Trend analysis of new plastic water supply pipes instead of galvanized steel pipes

  The replacement of galvanized steel pipes with new plastic water supply pipes is also a general trend. Now I will make a simple analysis of the product quality control, quality inspection and its installation. THank you for everyones suggestions.
1. Product quality control
  Because the water supply pipe transports human drinking water or even direct drinking water. Therefore, the quality and stability of its products will directly affect people’s health. This effect may not be immediately apparent but will slowly emerge over time. Therefore, the quality control of the government water supply pipes must be particularly strict. The quality control of the products is one of the product quality control of the manufacturer, and the other is the management control of the sales process. In addition to regular and irregular inspections on the product quality control of manufacturers, the focus should also be regular and irregular inspections on whether the manufacturer’s quality management system is complete. Because for plastic products, the quality of raw materials and the control of the production process have a great impact on product quality. The emphasis on regular and irregular inspections is because China’s market laws and regulations are not yet complete and enterprises have poor self-discipline. If they are not strictly controlled, product quality cannot be guaranteed. The management and control of the sales process is due to the fact that the sales of the products of the manufacturers are mostly carried out by the agents, so the possibility of mixing fake and inferior products in the sales process is not ruled out. The government management department should verify the agent’s information while verifying the product license, so that the product quality can be controlled to the greatest extent.
2. Product quality inspection
  Products are generally divided into composite pipes and plastic pipes. In the inspection items, the composite pipe should have several more physical inspection indicators than pure plastic. Such as the bonding strength of the plastic tube layer and the metal tube layer, and the effect of the different thermal expansion coefficients of the two materials on the bonding strength between the two materials when the high and low temperatures or the temperature inside and outside the tube are different. At present, the country has no clear and targeted inspection standards for these new pipes. Judging from the manufacturer’s data, there are more and less inspection items, and there are several domestic and foreign standards for inspection standards. The government management department should work out the corresponding inspection items and indicators as soon as possible. The inspection items of water supply plastic pipes (including composite pipes) are mainly divided into two categories. The first is physical and chemical index inspection, which mainly inspects the physical and chemical performance indexes of pipes and fittings themselves (composite pipes should add special inspection items, but the current manufacturers basically No). The second is the inspection of sanitary indicators, including the contrast test of soaking water and the toxicology test (including the acute oral toxicity test in mice, the micronucleus test in mouse polychromatic erythrocytes and the Ames test). Generally, manufacturers lack toxicology tests. In view of the large climate difference between North and South China and the design characteristics of modern buildings, items such as UV impact testing, high-temperature water immersion testing, and low-temperature water physical performance testing should be specifically added. In short, the management department should formulate standards as soon as possible to adapt to the development of water supply pipes.
3. Installation of new water supply pipes
  Judging from the actual use of water supply pipes in Shenzhen, there are two distinctive features, one is that there are more open water supply pipes on the outer wall, and the other is that there are more buried pipes indoors. Let’s talk about some views on the issues that should be paid attention to in these two installation methods.
1) When the pipeline is laid on the outer wall, the anti-ultraviolet ability and linear expansion of the pipeline should be considered. Ultraviolet rays have certain damages to plastic materials. Among the existing various plastic pipes (including aluminum-plastic and steel-plastic composite pipes), only PB (polybutene) pipes containing gray pigment have strong UV resistance (see GEORGE FISCHER’s PB pipe technical manual). Other pipes are still There is no test data, but it only indicates that it cannot be exposed to the sun. Shenzhen and Guangdong regions have high sunshine intensity, and users should consult with the manufacturer to consider the issue of UV protection when considering using plastic water supply pipes for external walls. The manufacturer should consider the corresponding protective measures (such as brushing protective paint). Otherwise, it should be stated in the manual that it is not suitable for external wall covering. Linear expansion is mainly harmful to longer pipes, such as 10m pipes with a temperature difference of 5℃: PE and PEX are 10mm, PP-R is 9mm, PB is 6.5mm, and steel is 0.6mm. From a theoretical point of view, this hazard will cause the pipeline to be twisted, the joint seal will be broken, and the aluminum-plastic pipe and steel-plastic pipe will cause the metal layer and the plastic layer to peel off. For pure plastic pipes, an expansion ring can be used to absorb this change in length. For composite pipes, there is no specific research data. From a practical point of view, due to the low thermal conductivity of plastic pipes (more than 100 times lower than steel) and the water in the pipe (especially flowing water) will also weaken the temperature rise due to sunlight, so the actual effect will be less than the theoretical value. In short, this problem must be solved in order to comprehensively promote new plastic water supply pipes in Guangdong.
2) Dark application of pipelines, including dark application of cast-in-situ concrete and dark application of pipe grooves. Because the pipeline burying construction now mostly uses direct concealing instead of casing type concealing-it can be replaced, such as burying the battery through the pipe. Therefore, various influencing factors that may lead to joint leakage, pipe damage, and insecure joint fixation should be considered. In the construction of concealed plastic water supply pipes or composite water supply pipes for cast-in-place concrete floors or walls, the unfavorable factors that may be encountered are: ①The temperature rise changes caused by heat during the concrete solidification process. According to our on-site water temperature measurement results of the water-filled aluminum-plastic pipe buried in the cast-in-situ floor slab, the temperature rise can reach about 5°C. If the pipe is longer, the impact on the pipe body (especially the composite pipe) and the extrusion joint will be greater, and may lead to joint leakage and damage to the composite pipe, affecting the service life. The specific data is yet to be further tested and studied. ② When the concrete is mechanically vibrated, the vibrating force will have a destructive influence on the pipe through the stones. This point has the greatest impact on the aluminum-plastic pipe, because the aluminum metal layer and the plastic layer of the aluminum-plastic pipe are very thin, and the rigidity of aluminum is inherently poor, and the sharp stones may damage it under the action of irregular vibration. . ③The influence of the continuous temperature difference of the hot water pipe on the extrusion joint and the composite pipe. ④In the process of long-term use, the influence of the creep of the plastic pipe itself. The above problems still need to be studied and tested in detail. In the actual construction, we can adopt methods such as reducing or eliminating the direct water diversion of the buried joints, positioning and burying when burying the pipe, avoiding the position of the buried pipe when vibrating, etc. to minimize the impact of various unfavorable factors. . For the slotted (or reserved slot) buried pipe in various walls or floors, attention should be paid to the interface problems of the three-energy, elbow and other fittings of the outlet of each water supply fitting. Because the extrusion joint is not afraid of lateral tension (referring to the connection pipe Direction), and fear of stress in longitudinal or irregular directions. When the joint fittings (tees or elbows) are subjected to irregular torsion during the replacement of water supply fittings (faucets, angle valves and other frequently-changing fittings), if the joint fittings are not firmly fixed, it will damage the extrusion interface and cause water leakage. . At present, only a few manufacturers have their own fixing points on the market. This is a shortcoming and should be improved by each manufacturer. Another thing that should be paid attention to during the construction of buried pipes is the coordination with other types of work. Because the rigidity of the new plastic pipes is not very high, and the quality of the construction personnel is different, it is possible to conceal the concealed construction of the pipe head and the floor pipe groove in the cast-in-situ floor slab, and the pipe groove in the wall (mostly carried out by civil engineering personnel). Man-made sabotage should be solved by strengthening management.

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