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Is the tube suitable for outdoor exposure?
Oct 06, 2018

Usually there are two types of pipes for household, water supply pipes and drainage pipes. Both types of pipe have the possibility of being exposed to the outside, and account for outdoor installations of drainage pipe may be more than water pipes. If the pipes are installed outdoors, there are two main problems, namely, high temperature (insolation) and low temperature (snowy). Based on the material of prevailing pipe, there is no doubt that both weather conditions will reduce the service life of the pipe.


Next we will discuss separately what impact the pipe will have when it is installed outside and how the customer prevent it. First of all, water supply pipe. Water supply pipe is mainly divided into three categories: no.1 metal pipes: the earliest be used is galvanized pipe: galvanized pipe is to improve the corrosion resistance of steel pipes, undertake galvanization to general steel pipe. However, after a few years of use, a large number of rust and dirt are produced in the pipe. The yellow water that flows out not only pollutes the sanitary ware, but also contains non-smooth bacteria that grow on the inner wall. Corrosion results in excessive heavy metal content in the water, which seriously endangers human health.(the country has put a ban on drinking water pipes)


No.2 is copper pipe: it has the advantages of corrosion-resistance and bacteriostasis, is the first-class products in the water pipe, and anti-thermal expansion and cold shrinkage. There are two ways to connect the copper pipe, one is connecting by clamp sleeve and one is welding. The clamp sleeve has the problem of aging and leaking water for a long time. Welding is easy to rust and directly reduces the service life of the pipeline too. Another drawback is the high price of copper pipes, which are rarely used in water supply system. Moreover, the construction cost of welding is higher than other pipe installation, few home decoration uses welded copper pipe.


No.3 is stainless steel pipe. It is a kind of pipe that is very expensive. Its performance is similar to copper pipes. Because the construction technology requirements are relatively high, especially the strength of its material, it is very difficult to process on site. So, the probability that is chosen in decorating a project is low.

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Generally speaking, metal pipe (except galvanized pipe) has good performance, and it is also ok to use outdoors, without thermal expansion and cold contraction. However, two points should be noted. For the pipe installed outdoors, water should not be left in the pipe for a long time in snowy winter. Volume of ice water will become larger and pipes will burst. Also metal pipes will become brittle at low temperatures because of the decline of material strength. The use of metal pipes is also subject to price considerations.


Secondly, composite pipe: aluminum-ppr composite pipe is quite popular on the market. It is light weight, durable and convenient to install. Because of its flexibility it is more suitable for household use. The main drawback is that when used as a hot water pipe, long-term thermal expansion and contraction may cause dislocation of the clamp connection, resulting in leakage. Therefore, it is not recommended to install the composite pipe outdoors.


Thirdly, PPR pipe: PPR pipe in working temperature 70 , under the condition of working pressure (P.N) 1.0 MPa, service life can reach more than 50 years (the pipe must be S3.2 series or above); if pipe work in the room temperature (20 ) service life can reach more than 100 years. Non-polar materials, which have no chemical effect on all ions in water and chemical substances in buildings, will not rust or corrode.At the same time, the smooth inner surface can avoid the formation of scale.



However, the PP-R pipe has a certain degree of low temperature brittleness below 5, winter construction should be careful. Do not press and hit the installed pipe, and covered with protective objects to prevent from external forces if necessary. In addition, PP-R tube is easily aging and degradating after long-term exposure to ultraviolet radiation. If it is installed outdoors or in direct sunlight, ark protective layer must be wrapped. The linear expansion coefficient of PP-R pipe is large (0.15mm/m ). It is necessary to take technical measures to prevent the expansion and deformation of the pipe when the pipe is installed in non-buried way.


Therefore, PPR is currently the most cost-effective water supply pipe, safe, hygienic and easy to install. However, indoor installation or burial is more recommended. If the pipe is used outside, be sure to pay attention to insolation in summer and snowy in winter to extend the service life of the pipe.


The last is drainage pipe: the drainage pipe is mainly PVC pipe: pvc-u pipe has excellent acid resistance, alkali resistance and corrosion resistance, which is not affected by moisture and soil acidity, and no corrosion treatment is required when installing the pipe. The PVC-U tube is not a nutrient source, so it will not be eroded by rodents. According to the tests conducted by National Health Foundation in Michigan, mice do not bite PVC-U pipes.

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However, aging cause by insolation and cold contraction caused by low temperature will affect PVC tube the most Outdoor PVC pipes can be wrapped with aluminum foil tape that is the same as the protective layer wrapped on the pipes of solar water heaters,to extend their service life. In addition, the expansion capacity of pvc-u drainage pipeline is greater, and the amount of expansion generated by temperature change is greater. Expansion joints are required for each vertical pipe and longer horizontal pipe. The installation of expansion joint should be reserved for expansion, 5-10 centimeters in summer and 15-20 centimeters in winter. If it is installed outside, customers should pay attention to drain all the water within the interlayer of drainage pipe to avoid the formation of ice block and break the interlayer during winter.


Therefore, the working temperature of PVC pipe is generally 0 - 70 , and the ideal temperature is 5 - 60 . During the installtion of PVC pipes, they should be buried in the ground as far as possible, or the piping should be installed indoors, and avoid heat sources. If they need to be installed outdoors, insulation materials (such as asbestos, glass fiber, foam, etc.) should be used to keep them warm and prevent them from freezing and cracking in winter.

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