Advantages and disadvantages of drainage pipe in engineering use and improvement measures?

Advantages and disadvantages of drainage pipe in engineering use and improvement measures? The following Zhong Da consults the bidding teacher to answer your questions for your reference.

1.UPVC drainage pipe has incomparable advantages over cast iron drainage pipe in engineering use.

1. 1. Excellent physical and chemical properties.

UPVC pipe is a thermoplastic product, which is heated by PVC to a molten state (150 ~ 200℃) and contains about 56% chlorine (Cl), so it has a high oxygen index and is a flame retardant material with stable chemical properties. Its unique mechanical and physical properties enable it to be used normally for 50 years. At the same time, its corrosion resistance, aging resistance and wear resistance are also better than that of drainage cast iron pipe.

1.2. Good drainage performance

According to the theory of gravity around the water film, when the flow area of the drainage water film does not exceed 1/3~ 1/4 of the cross-sectional area of the riser, the maximum drainage capacity of the plastic riser is 60% higher than that of the cast iron pipe, and the water seal will not be destroyed. Therefore, for the same equivalent displacement, the diameter of the drainage pipe can be smaller than that of the cast iron pipe, or the same diameter can be used as far as possible within the scope permitted by the code.

1.3. The pipeline is light and convenient for construction.

For a long time, the drainage cast iron pipe has a large proportion, and it needs to be pitted, mixed with interface materials, stranded and maintained during installation, which not only has a large workload, but also takes a long time to install, which obviously reduces the construction benefit. The specific gravity of UPVC pipe is about 1.4t/m3, which is only 1/5 of that of cast iron pipe. Plastic pipes with the same length are much lighter than cast iron pipes, and only manual handling is needed for installation. Moreover, UPVC drainage pipe adopts socket-type adhesive joints, and its standard length (6m and 4m) is longer than that of cast iron pipe, which reduces the number of joints and installation procedures. For example, a plastic pipe with a standard length of 6m DN 1 10 can be installed by only one person, while the cast iron pipe needs 2~3 people, so that the installation time of the project can be reduced by more than 60% and the installation cost can be reduced by more than 50%. For the construction unit, it can save expenses, reduce costs, shorten the project cycle and improve the economy of the building.

1.4. Economical and beautiful.

According to the current market situation, the price of UPVC drainage pipe is only about 80% of that of cast iron drainage pipe, which means that the cost per thousand square meters of construction area is lower than that of the same cast iron drainage pipe by about 700 yuan. In addition, due to the light weight of UPVC pipe, its transportation cost is also obviously reduced.

The outer wall of UPVC drainage pipe is usually white, so there is no need to apply red lead and silver powder for anti-corrosion treatment, so there are no problems such as corrosion and peeling of the outer wall of cast iron pipe, and it is hidden in the tube well and does not need frequent maintenance. The advantages of surface-mounted pipes are more obvious than cast iron pipes: easy to clean, less harmful to visual effects, greatly improving people's living and working environment, and convenient for building property management.

1.5. Good social benefits

In today's increasingly short supply of steel in China, UPVC drainage pipes can replace other steel drainage pipes on a large scale, and greatly reduce the energy consumption in the steelmaking process and reduce the environmental pollution caused by this process. Has good social benefits.

Secondly, although UPVC drainage pipe has many advantages mentioned above, it is a new material and has its own inevitable shortcomings in popularization and application. This paper expounds the problems existing in UPVC drainage pipes and fittings from two aspects: defects and improvement measures.

2. 1. 1. The drainage noise is high.

Because the inner wall of UPVC drainage pipe is smooth, the water flow is not easy to form a water film to flow along the pipe wall, and it will hit the pipe wall in a chaotic state in the pipeline; Moreover, the wall of UPVC drainage pipe is thinner than that of cast iron pipe of the same specification, for example, DN 1 10 The former is 4.0mm and the latter is 5.5 mm.. In this way, UPVC tube can not effectively prevent the spread of noise, and bring "restless" factors to users' lives.

