1-1/2" NPT (National Pipe Taper): 48.26 mm major diameter, 11.5 thread, tapered, 60 degree. What it fits and the adapters to join it to other hose and tap threads.

Updated 05 September 2026.

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1-1/2" NPT (National Pipe Taper) (1-1/2-11.5 NPT)

Where 1-1/2-11.5 NPT is used, its real dimensions, and how to connect it to other standards.

1-1/2-11.5 NPTThread standard
Designation1-1/2-11.5 NPT
Major diameter48.26 mm
Threads per inch / pitch11.5
Thread formtapered, 60 degree
Seals onon the thread flanks with PTFE tape

Used on: US transfer pumps, tank flanges and main lines.

1-1/2-11.5 NPT is a National Pipe Taper thread, 11.5 TPI on a 1.9 inch (48.26 mm) outside diameter, cut to the 60 degree tapered form of ASME B1.20.1. It seals on the thread flanks with PTFE tape and will not mate cleanly with the 55 degree BSP thread of the same nominal size.

Quick-connect click fittings from Hozelock, Gardena and Karcher are proprietary and do not interchange. They all sit on top of a standard thread underneath, so the reliable way to move between brands is to adapt at the threaded tap or hose-end fitting, then use each brand's own connector above it.

Connect this thread

Connect to 1-1/2 inch camlock couplingneeds an adapterConnect to 1 inch camlock couplingneeds an adapterConnect to 1-1/4 inch camlock couplingneeds an adapterConnect to 2" camlock (cam-and-groove) couplingneeds an adapterConnect 1-1/2" NPT (National Pipe Taper) to 1-1/2" BSP parallel (G1-1/2 / BSPP)needs an adapterConnect 1-1/2" NPT (National Pipe Taper) to 1-1/2" BSP tapered (R1-1/2 / BSPT)needs an adapterConnect 1-1/2" NPSH straight hose thread to 1-1/2" NPT (National Pipe Taper)needs an adapterConnect 1-1/2" NH fire hose thread (NST) to 1-1/2" NPT (National Pipe Taper)needs an adapterConnect 1-1/2" NPT (National Pipe Taper) to 3/4" NPT (National Pipe Taper)needs an adapterConnect 1-1/2" NPT (National Pipe Taper) to 1" NPT (National Pipe Taper)needs an adapter

Questions and answers

What is the designation of the 1-1/2" NPT (National Pipe Taper) (1-1/2-11.5 NPT)?

1-1/2-11.5 NPT

What is the major diameter of the 1-1/2" NPT (National Pipe Taper) (1-1/2-11.5 NPT)?

48.26 mm

What is the threads per inch / pitch of the 1-1/2" NPT (National Pipe Taper) (1-1/2-11.5 NPT)?

11.5

What is the thread form of the 1-1/2" NPT (National Pipe Taper) (1-1/2-11.5 NPT)?

tapered, 60 degree