Not a direct fit. Joining 1" NPSH straight hose thread to 1" NPT (National Pipe Taper) needs a 1 NPSH to 1 NPT adapter. Sealing method, the real-world trap, and the exact adapter to buy.

Updated 05 September 2026.

HoseFitFinder / Every thread and fitting standard

Connect 1" NPSH straight hose thread to 1" NPT (National Pipe Taper)

How to join 1-11.5NPSH and 1-11.5 NPT, and what stops it leaking.

Needs adapter
End A
1" NPSH straight hose thread (1-11.5NPSH)
Seals on gasket in the coupling
via adapter
End B
1" NPT (National Pipe Taper) (1-11.5 NPT)
Seals on on the thread flanks with PTFE tape
Adapter needed1 NPSH to 1 NPT adapter

Not a direct fit. Joining 1" NPSH straight hose thread to 1" NPT (National Pipe Taper) needs a 1 NPSH to 1 NPT adapter.

The adapter to buy

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1 NPSH is a straight (parallel) hose thread and 1 NPT is tapered, so a 1 NPSH hose will not seal into a 1 NPT pipe port despite the matching nominal size. An NPSH-to-NPT adapter presents a tapered male for the pipe and a straight female for the hose.

The straight-into-tapered mistake weeps because the flanks never fully mate. Fit the adapter rather than forcing the 1 hose coupling onto a pipe thread.

Related connections

1" NPSH straight hose thread1-11.5NPSH1" NPT (National Pipe Taper)1-11.5 NPT1" NPSH straight hose thread to 3/4" NPSH straight hose threadadapter2-1/2" NH fire hose thread (NST) to 1" NPT (National Pipe Taper)adapter1" NPT (National Pipe Taper) to 1" BSP parallel (G1 / BSPP)adapter1" NPT (National Pipe Taper) to 1" BSP tapered (R1 / BSPT)adapter

Questions and answers

Connect 1" NPSH straight hose thread to 1" NPT (National Pipe Taper)?

Not a direct fit. Joining 1" NPSH straight hose thread to 1" NPT (National Pipe Taper) needs a 1 NPSH to 1 NPT adapter.