Methods and techniques of gas welding
Gas Welding Article
all about gas welding
Welding Torches
Types of welding torches, the device
Universal welding torch GS
a device of this classical gas burner
Technical Oxygen
oxygen use for gas welding, storage, production
Gas Welding Technology
Showing posts with label gas welding. Show all posts
Showing posts with label gas welding. Show all posts
11:36 PM
10:50 PM
Technical Oxygen
The use for gas welding, storage, production
Transportation and Storage of Oxygen
the welding technique of oxygen - a key gas. Article about oxygen technology.
When To Use Oxgen Gas Welding
about the use of oxygen in the welding process.
Production of Oxygen from Air
oxygen production is considered
Transportation and Storage of Oxygen
the welding technique of oxygen - a key gas. Article about oxygen technology.
When To Use Oxgen Gas Welding
about the use of oxygen in the welding process.
Production of Oxygen from Air
oxygen production is considered
10:41 PM
The Production of Oxygen From The Air
The production of oxygen from the air
The atmospheric dry air is a mixture containing by volume of oxygen and nitrogen 20.93% 78.03%, the rest - argon and other inert gases, carbon dioxide, etc. The content of water vapor in the air can vary widely depending on the temperature and degree of saturation. For technically pure oxygen, air, and subjected to deep cooling liquefies (the boiling point of liquid air at atmospheric pressure, -194,5 ° C.) resulting liquid air is subjected to fractional distillation or fractionation in distillation columns. The possibility of successful rectification is based on a rather large difference (about 13 °) boiling point of liquid nitrogen (-196 ° C) and oxygen (-183 ° C).
The air drawn multistage compressor, passes first through an air filter which is cleaned from dust, then passes sequentially compressor stage. For each stage of the compressor air pressure increases, and brought up to 50-220 atm, depending on the system installation and production stage. After each stage of the compressor air is drier, which is separated by water condensing in the air compression, and: water cooler, the cooling air, consuming the heat produced by the compression. In order to absorb carbon dioxide from the air turns the machine - calciner, filled with an aqueous solution of sodium hydroxide. Compressed air from the compressor runs out of battery drainage bottles, filled with lump caustic soda, which absorbs moisture and carbon dioxide balances. Complete removal of moisture and carbon dioxide from the air is of considerable importance, since freezing at low temperatures, carbon dioxide, water and clog the pipes of the oxygen machine and have to stop setting for defrosting and purging.
After a battery drainage, compressed air enters the so-called breathing apparatus, where the cooling and liquefaction of air and its fractionation with separation into oxygen and nitrogen. Nitrogen gas purity of 96-98% is usually not used and the heat exchanger is produced in the atmosphere. The oxygen is sent to the gas tank and fed to the filling of oxygen cylinders pressurized to 165 atm, 1 m3 of oxygen at 760 mm Hg. of Art. and 0 ° C weighs 1.43 kg and at 20 ° C, 1.31 kg, 1 liter of liquid oxygen weighs 1.13 kg and evaporates, forms a 0.79 m3 of gaseous oxygen at 0 ° C and 760 mm Hg ., 1 kg of liquid oxygen occupies a volume of 0.885 liters and evaporates, forming 0.70 l3 oxygen gas at 0 ° C and 760 mm Hg. Art.
According to GOST 5583-58 technical oxygen for flame treatment of metals is available in three varieties, the highest grade, with a purity of not less than 99.5%, 1st grade, not below 99.2% and 2nd grade, not below 98.5% oxygen by volume.
Significant economic interest in delivery of oxygen to the oxygen plant to customers in a liquid form, in which the tare weight is about 50% of the total weight of cargo, with the same weight of cargo transported liquid oxygen is 5 times greater than for the transport of its gaseous form. To be able to use liquid oxygen are necessary: 1) a transport tank for transportation of liquid oxygen, mounted on a vehicle, usually belonging to the oxygen plant, and 2) the gasifier, which serves to convert the liquid oxygen into gaseous, and is usually installed by the consumer of oxygen. The transport tank for transportation of liquid oxygen is essentially a ball of brass sheet, enclosed in a steel casing, the space between the ball and the housing is filled with insulating material - magnesium carbonate powder. Liquid oxygen is poured into the tank through the receiver-drain valve, fill the brass ball. The selection of oxygen should be performed through a flexible hose attached to the valve. Since the ambient air temperature is always above the critical temperature, oxygen, liquid oxygen will inevitably evaporate into the surrounding atmosphere. In good condition, tank insulation, this loss may amount to 0.5% per hour. In case of increase of pressure tank equipped with a safety valve.
Consumers should have a liquid oxygen gasifiers. Oxygen gasifiers are divided into stationary and portable, as well as: a) low pressure, or cold, feed oxygen into the distribution piping system at pressures up to 15 am, and b) high pressure, or warm, give oxygen cylinder filling pressure 150-165 am.
The most common plants in our standard stationary cold gasifier with a capacity of 1000 liters or 800 m3 of liquid oxygen gas. Gasifier is installed in a separate room. It consists of a thick-walled steel ball inside which is placed a thin-walled brass ball for liquid oxygen. The ball is in the gasifier housing, the space between the casing and a ball filled with chalk, as in the oxygen tanks. Gasifier is filled with liquid oxygen from a storage tank through a valve and flexible hose. From the gasifier liquid oxygen enters the evaporator coil, and thence gaseous oxygen is sent into the network of oxygen pipelines. To equalize the pressure fluctuations befall receiver (recipient) with a capacity of about 10m3.
See also:
Gas Welding Technology
Transportation and Storage of Oxygen
When To Use Oxgen Gas Welding
Production of Oxygen from Air
The atmospheric dry air is a mixture containing by volume of oxygen and nitrogen 20.93% 78.03%, the rest - argon and other inert gases, carbon dioxide, etc. The content of water vapor in the air can vary widely depending on the temperature and degree of saturation. For technically pure oxygen, air, and subjected to deep cooling liquefies (the boiling point of liquid air at atmospheric pressure, -194,5 ° C.) resulting liquid air is subjected to fractional distillation or fractionation in distillation columns. The possibility of successful rectification is based on a rather large difference (about 13 °) boiling point of liquid nitrogen (-196 ° C) and oxygen (-183 ° C).
The air drawn multistage compressor, passes first through an air filter which is cleaned from dust, then passes sequentially compressor stage. For each stage of the compressor air pressure increases, and brought up to 50-220 atm, depending on the system installation and production stage. After each stage of the compressor air is drier, which is separated by water condensing in the air compression, and: water cooler, the cooling air, consuming the heat produced by the compression. In order to absorb carbon dioxide from the air turns the machine - calciner, filled with an aqueous solution of sodium hydroxide. Compressed air from the compressor runs out of battery drainage bottles, filled with lump caustic soda, which absorbs moisture and carbon dioxide balances. Complete removal of moisture and carbon dioxide from the air is of considerable importance, since freezing at low temperatures, carbon dioxide, water and clog the pipes of the oxygen machine and have to stop setting for defrosting and purging.
