Copper pipe, also known as copper pipe, is a kind of non-ferrous metal pipe, corrosion resistance, not easy to be oxidized, widely used in modern residential and building water pipe, heating pipe and cooling pipe installation, copper pipe installation should be good welding, in order to ensure the normal use of the follow-up, so, what is the welding method of copper pipe? What are the precautions for welding? Today I made a detailed summary for you.

Welding methods for copper pipes

1. Prepare for welding

(1) Clean the oxide film on the outer surface of the copper pipe joint and the inner surface of the pipe joint, and evenly paint the welding paste or liquid solder on the outer surface of the cleaned pipe and the inner surface of the pipe fitting. When brazing copper pipe and copper pipe with copper phosphorus filler metal or low silver copper phosphorus filler metal, no brazing filler metal is required.

② Insert the copper tube into the pipe fitting, insert the bottom and rotate properly, keep the gap uniform, if coated with soldering flux, should use a clean rag to wipe off the excess soldering flux on the extruded joint.

Step 2: Weld

(1) When welding, it is necessary to preheat the welding parts, heat the welding parts of the copper tube with the flame, when the copper tube is heated to purple, remove the flame, the solder depends on the weld, so that the solder is melted into the welding copper, the heating temperature can be reflected through the color, dark red: 600 or so; Dark red: around 700; Orange: About 1000 degrees Celsius.

② Heat the copper tube joint evenly with the gas flame until it reaches the brazing temperature. When soldering, the joint can also be heated to the brazing temperature by electric heating.

③ Contact the joint heated to high temperature with the filler metal to determine the temperature of the joint. If the filler metal does not melt, it indicates that the joint temperature has not reached the brazing temperature, and the joint needs to continue heating; If the solder can be melted quickly, the temperature of the copper pipe joint has reached the brazing temperature, can continue to heat the joint, so that the temperature is maintained above the brazing temperature, at the same time, the solder is added in the joint gap, the heat of the joint will be used to melt the solder into the gap until it is filled with brazing weld, it is prohibited to melt the solder directly with the flame, coated on the surface of the gap.

3. Welding and cooling

Remove the heat source and stop heating so that the joint cools and crystallizes in a static state to prevent the vibration of the brazing filler metal from affecting the brazing quality. Remove oxides and welding slag in the copper pipe with dry nitrogen, and brush varnish for protection if necessary.

4. Repair welding after welding

In the process of copper pipe pressure test, repair welding should be carried out in the place where there is leakage in welding. When repairing welding, nitrogen gas of the system pressure test should be released, and pressure test should be carried out again after welding.

(2) Before repair welding with gauze to wipe the surface of the copper tube oxide layer, after welding, should be removed oxide skin, after quenching in water, copper tube to dry, there can be no water droplets, all after welding, the system should be blown with nitrogen.