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Apr 14 2012

Avoiding Welding Arc Flash

Welding Arc Flash

Welding Arc Flash

Arc flash is a common occurrence for those using electric arc welders or working around them. As anyone who’s had one will tell you, they’re not fun.

What is a Welding Arc Flash?

Welding arc flash is actually a burn of the outer layer of the eye ball caused by the intense ultra-violet radiation generated by electric welding arcs. It can also happen due to exposure to any electric arc including switchboard malfunctions. It’s just like sunburn, but instead of your back or shoulders or where-ever, it’s on your eyeball. Just like sunburn to other parts of your body, cells are killed and need to be replaced. The “gritty” feeling associated with arc flashes is actually the dead cells being shed from the surface of the eye (just like the peeling skin associated with sunburn) which irritates the inside of the eye lid. This is why your eyes gets “puffy” and red and weepy when you experience a flash.

Just like sunburn, there’s no cure for a welding arc flash. The eye drops your doctor gives you relieve some of the discomfort but don’t do anything to address the underlying problem. You just have to wait until the body’s healing processes have finished which can take days in severe cases.

You should always get medical attention as soon as you become aware that you’ve suffered a flash. While most are only mild they can be very severe and cause permanent damage to the eye and your vision and early medical treatment can reduce some of these more serious effects.

How to Avoid Getting a Welding Arc Flash?

Now we know what it is, how can we avoid it?

The best way is to avoid exposure to the arc flash in the first place by not being in areas where electric arc welding is happening. Obviously if you’re a welder or assisting a welder or can’t avoid being in the area then this is not possible.

The next best form of protection is placing a barrier between you and the welding process. Welding curtains or solid screens prevent the UV radiation from affecting those not directly involved in the job. Again, this is not always possible and certainly not for the person doing the welding.

As well as allowing the welder to view the arc, welding screens provide protection against damaging UV radiation and prevent arc flashes from happening. However, most arc flashes happen to those in the area and not involved in the welding process or to welders in the short period of time between striking the arc and putting the welding screen in place.Welding Arc Flash - Safety Glasses

These types of flashes can be prevented through the simple means of wearing safety glasses. Modern safety glasses have lenses made from poly carbonate which absorbs up to 99% the damaging UV radiation and also protects your eyes from welding sparks and other debris that maybe flying around the place.

Welding Arc Flash - PPE

Additional protection can be gained by using head mounted rather than hand held welding screens and preferably those with flip-up lenses and protective clear polycarbonate screens fixed into the welding screen.

Auto darkening welding screens provide the best protection. These screens have special technology that automatically (and almost instantaneously) darkens the lens wWelding Arc Flash - Auto Darkening Welding Helmethen UV radiation is detected and then clears it when the UV radiation is not present. These types of welding screens also provide much better face and head protection against damaging UV radiation and flying particles generated in the welding process.
So to recap on what to do to prevent welding arc flash:

  • Don’t be in an area where electric arc welding is being performed unless you absolutely have to be there;
  • If you’re welding or in the area always wear compliant safety glasses;
  • If practical, use welding curtains or other types of solid screen to prevent others being affected by the welding arc;
  • Always use a head mounted welding screen (and preferably an auto darkening one) when welding.

Following these relatively simple steps will prevent you from suffering the discomfort of a welding arc flash.




2 comments

  1. LMG

    Someone told me recently that if you’re five or six metres away from the welding you can’t get an arc flash. True or false?

    1. Dave

      This is probably more complicated than you really want but here goes.

      The degree of burn to the eyes from a welding arc or any other source of radiation is dependent on the energy reaching the eye. If we’re looking at distance, which was your question, then the amount of energy striking the eye is dependent on the strength of the source and the distance from the source. It’s a law of physics that radiation strength diminishes the further you move away from the source. The rate at which it diminishes is inversely proportional to the square of the distance.

      What does that mean in English? Firstly the first point – inversely proportional. That just means that the strength gets less as the distance increases – what you expect really. How much less, well that’s a function of the square of the distance so at 2 units of distance, the strength of the radiation is 1/4 (the inverse of 4); at 3 times the distance you are exposed to only 1/9th of the radiation as you would have been exposed to at the source (Inverse Proportionality Explained). So what distance is “safe”? You need to know the source strength and the exposure limits beyond which no damage will occur.

      Fortunately some clever people have already performed that calculation for various types of welding techniques and this can be downloaded from here American Welding Society Fact Sheet 26.

      There are three things to consider when reading this table:

      Firstly, the effects of the radiation are cumulative so exposure to a welding arc first thing in the morning may cause little or no damage but repeated exposures throughout the day will accumulate and may exceed the exposure limits and cause damage.

      Secondly, the eye is naturally attracted to light and particularly flickering light – think of a flickering candle at night. A welding arc flickers for a number of reasons and because of this the eye is drawn to it and it requires a conscious effort to not look at the arc.

      Thirdly, the lens of the eye is designed to focus light onto the retina – just like a magnifying glass. As a result, constant and regular exposure to UV radiation at these intensities may result in damage to the retina which is irreversible rather than just an arc flash which is a burn to the cornea and from which the body can generally recover.

      With these things in mind I simply don’t understand why someone would start quibbling over such stupid things as the distance from the arc. Just wear the damn safety glasses for God’s sake.

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