After a battery drainage, compressed air enters the so-called breathing apparatus, where the cooling and liquefaction of air and its fractionation with separation into oxygen and nitrogen. Nitrogen gas purity of 96-98% is usually not used and the heat exchanger is produced in the atmosphere. The oxygen is sent to the gas tank and fed to the filling of oxygen cylinders pressurized to 165 atm, 1 m3 of oxygen at 760 mm Hg. of Art. and 0 ° C weighs 1.43 kg and at 20 ° C, 1.31 kg, 1 liter of liquid oxygen weighs 1.13 kg and evaporates, forms a 0.79 m3 of gaseous oxygen at 0 ° C and 760 mm Hg ., 1 kg of liquid oxygen occupies a volume of 0.885 liters and evaporates, forming 0.70 l3 oxygen gas at 0 ° C and 760 mm Hg. Art.
According to GOST 5583-58 technical oxygen for flame treatment of metals is available in three varieties, the highest grade, with a purity of not less than 99.5%, 1st grade, not below 99.2% and 2nd grade, not below 98.5% oxygen by volume.
Significant economic interest in delivery of oxygen to the oxygen plant to customers in a liquid form, in which the tare weight is about 50% of the total weight of cargo, with the same weight of cargo transported liquid oxygen is 5 times greater than for the transport of its gaseous form. To be able to use liquid oxygen are necessary: 1) a transport tank for transportation of liquid oxygen, mounted on a vehicle, usually belonging to the oxygen plant, and 2) the gasifier, which serves to convert the liquid oxygen into gaseous, and is usually installed by the consumer of oxygen. The transport tank for transportation of liquid oxygen is essentially a ball of brass sheet, enclosed in a steel casing, the space between the ball and the housing is filled with insulating material - magnesium carbonate powder. Liquid oxygen is poured into the tank through the receiver-drain valve, fill the brass ball. The selection of oxygen should be performed through a flexible hose attached to the valve. Since the ambient air temperature is always above the critical temperature, oxygen, liquid oxygen will inevitably evaporate into the surrounding atmosphere. In good condition, tank insulation, this loss may amount to 0.5% per hour. In case of increase of pressure tank equipped with a safety valve.
Consumers should have a liquid oxygen gasifiers. Oxygen gasifiers are divided into stationary and portable, as well as: a) low pressure, or cold, feed oxygen into the distribution piping system at pressures up to 15 am, and b) high pressure, or warm, give oxygen cylinder filling pressure 150-165 am.
The most common plants in our standard stationary cold gasifier with a capacity of 1000 liters or 800 m3 of liquid oxygen gas. Gasifier is installed in a separate room. It consists of a thick-walled steel ball inside which is placed a thin-walled brass ball for liquid oxygen. The ball is in the gasifier housing, the space between the casing and a ball filled with chalk, as in the oxygen tanks. Gasifier is filled with liquid oxygen from a storage tank through a valve and flexible hose. From the gasifier liquid oxygen enters the evaporator coil, and thence gaseous oxygen is sent into the network of oxygen pipelines. To equalize the pressure fluctuations befall receiver (recipient) with a capacity of about 10m3.
See also:
Gas Welding Technology
Transportation and Storage of Oxygen
When To Use Oxgen Gas Welding
Production of Oxygen from Air
10:38 PM
When To Use Oxgen Gas Welding
about the use of oxygen in the welding process
The use of oxygen to gas welding are the ways in which the metal is heated high-temperature gas flame through a special welding torch. For welding of many metals is practically suitable flame at a temperature not lower than 3000 ° C. At the present time for gas-welding flame burn almost exclusively different fuels in a technically pure oxygen. Combustion of various fuels in air gives a flame with a very low temperature (not above 1800-2000 ° C), suitable for welding a very low-melting metals such as lead. Low temperature gas-flame and its suitability for small gas welding of metals is explained by a high content in the air, inert gases, mainly nitrogen, are not involved in the process of combustion, and dramatically reduce the effects and pyrometric temperature of the flame. When burning the same fuel and oxygen in the air, the overall effect of thermal or calorimetric combustion reaction in both cases is practically the same, but the flame temperature dramatically different. For ordinary cases, the welding industry, applies only flame obtained by burning fuel in a technically pure oxygen. Gas-flame can be kept in the welding technique is of limited use.
Technically, pure oxygen is the most important gas in welding technology, processes for gas welding and oxygen cutting. It is also necessary for other processes such as chemical, metallurgical and other industries, etc. For many of these productions do not require high purity of oxygen used, and sufficient supplies of cheap gas, containing oxygen in it only 50-90%. In the welding technique used high-purity oxygen, in any case not less than 98.5%
Methods of production of commercially pure oxygen may be different; industrial importance are two ways to obtain: a) from the air - a method of deep cooling and b) from the water - by means of electrolysis. In our industry is almost exclusively used method of producing oxygen from the air, as more economical, which consumes 0.5 - 1.6 kW / h of electricity per 1 m 3 of oxygen, for 1 m 3 of oxygen by electrolysis of water with simultaneous reception of 2 m three hydrogen requires 12.10 kW / h Getting oxygen means electrolysis of water can be profitable only if the simultaneous use of hydrogen produced.
See also:
Gas Welding Technology
Transportation and Storage of Oxygen
When To Use Oxgen Gas Welding
Production of Oxygen from Air
The use of oxygen to gas welding are the ways in which the metal is heated high-temperature gas flame through a special welding torch. For welding of many metals is practically suitable flame at a temperature not lower than 3000 ° C. At the present time for gas-welding flame burn almost exclusively different fuels in a technically pure oxygen. Combustion of various fuels in air gives a flame with a very low temperature (not above 1800-2000 ° C), suitable for welding a very low-melting metals such as lead. Low temperature gas-flame and its suitability for small gas welding of metals is explained by a high content in the air, inert gases, mainly nitrogen, are not involved in the process of combustion, and dramatically reduce the effects and pyrometric temperature of the flame. When burning the same fuel and oxygen in the air, the overall effect of thermal or calorimetric combustion reaction in both cases is practically the same, but the flame temperature dramatically different. For ordinary cases, the welding industry, applies only flame obtained by burning fuel in a technically pure oxygen. Gas-flame can be kept in the welding technique is of limited use.
Technically, pure oxygen is the most important gas in welding technology, processes for gas welding and oxygen cutting. It is also necessary for other processes such as chemical, metallurgical and other industries, etc. For many of these productions do not require high purity of oxygen used, and sufficient supplies of cheap gas, containing oxygen in it only 50-90%. In the welding technique used high-purity oxygen, in any case not less than 98.5%
Methods of production of commercially pure oxygen may be different; industrial importance are two ways to obtain: a) from the air - a method of deep cooling and b) from the water - by means of electrolysis. In our industry is almost exclusively used method of producing oxygen from the air, as more economical, which consumes 0.5 - 1.6 kW / h of electricity per 1 m 3 of oxygen, for 1 m 3 of oxygen by electrolysis of water with simultaneous reception of 2 m three hydrogen requires 12.10 kW / h Getting oxygen means electrolysis of water can be profitable only if the simultaneous use of hydrogen produced.
See also:
Gas Welding Technology
Transportation and Storage of Oxygen
When To Use Oxgen Gas Welding
Production of Oxygen from Air
10:13 PM
Transportation and Storage of Oxygen
the welding technique of oxygen - a key gas. Article about oxygen
Transportation and storage of oxygen
Oxygen from the air to receive special oxygen plants. Therefore, considerable importance is the transportation and storage of oxygen. Oxygen is usually stored and transported in gaseous form in steel cylinders under a pressure of 150 atm.
