Which of the following best describes the primary purpose of joint spacers in welding?

The primary purpose of joint spacers in welding is to maintain root opening. This is crucial because the root opening is the gap between the two pieces of metal being joined, which significantly affects weld quality. Proper root opening allows for consistent penetration of the weld metal into the joint, ensuring a strong bond. It also helps in controlling the heat distribution during the welding process, thereby minimizing distortions and defects.

Maintaining this specific gap ensures that the weld pool can be adequately formed and that there is enough space for the filler material, if used, to flow into the joint. This ultimately leads to a reliable and robust weld, which is vital for the integrity and strength of the welded assembly.