____ can be used to back any type of pipe if a welder is unsure about a less expensive substitution.
A) Nitrogen
B) Carbon dioxide
C) Oxygen
D) Argon

Question

Quizplus · Accepted Answer

Argon is the best choice for backing any type of pipe as it does not react with most metals and is non-flammable. It also has a higher density than air, which helps to prevent oxidation during the welding process. Nitrogen, carbon dioxide, and oxygen can pose risks and should not be used as a substitute for argon.

____ Can Be Used to Back Any Type of Pipe