What is the procedure for heating a brazed copper joint?

Heating the pipe first and then the fitting is the correct procedure for successfully brazing a copper joint. This method allows for optimal heat distribution throughout the joint. By heating the pipe, the heat transfers from the pipe to the fitting, which helps to create a more uniform temperature across the joint area. This increases the likelihood that the filler material, or brazing alloy, will properly flow into the joint by being drawn in by capillary action.

When the pipe is heated first, it ensures that the base metal reaches the necessary brazing temperature, promoting better adhesion between the filler and the surfaces being joined. This technique also helps avoid overheating the fitting, which could lead to damage or alter the mechanical properties of the fitting.

Other options may lead to improper joint formation. For instance, heating the fitting first could lead to overheating the fitting material while the pipe remains insufficiently heated, resulting in poor bonding. Heating both simultaneously might not produce the controlled heat necessary for effective brazing and can also cause uneven heating. Heating the solder before applying it does not ensure proper joint preparation or flow into the joint, which is crucial for effective brazing.