A Threaded Tee is a forged pipe fitting manufactured to ASME B16.11 standards, used to divide or combine fluid flow at a 90-degree angle. It features three internal thread connections (female) and is designed for high-pressure systems (Class 2000, 3000, 6000) where a reliable, leak-tight seal is required without on-site welding.  

Key Applications:

• Branching: diverting flow from a main header to a sub-line.

• Instrumentation: installing pressure gauges or sensors via a reducing outlet.

• Mixing: combining two fluid streams into one common line.

The primary difference is the outlet size configuration. An Equal Tee has three openings of the exact same nominal pipe size (e.g., 2″ x 2″ x 2″). A Reducing Tee has a branch outlet smaller than the main run, designated by the sequence: Largest Run × Opposite Run × Branch (e.g., 2″ x 2″ x 1″).   

• Equal Tee: Used when the branch line diameter matches the header.

• Reducing Tee: Used to feed smaller equipment or instruments without needing an extra bushing.

Specify NPT (National Pipe Taper) for projects in North America or oil & gas systems using ANSI standards; it uses a 60° thread angle. Specify BSPT (British Standard Pipe Taper) for European, Asian, or ISO-standard projects; it uses a 55° thread angle.

Warning: Never mix these threads. Although a 1/2″ NPT male may physically screw into a 1/2″ BSPT female, the 5° angular mismatch creates a spiral leak path that cannot be sealed, leading to failure under pressure.

Choose SS 316L for marine, chemical, or chloride-rich environments. It contains 2-3% Molybdenum, which provides superior resistance to pitting corrosion, and has Low Carbon (L) content to prevent weld decay. Choose SS 304 only for general-purpose, indoor, or non-aggressive fluid applications where cost is the primary factor.

Selection Guide:

• SS 304/304L: Standard use, fresh water, air lines.

• SS 316/316L: Sour gas, seawater, sulfuric acid traces.