What is NPTF Thread?

NPTF stands for National Pipe Taper Fuel. It’s a specific type of tapered pipe thread designed for sealing without the use of additional sealants. This makes it ideal for applications where sealants are undesirable, such as with:

• Food and beverage processing: NPTF threads prevent contamination from sealants leaching into the product.
• Oxygen lines: Sealants can introduce flammable materials into oxygen systems, posing a safety hazard.
• Medical equipment: NPTF threads ensure leak-proof connections on sensitive medical devices.

Here’s how NPTF threads achieve their tight seal:

• Tapered design: Like NPT (National Pipe Thread), NPTF threads have a slight taper, meaning they get wider as they screw in. This creates a wedging effect that tightens the connection.
• Deeper thread form: Compared to NPT, NPTF threads have a slightly deeper thread profile. This increases the surface area contact between the male and female threads, further improving the seal.
• Dryseal coating: Some NPTF fittings have a dry lubricant or dryseal coating applied to the threads. This reduces friction and makes them easier to assemble while still maintaining a leak-proof seal.

It’s important to note that while NPTF threads are designed for dryseal applications, they may not always be completely leak-proof, especially under high pressure or with certain fluids. In such cases, using a sealant in conjunction with NPTF threads might be necessary.

Here’s a table summarizing the key differences between NPT and NPTF threads:

This is why hydraulic quick connectors are usually marked with NPT instead of NPTF, because when used in hydraulic applications, they are often medium and high pressure applications.