This article is not meant as a thorough tutorial about proper oxy-propane cutting equipment. Rather, it is a brief overview of the equipment used and the process of setting it for cutting metal. This should not be used in lieu of official oxy-propane cutting training or of the manufacturer’s official instructions.
Cutting metal with a blade an immensely arduous process. Cutting metal with an ignited gas, however, can make the process much more simple with much less debris. In this article, we’re going to look at the components of an oxy-propone cutting torch rig and some of the settings necessary for an optimal cut.
Before opening the flow of any gas, one should make sure that propane and oxygen tank cylinders are secured. This is commonly done by making sure they are appropriately fastened to their cart system or some other stable frame, usually with chains.
Before attaching a regulator to your oxygen cylinder tank, cracking open the valve slightly is recommended to blow out any gathered debris in the connection areas. After this, the regulator should be attached securely to the cylinder with the appropriate wrench — leaving the gauges at a somewhat upturned angle for easy reading of the gauges. Before connecting the regulator on the propane tank, cracking the value is not necessary or recommended. Instead, a simple inspection of the connection areas is performed to spot debris or damage that may impede the flow of gas or possibly cause injury. Inspect the hoses to ensure they are in working condition and that flashback arresters are installed between the torch and the hoses.
The common torch used with oxy-propone cutting is known as a combination torch. The meaning of “combination” in this instance implies that the torch can be disassembled in the middle to diversify your choice of heating tips, multi-flame tips, welding tips, or braising tips. For cutting, you will need to install a cutting tip attachment. This can be installed by simply hand-tightening the components.
The most commonly used propone cutting tip comes in two-pieces with a spring in the middle to keep the shelf from falling off. One can distinguish a propane cutting tip from others by a recess in the tip face. The tip is attached to the torch head and the tip nut is firmly hand-tightened.
On most combination torches, there are three valves. One valve at the base of the torch is the fuel shut-off. The oxygen valve is left fully open when used as a cutting torch with the amount of oxygen adjusted by a forward oxygen valve further up the length of the torch.
On the oxygen cylinder, the valve is opened slowly until the appropriate regulator needle comes up fully and then drops down. The operator then fully opens the valve on the cylinder. Readings should appear on the high-pressure side with no reading on the outlet side at the time. The outlet adjusting screw should be loose. On the propane side, the cylinder valve should too be opened slowly, but completely with no pressure showing on the outlet gauge of the regulator.
When one is nearing time to ignite the torch, around 10 pounds of pressure is dialed into the propane cylinder’s outlet valve. On the oxygen regulator outlet, around 40 pounds of pressure is dialed in. Following the output, the process of purging should be used to ensure that the proper gas is at its appropriate place within the equipment hoses and torch assembly. To let the torch purge, the fuel valve on the base of the torch is opened for a few seconds and then tightened by down again. Similarly, using the oxygen valve on the base of the torch, the valve is opened for just a few seconds to allow the oxygen to run through the torch by itself. This purging allows the segregation of gases within the torch system and applies pressure.
Before the ignition of the torch can commence, all combustibles should be removed from the work area. A leak check of the appropriate connection points and hoses can be performed using an oil-free deluded dish-soap solution. When gently applied to hoses, valves, or connection points, any leaks will be detected via an apparent bubbling. Personal protective equipment donned by the torch operator includes tinted cutting eye protection, leather gloves, and appropriate clothing.
The torch is lit using a friction device. Open flame devices such as lighters are not used. Initial ignition is fuel-only. Oxygen is appropriately applied to the flame using the forward oxygen valve on the torch. As more oxygen is added, all flames match up with primary plane points on the torch tip. At this point, there is likely not enough fuel in the system. The operator adds additional fuel by adjusting the forward oxygen valve. As the tip received more oxygen, the flames will recede toward the tip. A shrill sound will begin to emanate from the torch tip — an indication of proper fuel flow.
Because a neutral flame is the most appropriate for cutting applications, testing for this is regularly done by bringing the tip to a metal surface. Once this is done, a star-pattern will begin to appear. The star pattern should be around 2 to 2.5 inches. A star pattern that is too short indicates the presence of too much oxygen.
A cut in metal is made by getting the metal up to a melt-point temperature. The tip is held approximately a half-inch from the metal the operator wishes to cut until an orange color is achieved. This color indicates that the metal is nearing optimal cut temperatures. To begin the cut, the oxygen blast trigger is engaged to release additional fuel that burns the metal into a metal oxide.
Once the appropriate cut has been made, the torch is turned off by turning off the oxygen valve on the forward end of the torch. The fuel valve at the base of the torch is then switched off. The cylinders are shut down in three steps.
First, the main cylinder valves to the regulators are completely closed.
Second, to remove all fuel remaining in the torch system, the torch fuel lines are opened up. Proper fuel drainage should be indicated by the propane cylinder regulator pressure indicators going to zero. The forward oxygen valve on the torch is opened which should lead the oxygen cylinder regulator pressure to drop to zero. Following releasing all fuel from the torch itself, the valves are re-shut for later use.
Third, the screw on the regulators should be loosened until no pressure is felt. They should be fairly loose to the touch.
We at DT Specialized Services hope that gives you an idea of what equipment protocols exist for oxy-propane cutting. Again, this article is no way meant to stand in place of an official oxy-propane cutting tutorial, but instead to give you an overview of some of the components involved.
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