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Table of Contents
Carbon Dioxide Blasting: Regulatory Requirements
Air
The Clean Air Act regulates particulate
matter in exhaust air (40 CFR Part 50). Large carbon dioxide blasting operations can create a sufficient amount
of particulate matter consisting of coatings residue to subject facilities
to Title V permitting requirements.
Solid and Hazardous Waste
Under the Resource Conservation and Recovery
Act (RCRA), organic finishing facilities are required to manage listed
and characteristic hazardous wastes (40 CFR Part
261). Waste from carbon dioxide blasting operations may be classified
as hazardous depending on the type of coating material removed. Hazardous
waste management (40 CFR Part 262) includes obtaining
permits for the facility in order to generate wastes, meeting accumulation
limits for waste storage areas, and manifesting waste containers for off-site
disposal.
Each state and/or region is primarily responsible for the regulation
of non-hazardous solid wastes (those not governed by the hazardous waste
provisions of RCRA).
Health and Safety
Carbon dioxide blasting creates adverse conditions inside facilities
which, while not regulated by EPA, should be addressed. Suspended
coating particulates and excessive noise created by equipment can impact
worker health and are regulated by the Occupational Safety and Health Administration. In addition, high levels of carbon dioxide gas, which is heavier than air,
may accumulate in confined areas causing breathing problems for workers.
Self-Audit/Inspection
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Do dry residual coatings or carbon dioxide blast media come in contact
with exhaust air streams? If so, do concentrations of particulate
matter exceed limits established by facility air permits?
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Do residual coatings come in contact with water streams? If so, do
concentrations of pollutants exceed limits established by the facility
NPDES permit or POTW discharge agreement?
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Are wastes contaminated with residual coatings classified as hazardous? If so, are the wastes handled and manifested in accordance with 40
CFR Part 262, Subpart B? Are hazardous wastes segregated from
non-hazardous wastes?
Carbon Dioxide Blasting: Common Causes of Violation
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Carbon dioxide blasting creates a large volume of carbon dioxide gas. The gas is denser than air and may accumulate in enclosed spaces above
acceptable limits for worker safety if proper ventilation is not provided.
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Residual coating material forms dust in the blast area. Some particles
may be small enough to qualify as respirable particulates capable of penetrating
lung tissue. Typical hazards include exposure to silica and lead.
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Carbon dioxide blasting technologies generate a high level of noise. Equipment used to compress and pump the air and solid carbon dioxide, the
exhaust of the carbon dioxide stream, and the media striking the substrate
create sufficient decibel levels to require process engineering controls
and hearing protection.
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Carbon dioxide blasting creates a waste of coatings residue. Based
on the coating constituents, the waste may be classified as hazardous according
to RCRA standards at 40 CFR Part 261.
Carbon Dioxide Blasting: Sources of Pollution
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Coating material and other contaminants are blasted off work pieces. This material can create a fine dust in the work area. Also, material
that falls to the ground must be collected and disposed.
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Depending on the constituents of the coating material, the residue may
be considered hazardous.
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Carbon dioxide gas may accumulate in the blasting areas.
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Noise is created from the equipment used to compress and pump the air and
solid carbon dioxide, from the exhaust of the carbon dioxide stream, and
from the media striking the substrate.
Carbon Dioxide Blasting: Pollution Prevention Alternatives
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Carbon dioxide blasting may be considered a pollution prevention alternative
since it aids in the proper application of coating materials thereby reducing
rework or reject parts.
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Carbon dioxide blasting reduces or eliminates the hazards associated with
chemicals, solvents, wastewater, and excess blast media created by organic
solvent cleaning, chemical coatings removal, and mechanical coatings removal.
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Perform carbon dioxide blasting in enclosed areas such as blast booths
or workcells that have adequate ventilation systems to contain noise and
maintain safe levels of carbon dioxide.
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Optimize process to strip properly with minimal aggression. Proper
adjustment of operating parameters, such as carbon dioxide pellet size
and exhaust velocity, will improve coatings removal without damaging the
substrate. Modify part arrangement to ensure that blast media reaches
all surfaces.
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Minimize need for coatings removal by improving other process steps. Reduce coating failure by handling parts carefully, and by performing good
cleaning, coating application and curing. Determine if time between
rework can be lengthened to reduce need for mechanical coatings removal.
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Train employees on the safe operation of equipment and handling of wastes
and encourage continuous improvement. Training familiarizes workers
with their responsibilities, which reduces accidents and spills.
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