In enhancement to elbows, carbon steel pipe fittings additionally include tees, which connect 3 sections of pipe, creating joints for liquid flow. Equal tees are used when the attaching branches are of the exact same diameter, while reducing tees are used when the branch pipe is of a smaller size. https://historydb.date/wiki/Maximizing_Piping_System_Efficiency_with_HighQuality_Flanges