NPT Pipe Thread Fittings are used primarily for joining and sealing fluid or pneumatic lines. This page summarizes where they fit, the industries that rely on them, and the practical points to get right when you specify them — to ASME B1.20.1. Stocked across roughly M1 to M312, they cover general to heavy-duty work.
Typical Applications for NPT Pipe Thread Fittings
The most common settings where these are specified:
- Fabrication & metalwork: bench and on-site assembly of steel frames, enclosures and weldments.
- Pneumatic systems: connecting air lines, cylinders and valves on automation rigs.
- Hydraulic & fluid power: sealed, pressure-rated joints in fluid lines.
- Process & plant piping: tapped connections on manifolds and equipment.
- General machine building: fastening covers, brackets, motors and sub-assemblies on production equipment.
How to Specify NPT Pipe Thread Fittings for Your Application
- Size: Match the nominal size to the mating thread or hole. This product spans M1–M312; check the full table below for the exact dimensions of each size.
- Thread & pressure: Match the thread form (BSP/NPT/metric) and pressure rating to the line, and seal appropriately (tape, sealant or O-ring).
- Environment: For damp, coastal or chemical exposure prefer A4/316 stainless or a suitable coating; indoors, plated steel or A2 is usually sufficient.
- Standard: This product is supplied to ASME B1.20.1. Quoting the standard on your order guarantees interchangeable dimensions between suppliers.
Where NPT Pipe Thread Fittings Are Not the Right Choice
Do not mix thread forms (BSP into NPT) without an adapter, and do not exceed the pressure rating of the lowest-rated component.