Copper pipe, also known as purple copper pipe, is a type of non-ferrous metal pipe with strong corrosion resistance and is not easily oxidized. It is widely used in the installation of modern residential and building water pipelines, heating and cooling pipelines. Copper pipes need to be welded well during installation to ensure their normal use in the future. So, what is the welding method for copper pipes? What are the precautions for welding?
1、 Copper pipe welding method
1. Preparation before welding
① Clean the oxide film on the outer surface of the copper pipe joint and the inner surface of the pipe fitting joint. Apply paste or liquid brazing agent evenly on the cleaned outer surface of the pipe and the inner surface of the pipe fittings. When using copper phosphorus brazing material or low silver copper phosphorus brazing material to brazing copper and copper pipe fittings, brazing agent may not be applied.
② Insert the copper pipe into the fitting, insert it to the bottom and rotate it appropriately to maintain a uniform gap. If there is any flux applied, the excess flux squeezed out of the joint should be wiped off with a clean cloth.
Ruiqi copper tube
2. Perform welding
① When welding, preheating must be carried out for the welded object. Heat the copper pipe welding joint with a flame. When the copper pipe is heated to a purple red color, remove the flame and place the solder against the welding joint, so that the solder melts and flows into the welded copper part. The temperature after heating can be reflected by the color, dark red: about 600 ° C; Deep red: around 700 ° C; Orange red: around 1000 ° C.
② Uniformly heat the joint of the copper tube with a gas flame until it reaches the brazing temperature. During tin brazing, electric heating can also be used to heat the joint to the brazing temperature.
③ Contact the joint heated to high temperature with brazing material to determine the temperature at the joint. If the brazing material does not melt, it indicates that the temperature at the joint has not reached the brazing temperature and further heating of the joint is required; If the brazing material can quickly melt, it indicates that the temperature at the copper pipe joint has reached the brazing temperature. While continuing to heat the joint to maintain the temperature above the brazing temperature, add brazing material to the gap of the joint, and use the heat at the joint to melt the brazing material into the gap until it is filled. Do not use flames to directly melt the brazing material 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 stationary state to prevent vibration during the cooling and crystallization of the melted brazing material, which may affect the quality of brazing. Clean the oxide and welding slag inside the copper tube with dry nitrogen gas, and if necessary, apply clear varnish for protection.
4. Repair welding after welding
① During the copper tube pressure test, if leakage is found in the welding, it should be repaired by welding. During the repair welding, the nitrogen gas used for the system pressure test should be released, and the pressure test should be repeated after welding.
② Before welding copper pipes, the surface oxide layer should be wiped clean with gauze. After welding repair, the oxide scale should be removed completely. After quenching in water, the copper tube should be dried and there should be no water droplets present. After all welding is completed, the system should be purged with nitrogen gas.
2、 Precautions for Copper Tube Welding
1. When welding, wait for the solder to solidify before moving the copper tube, otherwise the welded part will crack. Welding can only be carried out after the refrigerant is completely discharged, otherwise the refrigerant will produce toxic phosgene when exposed to open flames, which is harmful to human health.
2. Copper pipe welding requires the use of gas flames, and gas cylinders should be placed upright at a distance of more than 5 meters from open flames to avoid fire accidents. The connection method between the welding torch and the gas cylinder should be correct.
3. When welding copper pipes, construction should be carried out in a well ventilated area. Construction personnel need to wear protective goggles, and there should be firefighting equipment at the welding site.
