The composition of double set joints such as end straight joint, straight joint, tee joint, elbow, joint with movable nut, hinged joint, plug, transition joint, etc.: front snap ring, rear snap ring, nut. Common materials include stainless steel and carbon steel, with metric, American, and British threaded standard fittings NPT, PT, and G, all of which are pipe threads. NPT represents national (American) pipe threads, and according to American standards, it is a 60 degree taper pipe thread. GB/T12716-1991 can be found in North American national standards

PT stands for pipe thread, which is a 55 degree sealed conical pipe thread belonging to the Wyeth thread family. It is commonly used in the water and gas pipeline industry in Europe and Commonwealth countries, with a taper of 1:16. The national standard can be found in GB/T7306-2000G, which is a 55 degree non threaded sealing pipe thread belonging to the Wyeth thread family. The symbol G represents the national standard for cylindrical threads, which can be found in GB/T7307-2001

In addition, the 1/4, 1/2, and 1/8 markings in the thread refer to the diameter of the thread size, measured in inches. Internally, it usually refers to the thread size, measured in minutes. One inch equals 8 minutes, 1/4 inch equals 2 minutes, and so on

G is the general term for pipe threads (Guan), and the 55 degree and 60 degree divisions are functional, commonly known as pipe circles. Threads are machined from cylindrical surfaces.

ZG, commonly known as a pipe cone, refers to a thread machined from a conical surface. Most water pipe fittings are made in this way. The domestic old thread is labeled Rc, and the external thread is labeled R

Metric threads are represented by pitch, while American and British threads are represented by the number of threads per inch, which is their biggest difference. Metric threads have a 60 degree equilateral profile, British threads have an isosceles 55 degree profile, and American threads have a 60 degree profile.

Metric threads are measured in metric units, while American and English threads are measured in English units.

Pipe threads are mainly used to connect pipelines, with tight fit between internal and external threads. There are two types: straight pipes and tapered pipes. The nominal diameter refers to the diameter of the connected pipeline, and obviously the thread diameter is larger than the nominal diameter.

1/4, 1/2, and 1/8 are the nominal diameters of imperial threads, measured in inches.