The Nuts and Bolts of Copper Brazing
The copper brazing is very useful when it comes to strengthening the joints, especially so when it comes to systems that operate at more than 350 degrees. The key features of copper brazing are:
- Refrigeration and air-conditioning
- Protection from the fire
- Circulation of gas
- Water provisions
Copper brazing is highly active when it comes to joining pieces with or without oxygen oriented copper. The lap joint ensures stable copper brazed joint.
The flames used in copper brazing must be mildly carburizing. Almost all the silver brazing alloys are useful with the respective fluxes. Both copper-phosphorous and copper-phosphorous-silver alloys can be used to make a brazed joint without the flux. Using flux will ensure a better-looking outcome.
Copper Soldering vs. Brazing: The Difference?
The fundamental difference between the soldering and brazing is the process temperature. Copper soldering process requires temperature level between 350 to 600 degrees. The copper brazing, on the other hand, is done in 1100-1500 degrees.
The copper brazed joints are mostly sued to ensure healthy joints between the metal workpieces where the joints are run at more than 350 degrees.
In copper brazing procedures; lap, butt, and scarf joints are used. This is true no matter the workpieces is in rounding shape, flat, tubular or irregular cross-parts. Clearance permit includes the measurement of the filler metal (except large diameter pipe joints) to be within 0.002 to 0.003 inch (0.051 to 0.076 mm). In the case of the large diameter pipe joinings, the measurements are 0.008 to 0.100 inch (0.203 to 2.540 mm). In the copper, brazing joints can be achieved by feeding filler materials on the outer layer of the workpieces or by inserting filler metal.
The Best Instructions for Brazing Copper Tube
Follow all the directions on the same working day. Watch the video at the top of the page to fulfill the procedures.
- Ensure marking in the tube’s body to get accurate length measurement.
- Make sure to cut the tubes using a hacksaw/tube cutter/use any other useful method.
- Remove the end-points of the tube to get rid of metal spurs. Use reaming tools such as a reaming blade, deburring tool or a half-round file.
- Clean the joining areas of the workpieces properly before beginning the soldering process. Try to remove any oil or oxides in the metal pieces. A sand cloth/abrasive can be very useful. Ensure proper space between the tube and fitting that is .004 inch.
- Put the tube into the fitting and ensure that the fit is tight. But not too tight where there is not enough space for the capillary procedures of the solder. Appropriate space is .0004 inches. Turning the tube may help to achieve a firm support of the tube.
- Keep and hold the flame at a ninety-degree angle to the tube. Preheat the fitting cap and the tube while holding the flame. Do not apply too much hit to the tube, which might cause burn issue of the flux. An oxyfuel Torch is a good option while doing this procedure.Refrain from applying with a bare hand when using a flux to get rid of oxides. A pair of hand gloves will come in handy here. Protect your eyes and mouth during the process.Brazing flux can be used when brazing copper tube to the copper fittings. However, using a brazing flux is not mandatory. BCuP alloy can be used in this process. When using flux heat, hold it in a uniformed manner until the flux becomes apparent. Be sure to follow manufacturer’s guideline in this process.
- Apply heat to the point where the filler material will be melt. Also, apply heat to entering the end of the tube inside the socket of the fitting. At the time of applying the filler material use more heat to the base of the cup. When joining the workpieces horizontally, make sure to use solder a bit off the center point of the bottom part. Apply pressure and make sure that the solder is fit straight into the joint while ensuring the torch position in the base of the fitting.
- Use water to ensure better cooling process after joining the work pieces together. Clean the joint with a used rug after the whole procedure is done.
One thing to keep in mind is, the larger the circumference of the tube, the harder it is to maintain the uniform temperature. In this case, the entire fitting is needed to be preheated. Ensure the second set of the torch to keep the temperature level required.
Do not heat up the filler material at any cost. The temperature through the heating point should be at a point where the filler material will melt by itself into the joining point.
Same procedures should be followed in case of vertical soldering. Turn off the torch soon after completing the entire fillet.