(1 - Cap 2 - valve, 3 - ring 4 - the neck, 5 - shoe)
Oxygen cylinder (see Fig.) is a steel cylinder with a spherical head and neck for attaching shut-off valve. At the bottom of the cylinder skewer shoe that allows you to put the bottle upright. On the neck of a ring with a threaded protective cap navertyvaniya. Internal Tapered neck vvertyvaniya needed to vent. Cylinders made of seamless steel pipes carbon steel with a tensile strength not less than 65 kg / mm 2 , a yield strength of not less than 38 kg/mm2, and elongation of not less than 15%. Oxygen cylinders are made for different purposes, 0,4-50 liters capacity. In the welding technique used mainly cylinders capacity of 40 liters. This cylinder has an outer diameter of 219 mm, 1390 mm length of the body, the wall thickness of 7 mm, weighs balloon without oxygen about 60 kg. Weight cylinder of carbon steel for the working pressure of 150 atm to 1 liter capacity is 1.6-1.7 kg.
More recently begun commercial production of alloy steel cylinders, which makes it possible to increase the operating pressure of the cylinders and reduce their weight for the same capacity and pressure. To avoid dangerous mistakes when filling cylinders and use them for different gases are painted in different colors, in addition, connecting fitting shut-off valve has a variety of sizes and device. Oxygen cylinders are painted in blue on the outside and do them pa inscription in black letters, "Oxygen." Every five years, oxygen cylinder is subjected to mandatory testing, which is noted stamp, notch at the top of the spherical part of the cylinder. Produced the hydraulic test at one and a half working pressure, ie, at 225 atm
If any of the treatment with a balloon filled with oxygen under a pressure of 150 atm, an explosion may occur considerable destructive power. Therefore, when handling oxygen cylinders must adhere strictly to established safety rules. In the most responsible and dangerous workshops are advised not to make oxygen cylinders and place them outside the shop, in a separate annex, submitted to the department via the reduced oxygen low pressure, typically at 10.
Usually, the shop should not be at the same time more than ten tanks. The shop cylinders must be secured to a collar or chain wall, pillar stand, and so forth to eliminate the possibility of falling. At the plant containers should be transferred on a stretcher, or better, transported on special trucks, containers to carry on his hands is prohibited. In the carriage is recommended to use wooden pads to eliminate collision and rolling cylinders, rope, or ring, worn on the cylinders. Loading and unloading of containers should be done carefully, without jerks and shocks.
Cylinders must be protected from heat, such as a furnace, causing a dangerous rise in pressure of gas in cylinders. When working in the summer outdoors in sunny weather should cover the oxygen cylinders wet canvas. Do not allow contamination of the container, especially the valve oils and fats, which ignites spontaneously in oxygen, which can lead to an explosion cylinder. Oxygen cylinders should be stored in a designated individual stores. Transportation of oxygen gas in cylinders is expensive. Normal tank capacity of 40 liters, which weighs about 60 kg, capacity 6000 l = 6 m 3 of oxygen, weighing only 6 kg = 7.8 -1.3, so that the weight of 7.8 kg of payload to be transported container 60 kg m . is the tare weight of 88% and 12% of the payload. If we take into account maintenance, repairs and depreciation of cylinders, it is often the cost of oxygen on the spot by the consumer is much higher than its selling price at the oxygen plant. Treatment with oxygen requires strict adherence to safety rules. Oils and fats ignite spontaneously in contact with oxygen gas, which also gives explosive mixtures with combustible gases and vapors. Porous organic materials - peat, wood, cloth, etc., soaked in liquid oxygen form a powerful explosive - oksilikvity specifically used for blasting .
Oxygen cylinder valve made of brass. Connection nipple valve has the right pipe thread 3/4 ". When storing the valve is protected by a safety cap, which is shedding on the outer ring of the neck.
See also:
Gas Welding Technology
Transportation and Storage of Oxygen
When To Use Oxgen Gas Welding
Production of Oxygen from Air
Transportation and storage of oxygen
Oxygen from the air to receive special oxygen plants. Therefore, considerable importance is the transportation and storage of oxygen. Oxygen is usually stored and transported in gaseous form in steel cylinders under a pressure of 150 atm.
Oxygen cylinder (see Fig.) is a steel cylinder with a spherical head and neck for attaching shut-off valve. At the bottom of the cylinder skewer shoe that allows you to put the bottle upright. On the neck of a ring with a threaded protective cap navertyvaniya. Internal Tapered neck vvertyvaniya needed to vent. Cylinders made of seamless steel pipes carbon steel with a tensile strength not less than 65 kg / mm 2 , a yield strength of not less than 38 kg/mm2, and elongation of not less than 15%. Oxygen cylinders are made for different purposes, 0,4-50 liters capacity. In the welding technique used mainly cylinders capacity of 40 liters. This cylinder has an outer diameter of 219 mm, 1390 mm length of the body, the wall thickness of 7 mm, weighs balloon without oxygen about 60 kg. Weight cylinder of carbon steel for the working pressure of 150 atm to 1 liter capacity is 1.6-1.7 kg.
If any of the treatment with a balloon filled with oxygen under a pressure of 150 atm, an explosion may occur considerable destructive power. Therefore, when handling oxygen cylinders must adhere strictly to established safety rules. In the most responsible and dangerous workshops are advised not to make oxygen cylinders and place them outside the shop, in a separate annex, submitted to the department via the reduced oxygen low pressure, typically at 10.
Usually, the shop should not be at the same time more than ten tanks. The shop cylinders must be secured to a collar or chain wall, pillar stand, and so forth to eliminate the possibility of falling. At the plant containers should be transferred on a stretcher, or better, transported on special trucks, containers to carry on his hands is prohibited. In the carriage is recommended to use wooden pads to eliminate collision and rolling cylinders, rope, or ring, worn on the cylinders. Loading and unloading of containers should be done carefully, without jerks and shocks.
Cylinders must be protected from heat, such as a furnace, causing a dangerous rise in pressure of gas in cylinders. When working in the summer outdoors in sunny weather should cover the oxygen cylinders wet canvas. Do not allow contamination of the container, especially the valve oils and fats, which ignites spontaneously in oxygen, which can lead to an explosion cylinder. Oxygen cylinders should be stored in a designated individual stores. Transportation of oxygen gas in cylinders is expensive. Normal tank capacity of 40 liters, which weighs about 60 kg, capacity 6000 l = 6 m 3 of oxygen, weighing only 6 kg = 7.8 -1.3, so that the weight of 7.8 kg of payload to be transported container 60 kg m . is the tare weight of 88% and 12% of the payload. If we take into account maintenance, repairs and depreciation of cylinders, it is often the cost of oxygen on the spot by the consumer is much higher than its selling price at the oxygen plant. Treatment with oxygen requires strict adherence to safety rules. Oils and fats ignite spontaneously in contact with oxygen gas, which also gives explosive mixtures with combustible gases and vapors. Porous organic materials - peat, wood, cloth, etc., soaked in liquid oxygen form a powerful explosive - oksilikvity specifically used for blasting .
Oxygen cylinder valve made of brass. Connection nipple valve has the right pipe thread 3/4 ". When storing the valve is protected by a safety cap, which is shedding on the outer ring of the neck.
