At present, the plastic pipes used in China are still mainly based on upvc pipes, which have historical reasons and scientific reasons. The plastic pipe used in China's water supply network is mainly pvc pipe. The pe tube application is relatively late and relatively small. However, looking at the application experience and development of plastic pipes in the world, the development speed of pe pipes is obviously faster than upvc. The country's macro policy and market environment will stimulate the development of pe pipes and fittings, and the prospects are very broad. It is expected that the amount will gradually exceed the upvc pipe in the next few years. In a certain period of time, pvc pipe has certain market advantages and application advantages. However, the development of the pe tube will eventually catch up, even beyond the pvc tube, which is also the trend of the times.
1. The status and development of pvc and pe pipes
The development of pvc water supply pipeline has entered a mature stage, and the product quality and construction quality are guaranteed, thus ensuring the use of pvc water supply pipeline. In the early 1980s, the state vigorously promoted the application of upvc tubes, and formulated a series of policies, systems, and standards. Today, it has developed a complete product standard, testing method standards and testing methods, construction engineering technical specifications, etc. In order to unify the product's specifications and quality indicators, the product interchangeability is achieved.
In the past ten years, with the development and application of pe pipeline in the European water supply industry, the pe pipeline has begun to receive people's attention. The international standard for water supply pe pipes (ISO4427) was not officially released until 1996. In 1999, China compiled the national standard GB/T13663 with reference to ISO4427, and it was released and implemented in 2000. Since the second half of 2003, the water supply and gas supply pipe network have adopted environmentally-friendly Polyethylene (pe pipe).
2. Comparison of mechanical properties of two pipes
2.1 Material strength comparison at room temperature
The short-term and long-term strength of pvc materials are much higher than that of pe materials.
2.2 Comparison of minimum required strength (MRS) and safety factor (C)
Both theoretical and practical experience show that the MRS and safety factor of pvc are much higher than pe, that is, the strength and safety of long-term use are higher than pe. Therefore, the same 75mm pipe material, pvc material is much thinner than the pipe material produced by pe material. This is because the strength and long-term strength of pe material are not as high as pvc at room temperature, and the strength can only be increased by increasing the wall thickness. If the same wall thickness is taken, the pe tube does not reach the required strength. If the same pipe diameter is taken, the pvc pipe can have a larger water delivery path than the pe pipe. On the other hand, if the same amount of water is to be reached, a larger diameter pe tube is required, and the engineering cost is significantly increased. It shows that the higher strength and rigidity of the pvc material is economical as a water supply pipe.
2.3 Life comparison
Polyvinyl chloride (pvc) is a polar macromolecule that is more stable than monomeric vinyl chloride (pe) and some small molecules and therefore less susceptible to environmental influences. However, the emergence of polymers such as crosslinked vinyl chloride will increase in this respect.
3. Hygienic performance comparison
3.1 pvc and pe are environmentally friendly materials
Both can be recycled and reused, which is a material that saves resources and is environmentally friendly.
3.2 pvc can be as hygienic and non-toxic as pe.
The most prone to misunderstanding of plastic products is the so-called "toxic and non-toxic" problem. Polyvinyl chloride is probably the deepest of these misunderstandings. Scientifically speaking, there is no problem of toxic and non-toxic classification of plastic products, but the problem of ordinary plastics and food hygiene plastics. In fact, most plastics are non-toxic, they can be used to make food packaging, medical supplies, and even to make certain bones and organs in the human body.
Polyvinyl chloride products are available in both general and food grades. Food hygiene grade pvc products have strict requirements on the content of heavy metals in additives and vinyl chloride monomer (vcm) in pvc. However, this does not mean that ordinary grade pvc products are toxic, but not suitable for use in food hygiene. In general, processing pe materials with less additives is considered to be hygienic and non-toxic.
4. Construction technical difficulty and cost
The use data for many years shows that the entire construction cost of upvc is 8% to 10% of the main material. Compared with pe pipe, the construction cost is roughly the same. Due to the complicated installation of the pe pipe, the installation site must have a construction power source to melt the joint, the technical requirements are high, and the quality requirements of the melted joint are high, and it is easy to cause water leakage or joint bursting due to improper operation. The pvc pipe joint is easy to install, no power supply is needed at the installation site, the installation method is simple, and it can be installed without special training, and there is little leakage or joint burst.
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