There are various ways to connect stainless steel pipes. The common key types include compression, union, compression, push-on, taper thread, socket welding, union flange connection, welding, and a series of connection methods that combine welding and traditional connection. These connection methods have different application scopes according to their principles, but most of them are easy to install, firm and reliable. The sealing valve or gasket material used in the connection is mostly made of silicone rubber, nitrile rubber and EPDM rubber that meet national standards, eliminating the user’s worries.

Here are some common ones for a brief introduction:

1. Compression connection

Compression connection: insert the pipe into the pipe mouth of the pipe fitting, tighten it with a nut, and use the spiral force to compress the sleeve of the pipe mouth through the sealing ring to seal and complete the connection of the pipe.

Features: From the perspective of connection alone, the pipe wall can be relatively thin, save materials, easy to install, can be disassembled, easy to repair, and the tool has a large pulling force.

Scope of application: DN50 or less, can be exposed.

Note: Compression connection requires flanging the pipe end of the pipe, or using a groove tool to spin a convex groove on the pipe end of the pipe, or adding a C-type thrust ring to the groove on the pipe end. The workload of on-site processing is large and the quality cannot be guaranteed.

2. Compression connection

Compression connection: A special rubber sealing ring is installed in the U-shaped groove at the end of the compression pipe fitting. During installation, the stainless steel pipe is inserted into the socket pipe fitting to the positioning step position, and the U-shaped groove and the compression part on one or both sides of the U-shaped groove are squeezed simultaneously with a special compression tool. The rubber sealing ring plays a sealing role after being squeezed, and the pipe fittings and pipes at the compression part shrink and deform at the same time (the cross section forms a hexagonal shape) to play a positioning and fixing role, thereby effectively realizing the connection of stainless steel pipes.

Features: Easy and quick installation, reliable sealing, but cannot be disassembled.

Scope of application: DN100 or less, can be installed openly or buried.

Description: The construction site of the compression connection requires little work, and only requires pipe cutting, deburring, pipe positioning, and compression. No other processing is required for the connecting pipes, avoiding quality defects caused by human factors.

3. Flexible connection

Flexible connection: insert the pipe into the pipe mouth of the pipe fitting, tighten the cap nut with a special wrench, and seal the sealing ring with a clamping ring to complete the connection between the pipe and the pipe fitting.

Features: easy installation, disassembly, and adaptable to harsh environments such as foundation sinking.

Scope of application: DN60 or less, indoor open installation, underground buried pipes, earthquakes, ground subsidence, and heavy vehicles passing through the environment.

Description: A groove machine is required to roll a groove on the end of the pipe on site to fix the C-ring.

4. Welding connection

Welding connection: Process the groove at the end of the pipe, and use manual or automatic welding to make a ring welding on the pipe.

Features: Traditional connection method, high welding strength, but welding conditions are required on site.

Scope of application: Both large and small pipe diameters are available, and can be exposed or buried.

Note: The wall thickness of the pipe is required to be thicker, and on-site welding has high technical requirements for the installer. It is impossible to perform solid solution treatment, and the welding quality cannot be fully guaranteed.

5. Socket welding connection

Socket welding connection: Insert the pipe into the socket pipe fitting, and the pipe fitting and the pipe are sealed by annular argon arc welding to complete the pipe connection.

Features: Traditional connection method, high strength, less leakage in the pipe network.

Scope of application: Both large and small pipe diameters are available, and can be exposed or buried.

Note: On-site welding cannot be performed for solid solution heat treatment, and the corrosion resistance of the weld is reduced. It is basically the same as carbon steel, and intergranular corrosion and stress corrosion will occur, affecting the service life of the stainless steel pipeline system.

6. Flange connection

Flange connection: The flange and the pipe are annularly welded, and fastened with quick clamps or bolts to make the sealing gasket between the flanges seal and complete the pipe connection.

Features: Traditional connection method, safe and reliable.

Scope of application: DN125-200, public buildings or large buildings pipelines.

Description: The traditional flange welding method can also be transformed to make the flange into a flexible flange, the pipe port is flanged or welded, the ring mouth is embedded in the groove, and the rubber seal is placed in the groove, and the sealing element is protected by limited compression.

7. Cone thread connection

Cone thread connection: The external thread and the pipe are annularly welded with argon arc welding, and the internal thread pipe fittings are connected with cone threads to seal and complete the pipe connection.

Features: Traditional connection method, simple, and strong pulling force.

Scope of application: DN65-100, public buildings and large buildings pipelines, adapt to harsh environments such as foundation sinking, and are more suitable for high temperature and high pressure projects.

Description: Welding is required on site, the external thread may be welded obliquely, the welding quality cannot be guaranteed, and rework or sealing failure may occur. There is also a problem of reduced corrosion resistance at the weld.