(1) Welding connection: If there is no need to disassemble, welding can be used. Compared with the traditional connection method, this method has a simple structure, and any components can be directly connected; the material is economical and the cross-section is not weakened; the manufacturing and processing are convenient and can be automated; the connection is airtight and the structure is rigid. In terms of emergency repair efficiency, it is not suitable for today's environment.

(2) Flange connection: The flange is welded to the pipe mouth. The connection between the two pipe mouths is first welded with flanges or threaded with flanges, and then the two welded flanges are connected, and a gasket is added in the middle.

(3) Grooved pipe fitting connection: This connection method is the main technology for the connection of liquid and gas pipelines. The pipe fittings required for this connection method are: rigid joints, flexible joints, mechanical tees and grooved flanges, elbows, tees, crosses, reducers, blind plates, etc.