Useful Tips

Advantages and disadvantages of acetylene-oxygen welding

Pin
Send
Share
Send
Send


  • acetylene sleeve (hereinafter referred to as C2H2) of the 1st category for supplying acetylene with a pressure of up to 0.63 MPa
  • oxygen (hereinafter O2) 3rd category for supplying oxygen under pressure up to 2 MPa
  • Reducer to O2 (BKO-50DM)
  • Reducer C2H2 (BAO-5DM)
  • two matching 40 liter containers
  • gas torch Donmet G3 with a mouthpiece No. 3

Further actions

In order to set the working pressure of 0.2 MPa on the C2H2 gearbox, you need to open the wing of the cylinder counterclockwise, then unscrew the screw on the gearbox clockwise. In the same way, the pressure on the O2 gearbox of 0.5 MPa is set.

There are two ways to set up a welding flame:

  • Open the valve C2H2 on the burner, then ignite the flame, it should not come off the mouthpiece, then adjust it with oxygen. The flame must have a core, a recovery section and a torch,

  • or open both valves at once, each half a turn, and then set fire to the flame. Then adjust it to normal. You should get three pronounced zones.

As you can see, the first method is most suitable for beginners.

Metal heating to melting point

In order to make a weld pool, you need to position the torch at 90 degrees relative to the base metal, and the distance between the flame core and the metal should be about 1-3 mm. The metal will gradually heat up to red. First, a characteristic straw color appears, then a weld pool is formed. To begin with, try to make oscillatory movements “crescent” without an additive. For surfacing, you need to take the burner 30-40 degrees and feed the rod from above dropwise or by immersion in a liquid bath. At the same time, do not forget to “draw” the “crescent” burner, slowly moving along the seam. Try to prevent the core from touching the weld pool.

Burner closing

After you complete the welding, close the torch in the following order:

  • close the C2H2 valve
  • blow and close the O2 valve.

The quality of the seam can be checked visually. The seam should be tight, and the flakes should be even, its width 5-6 mm, height 1-2 mm.

Work completion procedure

The cylinder wing with C2H2 closes, then the gearbox adjustment screw is loosened. Then the same procedure for the cylinder with O2

Then you need to drain the residual gas from the sleeves. To do this, open both valves on the burner, on the operating pressure gauges you can see how the gas leaves the hoses, the arrow will slowly drop to zero. Close the valves on the burner.

Advantages

Why is acetylene the main gas in gas welding of metals? Its burning temperature exceeds the melting degree of steel and other materials. With a high qualification of a gas welder, the advantage of acetylene welding is its high productivity at low gas and material costs. The remaining pros and cons will be discussed below.

The main advantage of oxy-acetylene welding is mobility and welding control. There are other benefits:

  • during acetylene welding, cylinders are easily transported on a trolley. It is convenient to cook a fixed seam, with a small distance to the wall. In this case, it is not necessary to make an operational joint,
  • With the help of a gas burner, one-piece connection of metals with various melt temperatures can be carried out. By adjusting the strength and type of flame, it is possible to achieve optimal conditions for acetylene welding,
  • when welding parts of small thickness from structural steel, copper, cast iron, brass, the acetylene method is indispensable,
  • you can improve the quality of the seam by using alloy steel wire or other additives.

By adjusting the heating temperature, you can prevent severe deformation of the structure and joint. At the same time, an optimal metal welding speed is also achieved.

disadvantages

But the acetylene type of welding also has some disadvantages. These include:

  • when heated, a large area is formed with changes in the properties of the material, therefore acetylene welding is not used in mechanical engineering,
  • when connecting parts with a thickness of more than 5 mm it is better to replace gas welding with manual or semi-automatic electric welding,
  • connection of high carbon steel not for oxygen-acetylene welding,
  • when overlapping, the metal will deform significantly, and areas with significant stress will form in it,
  • requires increased costs for materials and equipment, compared with the electric arc type of welding.

The main drawback is the high explosiveness. But a lot of this depends on the human factor.

Non-observance of safety rules, incorrect actions during a reverse impact are the main errors leading to accidents. When working with acetylene, the welder must have skills higher than those that are sufficient for semi-automatic and automatic welding.

The acetylene welding method is most suitable for butt joints of parts. And the quality of the seam directly depends on the quality and purity of acetylene and oxygen.

With all the shortcomings and high explosiveness, this type is the main one for welding thin-walled parts and some non-ferrous materials. To this can be added the fullness and accuracy of the seam.

