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    Manage technical guidance documents for construction organization

    2019-12-28 16:18:22

      1、 Inspection of pipes and fittings

      After the pipe enters the construction site, first check whether the pipe size error exceeds the standard.Whether the pipe wall thickness is uniform and deformed.Whether the socket is cracked.Whether the pipe contains impurities.Whether the chamfering of socket end meets the standard.Whether the socket is inserted with depth marking.Whether the specifications, materials and standards of pipe fittings and pipes are consistent, etc.If there is any sign of damage, deformation, deterioration or storage beyond the specified time limit, timely conduct sampling identification.

      . on site inspection of pipes (1) the inner and outer walls of the appearance pipes shall be smooth and clean without scratches and other defects. Bubbles, cracks and obvious depressions, impurities, uneven colors, decomposition discoloration lines, etc. are not allowed.Pipe ends shall be cut flat and perpendicular to the axis of the pipe.(2) the working surface of the pipe and the socket must be flat and accurate in size, so as to ensure easy insertion during installation and the sealing performance of the interface.(3) the wall thickness deviation of the same section of the pipe shall not exceed.

      (4) the bending degree of the pipe is no more than.

      . field inspection of pipe fittings (1) the wall thickness of pipe fittings shall not be less than that of pipes of the same specification.(2) the appearance surface must be smooth without cracks, bubbles, peeling, severe cold spots, obvious impurities, uneven color decomposition and discoloration.2、 Transportation and stacking of pipes and fittings (1) pipes and fittings shall be handled with care during transportation, loading, unloading and stacking. Throwing or violent collision is strictly prohibited.(2) the pipes shall be protected from the sun, and shall be covered for short-term stacking. If the storage period is long, they shall be placed indoors or in a sunscreen shed warehouse to prevent deformation and aging, strength and toughness from decreasing.(3) when stacking pipes and accessories, they shall be laid flat and cushioned, and the stacking height shall not exceed.For spigot and socket pipes and fittings, the sockets of adjacent two layers of pipes shall be inverted and let out of the socket to avoid concentrated load on the socket.(4) during transportation and stacking of pipes, the form of large pipe sleeve and small pipe can be used, but the pipe sleeve must be in a free state to avoid the internal and external pipes being in the state of excessive extrusion.(5) pipes shall be stacked in order to avoid disorder and permanent deformation caused by extrusion.

      (6) pipes of different specifications shall be stacked separately to avoid pipe burst due to size mismatch or wrong use of pipes.(7) it is strictly prohibited to drag the pipe at the construction site to prevent the pipe body, especially the sealing contact part at the end of the spigot from scratching, resulting in water leakage at the joint. 3. The pipe installation shall be carried out after the excavation section of the pipe installation trench is completed and accepted.Before installation, the pipe diameter of socket and spigot shall be measured, numbered and recorded, and the tolerance shall be matched, so as to facilitate the insertion and ensure the tightness of the interface.The pipe installation procedure is: pipe laying → working face cleaning → trial insertion → adhesive connection → maintenance

      Lower tube

      When the pipe is put into the trench, reliable soft belt sling shall be used to run the pipe into the trench stably and avoid severe collision with the trench wall or bottom.

      , adhesive connection

      The adhesive connection procedure is:

      Preparation → cleaning working face → trial insertion → brushing adhesive → bonding → maintenance.

      Preparation

      Check the quality of pipes and fittings, and prepare construction tools.

      (2) clean the working face

      Wipe the inside of the socket and the outside of the socket with cotton yarn or dry cloth.

      3. Trial insertion

      Before bonding, test insert the two pipes once, and mark the depth of inserting socket on the surface of inserting end.

      (4) application of adhesive

      When brushing the adhesive on the joint surface outside the socket and inside the socket rapidly with a brush, the socket shall be coated first, then the socket, and the axial brushing shall be even and appropriate.

      Bonding

      After the socket is coated with adhesive, immediately align the direction, insert the pipe end into the socket, press hard to make the depth of the pipe end inserted to the marked line, and ensure the straightness and position of the socket interface are correct.

      Curing

      After the socket joint is connected, the extruded adhesive shall be wiped clean in time.After bonding, it is not allowed to force load the joint immediately, and it is required to stand and solidify.

      4、 Pipeline pressure test and acceptance

      . pressure test section

      The length of the pressure test section of the water supply pipeline depends on the specific situation.For pipes without joint connection, the length of pressure test pipe should not be greater than.For pipes with joints, the length of pressure test section should not be greater than.

      . pipeline water filling

      The pipeline shall be filled slowly and the air in the pipeline shall be discharged at the same time.After the pipeline is full of water, it shall be kept at least without pressure.

