The pp fitting is used in piping systems to change direction of the liquid flow, connect pipes of different sizes, change pipe diameter and branch the liquid flow from one pipe into multiple pipes.Integrating fittings into piping systems is a various important task. After all, it\u2019s at the connections between pipes where the system is most susceptible to leaks and failure. As such, many pipe fitting connection methods require special training to be executed.From soldering, to threading to brazing, there are many types of connection methods. One of the most popular, however, is welding.Welded pipe 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.