Straight AN to Thread Adapters (NPT, ORB, Metric)

Straight AN to Thread Adapters (NPT, ORB, Metric) – standard interfaces for tidy routing, easy servicing and dependable sealing

Straight AN to Thread Adapters (NPT, ORB, Metric) is for joining AN hose ends to threaded ports without guesswork: NPT tapered threads, ORB O-ring boss ports, and metric threads found on many automotive components. This is where you typically reach for straight transitions, unions, reducers and nipple-style joiners when you want a service-friendly system that stays dry.

The category currently lists 232 products and is commonly filtered by brand, including TurboWorks, Aeromotive and DeatschWerks. The fastest way to avoid leaks is to treat “thread type” and “sealing method” as separate checks, because a part that threads in is not automatically a part that seals correctly.

Technical Basics

On the AN side, sealing is typically made on a 37° flare seat, not on the thread. If an AN joint seeps, the usual cause is a nicked or dirty seat rather than insufficient torque.

NPT is a tapered thread that often seals on the thread itself, so thread sealant (for example PTFE) is commonly used where specified. One short warning: mixing similar-looking thread standards can damage ports and create slow weeps that are hard to trace.

ORB (O-ring boss) seals with an O-ring at the port face while the thread mainly clamps the joint. For ORB, O-ring condition and a clean, undamaged seat matter more than tightening harder.

Metric ports may use fine pitches (for example M12x1.5) and you will also encounter crush-washer style sealing on certain interfaces. In those cases, flat mating faces and a fresh washer after disassembly often determine whether the joint stays dry.

Selection Criteria

Start at the receiving port: is it NPT, ORB or metric, and where does it actually seal (flare seat, O-ring, washer, or thread)? Then choose the AN size (for example AN6, AN8, AN10) based on the job of the line: a gauge/sensor take-off is different from a main feed or return.

If you need to join two AN sizes, that is typically a reducer or a union. If you are adapting a component port, a straight AN-to-thread adapter is usually the cleanest solution; nipple-style joiners and bulkhead fittings come into play when packaging and mounting require them.

For metric-to-AN10 transitions on specific ports (for example M20x1.5, M22x1.5, M24x1.5), see: PMC Motorsport Straight AN to Thread Adapters (NPT, ORB, Metric). In these cases, pitch and engagement length are critical, because near-matches can damage the port and still leak under pressure.

Installation & Maintenance

Clean threads and sealing faces before assembly and start threads by hand to avoid cross-threading. On AN joints, protect the 37° seats from scratches because that is where the seal is made.

On NPT, apply thread sealant only where appropriate and avoid over-tightening tapered threads. On ORB, ensure the O-ring is correctly seated and replace it if it shows flattening, cuts or hardening.

After installation, leak-check under operating pressure and temperature. If the system is serviced frequently (track days, maintenance), replacing wear items (O-rings, crush washers) is typically more reliable than repeated “nip up” tightening.

FAQ

What is the difference between AN, NPT and ORB?
AN usually seals on a 37° flare seat, NPT is tapered and commonly seals on the thread (often with sealant), and ORB seals with an O-ring at the port face. They are not interchangeable even if a thread seems to fit. Always match the port standard and sealing method on the component.

How can I identify the thread in my port?
The safest route is the component manufacturer specification. If you measure, confirm both diameter and pitch (for example M12x1.5), not just “it looks like M12”. Forcing a near-match can damage the port and create persistent leaks.

Do I need thread sealant on the AN side?
Typically no, because AN seals on the flare seat rather than the thread. If an AN joint leaks, inspect the seat for dirt or damage and confirm the matching size. Thread sealant is more commonly relevant on NPT threads.

What does ORB (O-ring boss) sealing rely on?
ORB relies on the O-ring and the port face for sealing, while the thread provides clamp load. If it leaks, the fix is often cleaning the seat and replacing the O-ring, not extra torque. Use an O-ring material compatible with your fluid and temperature.

How do I choose between AN6, AN8 and AN10?
Match the size to your existing hose ends and the role of the line (main feed/return vs a smaller branch). The AN size must be consistent across the full joint (hose end, adapter, mating fitting). Also consider packaging: larger sizes need more spanner clearance and bend radius.

Why does a new adapter joint leak after installation?
Common causes are the wrong sealing method for the port (for example ORB without the correct O-ring), contaminated sealing faces, or a mismatched thread/pitch. Check where the joint seals, not just whether it tightens. A pressure test under real conditions usually reveals the source quickly.

Filter by thread type and size, confirm the sealing method on the product page, and order the adapter that matches your ports.