Dry goods! Guidance for welding copper pipes of refrigeration equipment

Dry goods! Guidance for welding copper pipes of refrigeration equipment

The air conditioner is mainly composed of a compressor, a radiator, and an automatic control system. The copper tube in the radiator is called the "blood vessel" of the air conditioner. The quality of the "blood vessel" will directly determine the quality of the air conditioner. Copper pipe is an important raw material for refrigeration equipment, it has two main purposes: ① making heat exchangers, such as commonly used evaporators, condensers, commonly known as "two devices"; ② making connecting pipes and pipe fittings. No matter what kind of use, it is a refrigerant channel, and its role is very important, which requires air conditioning and refrigeration construction technicians to properly use copper pipes.

Preparation before construction: ①Reading and familiarization of the construction drawings; ②Checking the construction site: See whether the construction site has the construction working conditions; ③The preparation of pipes and accessories; ④The preparation of machinery and measuring tools: oxygen-acetylene, cutting knife, Hacksaw, electric hammer, wrench, spirit level, tape measure, file, etc.

Construction began:

(1)Process flow

(2) Installation process

　　① Straightening of the copper pipe: Use a wooden hammer to tap lightly along the pipe to straighten it section by section. During the straightening process, pay attention not to use too much force, and do not make hammer marks, pits, scratches or rough marks on the surface of the pipe.

②Pipe cutting: hacksaws, grinders, copper pipe cutters can be used to cut copper pipes, but oxygen-acetylene cutting is not allowed. Copper pipe bevel processing uses files or beveling machines, but oxygen-acetylene flame cutting processing is not allowed. The two sides of the jaws of the bench vise holding the copper pipe should be lined with wooden boards to prevent the pipe from being pinched.

(3) End cleaning

　　The surface of the part where the copper pipe is inserted into the joint must not have any kind of grease, oxide, stain or dust, otherwise it will seriously affect the welding performance of the solder to the base material and cause defects. Therefore, the surface should be scrubbed with other organic solvents. Copper pipe joints are generally free of dirt. If there are copper wire brushes and steel wire brushes, the ends can be treated, and other unclean tools should not be used for treatment.

Use sandpaper to insert the copper pipe into the joint part of the surface of the grease, oxides, stains and dust.

(4) Preheating and welding

　　 Heat the welded pipes uniformly, use the heated solder to dip a proper amount of solder (solder powder) evenly on the gap, and send the solder when the temperature reaches 650℃-750℃. Never use flames to heat the solder directly, and stop heating when the solder is completely melted.

　　①Vertical method: Heat the pipe and the joint one after the other, making sure that the heating temperature of the two is even. If the tube is overheated, the solder will flow down the tube instead of gathering at the weld, which will affect the quality of the welding.

②Horizontal welding: heat around the pipe first, and then heat the joint. As for where to add solder, it depends on the size of the pipe and the operator’s habits. For large-size pipes, it’s best to start welding from the bottom, that is, from the bottom. Start adding solder, and then solder it on all sides.

　　In this way, because the peripheral part of the joint is filled with solder, after the solder solidifies, a "plug" will be generated, which helps prevent the outflow of other solder. When solder is added, the temperature of the pipe and the joint is higher than the melting point of the solder.

(5) Post-welding treatment

　　A few minutes after the end of brazing, wipe the connection part with a damp cloth. In this way, the welding part can be stabilized, and the slag on the welding surface can be removed to prevent corrosion. The normal weld after welding should be free of porosity, cracks and unfusion. Concealed installation of plastic copper pipes can only be connected by welding, and the exposed parts and the parts inlaid with sanitary appliances can be connected by threaded connections. The threaded connection requires the installation of galvanized pipes. The welded part of the pipeline should be wrapped and protected with thermoplastic material. The thermoplastic material should be provided by the manufacturer, and the material provided should meet the anti-corrosion requirements. Use cloth and sandpaper to clean the oxide on the copper pipe, and the surface is smooth, without blisters. After the pipeline is welded, it is protected by varnish after removing the oxide layer. The surface of the pipe is bright and beautiful, and the pipe support and the copper pipe are separated by a rubber pad to avoid electrochemical corrosion.

　　(6) Welding of plastic-lined copper pipe

　　 Use a cutting knife to scratch 10cm at the front end of the copper pipe, and the depth cannot exceed the thickness of the lining plastic (no scratches on the copper pipe). Separate the plastic-lined part from the copper tube with a cutter at the front end of the copper tube, and then peel off the 10cm front end of the plastic-lined copper tube with your hands and pliers to prevent peeling with a knife, which may cause scratches on the copper tube. Use the thermoplastic material provided by the manufacturer to restore the lining of the welding area. (It is also possible to use a plastic coating with a peel length of not less than 200mm at the welding end, and wind a wet cloth on both ends, and restore the plastic coating after brazing is completed.)