Final answer:
A crack perpendicular to the weld length is a transverse crack. It's a serious defect that suggests potential structural issues and requires prompt attention.
Step-by-step explanation:
A crack that is perpendicular to the length of a weld is referred to as a transverse crack. This type of crack is often a significant concern in welded structures because it can be an indicator of structural weakness or failure. Transverse cracks can occur for a variety of reasons such as improper welding technique, high stress concentration at the weld, or thermal cycling. It's important to detect and repair transverse cracks promptly to ensure the integrity of the welded structure.