Match the tee size to your existing pipe's nominal pipe size (NPS). For example, a 1/2" tee fits 1/2" NPT-threaded pipe. If you're reducing flow from a larger main line to a smaller branch, choose a reducing tee such as FMM or FFM. When in doubt, measure the outer diameter of your pipe and compare to standard NPT sizing charts — 1/2" NPT pipe typically has an OD of approximately 0.840" (21.3 mm), 3/4" is approximately 1.050" (26.7 mm), and 1" is approximately 1.315" (33.4 mm).

These codes describe the thread gender on each of the three ports of the tee fitting. F = Female (internal thread, NPT) and M = Male (external thread, NPT). The three letters correspond to the run-inlet, run-outlet, and branch port respectively. For example, FFF means all three ports are female NPT — you thread male-ended pipes or fittings into all three openings. FMM means one female inlet and two male outlets.

201 stainless steel offers good corrosion resistance for general indoor and light outdoor use. It performs well in dry-to-moderate humidity environments. For prolonged outdoor exposure, salt spray, or marine environments, 304 or 316 stainless steel is generally recommended. Always apply PTFE thread tape to ensure a watertight seal regardless of environment.

These fittings use NPT (National Pipe Taper) threads, the standard for pipe fittings in the United States. NPT threads are tapered and create a pressure-tight seal when used with PTFE thread tape or pipe dope. They are not directly compatible with BSP (British Standard Pipe) threads — the thread angle and pitch differ. An NPT-to-BSP adapter is required if connecting to BSP-threaded components.

The working pressure rating depends on the pipe size, wall thickness, and installation conditions. Generally, 201 stainless steel NPT fittings in the 1/2"–1" range are suitable for moderate-pressure water and air applications. For exact pressure ratings specific to your system, please contact us to confirm before installation in high-pressure or safety-critical applications.

Yes. NPT threads are tapered but not inherently leak-proof on their own. Always apply PTFE thread tape (plumber's tape) or a compatible pipe thread sealant compound to the male threads before assembly. Wrap the tape clockwise (when facing the thread end) 2–3 times for a reliable seal. Thread sealant is not included.

These fittings are generally used for water, air, and fluid transfer applications. For gas line use, local codes and regulations apply. We recommend consulting a licensed plumber or gas fitter and verifying compliance with your local building codes before using any fitting in a gas application.