One, the selection of solder
Copper tube is an important raw material of refrigeration unit, mainly used for making heat exchanger and connecting pipes and fittings. Refrigeration pipe fittings are mostly copper (purple) pipe, commonly used solder types are copper phosphorus solder, silver copper solder, copper zinc solder and so on.
When welding, according to the characteristics of pipeline materials, the correct choice of solder and skilled operation, to ensure the quality of welding.
Copper and copper welding: can choose phosphor copper solder or low silver content phosphor copper solder, such as 2% or 5% silver based solder. This solder is cheaper, has a good solution, uses a caulking and wetting process, and does not require flux.
Copper and iron welding: phosphor copper solder or brass strip solder can be used, but the corresponding flux, such as borax, boric acid or boric acid mixed flux.
Two, welding operation
Use sandpaper to remove grease, oxide, stains, and dust from the surface of the connector where the copper tube is inserted. The copper pipe is inserted into the weld. The length of the neutral flame is generally 20 ~ 30cm for pipeline welding. When the gas output is greater than the oxygen output, the carbonization flame that is not suitable for welding operation will be generated. Heat the copper pipe interface with a welding torch.
Then evenly heat the welded pipe fitting until the welding interface is dark red, put the electrode in and make the melted electrode wrap more than 0.8cm around the solder joint to remove the electrode, stop heating when all the solder melts.
Wipe the joint with a wet cloth after a few minutes. In this way, the welding part can be stabilized and the slag on the welding surface can be removed to prevent corrosion. After welding, normal welds should be free of pores, cracks and unfused.