1 8" 1 4" 3 4" 1 2" 1" BSP Brass Reducing Coupler Hex Bush Connector Fittings

Identify the thread size on your existing male pipe or fitting (the larger, outer-threaded end) and the thread size of the port or fitting you are connecting into (the smaller, inner-threaded end). The male size of the hex bush must match your pipe's male thread, and the female size must match the receiving port. If you are unsure, use a thread gauge or count threads per inch and compare against BSP size charts — 1/4" BSP has 19 TPI, 3/8" has 19 TPI, 1/2" has 14 TPI, 3/4" has 14 TPI, and 1" has 11 TPI.

These fittings are BSP (British Standard Pipe) parallel thread, also called BSPP or G-thread. BSP and NPT threads are not directly interchangeable — they differ in thread angle (55° BSP vs 60° NPT) and taper profile. Forcing a BSP fitting onto an NPT port risks cross-threading and leaks. If your existing system uses NPT threads, you will need a BSP-to-NPT adapter rather than these fittings.

BSP parallel (BSPP) threads rely on a face seal or thread sealant to achieve a pressure-tight joint — the threads alone do not seal. Apply two to three wraps of PTFE (plumber's) tape to the male thread before assembly, or use a thread sealant compound rated for your service fluid (water, air, or hydraulic oil). Do not over-tighten; brass threads can strip if excessive torque is applied.

Brass offers good corrosion resistance in fresh water and air service and performs well in damp indoor environments such as basements and utility rooms. For direct outdoor exposure or salt-air environments, consider whether a protective coating or periodic inspection is appropriate for your installation. Brass is not recommended for contact with ammonia-based fluids or certain industrial chemicals.

Yes. Brass BSP hex bush fittings are widely used in compressed air distribution systems. Ensure the pressure rating of the fitting meets or exceeds your system's working pressure — if the rated pressure for your specific size combination is not listed, contact us to confirm before installation in high-pressure circuits.

A hex bush (also called a hex reducing bush) has a male thread on the outside and a female thread bored through the center, with a full hex profile on the body for wrench engagement. It screws into a female port and accepts a smaller male pipe or fitting. A reducing socket (coupler) typically has female threads on both ends and connects two male pipe ends. Choose a hex bush when you are threading into an existing female port and need to reduce the opening size.

For a single repair or replacement, the 1-piece option is the most economical choice. If you are working on multiple connection points of the same size — for example, fitting out a manifold or servicing several branch lines — the 4- or 10-piece packs offer a lower per-unit cost. The 20-piece pack is suited to trade use or stocking a workshop parts bin for ongoing maintenance work.