Chemical Engineer and a Registered Environmental Professional specializing in safety and environmental (emission controls, water and wastewater) engineering for the metal finishing industry. The company focus is on OSHA and environmental site assessments and audits, and programs to eliminate CFCs. Moleux is a member of the AESF OSHA committee and the Boston Branch of AESF.