After starting the nitrogen purge, what is the next action in brazing?

• A. Apply heat and filler metal
• B. Clean and inspect
• C. Assemble additional pieces
• D. Check for proper fitting

Answer: (A)

The key idea is that the nitrogen purge creates an inert environment to prevent oxidation during brazing. Once that protective atmosphere is established, you move to the actual braze: applying heat to the joint and feeding in the filler metal so it melts, wets the surfaces, and flows into the joint by capillary action. The inert gas helps keep the surfaces clean as the filler flows, which is essential for a good bond. Cleanliness, fit-up, and proper assembly are steps done before heating, so they’re typically completed prior to starting the heat and filler deposition.