For a long complete penetration groove weld, what is the minimum length of each spot test as determined by the design professional?

The minimum length of each spot test for a long complete penetration groove weld is determined by specific guidelines to ensure the integrity and quality of the weld. The correct choice indicates that for every 4 inches of weld length, there should be a 1-inch long spot test. This ratio is significant because it allows for adequate evaluation of the weld's performance, effectiveness, and adherence to standards.

A ratio of 1 inch in 4 inches strikes a balance between thorough testing and practical application in the field. It ensures that there are sufficient intervals for testing within a reasonably short length of weld, thus promoting quality control without excessively burdening the fabrication process.

In contrast, the other choices suggest different lengths that either do not align with established practices or could lead to inadequate assessment of the weld integrity. A longer spacing might reduce the number of tests conducted, which is not optimal for quality assurance in critical applications.