See also:
Gas Welding Technology
Transportation and Storage of Oxygen
When To Use Oxgen Gas Welding
Production of Oxygen from Air
8:40 PM
Universal Welding Torch GS
is considered a device of this classical gas burner
Gaza to the burner comes on a rubber hose, worn on the nipple for oxygen and an acetylene 2. Further, the oxygen goes through the tube 3, the acetylene - the tube 4 and the approach to adjusting valves for oxygen and acetylene 5 (not shown). Then the gases are fed to the injector 6, further into the mixing chamber 7 and the tip of the tube goes into the mouthpiece 10, the output of the burn, which, forming a welding flame. The barrel and tip are connected nut 9. Gas control valves are conveniently located and allow the welder to adjust the burner, without interrupting the operation, the fingers of the same hand that holds the handle. The location of valves favorably shifts the center of gravity burners, improves balance and reduces fatigue welder.
A significant advantage of the burner HS is approximately the same oxygen pressure of about 3 atm for all sizes of tips. Standard burners are made of four types-GS-1 GS-2 GS-3 GS-4.
GS-1, a small or micropower, used for welding of thin and very thin metal, 0.05-0.6 mm. It comes with two tips number 00 with acetylene flow rate 10-25 l / h and the number 0 at a rate of 25-60 l / h, 0.24 kg weight of the burner. Burner HS-2, low-power, is used for welding of thin metal, 0,3-4 mm, with four tips, № 0, 1, 2 and 3, weight 0.32 kg burner. Burner HS-3, the average power, the most widely used in industry for welding metal thickness 0.5-30 mm, equipped with seven tips, № 1,2, 3, 4, 5, 6, 7, Weight Burner 0.5 kg . The burner is a great power, the HS-4 for metal thickness of 30-100 mm, equipped with two tip number 8 with a flow rate of acetylene 2800-4500 l / h and the number 9 with a flow rate of acetylene 4500-7000 l / h, weight 1.34 kg burners . When the ignition burner, first open the oxygen valve and a jet of oxygen creates a vacuum in the chamber of the injector, producing a leak of acetylene. Next, open the acetylene valve and ignite the mixture. Regulate the flame acetylene valve until the proper character of the flame and the gas composition: size, shape and color the inside of the flame, the so-called core of the flame. extinguish the flame in the reverse order: first close the acetylene valve, and then oxygen. Acetylene valve cover and when the reverse shock, faults noticed the burner and burner malfunction, etc. are usually affects the appearance of the flame, which receives an irregular shape. welding torch is quite complex and accurately manufactured instrument and requires careful and gentle treatment. When breaks in the gun rack or hang on a hook in the workplace. With a significant heating of the burner cool dip in a bucket of water, located at the welder's job, the oxygen valve is opened at the same time, eliminating the possibility of water ingress into the burner. Channels can be cleaned just the mouthpiece copper or brass prochischalkami. Use for this purpose steel wire is prohibited as it scratches and develops channel mouthpiece and quickly leads him into disrepair. addition to the normal, standard, widely used in industrial welding torches, there are numerous specific types of burners used relatively rarely. It may be noted a special form of tips for welding in confined spaces, two-and trehplamennye burners, burners for heating, soldering torch, whose mouthpiece has side openings for air leaks, reducing the very high temperature acetylene-oxygen flame, especially the powerful water-cooled torch etc. All these special burners in our industry are very limited application. In recent years, there were special mnogoplamennye welding torches with a lot of flame in a burner.
See also:
Gas Welding Technology
Gas Welding Article
Welding Torches
Universal welding torch GS
Technical Oxygen
Gaza to the burner comes on a rubber hose, worn on the nipple for oxygen and an acetylene 2. Further, the oxygen goes through the tube 3, the acetylene - the tube 4 and the approach to adjusting valves for oxygen and acetylene 5 (not shown). Then the gases are fed to the injector 6, further into the mixing chamber 7 and the tip of the tube goes into the mouthpiece 10, the output of the burn, which, forming a welding flame. The barrel and tip are connected nut 9. Gas control valves are conveniently located and allow the welder to adjust the burner, without interrupting the operation, the fingers of the same hand that holds the handle. The location of valves favorably shifts the center of gravity burners, improves balance and reduces fatigue welder.
GS-1, a small or micropower, used for welding of thin and very thin metal, 0.05-0.6 mm. It comes with two tips number 00 with acetylene flow rate 10-25 l / h and the number 0 at a rate of 25-60 l / h, 0.24 kg weight of the burner. Burner HS-2, low-power, is used for welding of thin metal, 0,3-4 mm, with four tips, № 0, 1, 2 and 3, weight 0.32 kg burner. Burner HS-3, the average power, the most widely used in industry for welding metal thickness 0.5-30 mm, equipped with seven tips, № 1,2, 3, 4, 5, 6, 7, Weight Burner 0.5 kg . The burner is a great power, the HS-4 for metal thickness of 30-100 mm, equipped with two tip number 8 with a flow rate of acetylene 2800-4500 l / h and the number 9 with a flow rate of acetylene 4500-7000 l / h, weight 1.34 kg burners . When the ignition burner, first open the oxygen valve and a jet of oxygen creates a vacuum in the chamber of the injector, producing a leak of acetylene. Next, open the acetylene valve and ignite the mixture. Regulate the flame acetylene valve until the proper character of the flame and the gas composition: size, shape and color the inside of the flame, the so-called core of the flame. extinguish the flame in the reverse order: first close the acetylene valve, and then oxygen. Acetylene valve cover and when the reverse shock, faults noticed the burner and burner malfunction, etc. are usually affects the appearance of the flame, which receives an irregular shape. welding torch is quite complex and accurately manufactured instrument and requires careful and gentle treatment. When breaks in the gun rack or hang on a hook in the workplace. With a significant heating of the burner cool dip in a bucket of water, located at the welder's job, the oxygen valve is opened at the same time, eliminating the possibility of water ingress into the burner. Channels can be cleaned just the mouthpiece copper or brass prochischalkami. Use for this purpose steel wire is prohibited as it scratches and develops channel mouthpiece and quickly leads him into disrepair. addition to the normal, standard, widely used in industrial welding torches, there are numerous specific types of burners used relatively rarely. It may be noted a special form of tips for welding in confined spaces, two-and trehplamennye burners, burners for heating, soldering torch, whose mouthpiece has side openings for air leaks, reducing the very high temperature acetylene-oxygen flame, especially the powerful water-cooled torch etc. All these special burners in our industry are very limited application. In recent years, there were special mnogoplamennye welding torches with a lot of flame in a burner.
See also:
Gas Welding Technology
Gas Welding Article
Welding Torches
Universal welding torch GS
Technical Oxygen
8:35 PM
Welding Torch
Types of welding torches, the device
Welding torch is a working tool for gas welders, and allows for autogenous welding flame, heated, and molten metal. The modern torch must meet many stringent requirements: to provide stable welding flame of the desired shape, to have precise control, consistently support the established mode of fire, have sufficient strength not to require frequent repairs, be simple, convenient and safe to use, have the lowest possible weight and m . etc. These requirements can be sufficiently well designed to meet a torch, carefully and precisely manufactured from quality materials.