      . pressure test method

      The water pressure test of HDPE water supply pipeline includes two parts: tightness test and strength test.

      (1) tightness test

      After the pipe is filled with water, add the water pressure in the pipe, keep it, and check whether there is leakage or other abnormal phenomenon in each part.During the test, water can be supplied to the pipe to maintain the pressure in the pipe.If there is no leakage in the tight test, it is qualified.

      (2) strength test

      After the tightness test is qualified, carry out the strength test. The test pressure in the pipe is times of the design working pressure, but not less than, maintain the test pressure. When the pressure drops, make up water to the pipe, and record the total value of the water added to maintain the test pressure. If the water leakage does not exceed the allowable water leakage in the specification, it is considered that the test pipe section bears the strength test.

      5、 Pipe trench backfilling

      (1) trench backfilling is generally carried out twice:

      Along with the pipeline laying, the two ribs of the pipeline shall be backfilled with the original soil that meets the requirements. The manual backfilling shall be adopted, and the light tamping shall be carried out in layers until the backfilling reaches at least the place above the pipe top.The pipe joint shall not be backfilled in the front and back range so as to observe the leakage during pressure test.

      (2) large area backfilling after the pipeline pressure test is qualified should be carried out when the pipeline is full of water but without pressure. During backfilling, backfilling should be carried out from both sides of the pipeline at the same time, and the machinery should not be driven on the pipeline.

      (3) the backfill within the pipe top shall be tamped by light tamping, and the backfill from the pipe top to the ground shall be filled in layers to make its compactness meet the requirements.

      6、 Key points of quality control

      . before construction, the quality status, specification and quantity of each material shall be checked and accepted. The product shall conform to the current product standard, have the product qualification certificate issued by the quality inspection department, and the accessories shall be matched with the pipe model.. the horizontal clear distance between the pipeline and other adjacent pipelines shall not be less than the width of slotting required by construction and maintenance and the width required by the setting of gate shaft and other auxiliary structures.The horizontal clear distance between the pipeline and the high-temperature pipeline such as hot water pipe and the toxic gas pipeline such as high-pressure gas pipe shall not be less than.

      . the socket and spigot shall be wiped clean, and the adhesive shall be applied quickly, evenly and appropriately without omission.After applying the adhesive, the pipe shall be inserted into the socket in the right direction and straightened.

      The horizontal distance between the center line of the pipeline and the outer wall (column) skin of the building shall not be less than the following requirements: when the nominal outer diameter is not greater than., when the nominal outer diameter is greater than.The pipeline shall not cross under the building.When crossing is necessary, reliable protective measures such as additional casing shall be taken.

      . when there is no provision in the design, the pipeline shall not be treated with full wrapped concrete or the bearing capacity of the pipeline shall not be increased.The buried depth of the pipe top under the road shall not be less than.Under the sidewalk, when the nominal outer diameter is greater than, it should not be less than.When the nominal outer diameter is not greater than, it should not be less than.In permafrost or seasonal frozen soil layer, the buried depth of pipe top shall be below the freezing line.. in order to avoid twisting and confusion during pipe laying and to ensure smooth and continuous construction, butt joint must be carried out according to the end face of pipe typing during pipe connection.

      The indoor open laying pipeline shall be installed after the finishing of the earth building.The position of reserved holes shall be rechecked before installation.

      . before installation, pipe clamp should be set up as required, with accurate, flat and firm position.Long shall be in close contact with the pipe, but shall not damage the pipe surface.At the connection part of metal pipe fittings and pipe fittings, the pipe length shall be set at one end of the metal pipe fittings and shall be as close to the metal pipe fittings as possible.

      . when the pipeline passes through the floor slab, the casing must be set, and the plastic pipe can be used for the casing.Metal casing must be used when passing through the roof.The casing shall be higher than the ground and the roof shall be no less than mm, and strict waterproof measures shall be taken strictly.

      . the pipeline shall not be subject to axial distortion and forced correction. When it is parallel to the metal pipe, a certain distance shall be reserved, and the clear distance shall not be less than mm.The pipe should be inside the metal pipe.

      When the pipeline crosses the road or highway, reinforced concrete shall be set, and steel pipe shall be used as protective casing. The inner diameter of the casing shall not be less than the outer diameter of the pipe plus mm. When crossing the river, measures such as outsourcing concrete shall be taken.The pipeline shall be laid on the undisturbed soil foundation or the dense stratum backfilled after trenching.The buried depth of pipe top shall not be less than.The bending radius should not be less than times of the outer diameter of the pipe, and the length of the pipe should not be less than.If the pipe diameter is larger than mm, it should not be laid by cold bending.And pour the buttress to fix the pipe arc.


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