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Precautions for construction and installation of PE water supply pipe
1. pipe groove excavation 1. The pipe groove excavation should be straight line, and the groove bottom excavation width is DN 0.30m. When the pipeline is connected underground, the width of the groove bottom at the interface shall be appropriately increased, and the width of the groove bottom of the pipeline shall not be less than DN 0.50m to facilitate the installation and docking. 2. When the pipeline is buried, the minimum pipe top covering depth shall meet the following requirements: ① When buried under the roadway, it shall not be less than 0.80m. When buried under the sidewalk, it should not be less than 0.60m. 3. When the design depth is not reached across the carriageway, steel casing shall be laid for protection. 4. When the pipe groove must be turned, the turning angle should not be used.
Excavation of 1. pipe groove
1.Straight line is appropriate for pipe trench excavation, and the width of trench bottom excavation isDN 0.30m. When the pipeline is connected underground, the width of the groove bottom at the interface should be appropriately increased, and the width of the groove bottom of the pipeline should not be lessDN 0.50m, in order to facilitate the installation of docking is appropriate.
2.When the pipeline is buried, the minimum pipe top covering depth shall meet the following requirements:
① When buried under the roadway, it shall not be less0.80m.
② When buried under the sidewalk, it should not be less0.60m。
3.When the design depth is not reached across the driveway, steel casing shall be laid for protection.
4.When the pipe groove must be turned, the turning angle should not be too large, and the bending radius should meet the following requirements:
PEPiping Allowable bending radiusR（mm）
D≤50 30D;50D≤160 50D;160D≤250 75D;D>250 100D.
5.When the pipe trench is excavated manually, the bottom of the trench shall be flat and dense without sharp objects. The trench bottom may have undulation, but the pipe must be smoothly supported. If there is over excavation, it must be backfilled and compacted.
2. pipe connection
PEThe water supply pipeline is connected with hot melt connection and electric fusion connection. HeatThe fusion connection is divided into the fusion socket connection and the fusion butt connection, and the fusion connection is divided into the fusion socket connection and the fusion saddle connection. We use the hot melt butt connection mode of construction, its main steps are:
1.Material preparation: Place the pipe or fitting in a flat position,Put it on the docking machine, stay enough10-20mmof the cutting allowance.
2.Clamping: according to the welding pipe, pipe fittings to select the appropriate slip fixture, clamping pipe, ready for cutting.
3.Cutting: cutting the welded pipe section, pipe end surface impurities and oxide layer to ensure that the two butt end surfaces are smooth, smooth and free of impurities.
4.Center: the end faces of the two welded pipe sections shall be completely aligned. The smaller the wrong side, the better. The wrong side shall not exceed the wall thickness.10%. Otherwise, the docking quality will be affected.
5.Heating: the docking temperature is generally210-230between ℃ is appropriateThe heating time of the heating plate is different in winter and summer, with the melting length of both ends1-2mmFor the best.
6.Switching: remove the heating plate and quickly stick and pressurize the two hot melting end faces. In order to ensure the quality of melting butt joint, the shorter the switching period, the better.
7.Melting butt joint: is the key to welding, the butt joint process should always be carried out under melting pressure, the width of the hemming is2-4mmis appropriate.
8.Cooling: Keep the docking pressure unchanged and let the interface cool slowly. The cooling time shall be subject to the hardness of the curling edge by hand and no heat.
9.Docking is completed: after cooling, loosen the slips, remove the docking machine, and prepare for the next interface connection again.
3. installation construction
1.Before installation, check whether the pipe groove meets the installation requirements, and then check the appearance of the pipe for obvious dents, cracks, scratches, and scratches, and replace it in time if quality hazards are found.
2.Used in pipe elbows, tees, tapered joints, fire hydrants, etc.C20The concrete is provided with concrete abutments, and the flange valve is reinforced with brick abutments.
3.PEWhen water supply pipe is connected with metal pipe, valve and fire hydrant, steel plastic transition joint or special flange connection must be adopted.
4.An exhaust valve shall be set at the elevated part or uphill section of the pipeline to reduce the impact of gas and water mixed pressure on the pipeline. The ratio of the pipe to the exhaust valve is designed1:8.
