During brazing, which step comes first in the general brazing procedure?

• A. Assemble pieces to be brazed
• B. Check for proper fitting
• C. Start nitrogen purge
• D. Apply heat and filler metal

Answer: (B)

The first thing to do is verify the joint fits properly. Brazing relies on capillary action to pull the molten filler metal into a very small clearances between parts, so the joint needs the right alignment and a suitable gap. If parts don’t fit correctly, the capillary flow can be disrupted, leaving voids or causing unpredictable wetting, which weakens the joint or causes leaks. By checking and confirming proper fit before any heating, you set up the joint for a successful braze.

Once proper fit is confirmed, you would typically assemble or clamp the pieces, apply flux to protect the surfaces from oxidation, and, as needed, start a purge to create an inert or reducing environment. Heating and applying the filler metal is the step that actually completes the brazed joint, and nitrogen purge, if used, is part of the heating process rather than a pre-check step.