A pipe fitting tee is a type of chemical pipe fitting that has three openings, which means it can have one inlet and two outlets or two inlets and one outlet. Tee pipe fittings can be T-shaped or Y-shaped, with either equal diameter outlets or different diameter outlets, and are used where three identical or different pipelines converge. The primary function of a pipe fitting tee is to change the direction of the fluid flow.
For pipe fitting tees, the commonly used processes are hydraulic bulging and hot press forming.
The hydraulic bulging of a pipe fitting tee is a forming process where a branch pipe is expanded out by the axial compensation of a metal material. The process involves using a special hydraulic machine to inject liquid into a tube blank with a diameter equal to that of the pipe fitting tee. The two horizontal side cylinders of the hydraulic machine then move simultaneously towards the center to compress the tube blank. As the tube blank is compressed, its volume decreases, causing the liquid inside to increase in pressure. When the pressure reaches the level needed to expand the branch pipe, the metal material flows along the inner cavity of the mold due to the dual action of the side cylinder pressure and the internal liquid pressure, thus expanding the branch pipe.
The hydraulic bulging process for pipe fitting tee can form the fitting in one go, resulting in higher production efficiency. Both the main pipe and shoulder wall thickness of the pipe fitting tee increase. Because the equipment required for the hydraulic bulging process for seamless pipe fitting tee has a relatively high tonnage, it is mainly used domestically for manufacturing standard wall thickness pipe fitting tee that is smaller than DN400. The applicable forming materials include low-carbon steel, low-alloy steel, stainless steel, and some non-ferrous materials such as copper, aluminum, and titanium.
Hot press forming of a pipe fitting tee involves flattening a tube blank larger than the diameter of the pipe fitting tee to approximately the diameter of the fitting, then creating a hole at the location of the branch pipe. The tube blank is heated and placed into a forming mold, and a stretching punch is inserted into the branch pipe area. Under pressure, the tube blank is radially compressed, and during the radial compression, the metal flows towards the branch pipe and forms it under the stretch of the punch. The entire process is thus completed through the radial compression of the tube blank and the stretching process of the branch pipe area. Unlike hydraulic bulging, the metal of the branch pipe in hot press forming is compensated by the radial movement of the tube blank, so it's also called radial compensation process.
Since the material is heated before pressing, the required tonnage of the equipment decreases. Hot press forming of pipe fitting tee is more adaptable to various materials, making it suitable for low-carbon steel, alloy steel, and stainless steel. This forming process is particularly used for large-diameter and thick-wall pipe fitting tee.
The welding process significantly impacts the pressure resistance of pipe fitting tees—incorrect techniques (e.g., excessive heat or incomplete penetration) create weak points that reduce burst strength by up to 30%. Example: For maximum durability in hotel pipeline systems, orbital TIG welding with precision-controlled purge gas ensures full-penetration joints without carbide precipitation, maintaining the fitting’s original 1500 PSI rating while preventing micro-cracks in high-traffic pipe networks.
304 stainless steel: suitable for general water systems (cold water/hot water), cost-effective, but long-term contact with chloride ions (such as swimming pools, coastal areas) may cause pitting.
316 stainless steel tee pipe joint: contains molybdenum, and its resistance to chloride ion corrosion is increased by 50%+. It is recommended for coastal hotels, chemical media or high-salt environments (such as floor heating return water systems).
Duplex steel (2205): extremely harsh working conditions (high temperature and high pressure + corrosive media), such as seawater desalination pipelines in island resort hotels.
Automatic argon arc welding (TIG): all-position welding, no oxides in the weld, suitable for food-grade pipelines (such as hotel water supply pipeline systems), and pressure stability of more than 1500 PSI.
Laser welding: ultra-thin wall TEE (<2mm) is the first choice, with a small heat-affected zone, but the equipment cost is high, suitable for precision medical gas pipelines.
Post-weld treatment: Pickling and passivation (removal of welding oxide layer) can improve the corrosion resistance of 316L pipe fittings in acidic medium by 30%.
