Pipe union fittings are used to connect two pipes of different sizes or materials. They are available in various types, such as male and female 

threads, compression fittings, and push-fit fittings. These fittings are designed to provide a secure and leak-tight connection, ensuring proper flow 

of fluids in plumbing and industrial applications.

Pipe union fittings are widely used in pipelines. The main uses are: first, it can extend the connection of the pipeline to transport liquid; second, it can make the pipeline 

carry out two-way construction to overcome the small size error at the jointing point; third, it can be temporarily folded during local repair; fourth, it 

can be used for large-scale machine pipelines factory processing, disassembly and on-site assembly, etc.

It is composed of three pieces, called piece No. 1, piece 2, and piece 3 (as shown in the picture). According to its internal sealing form, it can be 

divided into two types: soft seal and hard seal. Soft seals are also called flat seals and require a gasket (mostly Teflon material). Hard seals are 

divided into two types according to the sealing surface, one is spherical seal, the sealing surface is spherical, the other is cone seal, the sealing 

surface is cone surface. The selection of the sealing surface can be determined according to the medium being transported. If the medium does 

not need to be in contact with materials other than stainless steel, a hard sealing surface can be selected. Hard-seal spherical seals are mostly used 

when the pipeline has a certain small angle in the axial direction, but spherical seals have strict installation requirements. In terms of ease of installation, 

soft seals are the easiest to install, followed by cone seals, and spherical seals are the most difficult to install, so try not to use spherical seals.

The optional No. 1 and No. 3 parts can be processed into paired welding ends, socket welding ends, external threaded ends and internal threaded ends respectively. 

This is also due to the flexibility of connecting to the outside. According to needs, different interface ends can be formed at both ends, which depends on the situation

 of the connected end. Therefore, when purchasing a controller, be sure to specify the interface type of the part number.

During the processing of Pipe Union, due to the error of the measuring tool, it may cause the non-interchangeability of Union, which is allowed. However,

 in the case of factory processing and on-site assembly of large machinery (devices), there may be requirements for interchangeability, which must be

 explained when purchasing. Avoid unnecessary trouble during on-site assembly.