Not a direct fit. Joining 3/4" NPT (National Pipe Taper) to 3/4" BSP tapered (R3/4 / BSPT) needs a 3/4 NPT to R3/4 BSP tapered adapter. Sealing method, the real-world trap, and the exact adapter to buy.
Updated 05 September 2026.
Connect 3/4" NPT (National Pipe Taper) to 3/4" BSP tapered (R3/4 / BSPT)
How to join 3/4-14 NPT and R3/4, and what stops it leaking.
Not a direct fit. Joining 3/4" NPT (National Pipe Taper) to 3/4" BSP tapered (R3/4 / BSPT) needs a 3/4 NPT to R3/4 BSP tapered adapter.
The adapter to buy
3/4 NPT and R3/4 BSPT are both tapered 3/4 inch threads, which fools people into forcing them together, but the flank angle differs: 60 degree on NPT, 55 degree on BSPT. They cannot seal against each other, so an NPT-to-BSP-tapered adapter is the correct fix.
Both being tapered at 3/4 inch is the trap. Same taper, wrong flank angle: the joint starts smoothly then leaks. Use the adapter, not extra tape.
Related connections
Questions and answers
Connect 3/4" NPT (National Pipe Taper) to 3/4" BSP tapered (R3/4 / BSPT)?
Not a direct fit. Joining 3/4" NPT (National Pipe Taper) to 3/4" BSP tapered (R3/4 / BSPT) needs a 3/4 NPT to R3/4 BSP tapered adapter.