1. Schematic diagram and photos from the site
Scheme of installation of cast iron pipe and photographs of the object are shown in Figure 6-1 and Figure 6-2, respectively.
Figure 6-1 Cast Iron Pipe Installation Diagram
Note: 1—scrap; 2—down tube cable
Fig. 6-2. Photos of the installation of cast iron pipes on site
2. Precautions
①Main materials, finished products, semi-finished products, accessories, instruments and equipment used in the project must have Chinese quality certification documents, and specifications, models and performance test reports must comply with national technical standards or design requirements. It must be in good condition when it enters the site and this has been checked and confirmed by the Supervisory Engineer.
②Major appliances and equipment must have complete installation and operation instructions. During transportation, storage and construction, effective measures must be taken to prevent damage or corrosion.
③Specifications and varieties of cast iron pipes and fittings for water supply must meet the design requirements. The inner and outer diameters of the flare and nozzles must be of the correct form and have a factory certificate.
3. Detailed explanation of construction methods
Technical process: preparation for installation → downpipe and pipe arrangement → coordination → connection of cast iron pipes with socket.
（1）Preparing for installation
Provide technical and safety information to the working group. Determine the method of lowering the pipe and the organization of work, prepare equipment and ropes for lowering the pipe, conduct a safety check. Next, check whether the specifications and varieties of pipes, fittings, connecting materials and accessories meet design requirements, as well as the presence of blisters, defects and cracks. Do not use defective pipes and fittings.
(2) Drainpipe and exhaust pipe
①The choice of pipe loading method should be determined according to the length and quality of pipe connections, the amount of engineering work and site construction conditions. It is generally divided into two methods: manual pipe loading and mechanical pipe loading. The manual descent method can take many forms, such as the sliding tube method, the hold-down cable descent method, and the chain support descent method.
② Using the tees, valves, fire hydrants and other parts calibrated by the surveyor, start lowering and unloading the pipes. Please note that the outlet is located in the direction of water flow.
③The large rope used for the downpipe should be firm in texture, free of strands, and not rotten.
④The mechanical downpipe should not rise at one point, but should rise at two points. At the same time, when lifting and moving pipes and fittings, protective measures must be taken to protect the working surface of non-metallic sockets, flange surfaces and anti-corrosion layers of metal pipes from damage. When lifting auxiliary equipment such as valves, the cable must not be tied to the impeller and bolt holes.
（3）Double
ConnectionInsert the socket into the socket and adjust the backlash and circumferential clearance within the specified range. This process is called reconciliation. The key points of the counterparty are as follows.
①When stabilizing the first pipe, the center of the pipe must be aligned with the center line of the inclined plate (positioning) and the height of the pipe bottom. The end of the pipe is blocked with a wooden square so that the pipe does not move when the mouth is open.
②Before leveling, remove the debris from the nozzle and clean it with a rag, then continue leveling, and then dig a working pit at the lower end of the socket. the pit must meet the opening conditions.
(4) Cast iron pipe socket interface
Connections of socket-type cast iron pipes are divided into rigid connections and flexible connections. Rigid joints usually consist of two parts: sealant and sealant. The flexible interface is only sealed with a special rubber ring.
The materials used for the interface must comply with the design requirements and current national technical standards, and must have certificates such as product qualification certificates and sample inspection reports. The pipeline interface and operation method are as follows.
①Interface of oil hemp and asbestos cement
A. Working method.
Ⅰ Clean the nozzle and then use special iron teeth to close the annular gap evenly.
Ⅱ.Twist the oiler into a bundle with a diameter 1.5 times wider than the annular gap, and the circumference of the pipe diameter plus 100mm. Insert the hemp braid into the input from the bottom of the interface up, drive the side fork into the socket with a hemp chisel, press the chisels together and tighten them alternately. After the first round of linseed oil has hardened, the iron teeth are removed. The depth of the hemp should be 1/3 of the total depth of the nest (2 - 3 circles), while it is desirable to have a rebound feeling when beating the hemp and hammering.
Ⅲ. After the hemp mouth reaches the standard, you can mix the ash and prepare the sealing material (asbestos cement). Use the mixed asbestos cement and fill it into the socket from the bottom up with twisting ash Stuff in layers, beat layer by layer until the knock is clear, gray surface will not become black, and the hand will not feel elastic. Beat until the surface is concave into the nest by 2 mm, and the depth should be constant.
Ⅳ. Cover immediately and scrub with wet dirt after removing dust.
b. Ingredients.
Ⅰ Use hemp (marijuana) to soak in 5% No. 65 or No. 75 heated regular petroleum bitumen and a mixture of 95% gasoline, and then dry it to become flaxseed.
Ⅱ. It is made from asbestos grade above 4 and Portland cement grade not lower than 32.5. Mixing ratio: asbestos:cement=3:7, water-cement ratio 1/10~1/9. It is advisable to use asbestos ash within 1 hour afteradding water and mixing.
②Asbestos cement apron (semi-rigid interface)
A. Working method. Its working method is basically the same as the flax asbestos cement interface, except that the insert material uses a rubber ring instead of linoleum. The rubber ring filling method is as follows.
Ⅰ. Put the rubber ring on the socket before fitting.
