Thread connection is mainly suitable for small diameter pipelines. When joining, it is usually necessary to wrap fluoroplastic sealing tape around the threaded joints, or coat with thick paint, wrap hemp wire and other sealing materials to prevent leakage. When the pressure is above 1.6 MPa, gaskets are usually added to the end face of the pipe. This connection method is simple and can be disassembled and reassembled, but the loose joint must be installed in the proper place of the pipeline for disassembly and assembly.

Flange connections are suitable for a wide range of pipe diameters. Different flanges and sealing gaskets are selected according to the nature of the fluid, pressure and temperature, and the gaskets are clamped by bolts to keep the sealing.

Flange connection is mostly used in pipeline sections which need to be disassembled and assembled frequently and where pipelines are connected with equipment. At present, plastic-lined steel pipes, steel-lined tetrafluoroethylene pipes, rubber-lined pipes, super-high pipes, and other anti-wear and anti-corrosion pipes on the market all use flange connections.

Socket connection is mainly used for the connection between cast iron pipe, concrete pipe, clay pipe and its connectors. Tetrafluoride pipe is only suitable for water supply, drainage and gas pipeline working under low pressure and normal temperature.

When connecting, linen, asbestos or asbestos rope is usually filled in the socket slot first, then filled with asbestos cement or lead, and rubber sealing ring can also be filled in the socket to make it more flexible and allow the pipe to move a little.

Welded joints have good strength and sealing. They are suitable for all kinds of pipelines and save labor and material. However, when disassembling, the pipe and pipe joints must be cut off.