The tee is a pipe fitting and a pipe connector. The tee is usually used at the branch pipe of the main pipeline. The tee is divided into equal diameter and different diameter, and the ends of the equal diameter tee are all the same size; The size of the main pipe is the same, while the size of the branch pipe is smaller than that of the main pipe. For the use of seamless pipes to manufacture tee, there are currently two commonly used processes: hydraulic bulging and hot pressing. Divided into electric standard, water standard, American standard, German standard, Japanese standard, Russian standard, etc.