Ⅱ.Clean the mouth of the nozzle with a brush, then close the annular gap with a special iron tooth, then move the iron tooth from bottom to top, and fill the rubber ring at the mouth with a chisel. On the first pass, drive into the waterline of the nest, glue the chisel to the wall of the nest so that the rubber ring goes in one direction to prevent “twisting”. We divide 2-3 times to nail the apron to the socket by 10-20mm so that the apron does not fall into the slot.
Ⅲ Fill according to the cement asbestos ash filling performance requirements, and perform maintenance after passing the test.
b. Ingredients. The type and specification of the rubber ring must comply with the design requirements and match the socket of the pipe. The surface of the rubber ring should be smooth, and there should be no cracks, unevenness or other defects on the surface and cut after twisting, pulling and folding.
4. Design Summary
①Before lowering the pipe, it must be carefully inspected, and the cracked pipe must be dealt with. If a crack develops at the flared end, cut off the cracked section of pipe before use.
② Determine the specific positions of the parts with tees, valves and fire hydrants, and then determine the positions of the working pits one by one according to the direction of water flow from the bell. If the pipeline is long, due to the different lengths and specifications of the cast iron pipes, the one-time positioning of the working pit is often inaccurate, so it can be positioned segment by segment.
③ Depending on the length of the cast iron pipe, locate the working pit of the pipe section and excavate the working pit before laying the pipe.
④The asphalt anti-corrosion layer inside and outside the socket of the cast iron pipe is annealed by gas welding and cleaned with a brush.
2. ductile iron pipe installation1. Schematic diagram and photos from the site
Figure 6-3 and Figure 6-4 show a schematic diagram of the cast iron pipe insertion interface and photographs of the cast iron pipe installation site.
Figure 6-3. Schematic diagram of the cast iron pipe insertion interface
Fig. 6-4. Photo of the installation of a cast-iron pipe on site
2. Precautions
①The position of the installed pipe must meet the design requirements, and its height and center line must be accurate. When installing the pipe, the product mark on the flared end must be at the top of the pipe.
② When the pipe is lowered, the method of hanging the pipe at two points at the bottom of the bag should be used. The expander used should not damage the pipe and fittings. To prevent damage to the pipe, a rubber board or other flexible spacer should be placed between the pipe and the spacer.
③Rubber rings should be removed from the packaging as needed, and temporarily unused rubber rings should be sealed in the original packaging and stored in a cool, dry place.
④The flexible part of the pipe should make maximum use of the elbow. If it is really necessary to use the borrowing pipe interface, the pipe angle must be within the allowable range.
3. Detailed explanation of construction methods
Technological process: installation of ductile iron insert pipe → installation of mechanical ductile iron pipe → self-control after construction.
(1) Ductile iron pipe insertion
The installation of this type of rubber ring is different from the installation of an O-ring in a rigid joint of conventional cast iron pipes. It depends on the pulling force or lifting force of the machine to insert the bell into the bell. so that the rubber ring is compressed to prevent seepage. Its interface can withstand large deformation and axial tensile deformation, and has good impact resistance. The working conditions are improved, the operation is convenient, the quality is reliable, and the water can be used after the interface is installed.
①Preparation before installation
a. Check if the groove meets the design and installation requirements.
b.Check whether the cast iron pipe is damaged or cracked, and whether the nozzle size is within tolerance.
c. Remove burrs and debris from the nozzle.
d. The rubber ring must have a finished shape, smooth surface, no distortion or deformation.
e. Check that the mounting hardware is complete and in good working order.
②Installation points
a. Down the pipe. The pipe must be lowered to the bottom of the tank in accordance with the pipe specifications. If the pipe body has the sign up, the pipe must be placed in accordance with the standard.
b. Clear your nose. Remove all debris from the nest and wipe it clean, as any buildup can cause the nest to leak.
c. Put on the rubber ring. Place the rubber ring into the socket. Since the outside diameter of the rubber ring is slightly larger than the inside diameter of the groove of the socket, after inserting it into the groove, you need to lightly press it around the circumference with your hand so that it is evenly stuck in the groove.
d. Lubricant foristey. Use the lubricant provided by the manufacturer or evenly apply soapy water to the inner surface of the rubber ring and the running surface of the bushing.
e. Align the center of the socket with the center of the socket and install the pusher to lock it in place. Rotate the chain hoist to insert the socket evenly into the socket.
e. Check. The position of the push-in flare must comply with the regulations. Some manufacturers will mark the depth of the push-in at the end of the flare. After installing with a feeler gauge, insert the feeler gauge into the socket gap to ensure that the rubber ring is in the correct position.
(2) Mechanical installation of ductile iron pipe
Ductile iron pipe mechanical joints are mainly composed of cast iron pipes, rubber rings, pressure flanges, bolts and other components. The joint assembly does not require complicated tools to install and is easy to operate.
①Preparation before installation
a. Check your handset. Check whether the pipe is damaged or defective, whether the dimensional deviation of the outer diameter and circumference of the pipe is within the allowable range, comprehensively measure the dimensions of the pipe flare and nozzle, record and save the number, and select the pipe. with the smallest difference in diameter.
b.Clean the nozzle, check and repair the anti-corrosion layer.
c. Additional rubber ring.
d. Additional pressure flange and bolts.
e. Other drugs. Before installing the pipeline, it is necessary to thoroughly inspect and clean the groove, dig a working pit for mating, prepare lifting equipment and tools for pipe installation. Lifting equipment must be carefully inspected before installation to ensure safety.
