How to weld copper pipe? Introduction to copper pipe welding methods and precautions
Copper pipes, also known as copper pipes, are a type of non-ferrous metal pipes with strong corrosion resistance and resistance to oxidation. They are widely used in the installation of water pipes, heating and cooling pipes in modern residences and buildings. Copper pipes must be well welded during installation to ensure subsequent normal use. So, what is the welding method of copper pipe? What are the precautions for welding?
1. Copper pipe welding method
1. Preparation for welding
① Clean the oxide film on the outer surface of the copper pipe joint and the inner surface of the pipe joint. Apply paste or liquid flux evenly on the cleaned outer surface of the pipe and the inner surface of the pipe fittings. When using copper-phosphorus solder or low-silver copper-phosphorus solder to braze copper pipes and copper fittings, no flux is required.
②Insert the copper pipe into the pipe fitting, insert it to the bottom and rotate it appropriately to maintain a uniform gap. If it is coated with flux, the excess flux squeezed out of the joint should be wiped off with a clean rag.
2. Carry out welding
① When welding, the welded parts must be preheated. Heat the copper pipe welding joint with a flame. When the copper pipe is heated to purple-red, remove the flame and place the solder against the welding joint so that the solder melts and flows into the welded copper parts. The temperature after heating can be reflected by the color. The temperature is as follows: dark red: about 600°C; deep red: about 700°C; orange-red: about 1000°C.
②Use a gas flame to evenly heat the joints of the copper pipe until it reaches the brazing temperature. When soldering, electric heating can also be used to heat the joints to the brazing temperature.
③ Use the solder to touch the joint that has been heated to high temperature to determine the temperature of the joint. If the solder does not melt, it means that the temperature of the joint has not yet reached the brazing temperature, and the joint needs to continue to be heated; if the solder can melt quickly, it means When the temperature at the copper pipe joint has reached the brazing temperature, you can continue to heat the joint to keep the temperature at the joint above the brazing temperature, add solder to the gap in the joint, and use the heat at the joint to melt the solder. into the gap until the solder joint is filled. Do not use flame to directly melt the solder and apply it to the surface of the gap.
3. Welding cooling
Remove the heat source, stop heating, and allow the joint to cool and crystallize in a static state to prevent the molten solder from being vibrated during cooling and crystallization, which will affect the quality of the brazing. Use dry nitrogen to clean the oxides and welding slag in the copper pipe. If necessary, apply varnish for protection.
4. Repair welding after welding
① During the pressure test of the copper pipe, if any leakage is found in the welding, repair welding should be carried out. During the repair welding, the nitrogen used in the system pressure test should be released, and the pressure should be tested again after welding.
② Before repair welding of copper pipes, the oxide layer on the surface should be wiped clean with gauze. After repair welding, the oxide scale should be removed, and after quenching in water, the copper pipe should be dried without any water droplets. After all welding is completed, the system must be purged with nitrogen.
2. Things to note when welding copper pipes
1. When welding, wait until the solder solidifies before moving the copper pipe, otherwise the welded part will crack. When welding, wait until the refrigerant is drained before proceeding. Otherwise, when the refrigerant encounters an open flame, it will produce toxic phosgene, which is harmful to the human body.
2. Copper pipe welding requires the use of gas flame. The gas cylinder must be placed upright and at a distance of more than 5 meters from the open flame to avoid fire accidents. The connection method between the welding torch and the gas cylinder must be correct.
3. When welding copper pipes, construction must be carried out in a well-ventilated area. Construction workers need to wear good protective glasses, and fire-extinguishing equipment must be available at the welding site.
The copper pipe welding method must not only be carried out according to the above introduction, but also wear protective equipment during welding to prevent splashing sparks from scalding the skin. You must wear goggles, because the splashing firelight is very irritating to the eyes and can easily cause eye diseases.
