How to properly cut metal with a gas torch

Pros and cons

Gas cutting and metal welding has many advantages, but we are only interested in cutting, which has the following advantages:

  • It is in demand when a thick metal is cut or a stencil cut is needed, and an angle grinder cannot cope with curved sections.
  • The gas analogue is much more convenient for work, has a low weight, operates twice as fast as equipment with a gasoline engine.
  • Propane is cheaper than acetylene and gasoline, so its use is more cost-effective.
  • The cut edge is much narrower and the structure is cleaner than from an angle grinder or gasoline equipment.

Disadvantages. a narrow range of metals subject to similar processing.

Equipment set

Before starting flame cutting or welding, the equipment should be carefully prepared:

properly, metal, torch
  • Containers with gases.
  • Connection hoses.
  • Cutter.
  • A mouthpiece with specific dimensions.
  • Volume control and control reducers.

The equipment does not depend on the manufacturer, the valve marking is standard.

Application features

To understand how to properly cut metal with a cutter, you need to study the design and know that such equipment is not used for cutting steels with high carbon, since there is no way to create a temperature that can ensure stable melting. When cutting cast iron workpieces or structures, there is a concentration of graphite between the metal grains, which complicates the work.

can not be used for cutting products consisting of aluminum, copper and alloys based on it.


The main task of the performer is to maintain the speed correctly:

  • normal mode. sparks fly at right angles relative to the surface of the workpiece;
  • low speed. flying away from the performer and an angle of less than 85 degrees.

After the end of the process, the oxygen supply is first shut off, and propane is turned off last.

N. Ishkulov, education: vocational school, specialty: fifth grade welder, work experience: since 2005: “For the first time cutting with oxygen equipment, it is necessary to remember that after a sudden stop it is necessary to start a new cut from a different point, and not there where the process ended “.

How much gas is consumed

Gas consumption when cutting metal with a propane-oxygen cutter depends on the thickness of the structure and the configuration of the cut. For clarity, we present the table below:

How to Use a Torch to Cut Metal.

Workpiece size (thickness), mm Time per hole, sec Cut size (width), mm Consumption, per m 3 cut
propane oxygen
4.0 5-8 2.5 0.035 0.289
10.0 8-13 3.0 0.041 0.415
20.0 13-18 4.0 0.051 0.623
40.0 22-28 4.5 0.071 1,037
60.0 25-30 5.0 0.087 1,461

Gas consumption is significantly reduced when surfacing or brazing is performed.

Safety engineering

The equipment is classified as explosive, therefore, the work site must be equipped with the following accessories:

  • fire extinguisher;
  • sand box;
  • fire stand with appropriate tools.

Each performer must have a set of protective clothing.

Beginners Guide to Cutting With a Torch

It is not allowed to wear under the protection clothing made of flammable material, for example, synthetic materials, and the edges of the sleeves should fit tightly around the body so that sparks do not get inside.

properly, metal, torch

Propane to oxygen ratio

To properly cut metals with an oxy-propane torch, you need to adjust the flow of gases to the nozzle. Such adjustment is carried out according to the recommendations of reference books, where there are tables and diagrams; in the absence of the necessary literature, one must check the technology specified in the product documents. In the absence of regulatory documents, the ratio of one part of propane to ten parts of oxygen is used.

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Collection and adjustment of equipment

The assembly of the purchased equipment is carried out in the following sequence:

  • the fitting is pre-checked for defects. If available, the surface is processed with an ordinary file. Otherwise, a reducer installed on a defective fitting can “poison”, that is, little by little gas can pass;
  • then the reduction gears are installed: blue. to the oxygen cylinder, red. to the propane cylinder. In this case, you should make sure that the rubber gaskets are in good condition, as well as that there are no traces of fat or oil on the valves;
  • Hoses in accordance with the direction of the thread (left-hand or right-hand) are installed on the gearboxes and the torch using the clamps supplied with the equipment. Before installing them, make sure that there is no damage to their surface;
  • kickback valves are mounted on matching torch fittings.

After assembling the equipment, it must be configured, while checking its serviceability. The procedure is as follows:

properly, metal, torch
  • the supply of acetylene is checked by opening the appropriate valve for 1 turn of the hand. In this case, the pressure should not exceed a level of 1 atmosphere. The optimum pressure, which is recommended to be set using a control valve, is 0.34-0.54 atmospheres;
  • then purge the hose by opening the valve on the torch until the sound of gas escaping under pressure;
  • the oxygen pressure is adjusted in the same way. For him, the recommended level is 1.7-2.7 atmospheres;
  • after that, the hose is purged by sequentially opening the rear and then the front of the two valves that regulate the amount of oxygen supplied.

All the necessary instructions for assembling and setting up the equipment are contained in the delivery set. They need to be carefully studied and followed when working with the torch, which is easy enough to learn.

