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Construction management of plastic pipe

Expansion and contraction of plastic pipe

Both ends of the modified UPVC drainage pipe are plugs, and the pipe fittings are sockets. Most of them are connected by socket bonding method, which is an immutable permanent connection. The linear expansion coefficient of plastic products is large, and the expansion length of the pipe is caused by the change of ambient temperature and sewage temperature


UPVC problem

(1) The layout of drainage outlet pipe has a great impact on the design flow of the system. A reducing elbow shall be used for the connection between the riser and the discharge pipe. The outlet pipe shall preferably be one size larger than the riser. The outlet pipe shall discharge the sewage outdoors as smoothly as possible without elbow or b-pipe in the middle. Many projects have confirmed that the finer drainage outlet pipe and the increased pipe fittings on the outlet pipe will adversely change the pressure distribution in the pipe, reduce the allowable flow value, and it is easy to cause poor drainage of the toilet in the process of later use.

(2) UPVC spiral pipe drainage system in order to ensure the spiral drop of spiral pipe water flow and reduce drainage noise, the riser cannot be connected with other risers, so an independent single riser drainage system must be adopted, which is also one of the characteristics of UPVC spiral pipe. Avoid by all means adding superfluous details, copy the drainage system of cast iron pipes, and add exhaust pipes in high-rise buildings. If exhaust pipes are added, it will not only waste materials, but also destroy the drainage characteristics of spiral pipes.

(3) The special tee or four-way pipe fittings for side water inlet used together with the spiral pipe belong to the nut extrusion rubber ring sealing sliding joint. Generally, the allowable expansion and sliding distance is within the temperature difference range in the conventional construction and use stage. According to the UPVC pipeline expansion system, the allowable pipe length is 4m, that is to say, whether it is a riser or a horizontal branch pipe, as long as the pipe section is within 4m, Do not set another expansion joint.

(4) Connection of pipes. UPVC spiral pipe adopts nut extrusion rubber ring sealing joint. This kind of joint is a kind of sliding joint, which can play the role of expansion and contraction. Therefore, the appropriate reserved gap after the pipe is inserted should be considered according to the regulations. Avoid that the reserved gap is too large or too small due to the convenience of individual operators during construction, and the pipeline deformation will cause leakage with the change of seasonal temperature in the future. The prevention method is to determine the reserved gap value according to the construction temperature at that time. During the construction of each joint, the insertion mark shall be made on the insertion pipe first, and the insertion mark can be reached during operation.

(5) In the design of some high-rise buildings, in order to strengthen the water impact resistance of the bottom of the riser of the spiral pipe drainage system, the flexible drainage cast iron pipe is used for the steering elbow and discharge pipe. During construction, the outer wall of the plastic pipe inserted into the socket of cast iron pipe shall be roughened to increase the friction and fastening force with the caulking filler.

(6) Due to the influence of indoor and outdoor temperature difference and storm attack, expansion cracks often occur at the junction between the vent pipe circumference and the roof waterproof layer or thermal insulation layer, resulting in roof leakage. The prevention method is to make a water blocking ring 150mm-200mm higher than the top layer around the roof vent pipe.

(7) There are two common problems in the construction of buried discharge pipe: one is that the pipeline laying below the indoor floor is not carried out after the backfill is compacted. After the backfill is compacted, although the water filling test is qualified before compaction, the pipeline interface is cracked, deformed and leaked after use: the other is that the left, right and upper parts of the concealed pipeline are not covered with sand, resulting in sharp hard objects or stones directly touching the outer wall of the pipe, resulting in damage, deformation or leakage of the pipe wall.

(8) The installation of indoor exposed UPVC spiral pipe should be carried out continuously after the completion of civil wall painting. In fact, due to the construction period, most of them are carried out simultaneously with the decoration after the completion of the main structure. This will cause the smooth and beautiful surface to be polluted. The best solution is to wrap it with plastic cloth in time with the installation of UPVC spiral pipe and remove it after completion. In addition, it is necessary to strengthen the finished product protection of UPVC spiral pipeline during construction. It is strictly prohibited to climb on the pipeline, fasten safety rope, erect scaffold board, use it as support or borrow it for other purposes.

The top elevation of the floor drain shall be 5 ~ 10mm lower than the ground, and the water seal depth of the floor drain shall not be less than 50mm The purpose is to prevent the harmful gas in the sewage pipe from entering the room and polluting the indoor environmental sanitation after the water seal is damaged. However, it is rarely mentioned in the description of water supply and drainage design that in order to reduce the cost, the construction unit and construction unit use the floor drain with low price in the market. This floor drain seal is generally no more than 3cm, which can not meet the requirements of water seal depth. In addition, when residents decorate their houses, they choose the stainless steel floor drain in the decoration market to replace the original plastic floor drain. Although the appearance is bright and beautiful, the internal water seal is also very shallow. When draining, the water seal of the floor drain is damaged due to positive pressure (lower floor) or negative pressure (higher floor), and the odor enters the room. Many residents reported that there was a bad smell at home, and the kitchen range hood was more serious when it was turned on, which was the reason why the water seal was damaged due to pressure fluctuation. Some residential kitchens are equipped with floor drains. Because there is no water replenishment for a long time, especially in winter, the water seal is easy to dry up, so the floor drains should be replenished frequently. It is recommended to adopt high water seal or new anti overflow floor drain during design and construction. There is less water splashing on the interior of the kitchen, so floor drain can not be set.

Post time: Mar-16-2022