Threaded pipe fittings — nipples, couplings, reducers, elbows, tees, and adapters in NPT (National Pipe Taper) thread — are the foundational joining components for rigid piping systems in water, steam, air, oil, gas, and industrial process applications. NPT threads form a pressure-tight seal as the tapered thread flanks engage, typically requiring 2–3 wraps of PTFE thread tape or pipe dope on the male thread for a leak-free connection.
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3/8 in. Polypropylene Tee -
1/2 in. x 1/4 in. Black Polypropylene Reducing Hex Nipple -
1/2 in. x 1/8 in. Polypropylene Bushing -
3/4 in. Black Poly Hex Head Plug -
3/4 in. Male NPT x 3/8 in. Female NPT Black Polypropylene Reducing Hex Bushing -
3/4 in. Polypropylene 45 Street Elbow -
3/4 in. Polypropylene Street Elbow -
3/4 in. Polypropylene Tee -
3/4 in. x 1/4 in. Polypropylene Hex Bushing -
1-1/2 in. White Nylon Hex Nipple
Apex Flow Solutions stocks brass and steel pipe fittings across all standard NPT sizes for system assembly, repair, and extension. Brass fittings resist corrosion in water, oil, gas, and compressed air service. Steel (black iron) pipe fittings are specified for natural gas, steam, and high-temperature industrial systems.
Fitting Types
Nipples extend a threaded line from a valve or equipment port. Close nipples and hex nipples are nearly all-thread; long nipples leave a wrench-flat gap for assembly. Couplings join two equal or unequal (reducer) pipe threads in line. Elbows change direction 90° or 45°. Street elbows combine a male and female thread for direct fitting-to-fitting connections without a nipple. Tees create branch connections. Bushings and adapters reduce size or adapt between thread types.
NPT Thread Reference
NPT threads are tapered at 1/16 in. per in. on the diameter — the taper creates the seal as the thread engages. Hand-tight engagement is typically 2–3 threads; wrench-tight adds another 2–3 turns depending on pipe size. See our NPT Thread Tightening Reference for turns-past-hand-tight guidance by size.