Overview of NPT/PT/G pipe threads for machining

In the daily mechanical processing, we often encounter different types of thread, the function of different threads are also different,what are the commonly used thread in the machining drawing? What does each stand for? What standards should be followed?

Today, let's introduce NPT/PT/G Pipe Thread. NPT is the abbreviation of National(American) Pipe Thread, a 60-degree cone Thread used in North America. The reference National standard document is GB/T12716. PT is the abbreviation of Pipe Thread, a 55 degree sealed conical Pipe Thread, belonging to the Whitworth Thread family. It is commonly used in the water and gas pipeline industry in Europe and The Commonwealth of Nations. The taper is specified as 1:16. G is 55 degree non-threaded sealing pipe thread, belonging to the Wyeth thread family. Labeled G for cylindrical thread. The national standard is GB/T7307. In addition, 1/4, 1/2, 1/8 marks are the diameter of thread size in inches. People usually refer to thread size as cents. An inch is 8 cents, a quarter of an inch is 2 cents, and so on. G is the general name of pipe thread (Guan), 55,60 degree division belongs to the functional, commonly known as pipe circle. The thread is machined from a cylinder. ZG commonly known as pipe cone, that is, thread is processed from a cone surface, the general water pipe joints are like this, national standard marked as Rc. Metric threads are represented by their pitch, whereas American and British threads are represented by the number of threads per inch, and this is the biggest difference between them. Metric thread is 60 degrees of isosceles, inch thread is 55 degrees of isosceles, and US thread is 60 degrees. Metric threads in metric units, American and British threads in inch units.