One of the most common tools found in any shop, the portable grinder is incredibly useful for grinding and finishing material of all shapes and sizes.
The hazards associated with portable grinders are similar to those of pedestal or bench grinders. The rotating abrasive stone can cause severe abrasions and cuts. There’s also the potential or the abrasive stone to shatter and kickback from the spindle end. Other hazards such as flying fragments and sparks are present during grinding.
When using a powered grinder:
Portable grinders usually come with the manufacturer’s safety guard covering most of the wheel.
Exposure to the wheel should not exceed a maximum angle of 180 degrees, and the top half must be enclosed at all times. The guard should be mounted so it maintains proper alignment with the wheel.
Abrasive wheel tools must be equipped with guards that:
Vertical “right angle” grinders should have a 180-degree guard between the operator and wheel. The guard should be adjusted so that pieces of a broken wheel will be deflected away from the operator.
Cup wheel grinders should be guarded as described above or with special “revolving cup guards,” which mount behind the wheel and turn with it.
All abrasive wheels must be inspected and “ring-tested” before mounting to ensure that they are free from cracks or other defects. The spindle speed of the machine also must be checked before mounting the wheel to ensure it does not exceed the maximum operating speed marked on the wheel. Always follow the manufacturer’s recommendations.
To test the wheel, do the following:
To prevent an abrasive wheel from cracking, it must fit freely on the spindle.
An abrasive wheel may disintegrate or explode during start-up. To make sure you do not get injured during startup, do the following:
Abrasive wheels must be supplied with sufficient power to maintain the spindle speed at safe levels under all conditions. Do not run a wheel or blade faster than its maximum rated capacity.
Construction workers who perform concrete grinding and cutting may breathe dust that contains respirable crystalline silica (RCS).
Grinding/polishing Dry grinding and polishing is the method most commonly used in the industry. A NIOSH study found that workers dry grinding concrete to smooth poured concrete surfaces were exposed to high levels of dust containing RCS, ranging from 35 to 55 times the NIOSH recommended exposure limit (REL). Wet polishing uses water to cool the diamond abrasives and eliminate grinding dust.
Concrete cutting is a process of controlled sawing, drilling and removing concrete. Skilled operators use special saws to cut concrete and asphalt. As with grinding, dry cutting is most often used. Careful selection of saw blades can help reduce exposure. Diamond saw blades produce less dust and require less water which make them better than abrasive saw blades to cut.
The concrete saw should have a local exhaust ventilation (LEV) system, which can capture the majority of dust emitted during the cutting operation. When operating, the operator should always wear personal protective equipment (PPE).
A local exhaust ventilation (LEV) system can be used to reduce the exposure to silica dust. The LEV system consists of a grinder equipped with a ventilation shroud, a length of flexible hose, and a portable electric vacuum cleaner that acts as a fan and dust collector for the ventilation system. See illustration above.
An employee was using a grinder to grind a metal pin, when the pin became jammed and drawn into the space between the tool rest and the spinning grinding wheel. The employee’s left index finger was also drawn into and against the abrasive wheel, and it was amputated. He was hospitalized. The distance between the tool rest and the abrasive wheel is not known. It is also not known whether the rest was secured in that position. At the time of the accident, the grinder's tongue guard was adjusted to a position 0.875 inches from the wheel. (Source: OSHA)
Pneumatic tools are powered by compressed air and include chippers, drills, hammers, and sanders.
There are several dangers associated with the use of pneumatic tools. First and foremost is the danger of getting hit by one of the tool’s attachments or by some kind of fastener the worker is using with the tool. Be sure to know and comply with the following best practices when working with pneumatic tools:
Noise is another hazard associated with pneumatic tools. Working with noisy tools such as jackhammers requires proper, effective use of appropriate hearing protection.
Nail guns are used every day on many construction jobs. They boost productivity but also cause tens of thousands of serious injuries each year. Injuries resulting from the use of nail guns hospitalize more construction workers than any other tool-related injury. When they do occur, these injuries are often not reported or given proper medical treatment. One study found that two out of five residential carpenter apprentices experienced a nail gun injury over a four-year period.