Basic material for the manufacture of burners is a brass mouthpiece made of red copper, and sometimes to reduce the weight of the burners used lightweight aluminum alloys. Welding Torch can be made for different combustible gases, combusted in a mixture with oxygen or air. In the future, will be considered primarily oxygen-acetylene torch, prevailing in the welding technique. Burners have a different capacity, allowing welding thick steel 0.2-30 mm, but the special types of burners can have more power, and there are special burners and thin metal. On the basis of the most important constructive welding torches can be divided into two main types: the burner injector or low pressure, and bezynzhektornye, or high-pressure burners belonging to one or another type is determined by the presence or absence of the injector for the suction of the fuel gas. need to use the injector is determined by the pressure of fuel gas. If a combustible gas has a high enough pressure, not less than 0.5 atm, he can come to the burner by gravity, and the burner may not have the injector. Bezynzhektornaya burner can be operated only at sufficiently high pressure of fuel gas, so she called a high pressure burner. If the pressure of fuel gas slightly (less than 0.5 atm), it is necessary, moreover, forced feeding or leak of fuel gas, which is a special injector, oxygen is embedded into the burner. Therefore, injection burners are called low-pressure burners. This burner can be operated at a pressure of 0.005 atm of combustible gas. The burner can run low pressure and high pressure fuel gas (more than 0.5 atm), but in this case, apply a high pressure burner. At pressures below 0.5 atm injection burner is irreplaceable, unique fit. Given that the burner pressure (bezynzhektornoy) there is no injector, it is easier to design a low-pressure burner (see Fig. a). Oxygen is supplied to the burner on the rubber hose and a nipple and receiving a control valve passes to the mixer 3, where the oxygen flow is broken into thin streams for better mixing with fuel gas, and then passes into the nozzle mixing 4. Quite similar is the way fuel gas entering the burner through the control valve 2. Of the three mixer blend the fuel with oxygen gas enters the mixing chamber 5, where the cross section due to the increase of gas flow rate decreases, and it ends with a mixture of oxygen and combustible gas, which gives the output of the mixing chamber uniform throughout the volume of combustible mixture. From the mixing chamber 5 ready-mix tip passes through the tube 6 and the channel through a calibrated die 7 comes out, where and burns, forming a welding flame. For the formation of normal welding flame flammable gas mixture to flow from the canal orifice burner with a certain speed as burning a mixture of . By increasing the velocity of the gas mixture in excess of the flame separates from the mouthpiece, more and more away from it with increasing shear rate, and finally goes out. With decreasing velocity of the gas mixture from the flame jumps mouthpiece mouthpiece through a channel inside the burner ignites and the explosion of a combustible mixture within the burner. Thus, the torch can work properly only when a certain constant velocity of the gas mixture from the mouthpiece, which might vary only within narrow limits . This normal velocity of the flow depends on the composition of the gas mixture, the diameter of the output channel and the construction of the mouthpiece. For the acetylene-oxygen mixture, this rate for different sizes of burners is in the range 70-160 m / sec. To create such a rate at the outlet of the mouthpiece and to overcome internal resistance burner is required, as experience shows, the gas pressure at the inlet to the burner of the order of 0.5-0.7 atm. Required pressure is approximately the same for both oxygen and acetylene. Bezynzhektornye burner may be constructed for both acetylene and other flammable gases - hydrogen, methane. They are relatively simple in design, well-supported by the constancy of the gas mixture, provide stable welding flame. Despite these positive qualities, a high-pressure burners in our industry are used less often because they can only work on the acetylene sufficient pressure, and the industry makes wide use of low-pressure acetylene. Industrial applications are often injection burner (see Fig. b). Oxygen under pressure of 3.4 atm enters the burner through the nipple, and a control valve, the injector is in the cone 3 is a narrow channel injection cone and exits at high speed in the expanding mixing chamber 5. Breaking with great speed from a narrow channel injection cone 3, the oxygen creates a significant vacuum in the chamber injector 4 and thus force sucks or injects the fuel gas (usually acetylene), entering through the nipple and the valve chamber 2 in the injector, from which it enters the mixing chamber 5, thence in a combustible gas mixture of oxygen with the proper speed for moving the tip of the tube 6 and leaves the burner via a mouthpiece 7. Under the influence of the injection jet tiruyuschey oxygen pressure in the injector chamber falls below atmospheric pressure. Normally produced by our industry of welding torches in the vacuum chamber of the injector is 1000-3500 mm of water. of Art. for tips of different sizes, and the pressure of oxygen supplied to the burner for proper operation the injector should be about 3-3.5 atm. consumption of oxygen in the fuel injection burner remains almost constant and hardly depends on factors such as heating burner orifice, the resistance change expiration gas from the pipe mouthpiece, etc. On the other hand, the consumption of acetylene is easily changed by the influence of various factors and can vary significantly and quickly, disrupting the normal composition of the gas mixture leaving the burner and supplied to the welding flame. Strong influence on the consumption of acetylene in the torch injector and flow it into the welding flame heating is provided a mouthpiece and the tip of the burner, the increase in resistance to the exit gas from the mouthpiece, the change in pressure gas entering the burner. heating burner tip weakens the effect of injecting oxygen and reduces the vacuum in the chamber of the injector, which reduces the flow of acetylene torch. Since the oxygen supply to the burner at the same time remains almost constant, the content of acetylene in the gas mixture decreases against the rules and increased oxidative effect of the welding flame. To restore the normal composition of the mixture and the nature of the welding flame welder must periodically with increasing heating burner tip, increasing the flow of acetylene the burner by opening the acetylene valve on the torch. Resistance to the expiration of a mixture of the mouthpiece may increase, for example, by clogging the channel orifice spray of metal and, more importantly, due to approximations of the burner to the product, causing decreases the distance from the edge of the mouthpiece to the surface of the product. With increasing resistance to the expiration of the gas mixture increases the pressure in the tube tip and the rise in temperature similar to that of the tip reduces the content of acetylene in the mixture and increases the oxidative action of the flame. With the increase of oxygen pressure at the inlet to the burner increases the oxygen content in the mixture, with a decrease - is reduced. When the pressure at the inlet of acetylene torch enriched mixture of acetylene at low pressure reduces the content of acetylene in the mixture. Thus, the injection burner does not provide a constant gas mixture composition, since the composition changes during welding, the welder must continually monitor and adjust the nature of the flame the mixture acetylene torch valve. Variability of the mixture is a significant lack of injection burners. Its main advantage is that you can run on any low-pressure acetylene, ranging from 50 mm of water. of Art. This advantage is crucial, and now our industry has enjoyed almost exclusively injector burners, as the production of acetylene, medium pressure, sufficient to supply bezynzhektornyh burners are still low. However, the injection burner can work on acetylene not only low but also high blood pressure. The higher pressure of acetylene, the better the injection burner. Changes in the composition of the gas mixture under the influence of the burner and heat resistance increases the expiration of a mixture of the mouthpiece is especially noticeable at low pressure acetylene. With increasing pressure, changing the composition of the mixture decreases, and at work on acetylene medium pressure injection burner works almost as stable as bezynzhektornaya. Injection torch welding flame gives a certain size, a change which is possible only in a small range, since a significant increase in the gas flow causes the separation of the flame from the mouthpiece and its extinction, reducing the gas flow is jumping through the flames into the burner and the reverse shock. In this connection it is necessary to stop the burner operation, fully close the acetylene valve on the burner, and then reopen it, to re-ignite and adjust the welding flame. To change the size of the welding flame, such as the transition metal for welding different thickness, it is necessary to apply the torch of a different size. To reduce and simplify the tools normally used by welders universal burners with multiple interchangeable tips. This burner consists of a constant part of the trunk and replacement parts - the tip, which are connected nut. The trunk consists of a handle, adjusting valves, connecting tubes and nipples for gas; tip - from the injector, mixing chamber, the tube tip and mouthpiece. Each number denotes the size of the tip.
