Modern industry, engineering, construction industry and other industries are based 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 production of ships, reactors, aircraft, turbines, bridges, and other necessary structures.
Essence and specificity of the concept
The process of reliable connection of metal parts and obtaining an inseparable connection between them by 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 performed using thermal energy belong to the first group. Electric current, electron beam, electric arc, laser radiation, gas flame are the main sources of thermal effects. Based on this, there is a division into laser, electric and gas welding works.
Gas-flame connection of parts
Gas welding is performed 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 released during combustion, melting the filler material and the surface to be welded.
Recently, many acetylene is replaced by liquefied MAF. It provides faster performance of such works and excellent quality of the welded joint. MAF is also safer than acetylene, cheaper, more convenient to transport, but is used only with filler material containing silicon and manganese.
The heat from the combustion of gas and oxygen fuses the surface of parts and additive, forming a weld. The flame is controlled by the amount of oxygen, and the filler rods are selected based on the composition and thickness of the base metal.
Gas welding is characterized by uniform and gradual heating of the metal. Process scope:
- steel with a thickness of 0, 2 and no more than 5 mm;
- non-ferrous metal;
- speciessteels requiring mild heating and gradual cooling;
- cast iron;
- some steels that require heating to join.
This type of welding is also used in repair work.
Pros and cons of gas welding
Dignity:
- 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.
Flaws:
- Slow speed of heating parts with torch.
- Wide thermal heating zone, heat dissipation is strong.
- Decrease in efficiency of gas welding/cutting with increasing metal thickness.
The concept and principle of electric welding
Electric resistance welding involves only bringing the metal to softening and squeezing the parts together. The connection of metal by passing an 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 occurs between them. Under the influence of current, it melts the electrode, metal and connects the parts together.
Electric welding requires certain equipment:
- Apparatus for supplying current (transformer, rectifier, inverter).
- Welding electrode (in order to conduct current from the plug to the parts during melting, they come in different thicknesses depending on the connectedmetal).
The current strength must be regulated, because with a large metal it will burn out, and with a small one, the electrode will stick to the surface.
Welding hazards
Main gas hazards:
- explosive equipment in the form of gas cylinders;
- great fire hazard;
- risk of mechanical and burn injuries during work;
- negative effect on the human body of emitted vapors and light-beam effects on vision.
Safety can reduce the negative impact of gas welding products and reduce the risk of burns and injuries.
Rules of gas welding works
Persons who have reached the age of majority and have a special level of professional certification are allowed to perform operations of this type. Gas welding and electric welding work is carried out in compliance with the 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 December 23, 2014. These rules apply to employee behavior, workplace organization, tools and equipment.
Safety before starting work
To ensure harmless conditions, the following rules should be followed:
- gas welding work is carried out only in fire-resistant overalls, a protective mask or dark glasses;
- no smoking;
- constant checkthe safety and working condition of the equipment;
- work is carried out away 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 premises;
- when electric welding, electric shock is possible, therefore, power supply cases, products must be grounded before being connected to the network;
- checking by electricians of the working condition of the equipment;
- during outdoor work, the equipment must be protected from moisture and precipitation.
If these conditions are not met, welding is not allowed.
