Square tubes are widely used, including structural square tubes, decorative square tubes, construction square tubes, mechanical square tubes, etc. When using them, multiple square tubes usually need to be overlapped together. So how do you connect square tubes?
1. Compression type
Insert the square tube into the nozzle of the pipe fitting and tighten it with a nut. Use spiral force to compress the casing at the nozzle through the sealing ring to act as a seal and complete the square tube connection. Scope of application: DN (nominal diameter) s150mm, can be installed in the open or concealed.
2. Welding type
Circular arc welding is performed on the usually socket-type pipe fittings and supporting parts to achieve a sealing effect and complete the matching connection. Scope of application: Pipes in public buildings and large buildings, with DN between 15mm and 100mm. For DN greater than 100mm, conventional butt welding is the most common method; it can be installed exposed and concealed indoors, or buried outdoors.
3. Heat shrinkable pipe fittings
When connecting square pipes, on-site welding can be used. Since welding points cannot be processed at the construction site, heat-shrinkable pipe fittings are used for supplementary sealing. A rubber welding sleeve is put on the pipe welding point, and then a special cross-linked polyethylene sleeve is put on it, which shrinks under the action of heat, thereby achieving Shrink seal. Applicable scope: pipes with DN below 400mm road.
4. Taper thread type
The externally threaded sleeve and matching parts are welded in an annular shape, and the internally threaded pipe fittings are connected with tapered threads to play a sealing role and complete the matching connection. The applicable range DN is 65mm-100mm.
Pipes in public buildings and large buildings can be used in harsh environments such as foundation sinking, high temperature and high pressure.
5. Limit compression type
The square tube adopts flange or port welding ring, and the connection method is live joint or semi-live joint connection. After compressing the rubber sealing ring limit seal by 20%-30%, it enters the metal sealing groove and uses a limit seal to protect the sealing element. Joints can be made of copper or carbon steel. The applicable range is DN below 400mm, which is suitable for harsh environments such as foundation sinking and various types of high temperatures and pressures.
6. Quick connect flange type
Perform annular chlorine arc welding on the flange and matching parts, and use a quick clamp to compress the sealing gasket between the flanges to act as a seal and complete the matching connection. Applicable range DN is 15mm-100mm, pipes in public buildings and large buildings.
7. Union-type quick-connect flange
The traditional flange is turned into a free-jointed flange, the steel pipe port is flanged or welded, the ring is embedded in a groove, and a sealing rubber piece is placed in the groove, and the limit compression method is used to protect the sealing element. The applicable range is DN below 400mm and can be used as underground pipe.
8. Pressure type
Insert the square tube into the pipe fitting. Both ends of the pipe fitting have protruding U-shaped grooves with built-in sealing rings. Use a special pipe fitting tool to clamp the socket to connect. Scope of application: DN≤100mm, can be installed in the open or concealed.

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