See also:
Gas Welding Technology
Gas Welding Article
Welding Torches
Universal welding torch GS
Technical Oxygen
Welding torch is a working tool for gas welders, and allows for autogenous welding flame, heated, and molten metal. The modern torch must meet many stringent requirements: to provide stable welding flame of the desired shape, to have precise control, consistently support the established mode of fire, have sufficient strength not to require frequent repairs, be simple, convenient and safe to use, have the lowest possible weight and m . etc. These requirements can be sufficiently well designed to meet a torch, carefully and precisely manufactured from quality materials.
Basic material for the manufacture of burners is a brass mouthpiece made of red copper, and sometimes to reduce the weight of the burners used lightweight aluminum alloys. Welding Torch can be made for different combustible gases, combusted in a mixture with oxygen or air. In the future, will be considered primarily oxygen-acetylene torch, prevailing in the welding technique. Burners have a different capacity, allowing welding thick steel 0.2-30 mm, but the special types of burners can have more power, and there are special burners and thin metal. On the basis of the most important constructive welding torches can be divided into two main types: the burner injector or low pressure, and bezynzhektornye, or high-pressure burners belonging to one or another type is determined by the presence or absence of the injector for the suction of the fuel gas. need to use the injector is determined by the pressure of fuel gas. If a combustible gas has a high enough pressure, not less than 0.5 atm, he can come to the burner by gravity, and the burner may not have the injector. Bezynzhektornaya burner can be operated only at sufficiently high pressure of fuel gas, so she called a high pressure burner. If the pressure of fuel gas slightly (less than 0.5 atm), it is necessary, moreover, forced feeding or leak of fuel gas, which is a special injector, oxygen is embedded into the burner. Therefore, injection burners are called low-pressure burners. This burner can be operated at a pressure of 0.005 atm of combustible gas. The burner can run low pressure and high pressure fuel gas (more than 0.5 atm), but in this case, apply a high pressure burner. At pressures below 0.5 atm injection burner is irreplaceable, unique fit. Given that the burner pressure (bezynzhektornoy) there is no injector, it is easier to design a low-pressure burner (see Fig. a). Oxygen is supplied to the burner on the rubber hose and a nipple and receiving a control valve passes to the mixer 3, where the oxygen flow is broken into thin streams for better mixing with fuel gas, and then passes into the nozzle mixing 4. Quite similar is the way fuel gas entering the burner through the control valve 2. Of the three mixer blend the fuel with oxygen gas enters the mixing chamber 5, where the cross section due to the increase of gas flow rate decreases, and it ends with a mixture of oxygen and combustible gas, which gives the output of the mixing chamber uniform throughout the volume of combustible mixture. From the mixing chamber 5 ready-mix tip passes through the tube 6 and the channel through a calibrated die 7 comes out, where and burns, forming a welding flame. For the formation of normal welding flame flammable gas mixture to flow from the canal orifice burner with a certain speed as burning a mixture of . By increasing the velocity of the gas mixture in excess of the flame separates from the mouthpiece, more and more away from it with increasing shear rate, and finally goes out. With decreasing velocity of the gas mixture from the flame jumps mouthpiece mouthpiece through a channel inside the burner ignites and the explosion of a combustible mixture within the burner. Thus, the torch can work properly only when a certain constant velocity of the gas mixture from the mouthpiece, which might vary only within narrow limits . This normal velocity of the flow depends on the composition of the gas mixture, the diameter of the output channel and the construction of the mouthpiece. For the acetylene-oxygen mixture, this rate for different sizes of burners is in the range 70-160 m / sec. To create such a rate at the outlet of the mouthpiece and to overcome internal resistance burner is required, as experience shows, the gas pressure at the inlet to the burner of the order of 0.5-0.7 atm. Required pressure is approximately the same for both oxygen and acetylene. Bezynzhektornye burner may be constructed for both acetylene and other flammable gases - hydrogen, methane. They are relatively simple in design, well-supported by the constancy of the gas mixture, provide stable welding flame. Despite these positive qualities, a high-pressure burners in our industry are used less often because they can only work on the acetylene sufficient pressure, and the industry makes wide use of low-pressure acetylene. Industrial applications are often injection burner (see Fig. b). Oxygen under pressure of 3.4 atm enters the burner through the nipple, and a control valve, the injector is in the cone 3 is a narrow channel injection cone and exits at high speed in the expanding mixing chamber 5. Breaking with great speed from a narrow channel injection cone 3, the oxygen creates a significant vacuum in the chamber injector 4 and thus force sucks or injects the fuel gas (usually acetylene), entering through the nipple and the valve chamber 2 in the injector, from which it enters the mixing chamber 5, thence in a combustible gas mixture of oxygen with the proper speed for moving the tip of the tube 6 and leaves the burner via a mouthpiece 7. Under the influence of the injection jet tiruyuschey oxygen pressure in the injector chamber falls below atmospheric pressure. Normally produced by our industry of welding torches in the vacuum chamber of the injector is 1000-3500 mm of water. of Art. for tips of different sizes, and the pressure of oxygen supplied to the burner for proper operation the injector should be about 3-3.5 atm. consumption of oxygen in the fuel injection burner remains almost constant and hardly depends on factors such as heating burner orifice, the resistance change expiration gas from the pipe mouthpiece, etc. On the other hand, the consumption of acetylene is easily changed by the influence of various factors and can vary significantly and quickly, disrupting the normal composition of the gas mixture leaving the burner and supplied to the welding flame. Strong influence on the consumption of acetylene in the torch injector and flow it into the welding flame heating is provided a mouthpiece and the tip of the burner, the increase in resistance to the exit gas from the mouthpiece, the change in pressure gas entering the burner. heating burner tip weakens the effect of injecting oxygen and reduces the vacuum in the chamber of the injector, which reduces the flow of acetylene torch. Since the oxygen supply to the burner at the same time remains almost constant, the content of acetylene in the gas mixture decreases against the rules and increased oxidative effect of the welding flame. To restore the normal composition of the mixture and the nature of the welding flame welder must periodically with increasing heating burner tip, increasing the flow of acetylene the burner by opening the acetylene valve on the torch. Resistance to the expiration of a mixture of the mouthpiece may increase, for example, by clogging the channel orifice spray of metal and, more importantly, due to approximations of the burner to the product, causing decreases the distance from the edge of the mouthpiece to the surface of the product. With increasing resistance to the expiration of the gas mixture increases the pressure in the tube tip and the rise in temperature similar to that of the tip reduces the content of acetylene in the mixture and increases the oxidative action of the flame. With the increase of oxygen pressure at the inlet to the burner increases the oxygen content in the mixture, with a decrease - is reduced. When the pressure at the inlet of acetylene torch enriched mixture of acetylene at low pressure reduces the content of acetylene in the mixture. Thus, the injection burner does not provide a constant gas mixture composition, since the composition changes during welding, the welder must continually monitor and adjust the nature of the flame the mixture acetylene torch valve. Variability of the mixture is a significant lack of injection burners. Its main advantage is that you can run on any low-pressure acetylene, ranging from 50 mm of water. of Art. This advantage is crucial, and now our industry has enjoyed almost exclusively injector burners, as the production of acetylene, medium pressure, sufficient to supply bezynzhektornyh burners are still low. However, the injection burner can work on acetylene not only low but also high blood pressure. The higher pressure of acetylene, the better the injection burner. Changes in the composition of the gas mixture under the influence of the burner and heat resistance increases the expiration of a mixture of the mouthpiece is especially noticeable at low pressure acetylene. With increasing pressure, changing the composition of the mixture decreases, and at work on acetylene medium pressure injection burner works almost as stable as bezynzhektornaya. Injection torch welding flame gives a certain size, a change which is possible only in a small range, since a significant increase in the gas flow causes the separation of the flame from the mouthpiece and its extinction, reducing the gas flow is jumping through the flames into the burner and the reverse shock. In this connection it is necessary to stop the burner operation, fully close the acetylene valve on the burner, and then reopen it, to re-ignite and adjust the welding flame. To change the size of the welding flame, such as the transition metal for welding different thickness, it is necessary to apply the torch of a different size. To reduce and simplify the tools normally used by welders universal burners with multiple interchangeable tips. This burner consists of a constant part of the trunk and replacement parts - the tip, which are connected nut. The trunk consists of a handle, adjusting valves, connecting tubes and nipples for gas; tip - from the injector, mixing chamber, the tube tip and mouthpiece. Each number denotes the size of the tip.
