Hydraulic bulging of hydraulic bulging tee is a forming process of expanding branch pipes by axial compensation of metal materials. The process is to use a special hydraulic press to inject liquid into the tube blank with the same diameter as the tee, and extrude the tube blank through the synchronous centering movement of the two horizontal side cylinders of the hydraulic press. The volume of the tube blank becomes smaller after extrusion, and the pressure of the liquid in the tube blank increases as the volume of the tube blank becomes smaller. When the pressure required for the expansion of the tee branch pipe is reached, The metal material flows along the inner cavity of the die and bulges out the branch pipe under the double action of the side cylinder and the liquid pressure in the tube blank. The hydraulic bulging process of tee can be formed in one time with high production efficiency; The wall thickness of the main pipe and shoulder of the tee increased. Due to the large tonnage of equipment required by the hydraulic bulging process of seamless tee, it is mainly used for the manufacture of standard wall thickness tees smaller than DN400 in China. The applicable forming materials are low-carbon steel, low-alloy steel and stainless steel with relatively low cold hardening tendency, including some non-ferrous materials, such as copper, aluminum, titanium, etc. 2. Hot pressing forming of tee hot pressing forming is to flatten the tube blank larger than the diameter of the tee to the size of the diameter of the tee, and open a hole in the part of the stretching branch pipe; After being heated, the tube blank is put into the forming die, and the die for drawing the branch pipe is installed in the tube blank; Under the action of pressure, the tube blank is compressed radially. During the process of radial compression, the metal flows to the branch pipe and forms the branch pipe under the drawing of the die. The whole process is formed through the radial compression of the tube blank and the stretching process of the branch pipe. Different from the hydraulic bulging tee, the metal of the hot pressed tee branch is compensated by the radial movement of the tube blank, so it is also called the radial compensation process. As the tee is pressed after heating, the equipment tonnage required for material forming is reduced. Hot pressed tee has wide adaptability to materials, and is suitable for materials of low-carbon steel, alloy steel and stainless steel; Especially for tees with large diameter and thick pipe wall, this forming process is usually adopted. Carbon steel, cast steel, alloy steel, stainless steel, copper, aluminum alloy, plastic, argon asphalt, pvc, etc. It is divided into jacking, pressing, forging, casting, etc. according to the manufacturing method. The manufacturing standards are divided into national standards, electrical standards, chemical standards, water standards, American standards, German standards, Japanese standards, Russian standards, etc., as follows: GB/T12459-2005, GB/T13401-2005,ASMEB16.9,SH3408,SH3409-96,SH3410-96,HG/T21635,DL/T695,SY/T0510,DIN2615。