4 Occupational hazards of plasma cutting
Plasma cutting is a thermal process in which plasma beam, the ionized state of matter, is generated in a constricted arc using various gases. The plasma beam has high kinetic energy and temperature that melts or vaporizes the metal and blows away. While plasma cutters are known to make quality cuts with ease on heavy and thick metals, they do have drawbacks among which occupational hazard is a topper. Below are few occupational hazards that the workers are exposed to.
1.Respiratory, Eye and Skin hazards
The heat from the arc generates toxic gases and fumes that enter the body through the air we breathe. They do not cause immediate hazards, but breathing this air over a period can cause chronic effects. For example,
- Nitrogen oxide is formed when air or nitrogen is used as plasma gas. It can accumulate in areas of poor ventilation causing chronic effects of lung disorders and emphysema.
- Ozone gas formed during cutting aluminum or stainless steel causes chronic lung disorders.
- Inert gases, such as argon and nitrogen mixtures that are heavier than air, can accumulate in confined spaces and cause asphyxiation risk.
- Fumes are formed when vapors of hot metal compounds condense and stay suspended in the gas. The nature of fume depends upon the metal. When stainless steel is cut, the high temperature from plasma cutting oxidizes part of the chromium in stainless steel into a hexavalent state, resulting in the formation of hazardous hex chrome compound. They can enter your body through air or mouth, or through direct contact. This compound can cause risks of lung cancer, respiratory allergies, wheezing and shortness of breath in workers who are exposed.
- Ultraviolet and infrared light emissions that generate arc flash can burn and damage your eyes permanently. Eye burns can be caused by hot metal chippings, from handling hot tools and equipment, or from flashes.
- Compounds such as hexavalent chromium, nitrogen oxide and ozone compounds cause eye irritation. Direct eye contact can cause permanent eye damage.
- Hexavalent Chromium compounds are strong skin irritants, and can also cause burns and corrosions. Continuous exposure may also cause skin ulcers and rashes.
- Exposure to nickel fumes can cause itching called ‘nickel itch’.
2. High Noise
Dry plasma cutters can generate high levels of noise with significantly high frequency. Mechanized torches and cutters at power levels above 250 amps are likely to produce 100db of noise that is above threshold. The threshold noise tolerated by human ear is 85db.The method used in plasma heating generates noise in the range of 90 to over 120 dB that causes hearing damage. It is next to impossible to develop plasma cutters with a reduced operational noise. Using of ear plugs and muffs is a must for workers to prevent suffering of noise induced deafness.
3. Repetitive stress injury
Handling heavy machines and working in cramped up positions for long periods can cause neck pain leading to repetitive stress injury. The traditional helmets used for protection can weigh up to 2 pounds, and the heavy weight itself can cause neck strain.
A worker keeps the helmet up until he is ready to strike an arc. When ready, he jerks his head down with a nodding motion to bring the helmet’s hood into position. This repeated motion, in the long term, may lead to repetitive stress injury. Moreover, the jerking motion to bring helmet into ready position can also cause the gun, torch, or electrode to shift out of position that may lead to accidents, or may require rework and repositioning of the parts. This adds to the fatigue and frustration of workers. The solution to the above challenges is the use of auto darkening helmets.
4. Miscellaneous hazards
- Workers can experience hazardous electrical shocks caused by working in wet and damp conditions, damaged or worn out cables, inadequate grounding of equipment, and not using proper gloves.
- Fire and explosion are common hazards given the high temperatures, gases and radiations involved. Fire occurs from cutting in proximity of combustible materials, or leaking of cutting gases from poorly fitting hoses. Explosions occur from compressed-gas cylinders with damaged valves and when cylinders come in contact with inflammable gases in confined spaces.
Given all these hazards, it is inevitable that industries make safety an integral part of the profession.