What happens if you remove tubing before all the brazing material is molten?

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

Answer: (A)

When brazing, the filler metal must wet and flow into the joint as the tube and fitting are held in place until the metal cools and solidifies. If you pull the tubing out while the brazing alloy is still molten, you lose the support that keeps the tube aligned and the liquid metal can’t form a solid, continuous bond around the tube. The result is that the tube can be pulled away and the softened filler metal can separate at the tube interface, effectively breaking off in the joint. This is why removing the tube early leads to a failed joint.

The other outcomes aren’t the typical immediate result of removing the tube too soon. The tube wall cracking or the tube melting aren’t the usual failure mode in this scenario, and while the joint could shift, the most accurate description given the situation is that the tube breaks off in the joint due to loss of proper wetting and support while the filler is still molten.