②Installation points
a. Discharge flange and rubber ring location. After cleaning the nozzle, pressure flange and rubber ring, determine the installation position of the rubber ring on the nozzle, first guide the pressure flange into the nozzle, and then set the rubber ring to the specified position of the nozzle.
b. Brush grease. Before applying the lubricant, the flare and rubber ring should be cleaned again, and then evenly apply lubricant to the inner surface of the flare and the outer surface of the flare and rubber ring.
c. colleague. Raise the pipe slightly so that the flare is aligned with the flare and loaded. After adjusting the mating gap, fix the pipe body and remove the sling.
g. Temporary fastening. Insert the sealing rubber ring into the gap of the coupling, adjust the bolt hole of the discharge flange to match the bolt hole on the coupling, and temporarily fix it with 4 bolts in the vertical direction.
d. Tighten the bolts. Insert all the bolts into the bolt holes, install the nuts, and then tighten the bolts symmetrically and evenly at fractional times in transverse order.tightening up, down, left and right.
e. Check. After tightening the bolts, check the tightening torque of each bolt with a torque wrench.
4. Design Summary
①If the water supply pipe is laid underground, it must be below the local frost line. If it is necessary to lay above the frost line, measures should be taken to reliably retain heat and moisture protection. When laying underground in non-freezing areas, the depth of the top of the pipe should be at least 500 mm, the depth of the part crossing the road should be at least 700 mm. If the depth of penetration of the upper part of the pipe does not exceed 700 mm, in accordance with the design requirements, it is necessary to add a metal or reinforced concrete casing protection.
②Water pipes should not pass directly through sewers, septic tanks, toilets and other sources of pollution.
③Installing pipes in various wells of the water supply system, if there is no design requirement, the distance between the well wall and the flange or socket: when the pipe diameter is less than or equal to 450mm, it should not be less than 250mm; with a pipe diameter of more than 450 mm, it should not be less than 350 mm.
④Water and sewer pipes are laid in parallel at different heights, and when the vertical distance is within 500mm, if the diameter of the water pipe is less than or equal to 200mm, the horizontal distance between the pipe walls should not be less than 1.5m, if pipe diameter over 200 mm - at least 3 m.
3. Installation of a water pipe made of rigid PVC1. Schematic diagram and photos from the site
Scheme for calculating the amount of displacement of coordinates A of the end of the pipe and photos of the installation location of the PVC water pipe are shown in Figure 6-5 and Figure 6-6, respectively.
Fig. 6-5 Calculation diagram of the offset value of the coordinates of the pipe end A
Figure 6-6. Photo of installation of a PVC water pipe
2. Precautions
①Outlet plugs that have been fried and cleaned should be protected again from dirt accumulation, and should also be covered and protected on rainy days.
②After the interruption of construction or completion of the project, all openings must be closed.
③In general, the construction of lifting pipes should be carried out continuously without interruption to prevent accidental failure. If the accident is of a periodic nature, there must be a person on duty who will fix the accident. When a pipe jack is used as a casing, after the construction of the jack is completed and before threading the pipe, both ends of the casing must be temporarily blocked to prevent dirt from clogging the pipe.
④ Careful design and planning of the pile pit, strict measures and systems are the main prerequisites to ensure the quality of the pipe lifting project and the economic effect.
⑤ The error in the direction of each pipe rise must not exceed 50mm. If there are slope requirements, strictly follow the design requirements.
⑥The power and lighting equipment in the working pit and pipe should be equipped with leakage protection to prepare for power outage at any time, and the lighting voltage should not exceed 36V. All wires use safety waterproof wires.
3. Detailed explanation of construction methods
Flow diagram: preparation for installation → pipeline interface → valves, fire hydrants, outlet valves and other settings.
(1) Preparatory work before installation
In addition to the preparatory work that must be carried out in accordance with the normal installation of the pipeline, the following work must be carried out before installing the PVC-U pipe.
① All construction personnel should read the product instruction manual provided by the manufacturer in detail or complete construction training to understand the characteristics, construction methods and precautions for using PVC pipe.
②Pipes and fittings must be visually inspected and quality checked. If abnormal quality is found, it should be checked before use. Those with serious damage should be removed.
③Basic tools: electric cutter, tensioner, hand saw, rope, grease, brush, rag, gloves, file, ruler, adjustable wrench, etc.
（2）Building a pipeline interface
①General provisions
a. Piping connections can be made with push-in flexible connections with an elastic sealing ring or push-in connections with adhesive bonding, flange connections and other rigid connections.
b) Coupling rubber ring connections are suitable for pipes with DN not lessit is 63 mm, and couplings (quick couplings) can be used for pipes of various diameters.
c. Solvent connections are suitable for pipes with DN 20-200 mm, for pipes with DN over 90 mm, solvent connections must be made at the factory that supplies the pipes. execution of glue joints at the construction site, dn no more than 90 mm. Solvent connections typically use factory flared pipes; When flat pipes are used for on-site processing of sockets, the processing methods and facilities provided by the construction department must be approved by the construction and supervisory departments before use.
d. Flange connections are generally suitable for pipe transitions of various materials such as steel pipes and cast iron pipes, or pipe accessories such as valves and fire hydrants.
e. When the pipe is to be cut during laying, the cutting surface must be straight. The flare end of the push-in joint should be chamfered. The thickness of the pipe end after chamfering is usually 1/3~1/2 of the pipe wall thickness, and the chamfer is usually 15°. When finished, debris should be removed without leaving any burrs.
