ARC shields may remain in place after welding provided that:

For the question regarding ARC shields and their allowed duration after welding, the correct rationale centers on the requirement that these shields should not remain in place at all once the welding process is complete. The AWS D1.1 code emphasizes the importance of removing ARC shields because they can potentially trap heat or moisture, which could adversely affect the quality and integrity of the weld joint. Leaving the shields in place can ruin the desired mechanical properties of the weld and may compromise the overall strength and performance of the welded structure.

Among other choices, the idea that ARC shields could enhance the quality of the weld is not supported since their primary function is temporary protection during welding, not to serve as a long-term element. While using non-combustible materials for shields might be advantageous for safety during the welding process, it doesn't change the fundamental guideline that these shields should not be left in place after welding. This underscores the critical nature of adhering strictly to the code requirements while conducting welding work to avoid any potential issues.