After assembling the pieces, what is the next step in the brazing procedure mnemonic CCASACI?

• A. Start a nitrogen purge
• B. Apply heat and filler metal
• C. Clean and inspect the joint
• D. Preheat the joint

Answer: (A)

The next move is to start a nitrogen purge. Pushing inert nitrogen around the joint as you heat helps keep oxygen out of the immediate environment. Oxidation during heating creates oxide films on both the base metals and the brazing filler, which wetting and capillary action rely on to flow properly into the joint. By purging, you reduce oxide formation, so the molten filler can wet the surfaces cleanly and fill the joint more reliably. This step is done before and continued during heating to maintain a cleaner environment; applying heat and filler metal without purge would risk oxidation, while cleaning/inspecting and preheating belong to other parts of the process.