②Elastic O-Ring Flexible Interface
a. Characteristics of O-Ring (Rubber Ring): The O-ring used should not have cracks, air holes, thick leather, and seams, and its quality should meet the following requirements:
Ⅰ. Shore hardness ranges from 45 to 55 degrees.
Ⅱ. Elongation ≥ 500%;
Ⅲ.Tear strength≥16MPa;
Ⅳ.Permanent deformation<20%;
Ⅴ.Aging factor>0.8 (at 70°C for 144 hours).
b. operational requirements.
Ⅰ.Check the quality of pipes, fittings and rubber rings, clean the flare inside (including the groove of the rubber ring) and the outside of the flare.There must be no dirt or other debris.Install the rubber ring in the groove of the flare without twisted and special-shaped rubber rings must be installed correctly and not upside down.
Ⅱ.When the pipe end is inserted, the length must take into account the elongation due to temperature difference. The elongation must be calculated and determined according to the construction time and temperature difference.
Ⅲ The minimum insertion length of pipe connections must comply with the relevant specifications.
Ⅳ. After the insertion depth is determined, a circular mark should be made on the surface of the pipe end corresponding to one side of the insertion length. When joining, align the flare with the flare and keep the axis of the pipe straight and insert one at a time until the marked line is evenly exposed at the end of the flare.
Ⅴ.When inserting small-diameter pipes, it is advisable to use labor.m dn over 315mm. For pipes with larger nominal outside diameters, special pulling tools such as manual jacks can be used. It is strictly forbidden to use earth-moving machinery and other construction machinery to push and push the pipe for insertion.
Ⅵ. If there is too much resistance when inserting, pull out the rubber ring to check if it is twisted, and do not insert it forcibly. Once installed, use a feeler gauge along the interface gap to check if the rubber ring is in the correct position.
VII.When using a lubricant to reduce insertion resistance, the lubricant must be a certified lubricant provided by the pipe manufacturer. Lubricants must not damage pipes and flexible sealing rings. For pipelines carrying potable water, lubricants must be non-toxic, odorless, tasteless and bacteria-free.
Ⅷ.When applying grease, use a brush to evenly apply grease to the rubber ring built into the bell and the outer surface of the bell, and do not apply grease to the groove of the rubber ring installed in the bell. .
③Rigid interface for solvent bonding
a. Basic requirements for the characteristics of the solvent. The selected solvent must meet the following basic requirements:
Ⅰ. Strong adhesion and cohesion, easy to apply on the seam surface;
Ⅱ.Short curing time;
Ⅲ. The hardened adhesive layer does not pollute the water;
Ⅳ The strength of the connection must meet the requirements of the pipeline.
b. Operational requirements:
Ⅰ Preparatory work: The main preparatory work for gluing is to check the quality of pipes and fittings.
If the connected pipe needs to be cut off, the socket must be chiselled before connecting. When cutting the pipe, make sure that the fracture is flat and perpendicular to the axis of the pipe. The groove to be machined must meet the following requirements: the length of the groove is usually at least 3 mm, the thickness of the groove is from 1/3 to 1/2 of the pipe wall thickness. After processing the chamfer, remove debris.
Prepare the tools to use the interface.
Ⅱ. Clean your work surface. Before gluing pipes or fittings, wipe the inside of the flare and the outside of the flare with a dry cloth or cotton yarn to keep the bonding surface clean and free of dust, sand and water.
Ⅲ. Test insert. Before gluing, the two tubes must be inserted once, so that the insertion depth and fit meet the requirements, and the insertion socket depth marking line must be applied to the surface of the insertion end.
Ⅳ. Apply solvent. When applying a bonding solvent, the inside of the socket should be applied first, followed by the outside of the socket. The socket should be applied evenly and in the appropriatequantity along the axial direction from the inside to the outside. the use or absence of a coating is not allowed.
Ⅴ Bonding and curing. After applying the bonding solvent, immediately align the direction with the axis, insert the end of the pipe into the socket and press hard on the marked line. After insertion, rotate the tube 1/4 turn, maintain a constant applied external force for at least 60 seconds, and verify that the straightness and position of the interface is correct.
After the plug is completed, the adhesive solvent squeezed out from the outside of the joint must be wiped off in time. Stress or forced loading should be avoided.
④ Connecting the transition interface. When a rigid PVC water supply pipe is connected to pipes of various materials, valves, fire hydrants and other accessories, it is called a transitional interface connection. The method and requirements for the transitional connection are as follows.
a. Adapters can be used to connect pipes or valves in different materials at both ends and accessories such as fire hydrants. The structure of the connections at both ends of the adapter must be compatible with the shape of the connections at both ends.
b. The transition element usually uses special pipe fittings, and the connection to pipes at each end or to nozzles and fittings must comply with the following rules.
Ⅰ. When valves, fire hydrants, or steel pipes are flanged connections, the adapter and its connecting end must have corresponding flanged connections, and the position and diameter of the flange bolt holes must match the flange at the connecting end. .
