NEW OLD STOCK

3/8"-18 NPTF Tap 

National Pipe Taper Fuel

HSS

ground thread

The primary difference between these two pipe threads is that NPT threads require a sealant to prevent leakage, while NPTF threads do not. NPT sealants can dissolve under high pressure and high temperatures, contaminating fluids and gases.

Unlike standard NPT (National Pipe Thread), NPTF threads have a precisely controlled truncation (or removal) of the thread's crest and root, which creates a tight seal when the mating threads are crushed together. This makes NPTF ideal for critical applications like fuel, gas, and high-pressure systems where sealant contamination is a concern

Key differences between NPTF and NPT:

Sealing Method: 
NPT relies on thread deformation and sealant to create a seal, while NPTF forms a mechanical, metal-to-metal seal. 
Thread Quality: 
NPTF threads generally have a higher quality finish, often a result of being machined rather than rolled, leading to a more reliable connection. 
Compatibility: 
While NPT and NPTF threads have the same basic form and taper, they are not fully interchangeable or compatible. Mismatched NPTF and NPT fittings can lead to incomplete sealing and compromised system integrity, especially under high pressure. 
Gauging: 
NPTF requires more extensive gauging to verify thread quality, including inspection of the root and crest, which is not typically required for NPT.