See also:
Gas Welding Technology
Gas Welding Article
Welding Torches
Universal welding torch GS
Technical Oxygen
8:24 PM
Gas Welding Article
all about gas welding
Gas welding refers to a group of fusion welding methods. To carry out the welding process may use different fuels, respectively, which can distinguish between hydrogen-oxygen welding, gasoline-oxygen, etc. The overwhelming importance Oxyacetylene welding; other; fuels are of limited use. The significant difference of technological gas welding of welding - more, smooth and slow heating of the metal. This is the main difference between the gas flame from the welding arc is in some cases, the defect in the other - the advantage of a gas flame and identifies the following key areas of its application for welding: 1) steel of small thickness, 0.2-5 mm 2) non-ferrous metals, 3 ) metals that require welding mild gradual heating and slow cooling, such as many tool steels, and 4) metals that require heating during welding, such as iron and some grades of specialty steels, 5) for brazing, 6) for certain types of surfacing works.
Thanks versatility, relative simplicity and portability of equipment gas welding is very suitable for many types of repairs. Relatively slow heating of the metal gas flame rapidly reduces gas welding performance with increasing thickness of the metal and steel at a thickness of 8-10 mm above the gas welding is usually economically unprofitable, although technically still possible welding of steel thickness of 30-40 mm. During slow heating heats a large volume of the base metal adjacent to the weld pool, which, in turn, causes significant deformation (warping) of welded products. This important fact makes gas welding is technically impractical, not to mention I have about the economic disadvantages for such objects as building steel structures, bridges, railroad cars, ship hulls, large frame machines, etc. Slow heating also causes prolonged exposure to the metal zone of high temperatures, which leads to overheating, consolidation of grain a slight decrease of the mechanical properties of metals. Significant deformation of the metal, resulting in a gas cooking, limit the choices of rational forms of welded joints. Of the various forms of welds performed by arc welding, gas welding if used, usually only a simple butt joint. Fillet welds and joints and lap-fillet welding is used for the gas only when necessary because of the difficulties posed by significant deformation of the metal, characteristic of gas welding. They are used as the butt joints without the bevel edge, with no flare and flare edges (very convenient connection for gas welding), and with one-and two-sided bevel edges.
Burner is usually regulated to operate on a normal flame. The thermal effects of fire on the metal depends not only on the power of the flame, but also on the angle of inclination of the axis of the flame to the metal surface. The most intense flame effect, when its axis normal to the surface of the metal. With decreasing angle of inclination of the thermal effect of the flame is reduced and distributed over a larger area. Thus, besides the selection of the appropriate size burner, the welder can smoothly adjust the thermal effect of the flame to the metal, making the flames more than a soft or hard, changing the angle of the flame to the surface of the product. With increasing thickness of the metal taken to increase the angle of fire and reduce it to a decrease in the thickness of the metal.
Gas welding can be carried out in the bottom, vertical and overhead positions. Filler rods for gas welding of different composition are used, respectively, the nature of the base metal. The wire diameter is selected according to the thickness of the base metal.
Filler wires for gas welding of steels used is the same as for the electrodes in arc welding, and is manufactured according to GOST 2246-80. For gas welding low carbon steel wire used stamps Sv-08 Sv-Sv-08A and 15G. For welding of cast iron produced a special cast iron sterezhenki with a high content of carbon and silicon. For the deposition of hard wear-resistant coatings are manufactured of cast tungsten carbide rods.
Protection for gas welding
electrode coatings exchange used in arc welding, gas welding fluxes used quite widely, the use of which is necessary for the gas welding of cast iron, nonferrous metals and some special steels. Fluxes are added to the bath to dissolve the oxides and the formation of low-melting slag, good pop on the surface of the bath. Fluxes can be introduced into reductants and additives, alloying the weld metal. Fluxes are used in the form of powders and pastes, applied to the base metal or filler rod. Effect of fluxes on the chemical oxide can be physical and I, but often between them is difficult to draw a clear boundary.
Chemical fluxing action is the formation of metal oxides with a low-melting compounds are stable at high temperatures. For chemical fluxing metal oxides of basic character, such as ferrous oxide FeO, oxides in fluxes introduced acidic, such as silicon dioxide SiO2 (quartz sand, pounded glass window) and boric anhydride B2O3 (borax, boric acid). For fluxing acidic oxides such as silicon dioxide, SiO2, used compounds that provide the basic oxides. For this purpose, commonly used baking soda and potash Na2CO3 K2CO3, yielding, respectively, in the main zone of welding oxides Na2O and K2O. For flux-solvent used mainly halide salts of alkali and alkaline earth metals, NaCl, KC1, LiCl, CaCl2, NaF, KF, CaF2 and others ., as well as phosphate and carbonate salts of sodium. To enhance the flux of the solvent, they often add sodium bisulfate or potassium NaHSO4 and KHSO4.
The use of gas welding is extensive and varied. Gas welding is used in aircraft, where the predominant metal welding of small thickness (1-3 mm) in the manufacture of chemical equipment. It is important to forge welding in pipe laying and installation of a variety of purposes, particularly small-diameter, 100 mm. Gas welding is an indispensable powerful tool to repair and to this end is widely used in the repair shop for all modes of transport, agriculture, etc.
The quality of welded joints, gas welding performed higher than when the electrodes with a thin arc of coated ionizing, but a few inferior arc welding, electrodes made with quality. The main reason for a reduction of strength of welded joints is that when gas welding is not made of weld metal alloying, whereas in arc welding of high-quality electrodes containing coating alloys, produced a rather large doping. Thus, the gas protection afforded by reducing the welding zone of the flame to get a quality weld is less effective than the qualitative effect of electrode coatings in arc welding.
