Installation preparation → Dry pipe installation → Alarm valve installation → Stand pipe installation → Spray layered dry branch pipe, fire hydrant and branch pipe installation → Water flow indicator, fire water pump, high-level water tank, water pump combiner installation → Pipeline pressure test → Pipeline flushing → Sprinkler head Branch pipe installation (system comprehensive pressure test and flushing) → throttling device installation → alarm valve fittings, fire hydrant fittings, sprinkler head installation → system water test.
Key points of connection technology
1. General requirements
①Welding should not be used when the pipes of the fire hydrant water supply system adopt hot-dip galvanized steel pipes on the inner and outer walls. When the system pipeline adopts non-corrosive inner wall pipeline, it can be connected by welding, but the pipeline welding should meet the relevant requirements. The pipes of the automatic sprinkler system (behind the alarm valve) cannot be welded, but threaded, grooved pipe joints or flange connections should be used.
②The galvanized steel pipe with pipe diameter ﹥100mm of the fire hydrant water supply system shall be connected by flange or groove. Automatic sprinkler system pipe diameter ﹥100mm is not clear and cannot use threaded connection. It is only required that flange connections or groove connection points should be provided at a certain distance on pipe sections with pipe diameter ≥ 100mm.
③For the pipes of the fire hydrant water supply system and automatic sprinkler system, threaded flanges are recommended when flanges are used, and secondary galvanizing should be carried out when welding flanges are used.
④ When any pipe section needs to change the pipe diameter, reducer pipe joints and pipe fittings that meet the standard should be used.
2. Groove connection
① The maximum working pressure of grooved pipe joints with a nominal diameter of DN≤250mm is 2.5MPa, and the maximum working pressure of grooved pipe joints with a nominal diameter of DN≥300mm is 1.6MPa.
② Flexible joints should be used in places with vibration and buried pipelines. Rigid joints should be used in other places. When rigid joints are used, a flexible joint should be set every 4 to 5 rigid joints.
3. Threaded connection
①The inner and outer wall hot-dip galvanized steel pipes or inner and outer wall hot-dip galvanized seamless steel pipes with pipe diameters less than DN100 in the system can be connected by thread. When the system uses inner and outer wall hot-dip galvanized steel pipes, the pipe fittings can be forged cast iron threaded pipe fittings; when the system uses inner and outer wall hot-dip galvanized seamless steel pipes, the pipe fittings can be forged steel threaded pipe fittings.
②The steel pipe wall thickness less than δ<Sch30 (DN≥200mm) or wall thickness less than δ<Sch40 (DN<200mm) shall not be connected by threaded connectors.
③When the pipeline adopts 55° tapered pipe thread (Rc or R), the threaded interface can be sealed with PTFE tape; when the pipeline adopts 60° tapered pipe thread (NPT), sealant should be used as the seal of the threaded interface; The tape should be applied on the male thread.
④ Threaded unions shall not be used for pipes with pipe diameters> DN50, and single reducing joints shall be used at the diameter of the pipes.
4. Welding or flange joints
①Flange types can be divided into flat welding flanges, bimetal welding, butt welding flanges and threaded flanges according to the connection form. Bimetallic welded steel pipe is a new type of pipe, and flange selection must meet steel pipe flanges, steel butt-welded seamless pipe fittings, and PTFE-coated gaskets for pipe flanges.
②If the hot-dip galvanized steel pipe adopts flange connection, threaded flange should be used. When the system pipeline adopts non-corrosive inner wall pipeline, it can be welded and connected.