Female Thread Brass Coupling Adapter — Straight & Reducer Pipe Fittings

Measure the outer diameter of your pipe threads and match it to the nominal pipe size. For example, a 1/2" NPT fitting typically has an outer thread diameter of about 0.840" (21.3 mm). For reducer adapters, the first number is the larger (female) end and the second is the smaller end — e.g., 1/2"–1/4" means a 1/2" inlet reducing to a 1/4" outlet. When in doubt, use a thread gauge or caliper to confirm before ordering.

These fittings are generally compatible with NPT (National Pipe Taper) thread standards, which are the most common in US residential and commercial plumbing. If you are working with BSP (British Standard Pipe) threads, please contact us to confirm compatibility before ordering, as NPT and BSP are not directly interchangeable.

Brass is naturally corrosion-resistant and generally performs well in damp or humid environments, including outdoor irrigation and garden plumbing. For fully submerged or high-salinity applications, applying PTFE tape and a thread sealant compound is recommended to ensure a watertight, long-lasting connection.

Brass pipe fittings of this type typically handle working pressures up to 200 PSI for water and air at room temperature. Actual ratings may vary by size and wall thickness. Contact us to confirm the rating for your specific size and application before use in high-pressure systems.

Yes. Applying PTFE (Teflon) tape or a pipe thread sealant compound to the male threads before assembly is strongly recommended. Wrap the tape clockwise (when facing the thread end) for 2–3 layers. This ensures a leak-free seal and makes future disassembly easier without damaging the threads.

A straight coupling (e.g., 1/2") connects two pipes of the same diameter. A reducer adapter (e.g., 1/2"–1/4") connects pipes of two different diameters, allowing you to step down from a larger pipe to a smaller one in a single fitting. Both types in this listing feature female threads on both ends.

Brass fittings are commonly used in low-pressure gas applications in many regions. However, suitability depends on local plumbing and gas codes, the specific gas type, and operating pressure. Always verify compliance with your local codes and consult a licensed professional before installing any fitting on a gas line.