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Abrasive blasting applies to all operations where an abrasive is forcibly applied to a surface by pneumatic or hydraulic pressure, or by centrifugal force. An abrasive is a solid substance used in an abrasive blasting operation. Sandblasting is a type of abrasive blasting.
Abrasives and the surface coatings on the materials blasted are shattered and pulverized during blasting operations; the dust formed will contain particles of respirable size. The composition and toxicity of the dust from these sources must be considered in making an evaluation of the potential health hazards. The concentration of respirable dust or fume in the breathing zone must be kept below specified levels.
The hazards involved in abrasive blasting include the material that is being removed and the surface from which the material is being removed. Lead is an example of a hazardous material being removed, while exposure to silica comes from using sand and other silica-producing materials in the blasting process. Both of these materials involve inhalation hazards.
Silica has traditionally been used as a material in the abrasive blasting process. However, NIOSH recommends against the use of silica sand (or other substances containing more than 1 percent free silica) as abrasive blasting material.
Sometimes the dust that is formed from abrasive blasting can be flammable or explosive. This can involve obvious hazards of fire and explosion. Along with these risks are those of flying debris to the eyes, face, and any other exposed skin.
Protection can be implemented through engineering controls, administrative controls, safe work practices, and, last but not least, personal protective equipment. One form of engineering control is to find an alternative to abrasive blasting.
Substituting less toxic abrasive materials for the traditional high-silica-containing abrasive is becoming more common in the United States. The United States Navy has banned silica sand or any abrasive materials containing greater than 1 percent crystalline silica by weight for abrasive blasting on ships. However, even with a low-silica-content abrasive (less than 1 percent free silica), work in containment structures or in confined spaces may result in hazardous exposures.
Other alternatives to abrasive blasting include the following:
- Overcoating — Overcoating is the application of a new coating on top of existing coatings;
- Chemical stripping—Chemical stripping involves spraying an alkaline chemical on the painted surface, allowing it to react, and then scraping the decomposed paint and excess caustic from the steel surface.
- Wet blasting—Wet methods have been used to reduce dustiness associated with lead-based paint removal projects. Both high-pressure water alone and water mixed with abrasive have been used.
- Power tools—Power tools can be used to sand, scrape, or chip coatings from steel structures. However, the need to apply power tools firmly against the surface at all times can create worker fatigue and musculoskeletal hazards, and some tools may not be able to clean irregular surfaces.
Scope
Employees performing tasks with abrasive blasting include cleaning sand and irregularities from foundry castings; cleaning and removing paint from ship hulls, stone buildings, metal bridges, and other metal surfaces; and finishing tombstones. Applies to all operations where an abrasive is forcibly applied to a surface by pneumatic or hydraulic pressure, or by centrifugal force. It does not apply to steam blasting, or steam cleaning, or hydraulic cleaning methods where work is done without the aid of abrasives.
Where abrasive blasting is conducted using crystalline silica-containing blasting agents, or where abrasive blasting is conducted on substrates that contain crystalline silica, the employer must comply with other OSHA standards, such as 29 CFR 1910.1053 (Respirable Crystalline Silica) and 29 CFR 1910.94 (Ventilation).
If employers are performing abrasive blasting as a construction task, they will also have to comply with the other OSHA standards, such as 29 CFR 1926.1153 (Respirable Crystalline Silica) and 29 CFR 1926.57 (Ventilation).
Regulatory citations
- 29 CFR 1910.94 — Ventilation
Definitions
- Abrasive: A solid substance used in an abrasive blasting operation.
- Abrasive blasting: The forcible application of an abrasive to a surface by pneumatic pressure, hydraulic pressure, or centrifugal force.
- Blast cleaning room: A complete enclosure in which blasting operations are performed and where the operator works inside of the room to operate the blasting nozzle and direct the flow of the abrasive material.
- Exhaust ventilation system: A system for removing contaminated air from a space, comprising two or more of the following elements (a) enclosure or hood, (b) duct work, (c) dust collecting equipment, (d) exhauster, and (e) discharge stack.
Summary of requirements
- Keep the concentration of respirable dust or fume in the breathing zone of the abrasive-blasting operator below the levels specified in 1910.1000.
- Use combustible organic abrasives only in automatic systems.
- Ventilate blast-cleaning enclosures so that a continuous inward flow of air will be maintained at all openings in the enclosure during the blasting operation.
- Make sure the construction, installation, inspection, and maintenance of exhaust systems conform to the principles and requirements set forth in American National Standard Fundamentals Governing the Design and Operation of Local Exhaust Systems, Z9.2-1960, and ANSI Z33.1-1961
- Use only respirators approved by the National Institute for Occupational Safety and Health (NIOSH) under 42 CFR Part 84 to protect employees from dusts produced during abrasive-blasting operations.
- If using respirators, implement a respiratory protection program per 1910.134.
- Require operators to wear heavy canvas or leather gloves and aprons or equivalent protection to protect them from the impact of abrasives.
- Require operators to wear safety shoes to protect against foot injury where heavy pieces of work are handled.
- Require the protective footwear to comply with 1910.136(b)(1).
- Require eye protection (conforming to the requirements of 1910.133) for the operator when the respirator design does not provide such protection and to any other personnel working in the vicinity of abrasive blasting operations.
- Make sure air for abrasive-blasting respirators is free of harmful quantities of dusts, mists, or noxious gases, and must meet the requirements for supplied-air quality and use specified in 1910.134(i).
- Do not allow dust to accumulate on the floor or on ledges outside of an abrasive-blasting enclosure, and dust spills shall be cleaned up promptly.
- Keep aisles and walkways clear of steel shot or similar abrasive which may create a slipping hazard.