What does the "root opening" measure in a groove weld?

The root opening is defined as the gap between the edges of the base metal at the bottom of the groove. This measurement is crucial in groove welds as it determines how effectively the weld can fuse the base metals together. A proper root opening allows for adequate penetration of the weld metal into the groove, which helps to create a strong joint. If this gap is too small, it can restrict proper fusion, while if it's too large, it can lead to insufficient coverage and weak joints. Understanding the importance of root opening helps in achieving high-quality, structurally sound welds in various welding applications.