The four-way tees at Suntong are of opposite dimensions; the main tee of the unequal diameter tees faces each other, while the branch tee dimensions are 10mm smaller than the main tee. Stainless steel four-way tees are a type of piping fitting used at pipe branch points. For four-way tees made of seamless pipes, the current processes commonly used are hydraulic expansion and hot pressing. The hydraulic expansion of the hydraulic expansion four-way tee is a forming process that involves expanding the branch pipe through axial compensation of the metal material.

The process involves using a hydraulic press to inject liquid into a billet with a diameter equal to that of the four-way fitting. The billet is then uniformly compressed by the simultaneous movement of the two horizontal cylinders of the hydraulic press. As the billet is compressed, its volume decreases, causing the liquid inside to increase in pressure. When the pressure reaches the level required to expand the four-way fitting's branches, the metal material flows and expands into branches under the combined pressure of the side cylinder and the liquid pressure within the billet.

The four-way hydraulic bulging red art can be formed in one go, with higher production efficiency; the supervisor and shoulder wall thickness of the four-way have both been increased.