1/2" & 3/4" BSP Brass Pipe Fittings — Nipple, Elbow, Tee, Cross, Union, Plug & Bushing

BSP sizes refer to the nominal bore of the pipe, not the actual outer diameter of the thread. A 1/2" BSP fitting typically has an outer thread diameter of approximately 20.9 mm (≈0.82"), while a 3/4" BSP fitting is generally around 26.4 mm (≈1.04"). The easiest way to confirm your size is to measure the outer diameter of the male thread or the inner diameter of the female port with calipers, then match it to the BSP standard. If you're replacing an existing fitting, check for a size stamp on the body.

Both 1/2" and 3/4" BSP threads generally use 14 threads per inch (TPI) following the Whitworth thread form with a 55° thread angle. This is standard across BSPP (parallel, also called G threads) and BSPT (tapered, also called R threads) in these sizes. If you're unsure whether your system uses parallel or tapered BSP, check the fitting body or pipe specification — parallel threads require a face seal or sealant, while tapered threads can seal on the taper itself.

Brass generally performs well in indoor plumbing and moderate outdoor conditions. It resists corrosion from water and air better than iron or steel. For outdoor installations exposed to rain or humidity, applying PTFE tape and a quality thread sealant will help prevent moisture ingress at the joint. Brass is not typically recommended for highly acidic water, seawater, or environments with high chlorine concentrations without additional protective measures. If in doubt, consult a plumbing professional for your specific application.

Brass BSP fittings of this type typically support working pressures in the range of 150–600 PSI depending on the specific fitting configuration, wall thickness, and the medium being conveyed. Straight nipples generally handle higher pressures than tees, crosses, or unions due to their simpler geometry. Always verify the pressure rating against your system's operating pressure and apply an appropriate safety factor. Contact us if you need pressure specifications for a specific fitting type.

BSP and NPT threads are not directly interchangeable. BSP uses a 55° Whitworth thread angle; NPT uses a 60° thread angle. While a 1/2" BSP and 1/2" NPT fitting may partially engage due to similar pitch, this creates an unreliable seal and risks thread damage. If you need to connect a BSP fitting to an NPT system, use a dedicated BSP-to-NPT adapter. Always confirm your pipe system's thread standard before ordering.

For BSPP (parallel) threads, a thread sealant is required — the parallel thread form does not seal on its own. Use PTFE tape (2–3 wraps on male threads) or a pipe thread sealant compound. For BSPT (tapered) threads, the taper can create a mechanical seal, but sealant is still recommended for most liquid and gas applications to ensure a leak-free joint. Apply sealant to the male thread only, starting one thread back from the end.

Nipple: Connects two female-threaded ports in a straight line. Choose M×M, F×F, or M×F based on your port types. Elbow (90°): Changes flow direction by 90°. Elbow (45°): Changes direction at a gentler 45° angle — useful where space is limited. Base Elbow: Has a flat mounting flange for wall or surface mounting. Tee: Splits or combines flow in three directions. Cross: Four-way flow distribution. Union: Allows you to disconnect a pipe section without rotating the pipes — ideal for maintenance access points. Plug: Seals an open female or male port. Reducing Nipple / Bushing: Transitions between 1/2" and 3/4" lines.

Brass fittings are commonly used in low-pressure gas applications in many regions. However, local building codes, gas regulations, and utility requirements vary significantly. Always consult a licensed plumber or gas engineer and verify compliance with your local codes before installing any fitting in a gas system. Do not use these fittings for gas applications without professional guidance.