Ⅱ. When using flare connections to connect pipes of different materials, the adapter and its connecting end must have the appropriate flare connections, as well as the inner diameter of the flare or the outer diameter of the flare and the characteristics of the sealing ring. must meet the requirements of the socket or socket of the connecting end, when pipes of different materials have flat ends, it is recommended to use a socket connection, and the inner diameter of the sleeve must meet the requirements of the different outer diameters of the connectors at both ends.
Ⅲ. Flexible connections should be used to connect to PVC-U pipe ends, and quick-release connections such as unions and couplings are preferred. When the connected PVC-U pipe fittings are flare connections, the adapter must be connected to the appropriate flare or flare.
c. Transition pieces are factory made and injection molded or recycled PVC-U fittings are preferred. If the manufacturer cannot provide fittings for PVC pipes and steel adapters are used, material, tolerances, specifications, etc.. must comply with the relevant connection standards.
d.When connecting a flange, the positions and bolt hole diameters of two adjacent flanges must be the same, and the position of the gasket or gasket must be correct, and tightening must be done symmetrically position. It should be avoided that the axial stress generated during the tightening process can lead to cracking of the pipes at both ends or to the separation of connections.
(3) Setting valves, fire hydrants, outlet valves, etc.
① When installing valves, fire hydrants, outlet valves and other accessories and fittings on the pipeline, the weight must not be supported by the pipeline. Rigid buttresses such as concrete and masonry must be installed. Buttresses must have sufficient volume and stability, as well as anchoring devices for attaching attachments and accessories. The concrete strength grade of the pier must be at least C15, and the brick pier must use machine-made bricks and cement mortar masonry.
②When the valves are installed in the pipeline, the flat height size can be determined according to the valve specifications and maintenance requirements.
③ If a slab foundation is used in the valve pit, the valve buttress must rest on the concrete floor of the valve pit foundation. When the support is ribbed to the bottom plate, the bottom plate and support can jointly withstand the axial force generated when the valve is closed.
④If there is no foundation floor in the valve well, the valve must be provided with an independent buttress. When the valve is closed and can generate axial force, the buttress must also be able to support axial force. When the weight and stiffness of the support are not sufficient to support the axial load, other effective measures must be taken on the pipeline.
⑤ The clear distance between the bottom of the well and the outer bottom of the pipe should not be less than 200 mm. In the absence of a concrete floor at the bottom of the well, a layer of pebbles with a thickness of at least 150 mm should be laid on the bottom of the well.
⑥The foundation of the valve well must be poured over the original foundation or backfilled and compacted soil. The concrete strength grade of the concrete structure must be at least C15, the brickwork must be made on a cement mortar with a strength of at least M7.5, the bricks must be made of machine-made bricks. The outer walls of brick wells below the groundwater level must be sealed with cement mortar, plastered and waterproofed.
⑦ The upper part of the valve well shall be made of gray iron, ductile iron, manhole cover and ductile iron support; a manhole cover made of composite materials such as fiber reinforced concrete and glass fiber reinforced resin (GRP) manufactured by the factory and supports can also be used. The steps in the well must be made of ductile iron and malleable iron; steelsteps should use steel plastic steps with external steel injection molding.
⑧ When the pipeline passes through the valve pit, it must be rigidly connected to the pit wall. As a rule, to deepen the transition part into the wall, a special through casing is used, which, after laying the pipeline, is poured in layers with dry, hard, fine-grained concrete. When erecting a brick wall of a well on an existing pipeline, it is possible to leave a gap around the pipeline of at least 50 mm, and for pouring, dry solid fine-grained concrete should be poured in layers, and the inner lining of the brick wall should be made of concrete; Steel casing for waterproofing ribs. The inner diameter of the pipe through the wall must be at least the outer diameter of the pipe plus 100 mm.
⑨The dug deep part of the trench under the pipe connecting the structure should be backfilled with gravel. And make not less than 90° arched earth foundation according to the requirements of pipeline laying.
⑩ When laying valves, fire hydrants, outlet valves and other accessories by direct burying, the bushing buried in the ground to support the valve stem must rest on the backfilled dense layer of soil. When using cast-iron pipes, concrete pipes, etc. as sleeves, concrete or brick foundations should be poured under the sleeves, and the backfill soil around the sleeves should be compacted. The accessories of the opening part of the top sleeve are set according to the specific conditions of each location.
4. Design Summary
①When the buried depth of the PVC-U pipeline foundation is lower than the bottom surface of the foundation of the building (structure), the pipeline should not be laid in the pressure zone of the foundation diffusion angle under the foundation of the building, and the diffusion angle can be 45°.
②When crossing PVC-U pipelines with embankments such as railways and expressways, protective casings made of reinforced concrete, steel, cast iron pipes and other materials must be installed. According to the regulations of the embankment authorities, when crossing a river, measures such as wrapping concrete should be taken outside the protective sleeve.
③ PVC pipes should not pass under buildings (structures). If it is necessary to pass, reliable protective measures must be taken, such as external casings.
④ When PVC pipes intersect with other pipes, the net distance between the bottom of the pipe and the top of the pipe below must be at least 0.2m, and the foundation processing must be carried out in accordance with design standards.
⑤The horizontal clear distance between PVC-U pipes and adjacent pipes must not be less than the slot width required for construction and maintenance, and the width required for ancillary structures such as manholes with gates. Horizontal clear distance between high temperature pipes such as heat pipes and pipes for toxic gases such as gaseshigh pressure pipes, should not be less than 1.5 m. Drinking water pipes must not be laid under drainage and sewer pipes.
