Propane & Oxygen Torch Cutting How to Tips

Propane & Oxygen Torch Cutting How to Tips

I’m going to go through the proper equipment setup for cutting with an oxy propane cutting torch. Similar procedures could be used for using acetylene. I’ll also be discussing some basic cutting techniques and the proper way to shut down the oxy fuel system. As we begin our process there are a few things I want you to know. First of all, be sure that your cylinders are secure. Before a Victor, Harris, or Forney regulator is attached to an oxygen cylinder crack open the valve to blow out any dirt or debris that might be in this connection area and attach the regulator securely with a wrench. The angle of the regulator should be somewhat in an upward direction on the propane cylinder. Do not crack the valve, simply inspect to make sure there is no damage or debris in that valve connection area. Attach the propane regulator securely with the wrench but in this case note it’s a left hand connection. If you look closely, you can see a machining groove on the connection nut that will always refer to a left hand connection. It too is pointed somewhat in an upward direction on the outlet side of the propane regulator and is a left hand connection.


We need to inspect some more parts of our system, making sure the hoses are in good repair. Looking further downstream to our torch, you need to make sure that there are flashback arrestors installed between the hoses and the torch. The torch we’re using is called Smith equipment brand combination torch. What that means is by combination that you can take it apart in the middle, and you have the option or choice to put in heating tips, multi flame tips or a braising or welding tip. I’m gonna be simply using the cutting attachment for a cutting application, simply hand tighten a propane tip. Unlike an acetylene cutting tip, this propane cutting tip is a two piece style tip. There’s a little spring and that’s purpose is to keep the shell from falling off. Also notice there is a recess in the tip face that would signify a propane style tip. Simply put it into the torch head, place your tip nut around that and firmly hand tighten and that’s all we need to do. Also on a combination torch, there are three valves, a fuel shut off and the oxygen valve will be opened all the way when we use it as a cutting torch and we adjust our oxygen from the forward oxygen valve position.


Now let’s go back to our cylinders when we put pressure into the system. Open your oxygen cylinder valve slowly until the needle comes up and stops and then open it all the way. You’ll see pressure showing on the high pressure gauge. But nothing shows on the outlet side yet. The adjusting screw is loose and wiggly on the propane side of the system. Similarly open this valve slowly, but all the way. So no pressure is showing on the gauge. The tip we’re working with is SC 40-1, and that refers to SC heavy duty, 40 is a propane style and #1 is the size of the cutting tip. In order to set the tip correctly I’ll refer to the cutting chart found in the owner’s manual. There’s other literature for this that can be found and it’s also available on the Smith equipment web site, also on the Fornery, Harris, Victor, or Allied Welding websites. We will now dial in some working pressure on the propane side, we’ll dial in 10 PSI, on the oxygen we will dial in 40 PSI. The next basic step to follow would be purging. I want to make sure that the right gas is at the right place far enough downstream in the system in order to do that. Now that we have pressure crack open the fuel side and let it run for a few seconds. Fuel only is coming through the torch now. Shut it down. Similarly, on the oxygen side, we’ll also run oxygen through the system by itself for just a few seconds. That way, I know that oxygen and oxygen only is in this side of the system. Now that we have pressure in the system, let’s do an inspection of our work area. We want to make sure that all combustible items are removed, should there be any there a working fire extinguisher must be close at hand. We also want to do a leak check, and make sure all the connections that we have in our system have no leaks. One way to do that, is using an oil free dishwasher or dish soap and water solution. As you apply that to all connection points, if there was a leak in the system, you’ll see very obvious bubbling action occur. Should that be found tighten those connections and repeat your leak check.


As for personal protective equipment, safety glasses will now be changed into shade 3-5 cutting glasses. I happen to use a shade 3 cutting glass, shade 5 would be acceptable for acetylene. Different situations call for different shading. To get the correct shade, do a Hey Alexa or Hey Siri search for correct shading for oxy-acetylene cutting and welding. Now we’re ready to light the torch. Using a friction device, not an open lighter with a open flame. The safest and best way to light your oxy acetylene torch is to use a flint striker. Basically, this is a device that has a flint member that is fixed into a threaded socket that screws into a spring loaded member that moves back and forth against a hardened steel surface like a file. This assembly is held inside a protective steel cap about 1” in diameter x ½” deep. When the striker is activated by hand pressure, the flint moves across the steel file and creates sparks. These sparks, of course, will ignite the acetylene, and the steel cap will keep the flame from unexpectedly projecting too far. These strikers are made by many companies such as: Forney, Hobart, Ally Tools, Vas Tools, Hot Max, US Forge, Lincoln Electric, Worthington, Levado, and Tech Team Tech Team’s model 763 Flint Striker is the one we like the best because it has high quality construction with a durable zinc plating, and it contains 3 flints that can easily be rotated one to the next to the next as it wears down and becomes ineffective.


It probably also occurs to you that eventually these flints will wear out and oddly enough there are several companies that make replacement flints such as: Forney, US Forge, Shurlite, Zippo, and Tech Team We happen to like Tech Team’s item 761 contains 3 sets, each set having 3 replacement flints, which easily fits into their 763 3 Flint Striker. Crack open your fuel valve about a quarter turn so we have fuel only at this point, reach for your forward oxygen valve and add oxygen. You’ll notice as we add oxygen, all the flames come back to match up with your primary flame points. However, there’s not enough fuel in the system yet so add more fuel and it will mushroom out now add more oxygen and the flame will recede to it’s lowest position. You will commonly start to hear a bit of a shrill noise come out of your torch, and that is an indication of proper fuel flow. A neutral flame is what we need to have for a cutting application. One way to test for that is to bring the tip close to the bevel, and a star pattern will come out across the metal face. That star pattern should be approximately 2 to 2 ½ inches. Let’s change the oxygen one more time. With excess fuel the flame pattern is very long, as we add oxygen again, that star pattern becomes very, very short and sharp and we have a neutral flame. Now we will begin to make a cut. What we’re gonna do is use the flame to get metal to temperature so that an orange look is achieved, and we will depress the cutting lever. To make our cut hold the tip approximately a half an inch from your work.


To shut down then turn off the oxygen valve. The torch is now safely shut down. The next step is we’re gonna shut the complete system down. There’s three steps. Go to the source and shut off both cylinders so that everything is shut off. Step number 2 would be to drain out the system of all gasses. Open the torch fuel line, the needles now go to zero, shut the valve, and open the oxygen line. These needles now go to zero, shut the valve. The third and final step for a complete shut down is to back out the adjusting screws until no pressure is felt. The system is now completely shut down in a safe manner. This in no way covers all the safety rules and procedures for safely operating this equipment. Be sure and carefully read and understand the oxy fuel equipment manufacturers safety and operational instructions before operating any equipment of this type.