Purple Copper Pipe and How to Solder Purple Copper Pipe? What is copper tubing? How to weld the purple copper pipe? Purple copper pipe is one of our common non-ferrous metal pipe, purple copper pipe is very wide range of uses, often used in welding technology, the following we come to a specific understanding; purple copper pipe and purple copper pipe how to weld it. Copper pipe is also known as copper pipe. Non-ferrous metal tube a kind. Is limited and drawn seamless tube. Lighter weight, good thermal conductivity, high low temperature strength. Commonly used in the production of heat exchange equipment (such as condensers, etc.). Also used in oxygen equipment to install low-temperature piping. Small diameter copper tube is often used to transport the pressure of the liquid (such as smooth system, oil pressure system, etc.) and used as the appearance of the pressure measurement tube.
Welding method of copper pipe
1. Commonly used welding methods
Welding copper pipe welding methods have gas welding, manual carbon arc welding, manual arc welding and manual argon arc welding methods, large structures can also be used automatic welding.
(1) gas welding of copper pipe welding
Copper pipe is most commonly used butt joints, lap joints and butyl joints as little as possible. Gas welding can be used for two kinds of wire, one is containing deoxygenated elements of the wire, such as wire 201, 202; the other is a general copper wire and the parent material of the cut strips, the use of gas flux 301 as a flux, gas welding of copper should be used in a neutral flame.
(2) hand arc welding of purple copper pipe.
Welding thickness greater than 4 mm, the welding must be preheated before welding, preheating temperature is generally about 400-500 ℃. Welding with copper 107 electrode, the power supply should be DC reverse. Welding should be a short arc, the electrode should not make lateral swing. Welding rod for reciprocating linear motion, can improve the weld formation, long weld should be used step by step back welding method, welding speed should be as fast as possible.
Multi-layer welding, must thoroughly remove the interlayer slag. Welding should be carried out in a well-ventilated place to prevent copper poisoning phenomenon. After welding, the weld should be struck with a flat hammer to eliminate stress and improve the quality of the weld.
(3) copper pipe hand argon arc welding
In the purple copper pipe manual argon arc welding, the use of welding wire has a wire 201 (special purple copper wire) and wire 202, also use purple copper wire, such as T2.
Welding should be before the welding edge of the workpiece and the welding wire surface of the oxide film, oil and other dirt must be cleaned up to avoid porosity, slag and other defects. Cleanup methods are mechanical cleaning method and chemical cleaning method. Butt joint plate thickness is less than 3mm, no beveling;
Plate thickness of 3 ~ 10mm, open V-bevel, bevel angle of 60 ° ~ 70 °; plate thickness greater than 10mm, open X-bevel, bevel angle of 60 ° ~ 70 °; in order to avoid unwelded, generally do not leave a blunt edge. According to the plate thickness and bevel size, the assembly gap of the butt joint is selected within the range of 0.5 ~ 1.5mm.
Purple copper pipe manual argon arc welding, usually using DC positive connection, that is, the tungsten pole connected to the negative pole. In order to eliminate porosity and ensure reliable fusion and weld penetration at the root of the weld, it is necessary to increase the welding speed, reduce argon consumption, and preheat the weldment. When the plate thickness is less than 3mm, the preheating temperature is 150-300 ℃; plate thickness is greater than 3mm, the preheating temperature is 350-500 ℃. Preheating temperature should not be too high, otherwise the mechanical properties of the welded joints are reduced.
(4) Carbon arc welding of copper pipes
Carbon arc welding using electrodes have carbon electrode and graphite electrode. Carbon arc welding of copper and gas welding wire used in the same, can also be used to cut the base material, available gas welding copper flux, such as gas flux 301.
2. Copper pipe welding examples
Example 1. hand tungsten argon arc welding of copper tubes
A unit in the installation of equipment in 6 Φ180mm × 10mm copper pipe (grade T2) weld port needs to be welded, the use of manual tungsten argon arc welding method to achieve good results, the welding process is as follows:
1.1 Welding preparation
1.1.1 Welding equipment for WSE-350 type AC and DC tig welding machine, DC positive connection. Welding material selection of copper wire (wire 201), diameter 3mm. argon purity ≥ 99.96%.
1.1.2 Bevel grouping without leaving a gap.
1.1.3 Copper welding area and copper wire shall not have oil, oxide layer, water, etc., and reveal the metal luster.
1.1.4 Welding parameters: tungsten electrode: Φ3mm cerium tungsten electrode, nozzle: Φ14mm, welding current 160~180A, argon gas flow: 15L/min.
1.1.5 Preheating: Due to the thermal conductivity and thermal expansion coefficient of copper is large, and has the thermal brittleness, so the bevel of copper pipe and bevel on both sides of the 60mm preheating, preheating method using oxygen - acetylene flame heating, preheating temperature of 500 ℃ or so, the temperature measurement method is: point contact thermometer.
1.1.6 Positioning pipe fittings welded in two places (according to the pipe circumference in three equal parts, two for the positioning of welding, one for the start of the weld), the positioning of welding requirements length ≥ 10mm, weld height of 3mm is appropriate.
