American National Standard Pipe Thread Standard, referred to as the National Pipe Thread Standard (NPT). It is the American standard for threaded pipes and fittings. There are 60 degree tapered threads and straight pipe threads.
It features a 1:16 taper and requires thread sealant to ensure sealing, making it suitable for most threaded pipe connections.
NPTF (National Pipe Taper Fuel)
Similar to NPT threads, this is a “dryseal ” thread. NPTF is self-sealing between metal threads and requires no additional sealing material. It is suitable for most dryseal connections, such as fuel, gas oil and other liquid seals.
NPS (National Pipe Straight)
Straight pipe thread, good rigidity. No self-sealing, need to be sealed by external components such as O-ring or gaskets. In addition, NPS female thread and NPT male thread can be matched to realize the sealing effect of straight/taper connection. Mostly used in low pressure systems or non-sealed mechanical fittings.
NPSF (National Pipe Straight–fuel and Oil)
Mainly female threads, with male threads in special cases. NPSF female threads can’t realize self-sealing, but with NPTF male threads can reach the sealing effect of straight/taper*1 fit. Suitable for gas or liquid sealing.
NPSC (National Pipe Straight Coupling)
Straight threads, unsealed. Commonly used for piping systems and mechanical part fittings with non-sealed connections.
NPSH (National Pipe Straight Hose)
Straight pipe thread, no self-sealing. Typically used for hose couplings.
NPSI (National Pipe Straight Intermediate)
Similar to NPSF but slightly larger, mainly female thread. Thread sizes and tolerances are between NPT and NPS. Uncommon and mainly used where a precisely threaded connection is required but sealing by threads is not necessary.
NPSL (National Pipe Straight Locknut)
Straight thread, sealing is achieved by means of an O-ring or a gasket. NPSL is mostly used in fastening locknuts to prevent components from loosening under conditions such as vibration or temperature changes.
NPSM (National Pipe Straight Mechanical)
A type of thread for a piece of machinery or equipment. Generally used internally by a particular industry or equipment manufacturer.
NPTR (National Pipe Taper Railing)
Similar to NPT threads. But with unique thread tolerances and requirements specifically for the railway environment. Mainly used in railway equipment.
PTF-SAE Short (Pipe Taper, Fuel, SAE, Short):
Named after SAE International; similar to NPTF but one turn shorter. For use in small fuel or gas transfer units, especially where installation space is limited.
NPT Thread Chart
※ Data is for reference only, subject to actual measurement.
FPT and MPT thread Meaning
MPT (Male Pipe Thread) is a US 60° tapered male thread term that covers all NPT male threads. FPT (Female Pipe Thread) is a US 60° tapered female thread term that covers all NPT female threads. Both threads are used in conjunction with each other.
MNPT (Male National Pipe Tapered) and FNPT (Female National Pipe Tapered) simply emphasize the “National” standard in their names. MNPT=MPT; FNPT=FPT
FPT vs MPT vs NPT
MPT (MNPT) = NPT (Male) FPT (FNPT) = NPT (Female)
MPT is simply a term that emphasizes male threads. NPT and MPT female threads can be used together.
MIP vs FIP vs NPT
MIP (Male Iron Pipe) refers to male threads applied to metal pipe fittings or accessories.
FIP (Female Iron Pipe) refers to a female thread for metal pipe fittings or accessories.
MIP and FIP are 60-degree tapered threads that meet National Pipe Thread standards and can be used in combination.
MPI, FIP, and NPT threads are compatible with each other in typical applications.
NPT vs FIPT vs FIP
FIPT (Female Iron Pipe Thread) with special emphasis is a female thread for connecting metallic (Iron or steel) pipes and also belongs to the National Pipe Thread standard.
Range of use: NPT (Female) > FIP > FIPT
What is npt thread？
The standard taper is 1/16 inch per inch of thread length (about 1.79 degrees).
60° tapered sealing pipe threads in accordance with National Pipe Thread Standard.
What is 1/4 npt？
For example, 1/4 NPT threaded fittings are connected to solenoid valves.
1/4 inch is the nominal diameter of the corresponding connection port on the solenoid valve, i.e., the inside diameter of the connection port is infinitely close to 1/4 inch.
The outside diameter of a 1/4 NPT fitting is approximately 0.54 inches (about 13.72 mm).
Therefore NPT 1/4 does not refer to the inside and outside diameters of the pipe threads themselves, but rather matches the specification dimensions of the connecting pipe.
NPS vs NPT Thread
NPS is a straight pipe thread with no thread taper. NPT is a 60° tapered pipe thread.
Are npt and nps threads compatible？
Yes. NPS female threads and NPT male threads can be used in combination, and high sealing can also be achieved with threadlocker or thread sealing tape.
