How to install fire pipes

(1) Overview

Galvanized steel pipes are generally used for indoor fire-fighting pipelines with a diameter less than or equal to DN 100, and seamless steel pipes are used for pipelines with a diameter greater than DN 100. Diameter less than DN 100, threaded connection, greater than or equal to DN 100, clamp connection.

(2) Construction process

1) Fire hydrant system construction process flow chart

Fire hydrant system construction flow chart

2) Fire sprinkler construction process flow chart

Fire sprinkler construction flow chart

(3) Technical measures

1) Before construction, you should be familiar with the construction drawing, relevant technical requirements and acceptance criteria, as well as the construction methods and technical essentials of various pipeline installation, and prepare a detailed construction plan to guide the construction; Establish a construction quality assurance system, control the quality of each process in the construction process, and ensure that the pipeline construction meets the requirements of design and acceptance specifications;

2) pipe cutting: the galvanized steel pipe is cut by a grinding wheel cutter; When the diameter of seamless steel pipe is greater than DN80, oxyacetylene gas can be used for cutting, and the fracture of the pipe should be smooth without burr and other defects, and the oxide should be removed by angular grinding wheel.

3) Before pipeline prefabrication, the flatness of the nozzle must be checked, and the flatness must meet the specification requirements.

4) Casing shall be added when the pipeline passes through the wall or floor, and the gap between the pipeline and casing shall be filled with flexible non-combustible materials.

5) Bracket installation: The lower end of the vertically installed main (main) pipe should be provided with a load-bearing fixed bracket, and the upper end should be provided with an anti-sway bracket. The main tee and elbow of the pipeline shall be fixed with brackets, and the hanger of the pipeline shall be fixed firmly. Spacing between supports and hangers of spray pipeline shall not be greater than the following table:

Nominal diameter (mm) dn25dn32dn40dn50dn70dn80dn100dn150.

Maximum distance between spray pipes (m)

6) When installing the steam-water hanger of the spray system pipeline, the distance between the steam-water hanger and the nozzle should not be less than 300mm, and the distance between the steam-water hanger and the end nozzle should not be greater than 750 mm At least one steam-water hanger should be installed between two adjacent nozzles of each straight pipe section on the water distribution branch pipe. When the pipe diameter is greater than or equal to DN50, each pipe section shall be provided with at least one anti-sway bracket. When the pipeline changes direction, anti-sway support should be added.

7) The installation of water supply equipment, pressure relief valve, alarm valve, water flow valve, monitoring valve and experimental valve of fire protection system must be carried out in strict accordance with the requirements and design requirements of Code for Construction and Acceptance of Automatic Fire Extinguishing Systems (GB5026 1-96).

8) Pipe fittings such as tee joints, joints and bends of pipelines should avoid supports, walls and floors. The processing and prefabrication of pipelines should be concentrated in the processing shed platform, and the processing quality should be strictly controlled. Rectify and adjust in time when problems are found to ensure that the quality of pipeline prefabrication and installation is under control.

9) In order to ensure the beautiful installation of spray pipeline (the pipeline is horizontal and vertical, and all evenly distributed nozzles are evenly distributed and on the same horizontal line), the following points should be paid attention to in the construction process:

A. Material guarantee: ensure the straightness and concentricity of the pipeline, and the pipe fittings are straight without routing deviation.

B pipeline construction guarantee: in order to ensure prefabrication quality, the quality of threaded pipe fittings shall be strictly controlled, and unqualified products are strictly prohibited. After prefabrication, it is necessary to check whether the directions of tee and elbow are consistent, and the center line connection should be parallel to the center line of the pipeline. If there is skew (or deviation), it belongs to the internal thread quality problem of the pipe fitting and should be replaced. If the assembly and fastening are not in place, it should be reworked to finally ensure that the nozzle riser will be installed in cooperation with the decoration in the future.

C. Spray pipeline construction

● First install the spray main pipe, ensure that the concentricity of the main pipe is in a straight line during installation, and straighten the pipe at any time to ensure a straight line. The installation of branch pipes shall be carried out after the pressure test by the supervisor is qualified. Nozzle connecting pipeline perpendicular to a straight line should be cut, sheathed and installed in a unified way, and then re-check whether the nozzle is in a straight line. If it is not on the same line, it should be adjusted in time to ensure the construction quality. The horizontal pipeline of the sprinkler system shall have a slope of 0.002.

