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Metrische, US- und Zoll-Gewindestandards

Zeit: 2022-04-06 Zugriffe: 29

NPT, PT, and G are pipe threads.  

NPT stands for National (American) Pipe Thread. It is the American standard 60-degree taper Pipe Thread used in North America.  The national standard can be referred to GB/T12716-1991  

PT is short for Pipe Thread. PT is a 55 degree sealed conical Pipe Thread, a wyeth family of threaded threads, used in Europe and the Commonwealth countries. Commonly used in water and gas pipe industry, the taper is 1:16, the national standard can be referred to GB/T7306-2000. 

G is 55 degrees of non-sealed pipe thread, belongs to wyeth thread family, marked G on behalf of cylindrical thread, the national standard can be referred to GB/T7307-2001.

In addition, the 1/4, 1/2, and 1/8 marks in the thread are the diameter of the thread size, in inches.  

People in the industry usually use minutes to call the thread size, an inch is equal to 8 minutes, 1/4 inch is 2 minutes, and so on.  

G is not a general name for pipe threads (Guan), it is from the ISO standard, which provides for cylindrical pipe threads. The division of 55 and 60 degrees belongs to the functional, commonly known as pipe circle.  That is, the thread is machined from a cylindrical surface.  

ZG commonly known as tube cone, is the old NATIONAL standard marking method, that is, the thread is processed by a conical surface.  According to the ISO standard, R represents conical external thread, Rc represents conical internal thread, and Rp represents cylindrical internal thread. 


The biggest difference between metric threads and British threads is the number of threads per inch.  

Metric threads are 60 degrees equilateral, Inch threads are 55 degrees isosceles, and American threads are 60 degrees.  

Metric thread in metric units, British thread in inch units.  

The pipe thread is mainly used to connect the pipe. The internal and external threads are closely matched, including straight pipe and taper pipe.  The nominal diameter refers to the diameter of the pipeline connected, obviously the screw diameter is larger than the nominal diameter.  

1/4, 1/2, and 1/8 are the nominal diameters of inch threads.