Mechanical cleaning processes are viable alternatives to traditional solvent-based cleaning operations. Mechanical cleaning processes reduce waste production and eliminate potential safety problems with the handling and usage of toxic, ozone depleting, and often-flammable solvents. These cleaning processes are many and varied. Cleaning of almost any piece of equipment, surface, or component is possible if it is sturdy enough to withstand the friction and force produced by the mechanical work of cleaning operations such as sanding, grinding, polishing, brushing, and scraping.

Brushing - Wire or plastic brushes are used to remove grime or grease buildup from equipment. Metal and wooden surfaces can be prepared for painting or repainting by vigorous brushing of the surfaces to remove dirt, loose paint, scale, or corrosion.

Grinding - A rotating abrasive stone or disc is used to grind down some of the hardest and most difficult materials to remove, such as accumulated dirt, dry paint, long-standing corrosion, and mineral scale.

Polishing and Buffing - Light surface dirt, residue, tarnish, or scale is removed by polishing and buffing. These operations typically involve the use of a soft device like a fabric or fiber cloth, and a slightly abrasive polishing cream to remove dirt, corrosion, scale, tarnish, oxidized paint, and grease residue from painted or bare metal surfaces.

Sanding - Sanding is an abrading operation using a fiber (paper, cloth, plastic, etc.) sheet embedded with sand or other mineral grit particles that removes surface dirt or loose paint. It can be done manually or with a motor driven sander.

Mechanical cleaning allows a facility to decrease the amount of solvents used for cleaning. The decrease in cleaning solvents may allow a facility to remain below any of the reporting thresholds of SARA Title III for those chemicals (40 CFR 355, 370, and 372; and EO 12856). In addition, a decrease in toxic chemicals may decrease the need for a facility to obtain an air permit (40 CFR 70 and 71). Switching from a halogenated solvent (e.g., methyl chloroform, methylene chloride, perchloroethylene, carbon tetrachloride or chloroform) may also decrease the need for a facility to meet the NESHAPs for halogenated solvent cleaning (40 CFR 63). Eliminating an ODS will also help facilities meet the requirements under 40 CFR 82, Subpart D and Executive Order 12843 requiring federal agencies to maximize the use of safe alternatives to class I and class II ozone depleting substances, to the maximum extent practicable. Moreover, mechanical cleaning will decrease the amount of hazardous waste generated (i.e., no waste solvent generated). Waste reduction is required under RCRA, 40 CFR 262, Appendix. The reduction of hazardous waste may also help facilities reduce their generator status and lessen the number of regulatory (i.e., recordkeeping, reporting, inspections, transportation, accumulation time, emergency prevention and preparedness, emergency response) requirements with which they must comply under RCRA, 40 CFR 262. Mechanical cleaning may increase electricity consumption. Under EO 12902, federal facilities are required to reduce energy consumption.

The compliance benefits listed here are only meant to be used as a general guideline and are not meant to be strictly interpreted. Actual compliance benefits will vary depending on the factors involved, e.g. the amount of workload involved.

Consult your local industrial health specialist, your local health and safety personnel, and the appropriate MSDS prior to implementing any of these technologies.

• Significant reduction in the amount of hazardous waste generated compared to chemical stripping
• Reduces hazardous waste disposal costs
• Provides solvent cost savings
• Reduces the number of hours required for paint stripping in comparison to chemical stripping
• Reduces worker exposure to solvent, hazardous waste and hazardous air emissions

• Not appropriate for precision or delicate parts
• Stripping rate varies with the type of paint, coating condition and coating thickness

Costs associated with mechanical cleaning will vary on a case by case basis. Cleaning rates are dependent on the equipment used and the thickness and type of coating or grime being removed. Prior to full usage, performing a test case is recommended to ensure that the desired finish product is achieved. The following cost estimate is for stripping paint from a T-38 aircraft:

Assumptions:

• Paint removal and cleaning area: 2,410 ft²
• Labor rate: $45/hr
• One aircraft is de-painted per month

• Mechanical equipment (4 sanders) cost: $420
• Paint removal and cleaning time: 640 hr./aircraft or 7,680 hr/yr
• Dry paint waste residue: 30 lb/aircraft or 360 lb/yr
• Dry paint waste disposal cost: $2/lb

• Chemical procurement cost: $11/gal
• Paint and solvent sludge disposal cost: $2/gal
• Total chemical usage: 1,400 gal/aircraft or 16,800 gal/yr
• Paint removal and cleaning time: 600 hr/aircraft or 7,200 hr/yr
• Wet chemical waste residue: 1,200 gal/aircraft or 14,400 gal/yr

Annual Operating Cost Comparison for Mechanical Cleaning and Chemical Stripping

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Approval is controlled locally and should be implemented only after engineering approval has been granted. Major claimant approval is not required.