● When installing branch pipes, the pipe sections should be numbered first, and the cutting, casing and installation should be unified. First, pull out the tee of the same numbered pipe section nearest to the supervisor, and adjust the pipe section with deviation of the tee. If the deviation is too large, the pipe should be cut again to ensure that each nozzle is in a straight line. Then proceed to the installation of the next batch of pipe sections and joints, and the requirements are the same as before. At the same time, the installation of supports and hangers of pipelines is also vertically and horizontally aligned.

D. Construction of nozzle positioning tube

The installation position of the lower nozzle should meet the specifications and decoration requirements. Therefore, in order to ensure the accuracy of the final installation position of the nozzle, the blanking of the nozzle should be determined according to the plane position and installation height of the nozzle. The accurate positioning of the nozzle is the key to the construction, and the plane position of the nozzle pops up on the ground by decorating the given datum line; The installation height of the nozzle is subject to the fact that the threaded opening does not expose the decorative surface, so the reducing bottom of the sewer pipe receiving the nozzle is about 10mm on the finished ceiling surface.

E. Measures to ensure the normal operation of automatic sprinkler system

● In order to prevent the pipeline from shaking during normal operation and not interfere with the spraying effect of the nozzle, the hanger should be used for fixing. If there is no requirement in the design, the following provisions should be considered:

● The distance between the hanger and the nozzle should not be less than 300mm, and the distance between the hanger and the end nozzle should not be greater than 750mm.

● Hangers shall be installed on the pipe sections between adjacent nozzles. When the distance between adjacent nozzles is not more than 3.6m, one can be installed; when it is less than 1.8m, it can be installed at intervals.

(4) Main construction methods

1) galvanized steel pipe threaded connection

A galvanized steel pipes and threaded connections shall be adopted for fire protection system pipes smaller than DN 100. When installing the pipeline, the thread mouth should be smooth and complete without broken wires, and the filler of the thread mouth should be tetrafluoroethylene tape or white lacquer hemp. The pipeline shall be assembled tightly at one time, and the exposed part of the thread mouth shall be protected by antirust paint, and the filler of the thread mouth shall not enter the pipeline.

B the threaded connection of the pipeline is machined by electric thread, and the machining times are 1 ~ 3 times. Threads should be processed correctly, clearly, completely and smoothly, without burrs and broken wires, and the total length of missing wires should not exceed 10% of the thread length.

C. For threaded connection, the filler shall be white coarse lacquered linen yarn or raw material belt, which shall be tightened once and shall not be rotated back. After tightening, there shall be 2-3 threads.

D. After the pipeline is connected, clean up the filler extruded by the thread, and the filler shall not be squeezed into the cavity to avoid blocking the pipeline, and at the same time, carry out anti-corrosion treatment on the exposed thread.

2) Installation of mechanical slotted rigid interface pipes: Seamless steel pipes can be galvanized, and fire-fighting system pipes with sizes greater than or equal to DN 100 can be connected by slotted fittings.

A. Construction sequence: After the pipeline passes the inspection, do a good job in the inspection of galvanized processing of the pipeline, and then carry out the blanking and grooving of the pipeline according to the pipeline prefabrication single line diagram; At the same time, according to the coordinates, elevation and direction of the pipeline, prefabricate and install the bracket (crane) of the pipeline; Processed and prefabricated pipelines can be put into pipeline installation after passing the inspection.

