NPT & NPTF 3

[Mike4321]

Are NPT and NPTF threads compatible? I'd like to connect a filter which attaches to the tubing through a female NPT threaded inlet. Our supplier only has JIC to NPTF adapters, so if I can I'd like to order one of these from our regular supplier, rather than have to order a JIC to NPT from another company, so that all the fittings can be ordered from one source when the product goes into production.

I would just try it out, but I can't find any kicking around.

Thanks

 

[bcd]

Mike

NPT and NPTF threads of the same size will go together. NPTF threads are NPT threads with the tops and bottoms ounded off so they interfere at assembly. The intent of NPTF threads are that they can seal without using thread sealent (teflon tape or Loctite PST), hence they are also called "dryseal type".

Apply thread sealent and put them together, you will not have any problems.

BCD

 

[hacksaw]

NPTF generally refers to the female NPT connection. My own experience is that all NPT fittings require thread dope of some kind.

NPT: National Pipe Taper (Male or Female)

 

[kenvlach]

"Pipe Threads
Pipe threads are either tapered or straight (parallel). The two styles are not compatible except for NPSL (National Pipe Straight Locknut), which is compatible with NPT.
Tapered threads (as the name implies) have a slight taper. When mated together and tightened, the threads compress to form a seal. The most widely used pipe threads in North America are National Pipe Taper threads (NPT). Some confusion may result from the use of NPT, FPT, and MPT in describing threads. Both FPT and MPT are NPT threads, with FPT meaning female threads (internal) and MPT meaning male threads (external).
NPTF (Dryseal) threads are modified NPT threads, which are less likely to leak without a sealant. To assure a leak-free seal, we recommend using a sealant compound or Teflon tape. You can use NPTF threads with NPT threads, but you'll lose some of the leak-free characteristics."

From catalog page 3,

http://www.mcmaster.com/

 

[metalonis]

The NPTF designation definitely does not signify a female thread only. NPTF (Dryseal) threads may be male or female.