How to weld copper pipes, and how to weld copper pipes?

How to weld air conditioning copper pipes to copper pipes? Copper and copper pipe welding generally uses silver electrodes (which have a silver content of % or 5%) or copper phosphorus series electrodes, which have good fluidity and do not require flux. The specific welding steps are as follows:

1) Processing of welded copper pipes: expand the pipe, deburr, and remove the oxide layer and dirt with sandpaper for the old copper pipes. When the diameter of the welded copper pipe is different, in order to ensure that the weld gap is not too large, the pipe with a large diameter needs to be clamped small.

2) Nitrogen filling: The copper pipe is filled with nitrogen and then welded, which can make the inner wall of the copper pipe bright, clean and free of oxide layer, so as to effectively control the cleanliness of the system. 3) Turn on the welding torch to ignite, adjust the mixing ratio of oxygen and acetylene, and select a neutral flame.

4) Heat the insertion tube with a flame first, move the flame to the outer sleeve tube after it is slightly heated, and then heat the whole tube slightly, when the pipe joint is evenly heated to the welding temperature (microscopic red), add solder (silver electrode or phosphor copper electrode). The solder melting depends on the temperature of the pipe, and the temperature of the pipe joint is maintained by the outer flame of the flame, and the method of melting the solder and dripping into the soldering joint in advance cannot be used, and then heating the soldering joint, otherwise the strength and compactness of the joint will be affected. 5) Remove the flame and turn off the welding gun.

Check the quality of the weld and reheat the repair weld if it is found that there are still gaps in the weld or there is a sand heel.

How to weld copper pipes correctly, the little brother will teach you the easiest way, and novices can also weld well.

Copper-to-copper brazing.

Phosphor copper solders or phosphor copper solders with low silver content, such as 2% or 5% silver-based solders, can be used. This solder** is inexpensive, has a good solution, uses a caulking and wetting process, and does not require flux.

Welding steps: When welding, the operation should be strictly followed by the steps, otherwise, the quality of welding will be affected.

1. Preparation and piping.

Check that the amount inside the oxygen cylinder and acetylene bottle is sufficient.

Check the requirements of the drawings to ensure that the components are complete and functional.

Ensure that the optical path of the pipeline is horizontal and vertical, and pay attention to the directionality of each valve.

According to the size and pipe diameter required by the drawing, measure the corresponding length with a tape measure, and use the wire number pen to click the position a few times.

After the thicker copper pipe is fixed, it should be removed with a cutter to ensure that the cutting edge is flat and not deformed.

File the raw edge of the cut with a file and wipe it clean with a rag. Material flow and weld quality.

Except for copper and copper welding, all pipe fittings should be cleaned with gauze or stainless steel wire brush before welding, exposing the shiny metal surface. (The inner surface should be cleaned, and the metal scraps and sand particles should be removed).

Insert the copper pipes to be welded on top of each other (note the size) and align the center of the circle.

The insertion depth and clearance of copper pipe joints and copper pipes are shown in the table. (Insertion depth is approximately equal to pipe diameter).

2 Protection. When welding, low-speed nitrogen should be passed through the milk of the welded pipe to prevent oxidation.

Acetylene gas should pass through the non-oxidation welding generator to prevent oxidation of the outer surface of the welded object.

3. Welding. When welding, the weldment must be preheated. When the copper pipe is heated to purple red, the solder is leaned against the weld after the flame is moved, so that the solder melts and flows into the soldered copper parts

around 600 degrees Celsius; Deep red: around 700 degrees Celsius; Orange-red: around 1000 degrees Celsius.

When welding, the gas welding flame must not directly heat the electrode.

For the parts that are easy to deform and damaged under high temperature conditions, corresponding protective measures should be taken. For solenoid valves, expansion valves, liquid mirrors, and four-way valves, which can be disassembled, must be disassembled and welded, and the above measures are also taken if they cannot be disassembled.

When welding, when annealing the copper tube after welding, the annealing temperature is not less than 300 degrees Celsius. After welding, it is cooled and the oxides and welding slag in the pipe are cleaned with dry nitrogen.

Pipeline cutting: Hacksaws, grinders, and copper pipe cutters can be used for careful cutting of copper pipes, but oxygen-acetylene cutting is not allowed. The beveling of copper pipe is processed by file or beveling machine, but oxygen-acetylene flame cutting is not allowed.

The vise jaws for clamping copper pipes should be padded with wooden planks on both sides to prevent pinching of the pipes.

Copper tube insertion: The surface of the joint part shall not have any kind of grease, oxide letter, smudge and slippery dust, otherwise it will seriously affect the welding performance of the brazing metal to the base metal and produce defects. Therefore, the surface should be scrubbed with other organic solvents.

Copper pipe joints are generally free of dirt, if there is a copper wire brush and steel wire brush to treat the end, can not be treated with other unclean utensils.

Use sandpaper to polish the surface of the copper tube copper tube into the joint part to remove grease, oxide, stains and dust.

Evenly heat the welded pipe fittings, dip an appropriate amount of brazing agent (welding powder) with the heated brazing metal and evenly wipe it on the gap, and do not directly heat the brazing metal with the flame. Stop heating when all the brazing metal is melted. Let's take a look at the specific operation process.

Post-welding: After a few minutes after the end of welding, wipe the joint with a damp cloth. This not only stabilizes the welded part, but also removes the slag on the welded surface to prevent corrosion.

Normal welds after welding should be free of porosity, cracks, and non-fusion. Note, do not cool the weld with cold water.

Anti-oxidation treatment of copper pipe welding: If there is no necessary anti-oxidation and anti-corrosion treatment, the weld will soon be oxidized and corroded, and the blackening of the weld is the manifestation of oxidation, which will affect the overall aesthetics of the equipment.

Copper and iron welding, using copper welding rods, do not need to clean the appearance of the iron pipe, even if the appearance is painted, it does not matter, directly insert more than 1cm into the copper pipe. When welding, the copper electrode is heated and stained with welding powder, the welding gun should first heat the copper nozzle, when the copper pipe is slightly red, the welding gun is heated at the copper and iron seam at the same time, and when the two weldments are red, then the copper electrode stained with welding powder is heated at the same time with the two weldments, the flame is slightly more on the welding rod, and the welding rod leaves the electrode quickly after the welding rod melts.

Then re-dip the solder powder, and then move the position according to the above method until all the soldering is completed. The principle is that the melting point of the electrode must be completely fused with the weldment, smooth and flat. The bottom or reverse part can be repeatedly looked at with a small mirror to see if the welding is harmonious (mutual) and full.

In order to prevent the possible existence of trachoma or no penetration, the silver electrode can be heated and stained with solder powder, the welding torch first heats the position that has been welded, and the silver electrode is welded again when it is about to melt, the silver welding melting point is low, the flow is fast, it can fill the tiny trachoma and defects, and the solder joint can be guaranteed to be more smooth and flat. The electrode must be re-powdered after each melt. Iron pipes are thin, have a lower melting point than copper pipes, and are more likely to burn red, so you can see it at a try.