A butt weld pipe fitting is designed to be welded on site at its end to connect pipe together and allow change in direction or pipe diameter, or branching or ending. This fitting then becomes part of a system for transporting fluids (oil, gas, steam, chemicals, …) in a safe and efficient manner, over short or long distances. Other types of fittings can be threaded or socket welded.
Butt weld fittings are much like what their name suggests: the fittings are welded directly onto the pipes. Trained and licensed professionals often carry out this difficult feat, fusing the fitting to the pipe by carefully melting their metals together. Usually, the fitting and the pipe need to be made of the same or very compatible materials. After the welding is complete, the fittings are often tested to ensure their integrity.