B. Pipeline groove processing: the pipeline is processed by electromechanical grooving machine. When finishing the pipeline, the corresponding grooving fixture should be configured (adjusted) according to the diameter of the pipeline, and at the same time, the height of the pipeline rolling bracket should be adjusted to keep the processed pipeline horizontal and aligned with the center of the electromechanical grooving machine, so as to ensure the smooth rotation and groove processing quality during pipeline processing;

C. Inspection of pipe end: After the groove of the pipeline is pressed, it is necessary to strictly check whether the depth and width of the groove meet the requirements, and there shall be no defects such as scratches, bumps or roll marks on the pipe end and the outside of the groove to ensure the sealing performance of the pipeline; At the same time, anti-rust paint should be applied to protect the groove extrusion part of the inner wall of the pipeline;

E. Inspection and lubrication of pipeline assembly and clamp gasket: Before pipeline assembly and installation, the type and specification of clamp gasket used for inspection must meet the design and product requirements; When installing the clamp gasket, apply a thin layer of lubricant on the outside of the flange and gasket, and then place the gasket on one side of the pipeline to ensure that the gasket does not protrude out of the pipe end. After the other side of the pipeline is in place, install the gasket in place, and the gasket should not extend into any groove;

D. Installation of pipe sheath: Before assembling and installing pipes and fittings, it should also be checked that the model and specifications of the sheath used must meet the design and product requirements; When installing the jacket, first remove a bolt at one end of the jacket, then cover it outside the lining on the pipeline, move the jacket to make the two ribs of the jacket match with the groove, and then insert the bolt for positioning. When the concentricity of pipeline installation or the installation and opening direction of pipeline tee and elbow meet the requirements of design and construction drawing, the bolts on both sides can be tightened evenly in turn to ensure that the two ribs of the pipeline clamp shell are in uniform and close contact with the pipeline groove.

E. Installation of the pipe clamp type mechanical tee: after the pipe is installed in place, it shall be located at the site according to the coordinate position set in the construction drawing, and the hole shall be drilled with a special electric mechanical drill (using a special supporting drill bit), and its aperture shall be slightly larger than that of the "guide" installation ring of the mechanical tee; When installing the "mechanical tee", check whether the product specifications and dimensions meet the product design requirements. When installing the "guide" and the mounting ring, we should ensure that they are aligned with the opening. After installation and positioning, the two bolts should be tightened evenly, so that the "mechanical tee" and the pipeline can be closely and evenly combined, and the tightness, rigidity and strength of the interface part of the "mechanical tee" can be ensured.

F processing and prefabrication of pipelines: the processing and prefabrication of pipelines should be concentrated in the processing shed (platform) and prefabricated according to the construction drawing and the single-line diagram drawn after field mapping; Strictly control the prefabrication quality, conduct random sampling inspection and pressure test on the processed pipeline, and make timely rectification when problems are found to ensure that the prefabrication and installation quality of the pipeline is under control;

G. Flange connection between pipelines, valves and equipment: When connecting pipelines and equipment, flange connection should be made with short pipes first, then galvanized after positioning welding, and then connected with system pipelines after installation.

3) Installation of fire box and fire hydrant

A. Installation in fire hydrant box: The installation requirements in fire hydrant box are the same as those of sanitary wares, which require stability, accuracy and firmness. At the same time, in the specific installation process of the box body, the box body with the appropriate opening direction door should be selected according to the layout of fire hydrant box.

B before the installation of fire hydrant box accessories, the surface of the box body and the door glass of the fire box should be wiped clean one by one, and the hemp belt and water gun should be piled up according to the requirements of design or standard atlas.

C the location of indoor fire hydrant shall meet the design requirements. Without the consent of the design, it shall not be changed without authorization.

D. indoor fire hydrant. The bolt mouth should be outward and should not collide with the door frame. The center of the valve is 1. 1m from the ground, 140mm from the side of the box, and 100mm from the back inner surface of the box.

E. The hose of the fire hydrant is connected with the quick connector, and a special chuck shall be used to hang the hose on the hook or hose tray in the box according to the structure in the box.

F fire hydrants must be tightly sealed, leakproof and easy to open.

4) Installation of nozzle

A. When installing the spray riser, pay close attention to the construction progress of the decoration unit, coordinate with the decoration unit under the leadership of the owner and supervisor, and consider two preparations for pressure test after the riser installation. First, the gap between decorative ceiling and keel construction is long, so it is necessary to install the riser, that is, to carry out hydraulic test, and then cooperate with decoration to install the nozzle; On the other hand, the interval between decoration processes is very short, so the riser installation is completed, that is, the nozzle is installed together with the decoration, and the installation in each area is completed, and the system test can only be carried out after the air pressure test is qualified.

