NPT, NPS, MIP, FIP, MPT and FPT Thread Difference
National Pipe Thread (NPT) Standard
American National Standard Pipe Thread 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.
NPT (National Pipe Taper)
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.
FPT and MPT Thread Meaning
MPT (Male Pipe Thread) is a U.S. 60° tapered male thread term that covers all NPT male threads. FPT (Female Pipe Thread) is a U.S. 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
MNPT vs NPT
MNPT (MPT)=NPT (Male)
MNPT is simply an expression that emphasizes male threads.
Are MPT and NPT Threads Compatible？
Yes. NPT tapered female threads and MPT can be used together.
FPT vs NPT
FPT (FNPT)=NPT (Female)
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.
FIPT vs FIP VS NPT
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.
NPT Thread Chart
NPTF vs NPT Thread
NPTF has the additional feature of “dryseal ” over NPT threads otherwise it is the same. NPTF is self-sealing between metal threads and requires no sealant.
Are NPTF and NPT Compatible?
Normally NPTF can replace NPT threads, but the replacement use in high pressure environment will leak air need to add sealant. Therefore, the specific use should be adjusted according to the actual environment.
NPS vs NPT Thread
NPS is a straight pipe thread with no thread taper. NPT is a 60° tapered pipe thread. Both thread types are compatible.
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.
NPSF vs NPT
NPT is a 60° tapered thread sealant. NPSF is a straight pipe thread with no taper and is often used in combination with NPTF.
NPSF is designed to be more accurate than NPT and is designed for specific needs. If the two are used together there will be a problem of poor sealing due to the gap.
NPSC vs NPT
NPSC are straight threads with no taper and are sealed by a gasket or O-ring. It is usually used where sealing is not highly required.
NPT is a 60° tapered pipe thread. High sealing can be achieved by means of sealant and thread sealing tape and is suitable for high pressures and where high sealing performance is required.
The two are usually incompatible and may leak when used in conjunction, and should only be used where sealing is not required.
PT vs NPT
NPT is American 60° tapered pipe thread. PT (BSPT) is British tapered pipe thread. The two are not compatible. However, thread adapters are available for compatibility.
Differences between Rc, G, BSP and NPT threads click to view.
NPS vs NPSM vs NPT
NPS refers to a wide range of straight threads. NPSM refers specifically to straight threads used in certain mechanical equipment and has a much smaller definition. Neither has a thread taper, while NPT is a 60° tapered thread.
Difference Between NPT and UNF Thread
NPT is a 60° tapered thread conforming to ASME B1.20.1. suitable for piping and fluid transport systems with high sealing requirements.
On the other hand, UNF is a straight thread conforming to ANSI/ASME B1.1 and is ideal for high precision mechanical fasteners.
Two threads are incompatible.
◆ Other American National Standard Pipe Thread
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.
※1) Threaded straight/taper fit sealing
Tapered male threads and straight female threads generate forces during fastening that cause slight deformation of the threads. Thus filling the small gaps between the two and ultimately achieving a high-precision seal. This type of sealing does not require the use of external sealing elements, but can be achieved through threaded metal-to-metal.
With the exception of NPTF, which is self-sealing and certain special design threads. All threads require sealing material to ensure gas and liquid tightness.
※2) Different thread sealing methods
① Tapered threads: apply sealant or wrap thread sealing tape around the thread.
② Parallel threads: O-rings, washers or threadlockers. etc.
③ Metal sealing of straight/tapered threads (tapered male threads vs. straight female pipe threads).
※3) Sealant is to prevent leakage to ensure sealing. Threadlocker is to tighten threads to prevent loosening.
※4) Adapters allow for compatibility with components of different threads or sizes.
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