Red Seal Welding Practice Exam

What is used to purge a copper pipe for brazing?

1. Nitrogen

2. Oxygen

3. Hydrogen

4. Carbon Dioxide

The correct answer is: Nitrogen

Purging a copper pipe for brazing is an important step in the process as it ensures that any impurities or moisture are removed from the pipe before the brazing takes place. This helps to prevent any contaminants from affecting the quality of the brazed joint. Nitrogen is the best choice for purging as it is an inert gas that does not react with the copper or the brazing material. Oxygen, on the other hand, can cause oxidation and form a copper oxide layer on the inside of the pipe, which can negatively affect the brazed joint. Hydrogen and carbon dioxide are also not suitable for purging as they can react with the copper or contribute to oxidation. Therefore, A is the correct choice for purging a copper pipe for brazing.