What diameters of electrodes are qualified by a procedure test using a 5/64" diameter FCAW electrode?

The correct choice is based on the guidelines for the qualification of welding procedures, specifically in the context of FCAW (Flux-Cored Arc Welding). When a procedure qualification test is performed using a 5/64" diameter electrode, the qualification encompasses various aspects, including the range of electrode diameters that can also be used within the same procedure.

In welding standards, such as those set by the American Welding Society (AWS), the general rule is that smaller diameter electrodes can be qualified if a procedure test is performed using a larger diameter electrode. In this case, since an electrode diameter of 5/64" has been tested and qualified, it opens the door for the use of this diameter and any smaller ones for the applications covered by that qualification.

This means that not only can 5/64" diameter electrodes be utilized, but also any diameter below that, hence qualifying for "5/64" and smaller." This is consistent with industry practices where starting with a smaller diameter leads to being able to perform welding with larger sizes without the need for additional qualification testing.

Understanding this aspect of electrode qualification is vital for ensuring compliance with welding codes and achieving reliable welds across different electrode sizes.