What is necessary for obtaining a good joint when soldering copper pipe?

To obtain a good joint when soldering copper pipe, it is crucial that the pipe is free of water. Any water present in the pipe or at the joint can prevent the solder from adhering properly and create a barrier that keeps the joint from forming effectively. This is because water can boil and create steam when subjected to the heat of soldering, potentially causing the solder to not melt correctly or preventing a proper seal. Ensuring the pipe is dry allows the solder to flow smoothly and fill the joint completely, which is essential for establishing a strong, leak-proof connection.

While factors such as applying flux and proper assembly contribute to a successful soldering process, the primary concern is ensuring that moisture is not present since it can severely compromise the integrity of the joint being made.