Which code book governs welding structural aluminum?

The correct choice is the AWS D1.2 code book, which specifically governs welding structural aluminum. This code outlines the requirements for the design and fabrication of welded aluminum structures, ensuring that the materials and processes used meet safety and performance standards. It includes guidelines on welding procedures, qualification of welders, and inspection requirements tailored to aluminum, which has distinct properties compared to steel.

The other code books mentioned have specific applications that do not pertain to aluminum structures. For instance, AWS D1.1 is focused on steel, primarily governing welding practices related to steel structures. AWS D1.3 is related to welding carbon and low-alloy steels, whereas AWS D1.4 pertains to welding in the context of bridge construction. Understanding which code to apply is essential for ensuring compliance with safety standards and quality in welding processes.