1.2 Welding
Welding level for two layers, namely, bottoming layer and cover layer, are rotating welding, welding position in the clock at 10:00 to 11:30, randomly rotating upward welding.
1.2.1 Bottom welding: bottom welding using the left welding method, welding to prevent the production of porosity, slag, weld tumor and weld defects such as failure to weld through. Welding wire and pipe plane angle should be as small as possible, in order to strengthen the argon gas protection effect.
Welding gun movement is uniform, control the melt pool temperature should be appropriate, not too high or too low, the welding process can be carried out smoothly, the key is to pay close attention to the liquid flow of the molten pool of copper, to master the melting, weld through the timing of the molten pool of metal when the trend of a slight sinking indicates that the weld through (the root of the basic good shape).
Take "intermittent" wire feeding method for filling, that is, a copper wire to send a retreat, send a "sharp", retreat "clean", always keep this state of uniformity forward welding, if the welding If the welding speed is a little slow or uneven weld penetration will not be welded through or burned through, and the formation of weld tumor. The arc, joints and operating methods and the aforementioned argon arc welding pipe welding the same way.
1.2.2 cover layer welding: the welding torch swings left and right, the wire is also with the torch movement and wire feeding, arc movement to the bevel on both sides to pause, and add wire to fill the bevel, and higher than the pipe plane 1.5 ~ 2mm, the welding torch and the wire with each other properly, and swing evenly, in order to control the shape of the molten pool is the same, in order to weld inside and outside of the weld with excellent quality.
1.3 Precautions
(1) Welding is strictly prohibited "tungsten" (i.e., tungsten electrode and wire or tungsten electrode and molten pool contact) phenomenon occurs. Welding "tungsten" will produce a large amount of metal fumes, metal vapor into the molten pool, the weld will produce a large number of honeycomb pores or cracks, such as "tungsten" phenomenon, you must stop welding, processing and grinding before welding, and replace the tungsten electrode or the tip of the tungsten electrode re-trimming, the tungsten electrode is not allowed. Replace the tungsten electrode or reshape the tungsten electrode tip to achieve no copper spot metal.
(2) The contact of the lap wire should be firm to prevent the surface of the pipe from being scratched.
3)After the weld has cooled down a little, then turn the pipe fittings and pad them firmly.
(4) Control the temperature between layers, found that the application of welding melting difficulties, indicating that the temperature has been low, should be re-preheated to more than 500 ℃, and then welded, otherwise prone to unfused or poor fusion defects.
(5) in the case of ensuring good fusion, welding speed should be a little faster, and master the appropriate wire feeding, pay attention to the base material and wire melting and fusion at the same time, to prevent the production of unfused or poorly fused defects.
(6) welding arc off, the welding torch can not be lifted immediately, should continue to protect the molten pool using the lagging gas protection function, in order to prevent the generation of porosity.
1.4 Post-welding treatment
After inspection, there is no porosity, cracks, slag and other defects, the welded pipe joints will be welded to the welding area reheated to 600 ~ 700 ℃, with tap water cooled sharply, so that the welded area to increase plasticity.
Example 2 Oxygen - acetylene welding welding δ = 2mm thin copper plate
Blast furnace circulating cooling pool stopper is made of δ=2mm thin copper plate welded in pairs. Welding because of the copper thermal conductivity is very good, either due to the temperature is not enough to form a molten pool, resulting in the weld metal on the weld channel is not fused or fused poorly; either the temperature is too high, the weld area melted a large area, the formation of burn-through or weld tumor and other welding defects, the welding of thin copper plate is a relatively "tricky" problem.
According to the above situation using "brass brazing" welding method can be a good solution to this problem. Welding preparation and welding operation process is as follows:
(1) 60mm on each side of the weld to do the decontamination process and use a wire brush to polish the metal luster.
(2) weldments grouping not open bevel, grouping gap should be <1mm.
(3) Ф3mm silicon brass wire (wire 224) and flux 301 flux.
(4) will be welded at the pad flat (pad plate with flat steel plate, require thicker, in order to prevent thermal deformation).
(5) preheating, two welders using a medium-sized torch, neutral flame at the same time to heat the weld, the temperature reaches 500 ~ 600 ℃. One welding, the other is still in front of the welding position to continue to heat to ensure the stability of the welding process.
(6) preheating of the welder using neutral flame, welding welder using micro-oxidation flame.
(7) Positioning welding and formal welding should be carried out continuously, the positioning of the spacing of 60 ~ 80mm is appropriate, the positioning of the welding point should be smaller.
(8) heating and welding should pay close attention to the changes in the temperature of the welding area to prevent too high and too low, general visual inspection to dark red (550 ~ 600 ℃) is appropriate.
(9) The welding nozzle should swing smoothly and move forward at an even speed. The core of the flame (white point) should be higher than the melting pool 5~8mm. the outline of the flame should always shroud the melting pool, avoid contact with air. Ensure that the brass liquid is very natural, smooth diffusion to both sides of the weld, and immersed in the gap.
(10) In order to make the organization of welded joints crystallization of fine, improve the strength and toughness, after welding with a small hammer to properly beat the welding flesh.
(11) After welding to do the densification performance test.