At present, the UPVC spiral muffler pipes produced by many domestic manufacturers have regularly arranged spiral ribs on the inner wall, which increases the resistance of the pipe to water flow, makes the water flow forced to flow along the pipe wall in the form of water film, and reduces the impact on the pipe wall. According to the noise test results of Cangzhou Dongfeng Plastic Company by Institute of Acoustics of Tongji University, the noise power of UPVC spiral muffler drain pipe is only 50% of that of ordinary UPVC drain pipe. At the same time, according to the test of the water flow capacity of the product by the School of Environmental Engineering, due to the special structure of the spiral pipe, the water flow speed is reduced, the resistance coefficient of the water tongue is reduced, the air core in the riser is kept moving up and down, the pressure fluctuation in the riser is stabilized, and the most common negative pressure suction and positive pressure splash in the drainage riser are effectively reduced.

It should be noted that the spiral muffler pipe can only be used on the vertical pipe, but not on the horizontal pipe, otherwise the pipeline will be blocked easily because of the accumulation of impurities in sewage in the horizontal pipe.

2. 1.2. The bearing capacity is weak.

The bearing capacity of UPVC drainage pipe is far less than that of cast iron drainage pipe. The bearing capacity of UPVC drainage pipe with ordinary wall is less than 0.4MPa, and the bearing capacity of its matching expansion joint is even lower. Therefore, UPVC drainage pipes should not be used for horizontal main pipes of high-rise drainage or rainwater drainage pipes of high-rise buildings. Once the horizontal trunk line is blocked, it may bring greater losses to users. UPVC water supply pipe with strong bearing capacity can be used instead, because the axial stress of the pipeline caused by temperature effect can be relieved by the displacement between the pipeline and the rubber ring, without adding expansion joints, and the probability of water leakage is also reduced.

2. 1.3. Fire protection of buildings

At present, there is a general tendency to unilaterally pursue the improvement of oxygen index and ignore the research on smoke performance in the research of PVC plastic flame retardant technology in China. Statistics show that 79% of fires are caused by smoke. The oxygen index of some UPVC tubes is as high as 50% or more, but a lot of smoke is released when burning, and the Vicat temperature is only between 70℃ and 90℃. Therefore, UPVC pipe is difficult to burn, but it is easy to deform and has a strong smoke smell. In a fire, on the one hand, deadly smoke is produced; On the other hand, when the temperature exceeds 90℃, the pipeline softens and deforms, and the fire spreads at the intersection of the pipelines, while the wind speed of the drainage pipe or ventilation pipe passing through the roof is higher, so the fire spreads faster. Therefore, in the Code for Design and Construction of Rigid PVC Drainage Pipes for Buildings (CJJ29- 1998), the requirements of taking fire prevention measures for high-rise buildings are put forward, and designers must pay enough attention to this in engineering design. However, when some engineering pipelines cross the floor or tube well, there is still no requirement to set fire rings or fire sleeves. In this case, the construction technicians should deal with the design change negotiation in time, and don't stick to the word "specification". As construction units, they should be aware of the importance of taking fire prevention measures, so there is no need to save those few dollars for the benefit of end users.

2. 1.4. Temperature effect

UPVC pipe has poor heat resistance, and its tensile strength decreases above 60℃ (suitable for domestic sewage with continuous discharge temperature not exceeding 40℃ and instantaneous discharge temperature not exceeding 80℃). Therefore, it is necessary to stay away from heat sources in design and use, such as more than 400mm from the kitchen edge and more than 200mm from the hot water pipeline. At the same time, thermal insulation measures should be taken for hot water pipes, and they should not cross the flue and firewall.

The impact strength of rigid PVC plastic drainage pipe decreases at low temperature. Therefore, in the conversion layer of air conditioning equipment, cast iron pipes can be considered to replace hard PVC drainage pipes to ensure drainage safety.

Due to the great influence of temperature and large expansion coefficient, each layer of riser and longer horizontal pipe need to be equipped with expansion joints. Therefore, the notch effect of UPVC pipe should be considered when arranging other majors. When laying parallel to other pipes, plastic pipes should be pulled aside, and when laying crosswise, plastic pipes should be staggered, and metal casing protection should be considered. In addition, the riser crossing the floor and roof should be used as a fixed support point, and a flexible sheath should be installed.

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