5.DuePEThe pipe itself has good flexibility and scalability, and the installation of expansion joints is not considered in all pipe installations.
4. backfill compaction
After the installation and laying of the pipeline is completed, it shall be backfilled immediately after the acceptance of the concealed works.The following provisions shall be met:
1.Prevent the water in the tank from causing the pipeline to float. If there is water, try to drain it.
2.When backfilling the pipe groove in the stonework and earth-rock mixed section, the clay or sand shall be shipped to the top of the pipe first.200-300mmOther miscellaneous soil shall be backfilled after compaction.
3.Backfilling must be backfilled from both sides of the pipe at the same time, backfilling layer by layer.
4.Before pipeline pressure test, backfill soil should not be less500mm.
5.Large-area backfilling after pipeline pressure test should be carried out when the pipeline is filled with water, and the pipeline should not be left empty for a long time after laying.
PEWater supply pipe because of its corrosion resistance,Non-toxic,Smooth inner wall resistance is small,Anti-aging long service life(50Year),Light weight,Installation of labor intensity bottom,Less construction cost,Strong seismic performance,Material flexibility and other characteristics. In recent years,Hami city water company actively promote the use of new environmental protection pipe,Run by pressure test,Excellent effect,There has not been a single water safety incident. The key is to do a good job of installation and construction,Good quality off.
PEThe water supply pipeline is connected with hot melt connection, and we adopt hot melt butt connection.12) Material preparation2) Clamping32) Cutting4) Ax52) Heating62) Switching72) Fusion Butt82) Cooling9) Docking is completed.
Before installation, check whether the pipe groove meets the installation requirements. Then check the appearance of the pipe for obvious dents, cracks, scratches, scratches, and timely replacement of hidden quality hazards. Used in pipe elbows, tees, tapered joints, fire hydrants, etc.C20Concrete buttresses are provided with mixed concrete, and flange valves are reinforced with brick buttresses,PEWhen the water supply pipe is connected with metal pipes, valves and fire hydrants, steel-plastic transition joints or special flange joints must be used. Exhaust valve shall be set at the uplift of the pipeline or on the uphill land to reduce the impact of the mixed pressure of gas and water on the pipeline.
After the installation and laying of the pipeline is completed, it shall be backfilled immediately after the acceptance of the concealed works. Backfilling must be backfilled from both sides of the pipeline at the same time, backfilling layer by layer. Before the pipeline pressure test, backfilling should not be less500MMThe large area backfilling after the pipeline pressure test should be carried out when the pipeline is full of water, and the pipeline should not be in an empty pipe state for a long time after laying.
At present, plastic water supply pipes are: hard polyvinyl chloride(pvc-u)High density polyethylene(hdpe)Crosslinked polyethylene(pe-x)Polybutene(pb )Acrylonitrilebutadiene styrene(abs)Chlorinated polyvinyl chloride(pvc-c)Aluminum-plastic composite pipe(On-al-on),Pe-x-al-pe-x)Modified polypropylene(pp-r,Pp-c). Plastic water supply pipe has the advantages of light weight, convenient construction, smooth pipe, good hydraulic conditions, no scaling, no corrosion, and long service life. However, plastic water supply pipes have the disadvantages of brittleness, impact resistance and low mechanical damage resistance. With the high-grade residence, pipe laying is mostly concealed under the ground, and the wall trough is easily damaged by concealed operations, decoration construction, ground cleaning and other work. Therefore, it is difficult to complete the water tightness test of plastic water supply pipes at one time, and the water tightness test of pipes is an effective method to prevent water leakage of pipes. On the basis of lessons learned, the author summarizes the water supply pipeline in accordance with the progress of the project and the construction of the decoration project, effectively preventing the water supply pipeline damage caused by the installation, civil decoration and the protection of the finished product, and ensuring the construction quality.
