Which of the following conditions is acceptable for a 5/16 inch fillet weld that is 20 inches long on structural steel?

The correct choice reflects the tolerances specified in welding standards for fillet welds. In structural applications, fillet welds are required to meet certain minimum size criteria to ensure their strength and reliability.

For a 5/16 inch fillet weld, being undersized by 1/8 inch for a length of 2 inches is acceptable because it falls within the allowable limits for the overall weld length while still maintaining sufficient weld quality and integrity for a short section. The general rule allows small areas of undersizing as compensations are necessary for weld imperfections, but these should not exceed certain lengths relative to the overall weld.

In contrast, other options represent losses in size that may exceed standard allowances. Undersizing by 1/4 inch, regardless of the length, compromises the weld’s intended strength and can lead to failure under service conditions; hence, those options do not conform to acceptable welding practices. The specifications in welding codes emphasize the importance of maintaining a balance between weld dimensions and structural load-bearing requirements to mitigate risks in construction and fabrication.