What type of weld is specified for a 5/16 inch fillet weld in a T configuration?

In a T configuration, a 5/16 inch fillet weld is specifically defined as a fillet weld because it is employed to join two members at a right angle, typically in a corner joint.

Fillet welds are triangular in cross-section and are used effectively in various configurations, especially for joining two plates or sections at an angle. The specification of "5/16 inch" refers to the leg length of the triangular weld bead. This type of weld can efficiently handle the loads encountered in service, making it a suitable choice for structural applications.

The other types of welds listed have different purposes and applications: a groove weld involves preparing the edges of the materials to be joined, which is not necessary in the case of a fillet weld in a T configuration. A butt weld is a technique used to join two pieces of metal end to end, while a spot weld is a localized weld that is used mainly in thin sheets of metal. Thus, the defined requirements and application context lead to the conclusion that a fillet weld is the correct choice for this situation.