(1) When the pipes of the fire hydrant water supply system adopt hot-dip galvanized steel pipes with inner and outer walls, welding should not be used. When the system pipeline adopts a non-corrosion inner wall, it can be welded, but the welding of the pipeline should meet the relevant requirements. The pipes of the automatic sprinkler system (referring to after the alarm valve) cannot be welded but should be connected by threaded, grooved pipe joints or flanges.
(2) Galvanized steel pipes with a pipe diameter > 100mm in the fire hydrant water supply system shall be flanged or grooved. The automatic sprinkler system pipe diameter > 100mm does not specify that the threaded connection cannot be used. It is only required that the pipe section with a pipe diameter ≥ 100mm should be equipped with a flange connection or a groove connection point at a certain distance.
(3) For fire hydrant water supply systems and automatic sprinkler system pipes, it is recommended to use threaded flanges when flange connections are used, and secondary galvanizing should be performed when welded flanges are used.
(4) When the diameter of any pipe section needs to be changed, standard reducing pipe joints and fittings should be used.
(5) For the connection method and related technical requirements of fire-fighting pipelines, please refer to the relevant regulations in "Technical Measures for Design of Civil Construction Engineering - Water Supply and Drainage".