Modern industry, engineering, construction industry and other industries rely on the use of metal. The stability of structures, the strength and reliability of buildings depend on the quality and professionalism with which gas welding was carried out. Today, specialists who can work with metal are in demand, and the advantages of welding have ensured its widespread use in the economy, in the manufacture of ships, reactors, aircraft, turbines, bridges, and other necessary structures.
The essence and specifics of the concept
The process of reliable connection of metal parts and obtaining an inextricable connection between them by means of general or partial thermal heating is called welding. Depending on the energy used for the connection, it is customary to divide it into three groups:
- thermal
- thermomechanical
- mechanical.
All types of work carried out using thermal energy belong to the first group. Electric current, electron beam, electric arc, laser radiation, gas flame are the main sources of heat exposure. Based on this, there is a division into laser, electric and gas welding.
Gas-flame connection of parts
Gas welding works when using a gas flame as a heat source. Propane, acetylene, butane, MAF, hydrogen are the main substances that ignite in combination with oxygen, and heat is generated during combustion, melting the filler material and the surface to be welded.
Recently, many acetylene replaced with liquefied MAF. It provides a higher-speed performance of such work and excellent weld quality. Also, MAF is safer than acetylene, cheaper, more convenient for transportation, but it is used only with filler material containing silicon and manganese.
The heat emanating from the combustion of gas and oxygen melts the surface of the parts and the additive, forming a weld. The flame is regulated by the amount of oxygen, and filler rods are selected based on the composition and thickness of the base metal.
Gas welding is characterized by a uniform and gradual heating of the metal. Scope of the process:
- steel with a thickness of 0.2 and not more than 5 mm;
- non-ferrous metal;
- types of steel requiring mild heating and gradual cooling;
- cast iron;
- some steels requiring heating to join.
This type of welding is also used in repair work.
Pros and cons of gas welding
Advantages:
- Simple equipment.
- Gas welding does not require a powerful source of energy.
- The flame can be controlled and, by changing the power, regulate the heating of the metal.
Disadvantages:
- Low speed of heating parts with a burner.
- Wide thermal heating zone, heat dissipates strongly.
- Reducing the efficiency of gas welding / cutting with increasing thickness of the metal.
The concept and principle of electric welding
Electric contact welding involves only bringing the metal to softness and squeezing the parts together. The connection of the metal by passing electric current through it and the electrode is called electric arc welding.
Direct or alternating current is supplied to the plug in which the electrode is fixed, and to the metal. An electric arc arises between them. Under the influence of current, it melts the electrode, metal and connects the parts together.
To perform electric welding, certain equipment is required:
- Apparatus for supplying current (transformer, rectifier, inverter).
- An electrode for welding (so that during melting to conduct current from the plug to the parts, they come in different thicknesses, depending on the metal being joined).
Be sure to adjust the current strength, since with a large metal it burns out, and with a small one the electrode will stick to the surface.
Welding risk factors
The main hazards when working with gas:
- explosive equipment in the form of gas cylinders;
- high fire hazard;
- risk of mechanical and burn injuries during operation;
- the negative effect on the human body of the emitted vapors and the light-beam effect on vision.
Safety measures can reduce the negative effects of gas welding products and reduce the risk of burns and injuries.
Rules for gas welding
Persons who have come of age and have a special level of professional certification are allowed to perform operations of this kind. Gas welding and electric welding work is carried out in compliance with established technical safety standards, which can be found in more detail in the approved Order of the Ministry of Labor of Social Protection of the Russian Federation No. 1101n dated 12/23/2014. These rules relate to employee behavior, workplace organization, tools and equipment.
Safety before starting work
To ensure a safe environment, the following rules must be followed:
- gas welding works are carried out only in fire-resistant overalls, a protective mask or dark glasses;
- smoking is prohibited;
- constant safety check and operational status of equipment;
- work is carried out far from flammable materials, combustible mixtures and liquids;
- gas cylinders are placed at a distance of more than 20 meters from the place of gas welding;
- knowledge of the rules of operation, transportation of equipment;
- carrying out work only in designated and specially equipped rooms;
- during electric welding, electric shock is possible, therefore, the cases of power sources, products must be grounded before being connected to the network;
- electricians checking the working condition of the equipment;
- during outdoor work, the equipment must be protected from moisture and precipitation.
In the absence of these conditions, welding is not allowed.