Application of acetylene. Welding with acetylene

To understand where acetylene is used, it is necessary to study and understand what it is. This substance is a flammable, colorless gas. Its chemical formula is C ₂ H ₂ . The gas has an atomic mass equal to 26.04. It is slightly lighter than air and has a pungent odor. The production and use of acetylene is carried out only in industrial conditions. This substance is obtained from calcium carbide by decomposing the component in water.

What is dangerous acetylene

The use of acetylene is limited by its extraordinary properties. This gas is self-igniting. This occurs at a temperature of 335 ° C, and its mixture with oxygen at a temperature of 297 to 306 ° C, with air at a temperature of 305 to 470 ° C.

It is worth noting that acetylene is technically explosive. This was when:

1. Increasing the temperature to 450-500 ° C, and also at a pressure of 150-200 kPa, which is equal to 1.5-2 atmospheres.
2. A mixture of acetylene and oxygen at atmospheric pressure is also dangerous, if acetylene contains 2.3-93% of it. The explosion can occur from strong heating, open flame and even from a spark.
3. Under similar conditions, an explosion of the air mixture with acetylene occurs if it contains 2.2-80.7% acetylene.
4. If the gas is in contact with a copper or silver object for a long time, then acetylenic explosive silver or copper may be formed. This substance is very dangerous. The explosion can occur from a strong impact or as a result of an increase in temperature. Work with gas should be carefully.

Features of the substance

Acetylene, the properties and application of which has not been fully studied, can lead to an accident and severe destruction as a result of the explosion. Here are some data. In the explosion of one kilogram of this substance, 2 times more thermal energy is released than with the explosion of the same amount of TNT, and one and a half times more than with the explosion of one kilogram of nitroglycerin.

Areas of application of acetylene

Acetylene is a combustible gas that is used in gas welding. Often it is used for oxygen cutting. It is worth noting that the combustion temperature of a mixture of oxygen and acetylene can reach 3300 ° C. Due to this property, the substance is most often used in welding. Acetylene usually is replaced by natural gas and propane-butane. The substance provides productivity and high quality welding.

The supply of gas for cutting and welding can be carried out from an acetylene generator or from cylinders with acetylene. For storage of this substance, white containers are usually used. As a rule, they have the inscription "Acetylene", painted with red paint. It is worth considering that there is GOST 5457-75. According to this document for processing metals used technical dissolved acetylene grade B or the substance in the gaseous form.

Acetylene welding: verification

The technology of welding with this gas is quite simple. However, when working with a substance, patience and attentiveness are required. For welding, special burners are used, with the marking 0-5. Its choice depends on the thickness of the parts to be welded. It should be noted that the larger the burner size, the higher the flow rate.

Acetylene welding is carried out only after the equipment is checked and adjusted. In doing so, note the tip number and the number of the gas injector, which is located near the handle of the burner under the nut. Also check all seals.

Welding process

The use of acetylene in welding should be done carefully and in accordance with certain rules. To start, the burner should be purged with gas. This should be done until the smell of acetylene appears. After that, the gas is ignited. At the same time, oxygen should be added until the flame becomes more stable. From the reducer at the outlet, the acetylene pressure should be from 2 to 4 atmospheres, and oxygen from 2 atmospheres.

A neutral flame is required for welding ferrous metals. It has a well-defined crown and can be divided into three bright parts: the core is bright blue with a greenish tint, the restored flame is a pale blue tint, the flame of the flame. The last two zones are workers.

Before starting work, all parts must be cleaned, and then adjusted to each other. When working with the burner, the left and right methods are also used. In the latter case, the joint slowly cools. The filler material, as a rule, moves behind the burner. With the left method, the elasticity and strength of the seam increases. In this case, the flame is sent from the welding location. The filler material should be added to the weld pool only after the burner has moved to the next position.

Safety regulations

The use of acetylene without skills and experience is prohibited. There are several rules that should be observed when working with a substance:

1. The content of acetylene in a room in the air must be constantly monitored. To do this, use special automatic devices that are able to notify about the excess gas concentration. This indicator should not be more than 0.46%.
2. Areas of application of acetylene are completely different, but most often it is used in welding. Care should be taken when working with cylinders filled with this particular gas. It is forbidden to place containers near open flames or near heating systems. In addition, it is prohibited to work with cylinders that are in the horizontal position, and also if they are not fixed and defective.
3. When working with acetylene, use only non-sparking tools, electrical equipment and explosion-proof lighting.
4. If leakage of acetylene from the cylinder occurs, the valve of the container should be quickly closed. To do this, you can use a non-sparking special key. Determine the leakage can only be by sound or smell.

What to do if there is a fire

Incorrect use of acetylene can lead to unfortunate consequences. This gas explodes and causes severe destruction. What to do if there is a fire?

1. In the event of a fire, all tanks filled with acetylene should be removed immediately from the danger zone. Those cylinders that have remained should be constantly cooled with ordinary water or with a special composition. The tanks must be completely cool.
2. If the gas that comes out of the cylinder is ignited, then immediately close the container. To do this, use a non-sparking key. After that, the container must be cooled.
3. In case of severe fire, extinguish the fire only from a safe distance. In such a situation it is worth using fire extinguishers filled with a composition containing a phlegmatizing nitrogen concentration of 70% by volume, also carbon dioxide of 75% by volume, sand, water jets, compressed nitrogen, asbestos cloth and so on.