If you try to remove tubing before all the brazing material is molten, the tubing will:

• A. Break Off in the Joint
• B. Crack at the Tube Wall
• C. Melt
• D. Move Out of Place

Answer: (A)

In brazing, the filler metal must melt and flow into the joint to hold the tube in place. If you pull the tube out before the brazing material is molten, there’s no molten filler to secure the tube yet, so the mechanical act of removing it can shear the tube at the joint. The result is that the tubing breaks off in the joint rather than forming a proper brazed bond.

The tube wouldn’t melt or crack at the tube wall because the copper itself hasn’t been heated to its melting point, and there’s no bonding material yet to create a secure hold. It also isn’t expected to move out of place since, without the molten filler, there’s nothing holding the assembly together.