Four-way tees are used for pipe fittings and pipe connections. Also known as four-way pipe fittings or four-way tees, they are used at the main pipeline where branching occurs. Four-way tees come in both equal and unequal sizes; equal-sized four-way tees have the same diameter at the outlet ends; unequal-sized four-way tees have the main pipeline outlet with the same size, while the branch pipeline outlet is smaller. Four-way tees are a type of fitting used for pipe branching. The hydraulic expansion process involves using a hydraulic press to inject liquid into a pipe blank with a diameter equal to that of the four-way tee. The two horizontal cylinders of the hydraulic press synchronize to move and compress the pipe blank. As the pipe blank is compressed, its volume decreases, causing the liquid inside to increase in pressure. When the pressure reaches the required level for the branch pipe to expand, the metal material flows and expands into the branch pipe under the combined pressure of the side cylinder and the liquid pressure inside the pipe blank.

Four-way fittings are used for pipe joints and pipeline connectors. Also known as four-way pipe fittings or four-way connectors, they are employed where the main pipeline needs to branch off. Four-way fittings come in both equal and unequal diameters; equal diameter four-way fittings have the outlet ends with the same size, while unequal diameter four-ways have the main pipeline outlet size the same, but the branch pipeline outlet size smaller than the main pipeline. A four-way fitting is a type of pipe fitting used at pipeline branching points. The hydraulic expansion forming process for four-way fittings involves using a hydraulic press to inject liquid into a tube blank of the same diameter as the four-way, then synchronously squeezing the tube blank with the two horizontal cylinders of the hydraulic press. As the tube blank is compressed, its volume decreases, causing the liquid inside to increase in pressure. When the pressure reaches the required level for the branch pipe to expand, the metal material flows and expands into the branch pipe under the combined action of the pressure in the side cylinder and the liquid inside the tube blank.