3/8" NPT (National Pipe Taper) (3/8-18 NPT)
Where 3/8-18 NPT is used, its real dimensions, and how to connect it to other standards.
3/8-18 NPTThread standard
Designation3/8-18 NPT
Major diameter17.15 mm
Threads per inch / pitch18
Thread formtapered, 60 degree
Seals onon the thread flanks with PTFE tape
Used on: US pump ports, pressure-washer inlet and outlet fittings.
3/8 NPT shares the 18 TPI pitch of 1/4 NPT on a larger 0.675 inch outside diameter. It is common on US pressure-washer pump ports.
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 M22 x 1.5 pressure-washer, 15 mm bore to 3/8" NPT (National Pipe Taper)needs an adapter1/8" NPT (National Pipe Taper)related standard (1/8-27 NPT)1/4" NPT (National Pipe Taper)related standard (1/4-18 NPT)1/2" NPT (National Pipe Taper)related standard (1/2-14 NPT)3/4" NPT (National Pipe Taper)related standard (3/4-14 NPT)1" NPT (National Pipe Taper)related standard (1-11.5 NPT)
Sources: ANSI/ASME B1.20.1 (NPT pipe threads) · NPT thread dimensions chart (ASME B1.20.1), Machining Doctor