Gas welding performance, significant at small thickness of the base metal, rapidly decreases with increasing thickness. For small thicknesses (0.5-1.5 mm), gas welding performance can exceed the arc. With the increase of metal thickness to 2-3 mm in the rate of gas and arc welding are equalized, then the difference in speed increases rapidly with increasing thickness of the metal in favor of welding. For small thicknesses, the absolute consumption of gas per 1 m of the weld is small, the total cost of 1 m of the weld may be less than with other welding methods. With increasing thickness of the base metal is rapidly growing cost of gas and time spent on the weld seam 1 meter and gas welding arc becomes more expensive, the difference in cost increases rapidly with increasing thickness of the base metal. Thus, cost-gas welding is most appropriate for the welding of small metal thicknesses.
See also:
Gas Welding Technology
Gas Welding Article
Welding Torches
Universal welding torch GS
Technical Oxygen
Gas welding refers to a group of fusion welding methods. To carry out the welding process may use different fuels, respectively, which can distinguish between hydrogen-oxygen welding, gasoline-oxygen, etc. The overwhelming importance Oxyacetylene welding; other; fuels are of limited use. The significant difference of technological gas welding of welding - more, smooth and slow heating of the metal. This is the main difference between the gas flame from the welding arc is in some cases, the defect in the other - the advantage of a gas flame and identifies the following key areas of its application for welding: 1) steel of small thickness, 0.2-5 mm 2) non-ferrous metals, 3 ) metals that require welding mild gradual heating and slow cooling, such as many tool steels, and 4) metals that require heating during welding, such as iron and some grades of specialty steels, 5) for brazing, 6) for certain types of surfacing works.
Thanks versatility, relative simplicity and portability of equipment gas welding is very suitable for many types of repairs. Relatively slow heating of the metal gas flame rapidly reduces gas welding performance with increasing thickness of the metal and steel at a thickness of 8-10 mm above the gas welding is usually economically unprofitable, although technically still possible welding of steel thickness of 30-40 mm. During slow heating heats a large volume of the base metal adjacent to the weld pool, which, in turn, causes significant deformation (warping) of welded products. This important fact makes gas welding is technically impractical, not to mention I have about the economic disadvantages for such objects as building steel structures, bridges, railroad cars, ship hulls, large frame machines, etc. Slow heating also causes prolonged exposure to the metal zone of high temperatures, which leads to overheating, consolidation of grain a slight decrease of the mechanical properties of metals. Significant deformation of the metal, resulting in a gas cooking, limit the choices of rational forms of welded joints. Of the various forms of welds performed by arc welding, gas welding if used, usually only a simple butt joint. Fillet welds and joints and lap-fillet welding is used for the gas only when necessary because of the difficulties posed by significant deformation of the metal, characteristic of gas welding. They are used as the butt joints without the bevel edge, with no flare and flare edges (very convenient connection for gas welding), and with one-and two-sided bevel edges.
Burner is usually regulated to operate on a normal flame. The thermal effects of fire on the metal depends not only on the power of the flame, but also on the angle of inclination of the axis of the flame to the metal surface. The most intense flame effect, when its axis normal to the surface of the metal. With decreasing angle of inclination of the thermal effect of the flame is reduced and distributed over a larger area. Thus, besides the selection of the appropriate size burner, the welder can smoothly adjust the thermal effect of the flame to the metal, making the flames more than a soft or hard, changing the angle of the flame to the surface of the product. With increasing thickness of the metal taken to increase the angle of fire and reduce it to a decrease in the thickness of the metal.
Gas welding can be carried out in the bottom, vertical and overhead positions. Filler rods for gas welding of different composition are used, respectively, the nature of the base metal. The wire diameter is selected according to the thickness of the base metal.
Filler wires for gas welding of steels used is the same as for the electrodes in arc welding, and is manufactured according to GOST 2246-80. For gas welding low carbon steel wire used stamps Sv-08 Sv-Sv-08A and 15G. For welding of cast iron produced a special cast iron sterezhenki with a high content of carbon and silicon. For the deposition of hard wear-resistant coatings are manufactured of cast tungsten carbide rods.
Protection for gas welding
electrode coatings exchange used in arc welding, gas welding fluxes used quite widely, the use of which is necessary for the gas welding of cast iron, nonferrous metals and some special steels. Fluxes are added to the bath to dissolve the oxides and the formation of low-melting slag, good pop on the surface of the bath. Fluxes can be introduced into reductants and additives, alloying the weld metal. Fluxes are used in the form of powders and pastes, applied to the base metal or filler rod. Effect of fluxes on the chemical oxide can be physical and I, but often between them is difficult to draw a clear boundary.
Chemical fluxing action is the formation of metal oxides with a low-melting compounds are stable at high temperatures. For chemical fluxing metal oxides of basic character, such as ferrous oxide FeO, oxides in fluxes introduced acidic, such as silicon dioxide SiO2 (quartz sand, pounded glass window) and boric anhydride B2O3 (borax, boric acid). For fluxing acidic oxides such as silicon dioxide, SiO2, used compounds that provide the basic oxides. For this purpose, commonly used baking soda and potash Na2CO3 K2CO3, yielding, respectively, in the main zone of welding oxides Na2O and K2O. For flux-solvent used mainly halide salts of alkali and alkaline earth metals, NaCl, KC1, LiCl, CaCl2, NaF, KF, CaF2 and others ., as well as phosphate and carbonate salts of sodium. To enhance the flux of the solvent, they often add sodium bisulfate or potassium NaHSO4 and KHSO4.
The use of gas welding is extensive and varied. Gas welding is used in aircraft, where the predominant metal welding of small thickness (1-3 mm) in the manufacture of chemical equipment. It is important to forge welding in pipe laying and installation of a variety of purposes, particularly small-diameter, 100 mm. Gas welding is an indispensable powerful tool to repair and to this end is widely used in the repair shop for all modes of transport, agriculture, etc.
The quality of welded joints, gas welding performed higher than when the electrodes with a thin arc of coated ionizing, but a few inferior arc welding, electrodes made with quality. The main reason for a reduction of strength of welded joints is that when gas welding is not made of weld metal alloying, whereas in arc welding of high-quality electrodes containing coating alloys, produced a rather large doping. Thus, the gas protection afforded by reducing the welding zone of the flame to get a quality weld is less effective than the qualitative effect of electrode coatings in arc welding.
Gas welding performance, significant at small thickness of the base metal, rapidly decreases with increasing thickness. For small thicknesses (0.5-1.5 mm), gas welding performance can exceed the arc. With the increase of metal thickness to 2-3 mm in the rate of gas and arc welding are equalized, then the difference in speed increases rapidly with increasing thickness of the metal in favor of welding. For small thicknesses, the absolute consumption of gas per 1 m of the weld is small, the total cost of 1 m of the weld may be less than with other welding methods. With increasing thickness of the base metal is rapidly growing cost of gas and time spent on the weld seam 1 meter and gas welding arc becomes more expensive, the difference in cost increases rapidly with increasing thickness of the base metal. Thus, cost-gas welding is most appropriate for the welding of small metal thicknesses.
See also:
Gas Welding Technology
Gas Welding Article
Welding Torches
Universal welding torch GS
Technical Oxygen