NFPA-99 Practice Exam

What is the primary purpose of purging joints with dry nitrogen?

1. To cool the joint quickly

2. To remove surface oxidation

3. To prevent contamination within the joint

4. To enhance the joint appearance

The correct answer is: To prevent contamination within the joint

The primary purpose of purging joints with dry nitrogen is to prevent contamination within the joint. This process is particularly important in welding and brazing applications, where the presence of oxygen and moisture can lead to oxidation or the formation of undesirable compounds within the joint. By introducing dry nitrogen into the joint, the inert gas displaces any reactive gases, thereby creating an environment that minimizes the risk of defects and ensures integrity in the final product. This technique is critical in maintaining the quality of the joint, especially in industries where the reliability and safety of connections are paramount, such as in medical gas systems or high-purity applications. The use of dry nitrogen also helps in maintaining the cleanliness and quality during the procedure, leading to a stronger and more reliable joint.