In welding, what is meant by a "butt joint"?

A "butt joint" is defined as a joint where two pieces of metal are aligned edge-to-edge and welded together. This type of joint is commonly used in welding because it allows for strong connections between metal pieces, promoting uniform thickness and strength at the weld. In butt joints, the surfaces to be joined are typically prepared so that they are flush or aligned, allowing for effective welding without the need for additional connectors. This method is ideal for fabricating structures where seamless joints are desired, such as in sheets of metal or pipes.

Other joint types mentioned in the options, such as joints with overlapping edges, angled joints, or those using backing bars, serve different applications and have unique characteristics that distinguish them from a butt joint. For instance, overlapping joints can create additional stress concentrations, while angled joints may not provide the same load distribution and strength characteristics as butt joints. Therefore, understanding the definition and application of a butt joint is crucial for effective welding practices.