NPT Fittings, Adapters & Connectors

What Are NPT Fittings?

NPT fittings are threaded fittings that use a tapered National Pipe Thread to seal a connection. As you tighten the male and female threads, the taper wedges them together and forms a mechanical seal, which is why these fittings work so well on pressurized fuel, oil, coolant, and vacuum lines.

You'll see NPT sized by nominal pipe measurements like 1/8", 1/4", 3/8", and 1/2" NPT rather than by outside diameter, so the number is a plumbing standard, not a literal thread width. That sizing lets you match ports on carburetors, fuel pumps, oil pans, gauges, and adapters without guesswork.

NPT pipe fittings and NPT adapter fittings belong to the broader Fittings & Hose lineup, so you can plumb a full system from a single source. Steel handles higher pressure, while aluminum keeps weight down.

NPT vs AN Fittings: What's the Difference?

The key difference is how each fitting seals. NPT uses tapered threads that jam together and typically need thread sealant or PTFE tape on the male threads to stay leak-free. AN fittings use straight threads and seal on a 37-degree flare instead, so they don't take tape at the flare.

Because those two systems seal differently, AN and NPT are not directly compatible. When you need to move from one to the other, an AN to NPT adapter bridges the straight-thread flare side to the tapered pipe-thread side in one part. That's how you connect a braided AN hose end to an NPT port on a fuel pump, regulator, or oil cooler.

If you're building with braided line, browse the AN fittings and hose selection, and read our guide on how to flare tubing and brake lines before you cut anything.

Types of NPT Fittings and Adapters

This category spans the full range of NPT hardware you need to seal, adapt, and reroute a system.

• NPT pipe plugs and hex or allen-head plugs to cap unused ports, available as NPT caps and plugs
• AN-to-NPT adapters plus straight and 90-degree adapters, found among our adapter fittings
• NPT reducers and general threaded fittings to step between sizes, listed under general fittings
• Weld-in bungs for adding an NPT port to a tank, header, or panel, sourced from weld fittings and bungs

Between NPT thread adapters, NPT pipe plugs, and NPT to NPT adapter parts, you can finish nearly any plumbing job in one order. If you're stepping between two pipe threads, a reducer or NPT to NPT adapter keeps the connection tight without extra couplers.

How to Choose the Right NPT Fitting Size

Start by matching the NPT fitting to the thread size of the port you're sealing. NPT runs from 1/16" up to 1" in this category, and the size stamped on your component tells you which fitting threads in. When in doubt, thread-check the port before you buy.

Remember that NPT size does not equal AN dash size, so don't assume a 1/2" NPT port takes a matching AN number. Instead, use an adapter chart to line up the correct AN to NPT adapter fittings for the connection you're making.

Then pick your material for the job. Steel and galvanized steel take higher pressure and rough duty, while aluminum and anodized aluminum cut weight and resist corrosion on fuel and coolant lines. For sizing help, see our AN fitting sizes guide and learn how to assemble AN fittings and hose.

Top NPT Fitting Brands at JEGS

We stock NPT fittings and adapters from the performance brands builders already trust. Earl's is a proven name in motorsports plumbing with a deep catalog of adapters and plugs. Fragola Performance Systems is known for precise machining and clean anodized finishes.

Vibrant Performance covers a wide range of NPT pipe fittings and weld bungs for custom fabrication, and Aeromotive brings fuel-system expertise to its adapters and plugs. Each brand gives you consistent thread quality so your connections seal the first time.

Whether you need a single NPT pipe plug or a full set of NPT thread adapters, you'll find the size, material, and finish to match your build. Stick with these proven names and you'll spend less time chasing leaks and more time driving. Shop NPT Fittings Now and get your system plumbed right.