2Method for tightness test of plastic water supply pipe
2.1Water pressure test before concealment of inlet pipeline
The water supply from the water pipe well to the kitchen and toilet is installed, and the plastic water supply pipe is bonded.24 hAfter that, the hydrostatic test can be carried out. Its purpose is to check the tightness of pipe fittings and pipes, whether they are damaged during processing, transportation, storage and installation, and whether the pipes are blocked. The test pressure shall be tested according to the pressure test regulations of the pipe network, and can be concealed after being qualified. In this test, the openings at each end are plugged with pipe caps, and all water distribution appliances and water meters are not installed. In order to correctly identify the real location of the concealed pipeline, the location of the pipeline should be marked with red paint on the ground and wall to prevent damage to the pipeline during civil and other types of construction. The mortar covered by the concealed pipeline shall not be higher than the ground, so as not to damage the pipeline when cleaning the floor.
2.2Re-inspection of water tightness of pipeline before construction of decoration works
Before the construction of the decoration project is about to begin, a stratified water tightness re-inspection shall be carried out again for the incoming pipeline. Its purpose is to check the pipeline before the construction of the decoration project ground and wall cleaning leveling and other types of construction damage to the pipeline. If any damage or leakage is found, repair it in time to avoid hidden dangers and unnecessary losses. Use during re-inspection0.6 mpaAs the test pressure, the pressure in the pipe will be reduced to the working pressure after this test, so that the pipe will be in the state of water and pressure retention. The pressure gauge will not be removed until the decoration is completed.,Its purpose is to facilitate regular observation of pressure changes, to determine whether the pipeline is damaged during the renovation period. If leakage is found, timely maintenance shall be carried out to prevent rework after the decoration is completed, which will damage the decoration and affect the quality of the project. For the decorated room, after confirming that the pipeline is not damaged, the water in the household pipe can be drained and handed over to the civil engineering for decoration work.
2.3Water tightness test of sub-system
The pipeline has passed two water tightness tests of household and stratification, and the pipeline interface and pipeline damage caused by various factors are strictly inspected. The quality hidden danger is basically eliminated. However, in order to ensure that the hidden pipeline is free from damage and leakage, the water tightness test of each layer within the scope of the water supply system is carried out. This test is carried out after the decoration of the ground, wall and wall of all users is completed. The test pressure is working pressure, with water and pressure.1～2 h. Comprehensively check and observe the changes of the pressure gauge. If the pressure reduction of the pressure gauge does not meet the requirements of the specification, and no leakage position is found, the stratified and household test method can be adopted until it is qualified.
2.4Water tightness test of water supply riser
The water supply riser refers to the water delivery pipe from the water pump to the roof pool, and the water delivery pipe from the water pump to the control valve of each layer. The water tightness pressure test shall be carried out separately according to the different working pressure of the water delivery, and the test pressure and requirements shall be implemented according to the regulations.
2.5Full system water passing test and system flushing
After all the above tests are qualified, the water supply equipment has the water supply conditions, the pressure reducing device has been adjusted to the specified value, the water distribution device at the end of each user has been installed, and the indoor and outdoor drainage systems and facilities have the conditions of use, the whole system can be tested. The purpose is to check whether the water supply capacity and water pressure of the water supply system meet the design and specification requirements, and also check the tightness of the water distributor interface, flush the viscera of the pipe, and open the water distribution tap one by one. After the water is normal, open each layer.1/3Water distribution point, check the water pressure and water volume, this work can be carried out in layers until all tests are completed.
3Precautions for Hydraulic Test of Plastic Water Supply Pipeline
(1)The test pressure value refers to the pressure at the lowest point at the end of the pipe. But if the pressure at the highest point of pressure exceeds1.0 mpaThe pipeline shall be subjected to sectional pressure test.
(2)For pipes with bonding, the hydraulic test must be completed after the bonding installation.24 hAfter the curing time is not enough to prevent the interface from disengaging.
(3)Slowly inject water into the pressure test pipe section, discharge the air in the pipe at the same time, and gradually block each water distribution point.
(4)For suchpe-xFor flexible pipes such as pipes, too fast and too high pressure will cause slight expansion, resulting in errors in hydraulic test. Therefore, the hand pressure pump shall be used to slowly boost the pressure, and the boost time shall not be less10 minVoltage stabilization1 hIn order to eliminate the interference of pipeline expansion on the pressure test results.
(5)Voltage stabilization1 hAfter there is no leakage, make up the pressure to the specified pressure test value,15 minThe pressure drop within0.05 mpais qualified.