Final answer:
In welding butt joints, the bead width has evolved from being about 5 times the metal thickness side-to-side and 7-8 times in depth, to as much as 8 diameters wide and 15 diameters deep, indicating changes in welding standards.
Step-by-step explanation:
In welding, particularly when discussing a butt joint, the bead width of the weld is an important measure of the weld size relative to the thickness of the base metals being joined. An older rule of thumb suggested that the bead width in a butt joint should be approximately 5 times the metal's thickness from side to side and 7-8 times the thickness in depth. However, according to more recent practices and studies, the bead width may be considerably larger—up to 8 diameters wide side-to-side and 15 diameters deep. Thus, in a more contemporary context, the bead width of a butt joint could be many times greater than the base metal thickness, indicating a significant evolution in welding standards and techniques.