Depending on the purpose and pipe material, commonly used connection methods for the construction of steel pipes include threaded connection, flange connection, welding, groove connection (clamp connection), ferrule connection, compression connection, hot melt connection, socket connection, etc.

1. Threaded connection: Threaded connection is made by using threaded steel pipe fittings. Galvanized steel pipes with a pipe diameter of less than or equal to 100mm should be connected by a threaded connection, and are mostly used for surface-mounted steel pipes. Steel-plastic composite pipes are also generally connected with threads. Galvanized steel pipes should be connected with threads. The surface of the galvanized layer and the exposed threaded parts that are damaged when threading the threads should be treated with anti-corrosion. Flanges or ferrule-type special pipe fittings should be used for connection. The welds between galvanized steel pipes and flanges should be Secondary galvanizing.

2. Flange connection: Flange connections are used for steel pipes with larger diameters. Flange connections are generally used in main pipelines to connect valves, check valves, water meters, water pumps, etc., as well as on pipe sections that require frequent disassembly and maintenance. If galvanized pipes are connected by welding or flange, the welding joint should be secondary galvanized or anti-corrosion.

3. Welding: Welding is suitable for non-galvanized steel pipes. It is mostly used for concealed steel pipes and steel pipes with larger diameters and is widely used in high-rise buildings. Special joints or welding can be used to connect copper pipes. When the pipe diameter is less than 22mm, socket or casing welding should be used. The socket should be installed against the flow direction of the medium. When the pipe diameter is greater than or equal to 2mm, butt welding should be used. Stainless steel pipes can be socket welded.

4. Grooved connection (clamp connection): The grooved connector can be used for galvanized steel pipes with diameters greater than or equal to 100mm in fire water, air conditioning hot and cold water, water supply, rainwater, and other systems. It is easy to operate and does not affect the steel pipe. The original characteristics of the pipeline, are safe construction, good system stability, convenient maintenance, saving labor and time, etc.

5. Card sleeve connection: Aluminum-plastic composite pipes generally use threaded clamp sleeves for crimping. Put the fitting nut on the end of the steel pipe, then put the inner core of the fitting into the end, and use a wrench to tighten the fitting and nut. Copper pipes can also be connected using threaded ferrules.

6. Press-fit connection: Stainless steel press-type pipe fittings connection technology replaces traditional water supply steel pipe connection technologies such as threading, welding, and adhesive joints. It has the characteristics of protecting water quality and hygiene, strong corrosion resistance, and long service life. It will be used during construction. Socket pipe fittings with special sealing rings are connected to steel pipes, and special tools are used to compress the pipe mouth to seal and tighten. It has the advantages of convenient installation, reliable connection, and economical and reasonable construction.

7. Hot melt connection: The connection method of PPR pipes uses a hot melter for hot melt connection.

8. Socket connection: used for connecting cast iron pipes and fittings for water supply and drainage. There are two types: flexible connections and rigid connections. Flexible connections are sealed with rubber rings, while rigid connections are sealed with asbestos cement or expandable filler. Lead sealing can be used in important situations.