What can cause corrosion when excess flux is used inside a tube?

Using excess flux inside a tube can indeed lead to corrosion, as flux contains chemicals designed to help remove oxides and promote the bonding process during soldering or brazing. However, if too much flux is used, especially if it is acidic or not properly cleaned off after the process, it can remain trapped inside the tube. This residue can attract moisture and contaminants, creating an environment where corrosion can thrive.

The presence of moisture along with the acidic nature of some flux materials can initiate and accelerate the corrosion process on the metals involved. Therefore, it is essential to use an appropriate amount of flux and to ensure that all excess material is thoroughly cleaned from the surfaces after the soldering or brazing operation. This diligence helps prevent long-term damage and maintains the integrity of the metal components.