B. The model/specification of the automatic sprinkler shall comply with the design regulations, and the product certificate shall be attached.

C the number of nozzles shall be set in strict accordance with the design requirements and shall not be changed without the consent of the design.

D where the direction is consistent and the elevation is commensurate, when installing the nozzle, it is advisable to fix it between the front and rear spray chambers with a straight line, and then install the middle part to ensure its beauty.

5) Installation of alarm valve group

The nameplate, specification and model of alarm valve shall meet the requirements of design drawings.

B. The fittings of alarm valve assembly are in good condition; The valve is flexible to open and close, with good sealing performance, and the valve body is clean and free from foreign body blockage.

C. When installing the alarm valve, the main valve body should be installed first, and the connection with the fire riser should be consistent with the water flow direction, and then the auxiliary pipeline of the alarm valve should be connected. The alarm valve should be installed in a place that is obviously easy to operate, and the height from the ground is generally about 1 m. The distance between the two sides and the wall is not less than 0.5m, and the distance between the front and the wall is1.2m. ..

6) Installation and construction of valves

A. Before installing the valve, check its type, specification, model and quality according to the design requirements. The valve stem shall not be bent, and the valve shall be pressure tested as required. For closed-circuit valves installed on the main pipeline, strength and leakage tests should be carried out one by one. Strength and leakage test pressure should be the pressure specified by the valve manufacturer. And make valve test records. Check for leaks.

B the installation position of the valve is generally subject to the site conditions except the dimensions indicated in the construction drawing, so as not to hinder the operation and maintenance of the equipment, and also to facilitate the disassembly and maintenance of the valve itself.

C. The installation position of the valve on the horizontal pipeline shall ensure that the handwheel is upward or inclined at 45 degrees or installed horizontally as far as possible, and shall not be installed downward.

D. When the flanged valve is installed with the pipeline, the flange at one end of the pipeline can be welded, fastened and hoisted together; The flange at the other end is a movable joint. After the pipe flanges on both sides are adjusted, the flange and the pipe are spot welded, removed and welded, and then the pipe flange is connected with the valve flange after galvanized.

E the valve flange is parallel to the steel pipe flange, and the general error should be less than 2mm. Flange bolts shall be tightened symmetrically. Select a gasket suitable for medium parameters and put it on the central sealing surfaces of the two flanges, pay attention to alignment, then tighten the bolts diagonally first, and finally tighten all the bolts comprehensively.

F when hoisting a large valve, the rope should be tied to the valve body, and it is forbidden to tie the rope to the valve stem and handwheel. When installing the valve, pay attention to the flow direction of the medium. Stop valves and check valves are not allowed to be installed backwards.

G for threaded valves, the threads must be kept intact. After filling, the thread should be reserved with 3 buttons, and the outlet end of the valve is equipped with a movable joint for easy disassembly and maintenance.

H valves connected with threaded flanges must be installed under closed conditions, and the installation direction of valves should be determined according to the flow direction of media.

7) System pressure test

After the installation of pipeline system is completed, pressure test shall be carried out on the system. (Concealed works shall be pressure tested before concealment, and approved by the representative of the construction unit or supervision engineer).

A. For the fire sprinkler system, when the working pressure is equal to or less than 1.0Mpa, the hydraulic strength test pressure shall be 1.5 times of the designed working pressure and not less than1.4 MPa; ; When the design pressure of the system is greater than 1.0Mpa, the hydraulic strength test pressure should be the working pressure plus 0.4Mpa.

B the test point of hydraulic strength test is located at the lowest point of the pipe network. When injecting water into the pipe network, the air in the pipe network should be exhausted first, and then the pressure should be increased slowly. After reaching the test pressure, stabilize the pressure for 30 minutes and visually inspect the pipe network. There should be no leakage and deformation, and the pressure drop should not be greater than 0.05Mpa.

C. After the water pressure strength test and pipe network flushing are qualified, carry out the water pressure test. Leak test. The test pressure is the design working pressure, and the pressure is stabilized for 24 hours. No leakage is unacceptable.