Introduction to the difference between NPT, PT, and G threads

NPT, PT, and 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 sealed 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 thread size, and the unit is 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 is the general 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. The general water pipe joints are like this, and the national standard is marked as Rc
Metric threads are expressed by pitch, while American and British threads are expressed by the number of threads per inch. This is the biggest difference between them.
Metric thread is 60-degree equilateral profile, British thread is isosceles 55-degree profile, and American thread is 60-degree.
Metric units are used for metric threads, and imperial units are used for American and British threads.
Pipe thread is mainly used to connect pipelines. The internal and external threads are closely matched, and there are two types of straight pipes and tapered pipes. The nominal diameter refers to the diameter of the connected pipe, obviously the thread diameter is larger than the nominal diameter.
NPT is the American standard 60-degree tapered pipe thread, dry-sealed, and the national standard GB/T12716-1991.
PT is a 55-degree sealed tapered pipe thread with ptfe material for sealing. The national standard can be GB/T7306-2000.
ZG is a 55-degree pipe taper thread, sealed with ptfe material