NPT is the abbreviation of National (American) Pipe Thread, which is a 60-degree taper pipe thread of the American standard.
PT is the abbreviation of Pipe Thread, which is a 55-degree sealed tapered pipe thread. It belongs to the Whitworth thread family and is mostly used in Europe and Commonwealth countries. It is commonly used in the water and gas pipe industries, with a taper of 1:16.
G is 55 degree non-threaded seal pipe thread
In addition, the 1/4, 1/2, and 1/8 marks on the thread refer to the diameter of the thread size, which is in inches. People in the industry usually refer to thread sizes in points. One inch is equal to 8 points, 1/4 inch is 2 points, and so on.
G is the general name for pipe threads (Guan). The division of 55 and 60 degrees is functional, commonly known as pipe circles. That is, the thread is processed from a cylindrical surface.
Metric threads are expressed by pitch, and American and British threads are expressed by the number of threads per inch. This is their biggest difference.
Metric threads are 60-degree equilateral teeth, British threads are isosceles 55-degree teeth, and American threads are 60 degrees.
Metric threads use metric units, and American and British threads use imperial units.
Pipe threads are mainly used for pipe connections. The internal and external threads are tightly matched. There are two types: 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. 1/4, 1/2, and 1/8 are the nominal diameters of British threads, in inches.
Thread angle: Metric and American threads are both 60 degrees, British is 55 degrees, TM water pipe thread is 30 degrees, SM sewing thread and BC thread are also 60 degrees, metric trapezoidal thread is 30 degrees, British trapezoidal thread is 29 degrees, trapezoidal thread (TW29 degrees TR and TM30 degrees).
Ordinary thread: Metric thread M; British W; American UNC, UNE, UNEF.
Pipe thread: British PS, PT, PF; American NPS, NPT, NPTF, NPSM.
Nozzle thread: The outer diameter of CTV and TV 1/4-20 is
1A: 0.2367-0.2489 (6.012-6.322);
2A: 0.2408-0.2489 (6.116-6.322);
3A: 0.2419-0.2500 (6.1443-6.350).
British thread: Specifications are made according to nominal size and number of threads per inch.
For example, 1/4″-20, 3/4″-10, 1″-8, 1/4″-20 means the nominal size is 1/4, that is, the major diameter is 6.35mm (25.4 divided by 4 = 6.35) and 20 threads per inch, and so on.