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How To Cut With Oxyacetylene Systems, Part 1

For this season’s Shop Class Series we interviewed Cal Shaw, a welding instructor at SIAST’s Palliser Campus in Moose Jaw, along with reviewing training material and published text books to get background information for these how-to articles. Drawing on all that expertise, along with input from a few other expert sources on topics such as occupational health and safety requirements, we’re able to pass along tips on how to get the most out of your oxyacetylene torch in the farm shop.

Why did we choose oxyacetylene as this year’s topic? Aside from helping you safely get the most out of these useful tools, we want to ensure farmers understand the potential risks involved when using compressed gases.

To highlight what can go wrong when people don’t understand the risks, there is an incident that is infamous in the welding profession. A farmer, who was pretty handy in the workshop, decided to try and avoid paying the cost of tank rentals by fabricating his own own acetylene cylinder. When he took it to two different retailers, they both predictably refused to fill it, because it wasn’t an approved container.

Undaunted, he went to a friend’s workshop and transferred acetylene into it from that person’s proper set up. The filled tank was then loaded into a pickup and the farmer and his wife, who was long for the ride, headed back to the farm. The improperly-built, homemade container exploded on the way, killing them both.

While that may be an extreme example of people doing things the wrong way, little errors can also add up to serious problems. In this series we’ll look at the steps involved for safe routine assembly, daily use and storage practices. We won’t make you expert users, but we may help you improve your technique and safety.

Even though there are other oxy-fuel systems available on the market today, in this series we’ll deal with oxyacetylene. They can be used to weld and braze, but we’ll focus on using them to cut.

As a first step, let’s take a look at the science behind the cutting process. Basically, nearly any substance will burn if it is heated to a high enough temperature. Oxyacetylene systems cut through iron and steel by a process of rapid oxidization. Steel is heated to a kindling point, about 1,300 to 1,400 F. (704 to 760 C.) by the acetylene flame, then when the oxygen lever is depressed, a jet of compressed, almost pure oxygen oxidizes the steel.

Don’t forget oxygen is quite different than compressed air, and one cannot be substituted for the other.

Most oxyacetylene cutting on the farm will involve ferrous steel, which has iron in it and is magnetic. While oxyacetylene can cut non-ferrous steel like aluminum and stainless steel, there are additional considerations and requirements which have to be met.

One of the easiest ways to tell if you can cut a sample of steel is to see if it is magnetic. Placing a magnet on a piece of unknown metal will help establish its makeup. If the steel is magnetic, it is an indication that it contains iron and therefore will be a good candidate for oxyacetylene cutting. If it’s not magnetic, using a plasma cutting torch may be a better option.

Next time, we’ll jump right into the subject and look at what you need to know to select the right system for your farm shop.

ScottGarveyismachineryeditorof Grainews.Contacthimatscott. [email protected]

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Scott Garvey

Scott Garvey is a freelance writer and video producer. He is also the former machinery editor at Grainews.

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