Butt weld pipe fittings are used to join pipes end-to-end, creating a smooth, continuous surface without gaps or threads. They're common in high-pressure systems like steam lines or industrial plumbing, where a strong, leak-proof connection is critical. The welding process fuses the metal, making the joint as durable as the pipe itself, though it does require skill to avoid weak spots. butt weld pipe fittings 5