We often come into contact with various thread interfaces during equipment use and maintenance. How can we distinguish various thread interfaces?

Let me analyze the letters and numbers above the threads represent some of the above meanings. The threaded joints used in the industry are generally made of metal. The pressure resistance is high. The materials include carbon steel, stainless steel, alloy steel, brass, etc. The threading materials used in life generally include PC, PVC, PPR, etc.

1. The thread is distributed on the outer surface of the mother's body called the outer thread (public thread), and the inner thread (mother thread) on the surface of the mother's body;

2. The thread is divided into triangular thread, rectangular thread, trapezoid thread and jagged threaded according to its section shape (dental type); triangular threads are mainly used for connection, and other are mainly used for transmission;

3. The thread formed on the cylindrical mother is called cylindrical thread, and the thread formed on the cone mother is called a cone thread;

4. The tube thread is a thread used on the tube wall for connection. There are 55 degrees of non -sealing tube threads and a 55 -degree sealing tube thread. It is mainly used to connect the pipeline, so that the coordination of its internal and external threads is tight, there are two types: direct tube and cone pipe; common tube threads mainly include: NPT, PT, G, etc.

4.1 NPT is the abbreviation of National (American) PIPE Thread. It belongs to the US standard 60-degree spinal canal thread, used in North America, and the national standard review GB/T12716-1991.

4.2 PT (BSPT) is the abbreviation of PIPE Thread. It is a 55 -degree seal cone tube thread. It belongs to the Wyeth thread family. It is mostly used in European and Commonwealth countries. -2000. The domestic name is ZG.

4.3 G is a 55 -degree non -threaded sealing tube thread, which belongs to the Wyeth thread family. It is marked as G represents the cylindrical thread. The national standard review GB/T7307-2001.

 

The difference between public thread and British thread

Public threads are represented by thread distance, and the US -British thread is represented by the number of threaded teeth in each inches;

The public thread is 60 degrees and other border tooth types.

Public -made thread for public units (such as MM), British -made units for American British threads (such as inches);

"Inner people" usually use "points" to call the screw size. One inch is equal to 8 points, 1/4 inches is 2 points, and so on.

Moreover:

ISO -public thread standard 60 degrees;

Un -unified thread standard 60 degrees;

API -US petroleum pipe thread standard 60 degrees;

W — Wyeth thread standard is 55 degrees.

 

The difference between NPT, PT, G various threads

NPT, PT, G are all tube threads.

NPT is the abbreviation of National (American) PIPE Thread. It belongs to the US standard 60 -degree cone tube thread and is used in North America. National standards can consult GB/T12716-1991

PT is the abbreviation of PIPE Thread. It is a 55 -degree seal cone tube thread. It belongs to the Wyeth thread family and is mostly used in European and Commonwealth countries. It is often used in the water and gas pipe industry, and the conicalness regulations are 1:16. National standards can consult GB/T7306-2000

G is a 55 -degree non -thread seal tube thread, which belongs to the Wyeth thread family. It is marked as G represents the cylindrical thread. National standards can consult GB/T7307-2001

In addition, the 1/4, 1/2, and 1/8 mark in the thread refers to the diameter of the thread size, and the unit is inch. Inside people usually use points to call the thread size, one equal to 8 points, 1/4 is 2 points, such push.

G is the collective referred to as the screw (Guan). The division of 55,60 degrees is functional, commonly known as tube circle. That is, the thread is processed by a cylindrical surface. Seal tube thread (R)

 

British sealing tube thread's basic size and tolerance

Way of cooperation

There are two ways to match the British sealing tube thread:

The cylindrical thread and the cone external thread form "column/cone";

The cone internal threads form "cone/cone" with the cone external thread.

European countries mainly adopt "column/cone" and thread; while countries outside Europe mainly use "cone/cone" with threads. The test quantity regulations of the two threads are different; 2: 2000) It is designed by the system according to the "column/cone".

Label

The complete mark of the British sealing tube thread is composed of the thread feature code, the thread size, and the rotation code.

The characteristic code of the British sealing cylindrical inner thread is: RP;

The characteristic code of the British sealing cone internal thread is: RC;

The characteristic code of the British -made sealing cone external thread is: R1 (combined with the British sealing cylindrical inner thread); R2 (combined with the British sealing cone internal thread); Omitted.

For sealing tube threads, use RP/R1, RC/R2 represent "column/cone" and "cone/cone" thread.

 

The basic size and limit deviation of the British non -secret tube

Label

The complete labeling of the British non -sealing tube thread is composed of the thread characteristic code, the thread size, the middle diameter tolerance level code and the rotation code.

The characteristic code of the British non -secret cylindrical thread is: G

For the British non -densely sealed cylindrical inner thread, the level of the tolerance level of the diameter is omitted; while the British non -densely seal cylindrical outer threaded codes are A and B.

The rotation code of the left rotor thread is LH; the rotation of the right rotation thread is omitted.

When the thread of the British non -sealing tube thread is indicated, only the marking code of the external thread is marked.

Example:

The right rotation of the size is 2, non -sealing cylindrical inner thread: G2

The size of the size is 3, the right rotation, the non -sealing cylindrical outer thread: G3A

Class B with size 4, left rotation, non-sealing cylindrical outer thread: G4 B-LH

The right rotation of the size is 2, the non -sealing cylindrical inner thread and the A -class cylindrical threaded thread.

other  

The inner hole thread is the teeth of the pipe threaded thread processing outer thread.

 

55 ° cone tube thread transformation

The 55 ° cone tube thread means that the tooth angle of the thread is 55 ° and the thread has a taper of 1:16. This series of threads are widely used in the world. Its code -code regulations are different.

The ISO code of Japan, Britain, France, and Japan, Japan,, R (outer), G, PT, R, R (outer thread), RC (inner), R, RC

60 ° cone tube thread transformation

The 60 ° cone tube thread refers to a tube thread with a tooth angle of 60 ° and a threaded taper of 1:16. This series of threads are applied in my country's machine tool industry and the United States and the former Soviet Union. Its coded, my country used to regulate K, and later stipulated as Z, and now it is changed to the NPT. Thread standard, also known as the rice -made thread. The biggest difference from the British thread is the millimeter metering of the thread distance. There are ordinary thread (tooth type angle 60 °); trapezoidal threads (30 ° of tooth angle); jagged threaded (33 ° tooth angle); square teeth threads and other types.