Background: The manufacturing process evaluated was a rework operation that involved sanding of chromium-based paint primers to achieve adequate surface characteristics for subsequent painting steps.  Parts received from subcontractors had surfaces that were not uniform and had chips that had to receive additional sanding prior to being assembled or receiving the final surface painting.  Failure to address the inadequacy of the primer coat could result in quality issues in the finished products resulting in further and more costly rework later in the manufacturing process or, potentially, after receipt by the customer.

Hazard Identification

The imperfections in the primer coat had to be hand-sanded by manufacturing operators, resulting in additional in-process rework and potential chromate exposures to employees.  The danger of chromate dust exposure was well-recognized by the company and adequate steps were taken to provide and use personal protective equipment to ensure worker safety.  Previous sampling exposure monitoring determined that unprotected worker exposure to airborne hexavalent chromium was five times the permissible exposure limit (PEL) when spraying the primer, and two times the PEL during vacuum sanding.  In addition, OSHA had recently issued a new standard revising the current PEL downward (to 1 microgram per cubic meter of air as an 8-hour time-weighted average), thus putting additional focus on the chromium exposures at the facility.

Hazard Intervention

The company had long recognized the hazard associated with chromate-based paints.  However, in complex operations many priorities compete for management’s time and focus.  Since employees were receiving adequate protection from local exhaust ventilation and PPE, there was no sense of urgency to find options to eliminate the use of chromate-based primers.

The IH-generated project provided impetus to the re-evaluation of the requirement to use chromate-based primers in the aircraft manufacturing process.  The project required both time and resources from the production and engineering staffs to demonstrate that non-chromate based primers would be adequate substitutes to ensure a high level of both product quality and employee protection.  Once the testing was satisfactorily completed, additional costs were incurred to make the design change to the product specifications and communicate the changes to the appropriate sub-contractor.

Impacts of the Intervention

The new priming material reduced paint chipping, which resulted in improved quality of the primer-coated parts.  Along with a concurrent project to address the quality of vendor-produced parts, eliminating the need to rework chromate-primed parts resulted in a significant labor productivity savings.

The intervention eliminated worker exposure to chromate dusts from rework sanding.  Employees were still exposed to non-chromate dust, but as a result of the intervention the level of respiratory protective equipment required could be reduced from full-face powered air-purifying respirators (PAPRs) to half-face air-purifying respirators.

As a result of the elimination of chromate dust, the company was also able to avoid implementing costly changes to the facility’s exhaust ventilation systems.  The new hexavalent chromium standard would have required a more robust ventilation design to comply with the 2010 compliance date for the new OSHA PEL.  Without the need to comply with more stringent requirements, existing exhaust ventilation systems were deemed acceptable or would require significantly fewer design upgrades to meet company IH standards.

Other benefits of the intervention included:

1. Increased customer satisfaction due to product deliveries that required less follow-up surface rework

2. Elimination of chromate primers improved a corporate social responsibility metric associated with corporate Materials of Concern (MOC)

3. Increased employee morale due to the elimination of chemical exposures greater than the company’s occupational exposure limit (OEL)

4. Decreased regulatory risk due to the elimination of hexavalent chromium in this operation

5. Lessons learned from the project have the potential to be transferred to other products and facilities within the corporation.

Financial Metrics

A ROHSEI analysis was conducted on the benefits and costs associated with the intervention.  The analysis showed that the substitution of non-chromate priers resulted in an after-tax net present value savings of $504,694 over the 5-year duration of the project evaluation.  This represented profit that could be attributed to an additional unit of production per year.  In addition, the substitution resulted in significant productivity gains.

Lessons Learned

A key lesson learned for the project was that in some cases management is aware of the need for certain actions but is distracted by a multitude of other issues associated with operating the business or organization.  In addition, even in highly responsible organizations management may delay taking action if they have the perception that employees are adequately protected by PPE.  In this case management knew the right thing to do and the project should have proceeded on its own merit; however, the project did not rise up the company’s priority list until the proper management focus was created by IH professionals. 

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