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Different types of welding require different types of materials and equipment. A common type is gas welding or oxy-fuel welding, wherein you use a combination of oxygen and acetylene as fuels to weld metals. Gas welding was developed by Edmond Fouché and Charles Picard in 1903, and by 1906, it has become one of the standard ways to fabricate metals (1). Since then, acetylene has been known as one of the safest and most effective gas welding fuels.
It’s sometimes called oxy-acetylene welding because it essentially uses a mixture of acetylene and oxygen, which burns anywhere from 3,200 to 3,500 degrees Celsius. These are the highest temperatures for any gas fuel. This efficient process uses pure oxygen, not air (which is only 20% oxygen, 78% nitrogen, and 2% other gases). Pure oxygen causes a complete combustion of acetylene, which yields more heat and allows localized melting of the weld area.
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Why Acetylene is Used for Welding
There are a number of reasons why acetylene is a preferred fuel for gas welding. Perhaps, the most important is its being relatively safe. Process industries prefer safe fuels to anything else. Acetylene’s properties make it a safe gas. It’s lighter than air, so it will not sink to the floor or accumulate in the lowest compartments of a building. This means it’s great for underground welding operations.
Not only is acetylene a safe fuel, but it also produces the hottest flame when it reacts with oxygen. This means it can weld some of the toughest metals in industrial settings. In fact, oxy-acetylene welding is ideal for steel.
Another thing that makes acetylene great for welding is its flexibility. Because it has numerous applications, its use is cost-efficient.
Hazards of Oxy-Acetylene Welding
Anything that releases heat also releases infrared radiation. The hotter the material, the more infrared rays it releases. Exposure to this type of radiation is harmful to your skin and eyes. Nonetheless, workers sometimes don’t wear sufficient eye protection when welding with acetylene. Why is that so?
If you’ve been in the welding business for a while, you would have seen common practices that expose workers to known hazards. Despite knowing the dangers, many workers, especially the older ones, just get on with the task without safety glasses, goggles, or helmets. Guys want to look tough sometimes and sacrifice safety for some careless display of masculinity, and that’s why they suffer from eye injuries and later on succumb to visual impairment.
The human eye is not just vulnerable to sharp objects and metal splinters. It’s also defenseless against UV and infrared radiation, two types of harmful radiation released during welding. However, gas welding isn’t the most dangerous activity in a metal fabrication shop. It’s not as hazardous as arc welding, which emits light and heat so immense that you wouldn’t dare do it without safety gear. Even the toughest guy isn’t silly enough to leave his welding helmet.
Compared to arc welding, oxy-acetylene welding isn’t so harsh on the eyes at first. Many technicians will be able to adjust to the heat and light emitted by the flame. This is a false sense of assurance. Just because you don’t feel the damage right away, it doesn’t mean it’s not happening. The insidious radiation causes damage to the structures in the retina little by little. You don’t feel it at first because the sensitive structures in your eyes can repair themselves. But repetitive assault can cause irreversible destruction of these tiny structures in the retina and cause permanent damage.
Aside from causing retinal damage, exposure to UV and IR radiation can also burn and/or irritate the eyes and the skin. UV light can irritate the cornea and cause photokeratitis, sometimes called welder’s flash. Even harsh visible light can cause damage to the cornea and other structures in your eyes. If you survey old folks who have been in this industry for a long time, many of them probably suffer from a range of eye problems, including night blindness and cataracts. Some even suffer from color blindness.
Although you think you can perform oxy-fuel welding without shaded lenses, safety should be one of your priorities. But don’t just wear any filter lens. Welding lenses come in different shades.
Lens Shade for Oxy-Acetylene Welding
In many cases, shade 5 glasses should offer sufficient protection against intense light and heat. However, the range can be anywhere from shade 4 to shade 6, depending on what you’re working on. For light gas welding, you need a shade 4 lens. For heavy gas welding, you need a shade 6 lens. However, you may find that these are either too light or too dark for you. So you may want to choose the darkest shade that allows you to see what you’re working on. If you’re unsure, start with a shade so dark that you can’t see the weld area. Then work your way to the lighter shades until you find one that allows you to see the weld area.
In addition, acetylene burns with a strong yellow light, so a filter lens that absorbs yellow light is highly recommended.
Oxy-acetylene welding isn’t the most hazardous type of metal fabrication, but it’s still dangerous when done without protective gear. Welders should wear eye protection to spare their corneas and retinas from damaging radiation and prevent visual impairment down the road. Depending on the type of oxy-fuel welding you’re doing, you may need a shade 4, 5, or 6 lens.