A tee is primarily used to change the direction of fluid flow and is applied at points where a main pipeline branches off.

Classified by process

1. Hydraulic Bulging

The hydraulic bulging of a tee is a forming process that expands the branch pipe through axial compensation of the metal material. The process involves using a specialized hydraulic press to inject liquid into a pipe blank with a diameter equal to that of the tee. The two horizontal side cylinders of the hydraulic press synchronously move to center and compress the pipe blank. As the pipe blank is compressed, its volume decreases, causing the pressure of the liquid inside to rise. When the pressure reaches the level required to bulge the branch pipe, the metal material flows along the inner cavity of the mold under the dual action of the side cylinders and the internal liquid pressure, forming the branch pipe.

The hydraulic bulging process for tees can be completed in a single operation, resulting in high production efficiency. The wall thickness of both the main pipe and the shoulder of the tee increases.

Due to the high equipment tonnage required for the hydraulic bulging process of seamless tees, it is primarily used in China for manufacturing standard wall thickness tees smaller than DN400. The suitable forming materials include low-carbon steel, low-alloy steel, stainless steel with relatively low cold work hardening tendencies, as well as some non-ferrous metals such as copper, aluminum, and titanium.

2. Hot Press Forming

Hot press forming of a tee involves using a pipe blank larger than the tee's diameter, flattening it to approximately the tee's diameter, and drilling a hole at the location where the branch pipe will be stretched. The pipe blank is heated, placed into a forming mold, and a punch for stretching the branch pipe is inserted inside the pipe blank. Under pressure, the pipe blank is radially compressed. During this radial compression, metal flows toward the branch pipe and forms the branch pipe under the stretching action of the punch. The entire process involves radial compression of the pipe blank and stretching at the branch pipe location. Unlike hydraulic bulging tees, the metal for the branch pipe in hot press tees is compensated by the radial movement of the pipe blank, hence it is also referred to as a radial compensation process.

Since the tee is pressed after heating, the required equipment tonnage for material forming is reduced. Hot press tees have a wide adaptability to materials, suitable for low-carbon steel, alloy steel, and stainless steel. This forming process is particularly commonly used for large-diameter tees and those with thicker pipe walls.