Preparation for work

Before starting gas cutting, it is necessary to inspect the device to make sure that the propane torch is in working order. Next, you need to perform the following operations:

  • Preparing the cutting machine begins with connecting the hoses to it. Even before attaching the sleeve, it is purged with gas. this will remove debris and dirt from it.
  • The oxygen hose must be connected to a right-hand threaded fitting, a nipple and a nut are used for this purpose. As for the hose through which the propane will flow, it is attached to the fitting with a left-hand thread. Before connecting the gas hose, it is imperative to find out if there is a suction in the cutter channels. This task can be solved by connecting the oxygen hose to the oxygen fitting, while making sure that the gas fitting remains free.
  • Next, you need to set the oxygen supply level to 5 atmospheres, after which you need to open the valves that regulate the flow of gas and oxygen. Touch the free fitting with your finger. this way you will know if there is an air leak. If it is absent, you will have to clean the injector and blow out the cutter channels.
  • After that, you need to make sure that the detachable connections are sealed. If it is possible to identify a leak, fix it by tightening the nuts or replacing the seals. You should also make sure that the mountings of the gas reducers are sufficiently tight, whether the pressure gauges are in working order.
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Advantages and disadvantages

Cutting metal with propane has a number of advantages, among which the following can be distinguished:

  • Gas cutting is in demand in a situation where there is a need to cut metal of considerable thickness or create products according to templates that provide for the production of a curvilinear cut that cannot be performed using an angle grinder. Also, you can not do without a gas cutter, and then, as there is the task of cutting out a disc from thick metal or making a blind hole by 20-50 mm.
  • The torch is a very easy-to-use tool and is lightweight. All DIYers who have had experience with gasoline models are aware of the inconvenience associated with heavy weight, size and noise. In addition to the significant inconvenience caused by vibration, the operator is forced to provide serious pressure during operation. Gas models, on the other hand, seem to be a more attractive alternative due to the lack of all the above-mentioned disadvantages.
  • The use of cutting metal with gas allows you to speed up the work 2 times, which cannot be done using a device equipped with a gasoline engine.
  • Among most gases, including gasoline, propane stands out at a lower price. For this reason, it is better suited for a significant amount of work, for example, if there is a task to cut steel for scrap.
  • With propane cutting it is possible to create a narrower cut edge than with acetylene cutters. At the same time, the method under consideration allows you to create a cleaner cut than that which can be done using gasoline burners or an angle grinder.

Among the disadvantages that propane cutters have, only one should be highlighted: they can be used only for a limited range of types of metals. They are suitable for cutting extremely low to medium carbon steels and also ductile iron.

Preparation for work

Before starting work, it is imperative to inspect the device to make sure that the torch is fully functional. Then follow these steps:

  • The first step is to connect the hoses to the cutting machine. Before attaching the sleeve, you need to purge it with gas to remove any debris or dirt that has got there. The oxygen hose is attached to the right-hand thread with a nipple and nut, the second (for propane) hose to the left-hand thread. Remember to check the torch passages for leaks before attaching the gas hose. To do this, connect the oxygen hose to the oxygen connection, and the gas connection must remain free. Set the oxygen supply to 5 atmospheres and open the gas and oxygen valves. Feel the free fitting with your finger to see if air is leaking. If not, clean the injector and blow out the torch passages.
  • Next, check the detachable connections for leaks. If you find a leak, tighten the nuts or change the seals.
  • Do not forget to check how tight the mountings of the gas reducers are and whether the pressure gauges are in good working order.
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1 Insanely Easy Torch Cutting Hack for Perfect Cuts

Surface and shape cutting

In some situations, it may be necessary to emboss a surface by cutting a groove in the sheet. If it is decided to use a similar cutting method, then the heating of the metal will be provided not only by one flame of the torch. The molten slag will also contribute. As it becomes liquid, it will spread over the entire surface, which will lead to heating of the lower layers of the metal.

The first stage in the implementation of surface cutting is the heating of the selected area to the ignition temperature. After starting the supply of cutting oxygen, you will create a metal burning zone, and thanks to the uniform movement of the cutter, the cut line will get a clean edge. The operation itself must be performed in such a way that the cutter is at an angle of 70-80 degrees in relation to the sheet. When cutting oxygen begins to flow, the cutter is positioned so that it forms an angle of 17-45 degrees from the work surface.

To create grooves of suitable dimensions, it is necessary to change the cutting speed: to obtain a greater depth, the speed increases, and for a smaller one, it decreases. To create more depth, the angle of inclination of the mouthpiece must be increased, cutting must be done at a slow pace, while the oxygen pressure must also be increased. The width of the groove can be influenced by using the correct diameter of the cutting oxygen jet. It should be borne in mind that the difference between the depth of the groove and its width must be up to 6 times. over, the latter should have an advantage. Otherwise, you may encounter such an unpleasant phenomenon as the appearance of sunsets on the surface.

Gas torch basics

The process of cutting with a gas torch occurs due to the combustion of metal in a stream of oxygen supplied under pressure. The alloy must be preheated to the required operating temperature using a burning mixture of acetylene and oxygen. The only metals that can be cut in this way are various grades of carbon steel and unalloyed steel. Stainless steel, non-ferrous metals and alloys cannot be cut with an oxygen-acetylene cutter.

To perform this type of work, in addition to the corresponding set of gas equipment, you will need the following:

  • Fire extinguisher.
  • Protective equipment: special glasses; thick leather gloves; sturdy work shoes with leather soles.
  • Appropriate clothing. It is recommended to wear fire resistant clothing, but if not available, a well-fitting cotton will do. Do not wear clothes made of synthetic and flammable fabrics, loose fit, with torn or worn edges.
  • Measuring and marking tools: ruler, square and soapstone pencil.
  • Torch lighter. designed to properly ignite the torch flame. It is very dangerous to use ordinary matches, lighters.