Requirements for fire hose fittings
Main technical points of connection of fire water supply pipe4.3.1 General requirements(1) welding shall not be used when using hot galvanized steel pipes inside and outside the fire hydrant water supply system. The system pipe adopts the inner wall without corrosion, and the pipeline can be welded and connected, but the welding of the pipeline shall comply with the relevant requirements. Automatic sprinkler system (alarm valve), the pipe can not be welded, should be threaded, groove, pipe or flange connection.
(2) galvanized steel pipe with diameter > 100mm of hydrant water supply system shall be flanged or grooved. The automatic sprinkler system, 100mm diameter is not clear thread connection cannot be used in pipe diameter greater than 100mm shall be provided with flange connection or groove connection point at a distance only.(3) the water supply system of fire hydrant water supply system and automatic sprinkler system shall be threaded flange, and two zinc plating shall be adopted when welding flange is adopted.
4.3.3 thread connection(1) the galvanized steel pipe with inner diameter of less than DN100 and hot-dip galvanized seamless steel pipe both inside and outside wall can be threaded. When using internal and external wall of hot galvanized steel pipe, the pipe can be used malleable iron threaded fittings (GB3287-3289); when the system adopts internal and external wall of hot galvanized seamless steel pipe, the pipe can be used forged steel threaded pipe fittings (GB/T14626).(2) steel tube wall thickness is smaller than <Sch30 (DN = 200mm) or wall thickness is smaller than <Sch40 (DN<200mm), are not allowed to use thread connector.(3) when the pipe adopts 55 degree taper pipe thread (Rc or R), thread interface can be used PTFE sealing; when the pipe with 60 degree taper pipe thread (NPT), should be used as thread sealant to seal the interface; sealing tape should be applied in male thread.(4) pipe diameter > DN50 shall not use thread movable joint, and single variable diameter joint shall be adopted at reducing diameter of pipe.4.3.4 welding or flanged joint(1) according to the flange type connection form can be divided into: flange, welded flange and threaded flange etc.. Flange selection must comply with steel pipe flange (GB9112-9131), steel welded seamless pipe (GB/T12459), pipe flange with Teflon coated gasket (GB/T13404) standard.(2) if hot-dip galvanized steel pipe adopts flange connection, threaded flange shall be used. The system pipe adopts the inner wall without corrosion, and the pipeline can be welded and connected. Piping welding shall be in accordance with the specification for construction and acceptance of welding equipment for field equipment and industrial piping (GB5036).
