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How to distinguish between NPT and NPTF threads

2022-10-08 Page view : 6 views

Introduction to NPT and NPTF threads

NPT is the abbreviation of National(American)Pipe Thread. It is a 60 degree tapered pipe seal thread used in North America under the American standard ANSI- asmeb120.1-1983 (R2013) universal Pipe Thread. National standard can refer to GB/T12716-2011.
We are NPT threads manufacturer.
NPTF: Sealed conical pipe screw. NPTF is National Pipe Thread Fine NPT thread is called general purpose taper pipe thread, which is also what we used to call Brucellais taper thread. NPTF thread is called dry sealing taper pipe thread, it is connected to seal the principle is in the case of no lubricant or sealing packing completely rely on the thread itself to form a seal, the design intention is to make the internal and external thread tooth side, top and bottom contact at the same time, to achieve the purpose of sealing. They are both the tooth Angle, slope and other indicators are the same, the key is the top and bottom of the teeth of the Chopin height is not the same, so the setting of the gauge is not the same. NPTF thousand seal pipe thread tooth precision is higher than NPT thread, screw without any filler, completely rely on the thread itself to form a seal, thread ask without any sealing medium. T seal pipe thread has a strict tolerance, is a precision thread, only used in special occasions. This thread has high strength and good sealing property, and can be used in brittle and hard materials with thin cross section to reduce the phenomenon of breaking strength.
NPTF internal and external threads have no gap between the top and the bottom, which is an interference fit, while NPT thread is a transition fit. NPTF threads are mainly used in high temperature and high pressure places with strict sealing requirements. NPT internal and external threads are conical, while NPTF external thread is conical, internal thread is conical, cylindrical two kinds; NPT has both right-handed and left-handed handedness, while NPTF has only right-handed handedness.
NPTF taps are acceptable for NPT threads, but NPT taps should not be used for NPTF threads because they produce threads that leak. NPT has both right-handed and left-handed threads, while NPTF has only one right-handed thread.

NPT thread parameters:
H=0.866025 P =60° height of sharp Angle thread
Taper thread taper Angle B=1°47(single side), taper ratio =1/16(diameter: length)
H = 0.8P = product thread height FC = top cutting depth
P =1/n= pitch (measured parallel to the shaft) Fi = Depth of bottom cutting
N = Number of threads per inch Fc= width of the top plane of the tooth
A =30° Lateral Angle of thread Fr- width of bottom plane of tooth
The BASIC MAXIMUM depth OF THE THREAD truncation surface, H (see Figure 1), depends on the parameters of the tool and the mode of locking connection in the process.
The top and root of the internal and external threads can be cut parallel to the pitch line or parallel to the axis. The top and root of the pipe thread are cut at least 0.03P. The cutting height determines the tolerance value of the large diameter of the external thread and the small diameter of the internal thread.