⑥The horizontal distance between the center line of the PVC pipe and the outer wall (column) of the building (structure) must be at least the following standards: 1 m with a nominal outer diameter dн not more than 200 mm; 3.0 m if the nominal outside diameter dn is greater than 200 mm.
⑦Under the road, the depth of penetration of the upper part of the pipe should be at least 1.0m, under the sidewalk, when the nominal outer diameter dn is more than 63mm, it should be at least 0.75m, and when the nominal outer diameter dn is not more than 63mm , it should not be less than 0.5 m. In permafrost or seasonally frozen soils, the depth of penetration of the top of the pipe should be below the freezing line.
⑧Unless the design provides, 360° solid concrete shall not be used in the pipeline to treat the foundation or to increase the bearing capacity of the pipeline.
Installation of fire fighting equipment and construction of trenches and wells1. Installation of fire fighting accessories
1. Schematic diagram and photos from the site
Figure 6-7 and Figure 6-8 show a schematic diagram of the connection between an outdoor underground fire hydrant and a main pipe, and photographs of the fire pump connector.
Fig. 6-7 Connection between outdoor underground fire hydrant and main pipe
Fig. 6-8. Fire pump adapter photo
2. Precautions
①After installing the fire hydrant, water meter and gate, the well should be temporarily covered before the well cover is closed to prevent falling objects from falling into the well and damaging the equipment.
②If there is no temporary support for the bottom of the equipment, it is necessary to build or pour the buttress in time after the installation of the equipment.
3. Detailed explanation of construction methods
Workflow: installation of a fire pump connector → installation of an outdoor fire hydrant.
(1) Fire water pump adapter installation
①The water pump adapter is installed on the side close to the outer wall of the main building, and there is an open fire hydrant or fire water supply pool within 40 m nearby.
②Adjustment of the water pump adapter should be based on the design code, there are three types: underground type, above ground type and wall type. The installation site must be clearly marked, the valve position must be convenient, and there must be no obstacles near the adapter. The relief valve pressure must be determined according to the working pressure of the system, so that the external water pressure is not too high to damage the internal piping network and components, and the adapter must have a drain valve.
③The following accessories are included in the water pump adapter package: flange connection, gate valve, flanged tee, flanged presafety valve, flanged check valve, flanged elbow (with base), flanged elbow (without base, for wall-mounted type), flange connection, adapter body, fire interface. Among them, the factory length of the flange connection pipe is 340mm. During construction, it should be determined according to the height of the water pump adapter bolt installation center and the height of the ground, and cannot be generalized.
④The position and installation direction of the safety valve and check valve of the fire pump adapter must be correct, and the opening and closing of the valve must be flexible. The outlet pressure of the relief valve must be calibrated.
⑤ The distance between the top inlet of the groundwater pump adapter and the bottom surface of the fire hatch cover shall not exceed 400mm and shall not be less than the radius of the manhole cover. There must be sufficient working space in the well and a ladder must be provided.
⑥If the installation height of the fire pump wall adapter is not required by design, the distance from the center of the faucet to the ground should be 1.10m, and the net distance from the door, window, hole and hole in the wall should not be less than 2.0m , and it cannot be installed under glass curtain walls. Measures must be provided to prevent impacts from falling objects above it.
⑦ The installation dimensions of the fire pump adapter must comply with the design requirements, and the installation height tolerance of the bolt hole must be ±20mm.
(2) Installation of an outdoor fire hydrant
①Strictly check whether the fire hydrant switches are flexible, tight and strong, and attached accessories. Whether the equipment accessories are safe.
②Fire hydrant manholes must be built for outdoor underground fire hydrants, and fire hydrant valve manholes must be built for outdoor aboveground fire hydrants. Refer to the National General Water Supply and Sanitation Atlas for fire hydrant manhole specifications. On ordinary and ordinary roads, the upper surface of the manhole cover is the same as the surface of the road, and the tolerance is ± 5mm. When there is no ordinary road, the manhole cover is 50mm higher than the outer height, and a slope fence is made around the wellhead 2%.
③ The tee connecting the outdoor underground fire hydrant to the main pipe or the lower part of the elbow with or without a seat should be fixed on the concrete support first, the distance from the bottom of the manhole cover should not be more than 0.4m, and if it exceeds 0.4m, a short pipe should be added.
④According to the relevant specifications of this standard, install the flanged gate valve, double-flanged short pipe and hose connector labeled "Fire Hydrant".
⑤When installing an outdoor fire hydrantmounted on the ground, the height from the ground is usually 640mm. First, the base of the elbow belt of the lower part of the fire hydrant must be installed on a concrete support, and the installation must be stable.
⑥ Install opening and closing fire hydrant gates, the distance between which should not exceed 2.5 m.
⑦When installing an underground fire hydrant, if a lock well is installed, the fire hydrant water outlet must be blocked, and another water drain lock must be installed in the well.
4. Design Summary
①The system must be hydrostatically tested, and the test pressure must be 1.5 times the working pressure, but not less than 0.6 MPa.
② Before completing the construction of the fire extinguishing pipeline, it must be flushed.
