The commonly used standard thread in our country is the metric thread.

Commonly used screw thread standards at home abroad:

1. The American standard taper pipe zhi thread generally uses daoNPT, the tooth profile angle is 60°

2. PT thread is inch taper thread, profile angle is 55°, commonly used in sealing. The inch pipe thread is a fine thread, because the coarse thread has a large tooth depth, which will seriously reduce the strength of the pipe with the outer diameter of the thread.

3. PF thread is parallel thread for pipe.

4. G is a 55-degree non-thread sealed pipe thread, which belongs to the Wyeth thread family. Marked as G stands for cylindrical thread, G is the general term for pipe thread (Guan), the division of 55 60 degrees is functional.

5. 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, the old national standard is marked as Rc.

6. Metric thread is expressed by pitch, American British thread is expressed by the number of threads per inch. This is the difference between them. Metric thread is 60-degree equilateral thread, British thread is isosceles 55-degree thread, American thread 60 degrees.

7. Pipe thread is mainly used to connect pipelines. The internal external threads are closely matched. There are two types of straight pipe tapered pipe. The nominal diameter refers to the diameter of the connected pipe, obviously the larger diameter of the thread is larger than the nominal diameter.