General safety guidelines
Research has identified that the risk of a nail gun injury is twice as high when using a multi-shot contact trigger as when using a single-shot sequential trigger nailer.
Sequential mode and bump mode are the two basic trigger mechanisms used in pneumatic nailers and staplers. It is important to understand the differences between the two triggers in order to prevent injuries. To find out whether your nail gun is a sequential trigger or bump trigger model, fire a nail as usual and keep the trigger depressed. Lift the nail gun and carefully press its nose against the work surface again. If the gun fires a second nail, you have a bump trigger model. If the gun doesn’t fire, you have the safer sequential trigger model.
One nail is fired and you must release the trigger before you can begin the next nailing cycle.
Pneumatic tools that shoot nails, rivets, staples, or similar fasteners and operate at pressures more than 100 pounds per square inch (6,890 kPa) must be equipped with a special device to keep fasteners from being ejected, unless the muzzle is pressed against the work surface.To get more information read the Department of Labor’s Nail Gun Safety – A Guide for Construction Contractors and the CDC’s Straight Talk About Nail-Gun Safety.
Four potentially serious safety and health hazards exist when using pneumatic jackhammers:
Use of heavy jackhammers can cause fatigue and strains. Heavy rubber grips reduce these effects by providing a secure handhold. Workers operating a jackhammer must wear safety glasses and safety shoes that protect them against injury if the jackhammer slips or falls. A face shield also should be used.
Silica hazard: Construction workers are potentially exposed to hazardous dust containing respirable crystalline silica (RCS) when using jackhammers to break concrete pavement. NIOSH found such exposures could be reduced by using a water-spray attachment. This low-flow, water-spray control suppressed and reduced dust exposures by 70%–90%. (Source: NIOSH)
Two employees were using jackhammers to break up a 240-square-meter, 150-millimeter-thick concrete pad located in the center of a round condominium. The employees had used the jackhammers to break the concrete near a high voltage conduit line and were using hammers to break the concrete from around the conduit. One of the employees used a jackhammer to break the concrete over the conduit. The jackhammer slipped, and the employee lost his balance. He fell to the ground, and the jackhammer broke through the concrete and conduit and contacted the three-phase line. The bit of the jackhammer cut all three AWG #2 stranded copper conductors and causing an electrical fault. The ensuing electric arc burned the employee who had been using the jackhammer. The electrical fault also damaged the control cabinet in the fire pump room. The injured employee was treated at a hospital for burns to his face and released the same day.
Abrasive blasting may have several hazards associated with it at any given time. Abrasive blasting is more commonly known as sandblasting since silica sand has been a commonly used material as the abrasive, although not the only one always used.
Abrasive blasting entails accelerating a grit of sand-sized particles with compressed air to provide a stream of high-velocity particles used to clean metal objects such as steel structures or provide a texture to poured concrete. This process typically produces a large amount of dust from the abrasive, anything on the substrate being abraded, and/or the substrate itself.
Using good work practices workers will reduce the risk of exposure to toxic air contaminants and other safety and health hazards associated with abrasive blasting. Safe work practices include all of the following:
One of the most frequent types of spray operations is spray painting, with spray booths as a common engineering control used to protect workers. Spray booths serve two main purposes:
All spraying areas must be provided with mechanical ventilation adequate to remove flammable vapors, mists, or powders to a safe location and to confine and control combustible residues so that life is not endangered.
Mechanical ventilation must be kept in operation at all times while spraying operations are being conducted and for a sufficient time thereafter to allow vapors from drying coated articles and drying finishing material residue to be exhausted.
Employers must require that employees use proper personal hygiene practices. These practices are an important control measure for protecting employees from exposure to hazardous contaminants generated during abrasive blasting. Some contaminants, such as lead, are hazardous when inhaled or ingested. Others, such as beryllium, may be hazardous through inhalation and skin contact. Good personal hygiene practices to limit exposure to abrasive blasting dust include the following:
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