NPT, PT, G　 are all pipe threads.

NPT is the abbreviation of National (American) Pipe Thread, which belongs to the American standard 60-degree tapered pipe thread and is used in North America. National standards can be found in GB/T12716-1991

PT is the abbreviation of Pipe Thread. It is a 55-degree sealed tapered pipe thread. It belongs to the Wyeth thread family and is mostly used in Europe and the Commonwealth of Nations. Commonly used in water and gas pipe industry, the taper is 1:16. National standards can be found in GB/T7306-2000

 

G is a 55-degree non-thread sealing pipe thread, which belongs to the Wyeth thread family. Marked as G stands for cylindrical thread. National standards can be found in GB/T7307-2001

In addition, the 1/4, 1/2, and 1/8 marks in the thread refer to the diameter of the pipe in inches.

Insiders usually use points to refer to the thread size, one inch equals 8 points, 1/4 inch equals 2 points, and so on.

G seems to be the collective name of pipe thread (Guan). The division of 55 and 60 degrees is functional, commonly known as pipe circle. That is, the thread is processed by a cylindrical surface.

ZG is commonly known as pipe cone, that is, the thread is processed by a conical surface, and the general water pipe joints are like this

Rc means conical internal thread

 

 

ZG means taper pipe thread, 3/4" means inch mark, which is 3/4 inch taper pipe thread, which is available in the "Hardware Manual".

To be precise, its inner diameter is 19.05 mm, but this is the old standard and is no longer used. The current national standard stipulates that the inner diameter of the ZG3/4" thread is 20 mm.

Its representation method should be: ZG3/4〃. Among them (〃) ​​is the representative symbol of inches.

One inch is equal to 25.4 millimeters. An inch is equal to 8 cents. The origin of 3/4 is 6/8=3/4. Commonly known as 6 points.

Similarly, the inner diameter of the ZG1/2" threaded pipe ≈ 15 mm. Commonly known as 4 points.

The inner diameter of the ZG1" threaded pipe ≈ 25 mm. Commonly known as 1 inch.

The inner diameter of the ZG11/2" threaded pipe is ≈32 mm. Commonly known as 1 inch and a half.

Taper pipe thread is only used for hydraulic system connection; while pipe thread G3/4〃 is only used for water pipe connection. Taper pipe thread is very similar to pipe thread, the difference is only in the taper.

DN is the nominal diameter