The butt of electric arc welding cannot be as beautiful and reliable as that of gas welding, especially with a fixed joint.

Tools and materials

Acetylene welding will require quite affordable and relatively inexpensive equipment. Previously, gas generators were used to produce gas, but now balloon acetylene is more common.

The balloon is white. To maintain combustion, balloon oxygen is used. As a rule, they are transported on special carts.

Depending on the thickness of the metal being welded, several sizes of the burner and nozzle are provided. The smallest size that a burner can have is zero, and the largest is the fifth.

If you need strong heating of thick metal, the largest number is used with a hole that allows you to feed the gas mixture into the weld pool and provides normal heating of the joint.

Acetylene and oxygen hoses are suitable for the burner. Fastened with a threaded connection.

Reducers allow you to adjust the gas supply and lower the pressure of the gas coming from the cylinder. The pressure in the oxygen cylinder is about 150 atm. In addition, the gearboxes protect the cylinder against a back impact.

Depending on the type of material being welded, the filler wire can be made of steel or other metals with the addition of alloying additives. They improve the quality of the seam. For acetylene welding of steel water pipes, beaten electrodes are used for manual electric welding, but this is a more expensive option.

Gas welding process

The work process begins by opening the valves on the cylinders and adjusting the gas pressure using gears. The optimal value of gas pressure is 2 atmospheres. At higher pressures, flame adjustment may be difficult.

On the burner, open the acetylene feed valve and set fire to the gas. Then gradually opening the oxygen valve, adjust the flame. For welding of ferrous metals, the neutral flame of the burner is most often used. The torch itself consists of three parts that are clearly visible to the naked eye.

Blue with a slight greenish tint has a core that is located inside the flame.

Next is the workspace, which is responsible for heating and weld quality during acetylene welding. This is a reducing flame and it is usually light blue in color.

The biggest part is the torch burner. He is responsible for heating the metal.

To set the neutral flame, it is necessary to lean the burner against any metal surface and adjust it with gas valves. The core does not have to be very large, and the recovery flame is adjusted to a specific color.

First set the size of the torch. This is done by feeding acetylene. Then gradually increasing the oxygen supply, we achieve a normal flame.

In this case, you should not make a very powerful flame. It will increase not only the speed of acetylene welding, but also increase the number of burns and undercuts of the seam. Therefore, adjustment is one of the main operations that facilitates the execution of welding work.

Do not set the long and orange color of the torch. Such combustion will reduce the quality of the weld, introducing excess carbon into the weld pool.

The main methods of maintaining the burner and filler material

Experts apply two ways of conducting the tool: “from oneself” and “to oneself”.

When driving from itself, a wire is located in front of the burner. This method is used when welding structures of large thickness. In this case, the molten metal of the parts and additives simultaneously fills the weld pool.

This method requires the welder to ensure uniform mixing of the base and filler metal. With an insufficient amount of molten wire, the seam is weakened.

With the acetylene welding method, the torch is the first to go over, and when the base metal is melted, metal from the wire is added to the bath. The burner must be positioned correctly here.

It should go at an acute angle with respect to the details. This method is the simplest. It is necessary to heat the metal, remove a drop from the wire and stretch it along the seam. According to this principle, the leg of the seam is formed.

For greater convenience and to prevent the formation of burns, the burner is either a crescent or in circular motions.

An important role in the quality of the connection is played by the correct joining of parts, the absence of large gaps when welding thin sheets or pipes. It should be remembered - before acetylene welding, parts must be seized in several places. On pipes of small diameter, tacks are made after about 1200.

The welding characteristics are also influenced by the characteristics of the metal being welded.

Mode selection

To increase the quality of the seam and its tightness, depending on the material, it is necessary to know some secrets of professional gas welders.

High carbon steels are very rarely brewed using acetylene welding. But low-carbon, structural steels - this is the scope of gas welding.

In this case, good results are achieved with any spatial position of the seam. The average burning power should not exceed 120 cubic decimeters per hour.

The best way is to keep the burner away from you. The additive must be used in low carbon steel, but electrodes for electric welding can be encased. When the metal is melted, silicon, manganese leaves it and a coarse-grained structure of steel is formed. A wire from ST.2, with a silicon content of less than 1%, manganese 1.1% will provide a uniform weld in structure.