③ The position marks of the fire pump adapter and fire hydrant are obvious, and the position of the hydrant should be convenient for operation. When the fire pump connector and outdoor fire hydrant are wall-mounted, if not required by the project, the installation height of the center of the inlet and outlet hydrants should be 1.10 m from the ground, and objects should be provided above to prevent falling. them.
④The installation dimensions of the outdoor fire hydrant and the fire pump adapter must comply with the design requirements, and the installation height of the hydrant must have a tolerance of ±20mm.
⑤ The distance between the top inlet of the underground fire pump adapter or the top outlet of the underground fire hydrant and the bottom surface of the fire hatch cover should not exceed 400mm, and there should be enough working space. there should be a ladder in the well. Frost protection should be carried out in wells in cold regions.
2. Construction of trenches and wells
1. Schematic diagram and photos from the site
See Figure 6-9 and Figure 6-10 for a schematic diagram of a pipe pit and a photograph of the pipe ditch construction site, respectively.
Fig. 6-9 Schematic diagram of drainage with a well drainage channel
Figure 6-10 Photographs of the pipe trench construction site
2. Precautions
①Installation control piles, horizontal piles at the top and bottom of trenches, portal panels, etc. should not collide when digging and transporting soil, and should not sit on the portal panels to rest.
② Ditch walls and side slopes must be protected during earthworks to prevent them from collapsing.
③Construction during the rainy season should shorten the length of the groove as much as possible to achieve rapid groove formation and rapid backfilling. After the formation of the bubble reservoir, drain the water in time, remove the surface soil softened by the base, replace it with sand and gravel or medium and coarse sand, well processedLay the foundation, and then lower the pipe for installation.
④ Install a sump next to the installation pit in the pipe trench, and make an open drainage channel near the pipeline foundation to prevent water from soaking the bottom of the tank.
⑤During the excavation of the trench, if underground cultural relics are found, the public security and cultural relics evaluation department should be contacted in time, and the site should be separated with a yellow warning tape to prevent cultural relics from being damaged. . If underground pipelines, cables or communication facilities are found, it is necessary to contact the owner and relevant departments in time for a common solution.
3. Detailed explanation of construction methods
Technological process: precipitation, drainage → trenching → pipeline foundation → laying of the well chamber.
(1) Precipitation and drainage
For pipe trenches located below the water table, or if a large amount of surface water or rainwater enters the trench, or if the original water and drainage pipes in the trench accidentally burst, resulting in the accumulation of water in the trench, it is necessary to organize the drainage of accumulated water. Digging should start from the lowest level of the bottom of the ditch.
① Learn about the distribution status and environment of various underground pipelines.
② Take hydrogeological data and use measures such as drainage ditch collecting well at the bottom of the ditch and wellpoint method to conduct drainage.
③Drainage ditch can be installed in the middle part, and when it is dug to the bottom of the ditch, it can be installed on one or both sides for drainage.
④ When the depth of the bottom of the ditch is less than 400mm below the water table and the ditch is made of sandy clay, ditches can be dug on both sides of the ditch to drain the accumulated water.
⑤After introducing the accumulated water into the sump, pump it out with a water pump. In general, the width of the entrance of the catchment well is 1-1.2 m. The sides of the ditch are reinforced with dense supports or sheet piles. The distance between the inside of the catchment well and the bottom of the tank, that is, the length of the water intake well, is determined as follows: for clay 1 m, for silty clay 2 m, for coarse sand 4 m, for sand 6 m for fine sand.
⑥If it is a sandy soil layer, the drainage pipes and filter pipes can be buried in or near the ditch, and the groundwater can be pumped out to drain, which is called the light point method.
(2) Digging a trench
①Measurement and marking completed, you can dig a trench. First, determine the depth of the excavation of the trench in accordance with the design mark.
②The purpose of determining the slope of a trench is to prevent landslides. After digging a trench, a certain slope must remain. The amount of slope depends on the quality of the soil and the depth of the trench.
③ Calculate mouth width based on depthditch, side slope and ditch bottom width.
④According to the requirements of the design drawings and the center line of measurement and positioning, according to the width of the top hole of the groove, stretch the gray line.
⑤ Divide into sections according to the number of people and the best working surface, cut the contour line of the trench along the straight edge of the gray line, and dig in order from deep to shallow. When opening a trench by hand, it is advisable to lay mixed soil on the top of the trench and good soil on the bottom of the trench separately for backfilling.
⑥The first and second types of soil can be excavated layer by layer according to 300mm, and the excavation can be done step back.
⑦ When the excavation depth exceeds 2m, a side slope should be left. In case of various changes in the cross section of the soil layer, it can be made into a broken slope or a support can be added.
⑧Dig once to clear the bottom of each layer, dig 1m deep to cut the slope once, and at the same time level it, and place small wooden pegs on the slope to control the level.
⑨Strictly control the height of the base when excavating the ground and digging trenches. Undisturbed ground 0.2-0.3m above the design level of the base should be cleaned manually, and the height should be measured once. Before performing the next process, dig a level according to the leveled trench stakes. In case of local digging or violations, loose soil should first be cleared, and then replaced with natural graded sand-gravel or medium-sized sand with a particle size of 10-15 mm and compacted.
（3）Pipeline foundation
①Pipe foundation construction can be done if the pipe trench is qualified and the height and coordinates are correct.
②When digging a trench, the natural soil layer at the bottom of the trench is disturbed and should be replaced by a gravel or sand bed. In case of disturbed soil, sandy or gravel soil, it should be compacted before laying the cushion; in case of clay soil, the gravel-sand cushion should be laid after replacing the soil. Water or dirt must be removed beforehand.
③Before starting construction, the foundation must be compacted to the design mark after clearing the floating soil layer and laying gravel.
④Pour concrete after laying the sub-base, starting from the manhole, and after completing the pouring of the foundation of the pipe trench.
⑤Construction of mortar and concrete must be carried out in accordance with the relevant civil engineering technical standards.
(4) Laying chamber
①This part is only described in terms of water supply, drainage and heating, and the stone structure of the well chamber must also comply with the relevant civil engineering technical standards.
②The laying of the well chamber must be carried out according to the project or giventh standard drawing. When marking the bottom of the well chamber above the groundwater level, the base must be compacted with even soil, when located below the groundwater level, the base must be a concrete floor 100 mm thick. For masonry, cement mortar should be used, and the inner surface after plastering should be tightly impervious.
③ When laying the well chamber, the connection between the pipeline and the manhole must be rigid. Where the pipeline passes through the wall of the well, cement mortar should be used to fill it tightly and smooth it twice so that there are no leaks. During construction, it is necessary to use a 1:2.5 cement mortar to tightly connect the well and pipe, and the brickwork of this part of the well wall requires staggered joints and turning the top.
④ Strong cast iron or concrete well rings should not be placed directly on the brick wall of the well chamber, and the brick wall should be made of fine-grained concrete pad with a thickness of at least 80mm.
⑤ For all kinds of well chambers located under the roadway or under the community road, it is necessary to use strong well rings and well covers. The top surface of the well cover must be flush with the road surface, and the tolerance is ± 5mm. Light well circles and manhole covers can be used on the green lane and in places closed to traffic. The top surface of the well cover should be 50 mm above the ground, and the slope around the mouth of the well should be 2% towards the ground. solution outside.
⑥Manhole covers of different well chambers must meet the design requirements and have obvious text marks, and different well covers must not be mixed.
(5) Backfill
①Backfilling of earthworks can only be carried out after hydraulic testing and covert acceptance.
② Before backfilling, clear the trench of silt, wood, and other debris. When backfilling the soil, dirt and organic matter must not be covered. The backfill should be free of stones and other solid objects.
③ Do not fill with water during backfilling, and there should be no accumulated water in the tank. If drainage during construction is difficult during the rainy season, a backfill measure may be taken along with downspouts. To prevent pipe demolition, first backfill more than one pipe diameter at the top of the pipe.
④The backfill starts from the junction of the bottom of the pipe with the foundation and is backfilled symmetrically in layers on both sides of the pipe cavity and compacted, the backfill height of each layer should be 0.15-0.20m.
⑤ The top 200mm of the top of the pipe must be manually backfilled with sand or earth without stones and frozen soil blocks, mechanical backfilling is strictly prohibited.
⑥Top 500mm topparts of the pipe should not be covered with stones and blocks of frozen soil with a diameter of more than 100 mm; When backfilling the upper part with equipment, the equipment should not walk along the trench.
⑦When laying a pipeline under a roadway, when laying a road surface immediately after laying, or laying a pipeline in a soft layer of soil, low-lying, swampy or high-water areas, backfill the trench with medium and coarse sand first, fill the corners tightly, and then backfill with medium and coarse sand or stone chips layer by layer up to 0.4 m above the top of the pipe, and then backfill with good quality soil upwards.
⑧If the trench is supported, it should be gradually removed along with the backfill. For the cross brace slot, first remove the support and then fill it with soil and remove the support from the bottom up. If straight-bearing slabs or sheet piles are used, they can be pulled out after more than half filling and covered with sand immediately after being pulled out. If it is unsafe to remove the support, the support can be saved.
⑨Soil moisture should be measured after rain, and if it exceeds the specified value, it cannot be backfilled. If there is water in the tank, it must be drained, and you can fill it back after the requirements are met.
⑩ During the rainy season, the fill soil should be compacted as it is filled to prevent rain before compaction. The filling height cannot be higher than the manhole.
4. Design Summary
①After manual cleaning, the bottom layer of the pipe ditch should be the original soil or compacted backfill. The bottom of the ditch should be level and the slope should be even.
②If the bottom of the ditch is made of rocks, hard-to-remove blocks or layers of gravel, the bottom of the ditch should be excavated 100-200mm deep, covered with fine sand or fine-grained soil with a particle size of no more than 5mm, and compacted to the level of the bottom of the ditch before laying the pipeline .
③Find a local accurate constant reference before measuring. During the measurement process, temporary reference points connected to fixed reference points must be established along the pipeline route.
④The temporary reference point should be set in a stable and secluded place, try to choose a permanent building more than 10m away from the moat. Its accuracy must be at least class III, and the pressure pipeline outside residential buildings must be at least class IV. The closing difference of reference points should not exceed 4 mm/km.
⑤Water and sewer pipes are laid in parallel at different heights, and when the vertical distance is within 500mm, if the diameter of the water pipe is less than or equal to 200mm, the distance between the pipe walls should not be less than 1.5m, when the pipe diameter is more than 200 mm, the distance between the pipe walls must be at least 3 m.