Alloy steel is not recommended to be cooked using the acetylene method. With strong heating, deformation of parts occurs, therefore, when welding some steel grades, the following recommendations must be followed.

To join low alloy steels it is necessary to use fluxes. Acetylene welding is carried out with a normal flame. The burner must operate at low power, giving a low flame if welded with steel with a high content of chromium and nickel.

An additive with a content of 21% nickel and chromium 25% is used to join heat-resistant steels. Welding steel with high resistance to corrosion will be easier if you use a wire containing nickel, chromium and molybdenum.

Work with cast iron, copper and brass

Before welding cast iron, it is necessary to warm up the junction and only then carry out work. Otherwise, white iron forms in the structure of the base metal, and the joint becomes brittle. Work is done in normal flame.

Welding of copper parts is carried out without breaks and preliminary tacks. There is no gap between the parts. Copper is a very fluid material when heated and a very thermally conductive material. Therefore, it is necessary to set a more powerful burner flame. It is better to conduct acetylene welding under a flux layer to prevent oxidation of the joint.

Brass welding with acetylene and oxygen is the best option for this material. The melt temperature should not exceed 9000, while zinc does not completely evaporate. Thanks to acetylene welding, a reliable seam is formed, removing 25% of this metal from the weld pool.

It is necessary to maintain a low combustible gas content in the mixture, this will allow zinc to evaporate in the required volume. For best results, use fluxes and a high-quality additive. Using gas welding, you can also cook bronze parts and other metals.

# 1 dentws

In life, there was a need for the development of a burner, because I was tired of warming with a gas-air burner and the second reason: a gas-air burner heats up a large plane and the second when soldering, a situation arises that something may come off nearby. At home, the Armenian GZ-05 was honestly somewhere cn privatized Schaub Bulo along with gearboxes. Her darling and had to be put into action. Having naturally read the literature, he set about assembling a gas-welding post. Hoses purchased in general store at 50 p. meter. The oxygen cylinder was requested by the DRSU (by exchanging an unchecked empty one for a verified full one, or else “I will point Slavik”) Yes, we don’t refuel oxygen with more than 70 points, probably the cylinders undergo the most “strict” re-certification. I will make a reservation right away that I have never held gas welding in my hands. Well, it wasn’t at the mine. Everything was cut and cooked by handbrake basically. And more specific products were made by the fur factory and they came ready. Kerosinorez was in the RMC but after the explosions in 1998, they were immediately confiscated immediately in different places of oxygen cylinders. I stole one in the guise of one in the garage there and dabbled in it until oxygen ran out.

Deviated from the topic. So all this was twisted checked for gas leaks with soapy water. With the thought of "how I’ll start soldering right now" and a shit about the bummer. The burner didn’t want to be set on fire. She didn’t set fire, but didn’t want to work like in a book. Defective however. Helped in the forums. Let's drill the nozzle, twist the injector, etc. One figs blows off the flame then plows. Moreover, with each bang I want to solder less and less. And then I decided to go the other way. I describe the process itself.

1. Open the valve completely acetylene valve (read propane) and oxygen. Gearboxes are closed. Cylinder valve open.

2. We begin to slowly open the propane gear while holding fire at the nozzle. We open it very carefully so as not to get fattened or to underfill something. A gimmick lit up the light from the nozzle. Turn the propane gear further. Slow. The light increases and turns into an Olympic torch (figuratively). We turn further and begin to observe how the fire begins to break away from the nozzle. Turn the gearbox very slowly in the opposite direction. We return the fire to the nozzle. Propane is configured.

3. Now we begin to open the oxygen reducer. So slow. We observe how the flame changes and divide into zones. We twist until the light at the nozzle turns purple and has a minimum length. If the twist will bang. But we’re not afraid of the same bubilgum (a cartoon about a kesha parrot). Repeat the procedure.

The entire burner is now configured by its valves. No flame out nor any more bubelhums. We make the flame at least oxidative, at least restorative, at least neutral, at least “evil”, at least “good”. We twist the valve only on the burner. In this way, we control any acetylene or propane burner. With any nozzle no. The injector also needs to be regulated by the way. But this is both in literature and in YouTube. Maybe my method is also somewhere in the descriptions, but I did not find it. Maybe I'm wrong, but it's more convenient for me. I tried to describe so that everyone understood even those on the armored train. No offense.

If not so sorry.

Attached Images

To be or not to be, that is the question. Worthy

Pin
Send
Share
Send
Send